No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Lead Removal from Contaminated Water by Corn and Palm Nut Husks
... Thus, use of adsorption method using cheap and readily available agricultural waste materials and biomaterials began to gain traction [9][10][11]. Some of these agricultural wastes and biomaterials include SP (Spinach), coffee, tea [12], corn and palm husks [13], walnut, almond, and hazelnut, and pistachio shells [14] and other agricultural and industrial wastes [15,16]. ...
... Furthermore, agricultural wastes like banana peels (Annadurai et al 2003) have been employed successfully to remove heavy metals from wastewater. According to Agwaramgbo (2014), charred biomaterial or unmodified or un-activated biomaterial enhances its adsorption capacity as it opens and increases the pore size of the material. ...
Lead is among the deadliest heavy metal contaminants in water. Musa acuminata is one of the most common cultivars in the Philippines that is easily found in any local setting and is extremely in demand. In this study, the researchers evaluated the potential and effectiveness of charred banana peelings as a lead adsorbent in lead-contaminated water. The experimental design used was the Randomized Complete Block Design (RCBD). The study was composed of 2 treatments each having 5 replicates. The first setup used 5 grams of charred banana peelings and was labeled as CBP-5. The other setup used 10 grams of charred banana peelings and was labeled as CBP-10. Lead contaminated water was treated with the charred banana peelings, and un-agitated for 48 hours. The water samples were brought to the Zamboanga City Medical Center-Water Testing Laboratory for quantitative analysis. Laboratory results of the water test showed that the amount of lead in the water sample of the CBP-5 treatment decreased by 75.6%. For the CBP-10 treatment, the amount of lead in the water sample decreased by 35.4%. It was concluded that the charred banana peelings are effective in adsorbing lead in lead-contaminated water. In addition, using 5 grams of charred banana peelings adsorbed more lead than using 10 grams of the adsorbent. Furthermore, the researchers recommend the use of charred banana peelings in wastewater treatment and that other methods can be applied to enhance its adsorption capacity.
... Although many techniques exist for the removal of metals from contaminated water [14][15], however, adsorption method using low cost and readily available agricultural waste materials proved to be very effective in removing metals such as lead, and copper from contaminated water. These agricultural wastes and biomaterials include corn and palm husks [16], spinach [17], coffee and tea [18], groundnut shell [19] and chitin and peat moss [20], walnut, almond, and hazelnut, and pistachio shells [21], rice straw [22], and other agricultural and industrial wastes [23]. ...
Aim: The aim of this research is to evaluate the selectivity in metal removal by coffee waste from binary-metal polluted water from contaminated water.
Place: The work was done at Dillard University in New Orleans, LA, USA.
Duration: The project was carried out between November and December 2014.
There are reports that suggest that there is a steady increase in industrial effluents containing heavy metals that are being dumped into the water. The presence of these heavy metals in water is harmful for the environment, human health, and aquatic life. It is necessary to develop cheap and friendly method such as agricultural waste to remove these metals. These industrial effluents are known to contain more than one heavy metal; thus, the paper presented here examines the effects of dose of adsorbent, metal type, and the presence of another metal on heavy metal removal by coffee waste. Results showed that (1) increasing the dose of coffee waste increases the removal o heavy metal from the samples. As the adsorbent dose increased from 1 g - 4 g, the percent metal removal increased from 73-92% for copper and 50-74% for zinc from single-metal solutions and
from 26-78% for copper and 18-58% for zinc from binary-metal solutions (2) there is selectivity in favor of copper removal from the binary metal mixture by the coffee waste as shown above (3) ion type effect was observed in that more copper was adsorbed from both mono and binary metal samples (4) the presence of another metal as impurity increased metal adsorption hence, more adsorption occurred from binary metal solution than from the single metal solution.
... These elements are regarded toxic [2,3] and classified as carcinogenic [2,4,5]. For example, Galadima and Garba [6] and Agwaramgbo et al. [7] reported that poisoning by Pb in Nigeria killed more than 500 children, and left thousands in severe health conditions in 2010. Recent studies, also, have demonstrated that As and other toxic heavy metals like Cd and Pb were responsible for causing a chronic kidney disease, known as toxic nephropathy, in contaminated areas in Siri Lanka [8]. ...
A survey was conducted to investigate the levels of Cd, Pb and As heavy metals in soils, leafy vegetables (lettuce plant), and irrigation water in areas characterized by intensive agricultural activities in Jordan. Thirteen farms from three locations (Jordan Valley, Alyadoda, and Jarash) were selected for this purpose. Ten P fertilizers that are most widely used by farmers were also collected and analyzed for heavy metals content. The results indicated that the lettuce, used as an indicator plant for possible vegetables contamination with heavy metals, was within allowable levels of Cd and Pb of 0.2 and 0.3 mg kg-1 of fresh weight for leafy vegetables, respectively. The plant was, also, safe with respect to As as the level of this metalloid was much less than the established acceptable concentration of 1 mg kg-1 fresh weight. The results suggested that the most probable sources of the heavy metals (Cd and Pb) and metalloid (As) in the collected samples of soils and plant from the selected farms were soil parent materials and pesticides application. Long term P fertilizers additions are, also, likely sources of heavy metals in agricultural soils and crops. This implies a risk to the human health and environment in the future is expected.
Water is the most fundamental requirement for existence on Earth. There is a natural existence of metals in the water resources but various anthropogenic sources have added immensely to an abnormally high concentration of heavy metals. The main concern with these metals is they show toxicity at very low concentration and also associated with environmental degradation, poor water quality, and different human diseases. They bioaccumulates in the plant and animal system over a period of time by entering through food, air, and water. There are mainly two sources of water pollution, point and nonpoint source (NPS). Injudicious use of fertilizer and pesticide in agricultural practices contributes as NPS pollution to water resources through land run off and has been the source of heavy metals. Industries such as leather, paper and pulp, dye, steel, electroplating, fertilizer manufacture, ore processing and others often discharge untreated wastewater loaded with many criteria metals like Pb, Cd, Cr, etc., into the water and contributes to the point source of water pollution. These metals, once they enter the water, begin to accumulate in the food chain. Some metals also bioaccumulate in animal and human system causing various diseases like Minamata, cancer, etc. To control NPS pollution in water bodies, installation of suitable engineering structures can be undertaken in contaminated area to reduce land runoff. The wastewater generated in industrial facilities has to be treated up to WHO recommended limits before its discharge into water bodies.
The potentials of activated carbons of ten agricultural wastes, as adsorbents for removal of Pb (II) were investigated using pure lead nitrate Pb(NO 3) 2 on a batch mode. The waste peels were sun-dried for 24 hours, grounded and sieved through 150 microns sieve. These were washed with distilled water, dried in an oven at 105 o C. Chemical method was used in activation by soaking the charcoal in 100 ml 0.1 M KOH for 24 hours, then filtered, rinsed thoroughly with distilled water and carbonized in the furnace at 400 0 C for 3 hours. Batch treatment method was used to study adsorption capacity Qe and percentage lead removal R under pH 2, 4, 10, 12; 100 mg/l lead ion concentration, 100 g adsorbent loading, at 25 o C ± 1 and 20 minutes. The optimum pH for R% and Qe is 10 at 100 mg/l concentration of lead waste water, for all the studied biosorbents, 100 g loading , except carrot peels and rice husk that recorded optimum pH of 4 for R% and Qe (98.527%; 99.02 mg/g and 99.98%; 100.482 mg/g respectively). The highest R and Qe is 99.988% and 100.488 mg/g for corn husk while the least is 98.527% and 99.02 mg/g for carrot peels. Langmuir (R 2 = 0.950 to 1.00) and Freundlich isotherms (R 2 = 0.924 to 0.975) were used for fitting the equilibrium data. The system pH, adsorbent loading, concentration of metal ion, and the activation reagent all affect the R% and Qe. It is recommended that agricultural wastes be recycled to activated carbons for use in lead waste water treatments.
The study analyzed the effect of Industrial waste discharge on River Challawa and Tamburawa old water treatment plant, located downstream of the effluent discharge points. Mean level of heavy metals including chromium, copper, lead, zinc, iron and manganese discharged into the river were 2.297, 1.290, 1.051, 2.986, 9.408 and 2.054mg/l respectively. Similarly, mean level of total suspended solids (TSS), total dissolved solids (TDS), pH, and conductivity in the effluent were 47183mg/l, 3105mg/l, 10.11, and 5942 micromhos/cm respectively. With the exception of iron and manganese, discharge of other pollutants measured has exceeded the maximum permissible limit given by the Federal Environmental Protection Agency of Nigeria (FEPA) and WHO. Presence of some of these pollutants, at various points along the Challawa River, was observed and level of these pollutants at varying degrees was found. Similarly, it was discovered that level of chromium, lead, manganese, iron, and TSS in the raw water used by the treatment plant have exceeded the maximum permissible limits of drinking water recommended by FEPA and WHO. Since the treatment given to the raw water is disinfection alone, there is tendency of these pollutants to persist in the water and its uptake may cause long term health problems.
Activated carbon has been prepared from wood of Derris indica. Its adsorption capability in removal of cadmium from wastewater has been investigated through batch adsorption experiments. The adsorption kinetics of this carbon for various parameters like adsorbent dosage and contact time of the cadmium ion were studied. The cadmium adsorption behavior and the effect of the initial cadmium concentration on removal efficiency were also examined. The optimum dosage of wood of derris indica based activated carbon to remove 80 mg/L of cadmium from aqueous solution 0.5gms/150 mL and the optimum contact time was 20 minutes. The isotherm data confirm with both Langmuir and Freundlich isotherm models.
This paper reports the results of a survey conducted by the State of
Minnesota after the January 1, 1986 leaded petrol phasedown. The survey collected data on the soil-dust lead and children's blood lead concentrations in the oldest census tracts of Minneapolis, St 'Paul, Duluth, St Cloud and Rochester, Minnesota. The results reveal fundamental differences among cities. The proportion of children with blood lead concentrations equal or greater than 25 mcg/dL was 3.7% in Minneapolis, 3.1% in St Paul, and 0.7% in Duluth. The proportion of children with blood lead concentrations equal or greater than 15 mcg/dL was 17.7% in Minneapolis, 14.9% in St Paul, and 9.8% in Duluth. No children in the small cities of St Cloud or Rochester had blood lead contents above 15 mcg/dL. Soil lead concentrations of yards, streetsides and foundations showed a similar trend with the highest being in Minneapolis and the lowest in Rochester. For example, midyard soils above 150 mg/kg range from 67.5% in Minneapolis, 51.0% in St Paul, and 46.2% in Duluth, to 4.8% in St Cloud, and 4.5% in Rochester. Although the lead contents of foundation soils were highest, the concentrations found were not simply related to age of community dwellings. Children's blood lead and environmental lead contents were directly related to city size, which in turn is related to traffic density as well as quantity of community traffic flow. The survey provides essential information about the groups at risk, major sources of lead, and the geography of lead to set priorities for abatement and primary prevention of lead exposure in Minnesota.
The kinetics of sorption and intraparticulate diffusivities of Zn, Cd and Pb using maize cob was studied. The amount of the metal ions adsorbed increased with time. The highest sorption rates of the three metal ions were 71% for Zn 2+ , 32% for Cd 2+ , and 30% for Pb 2+ . The fractional attainment of equilibrium showed that Zn 2+ reached equilibrium before Pb 2+ ion and then Cd 2+ ion. This study showed that the sorption of Zn 2+ , Cd 2+ and Pb 2+ ions on maize cob is particle diffusion controlled. The rate coefficients for particle diffusion were 0.07 min -1 for Zn 2+ , 0.053min -1 for Pb 2+ and 0.081min -1 for Cd 2+ .
Lead is a toxic and naturally occurring substance with documented neurotoxin, toxic, and long-lasting adverse health effects globally. Lead exposure can cause impaired physical and mental development in children. Exposure to high lead levels affects the intestinal tract, kidneys, joints and reproductive system in adults. This study evaluates the removal of 1500 PPM of lead from contaminated aqueous solution using Celite, Louisiana Red Clay, Charcoal, and supernatants from aqueous extracts of Mustard Green (Brassica juncea), and Spinach (Spinacea oleracea). After shaking triplicate reaction mixtures for each substrate for 22 hours at room temperature, lead removal by the five substrates were ana-lyzed by EPA Method 6010, using Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES). Results sug-gest that the order of lead removal is Spinach (98%) > Charcoal (96%) > LA Red Clay (88%) > Mustard Green (87%) > Celite (4%). The study concludes that liquid substrates such as the supernatants from pureed spinach and mustard green can effectively remove lead from contaminated water.
The use of tea and coffee for the removal of heavy metal from aqueous lead solutions has been reported. However, those studies were limited to expended dry biomass of coffee and tea and the lead concentration in those studies range from 10 - 100 ppm of aqueous lead solution. This study compared the effectiveness of aqueous extracts of instant coffee (IC), coffee ground (CG), coffee bean (CB), Lipton tea (Tea), and spinach puree (SP) in removing lead from 1300 PPM of aqueous lead solution. After 24 hr of agitation at room temperature followed by centrifugation, the lead concentration (in ppm) in the liquid from each reaction tube was analyzed using EPA Method 6010 (Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES)). The results suggest that the order of lead removal was Spinach (99%) > Instant coffee (95%) >Tea (91%), > CG (62%) > CB (59%). In comparing the brewed versus the boiled extracts, the results demonstrated that temperature of the aqueous extract affected the lead removal potential of coffee and tea in decreasing order: IC (95%:79%), > Tea (91%:88%) > CG (62%:53%) > CB (59%:53%).
There is a growing global concern for the environmental and health hazards posed by heavy metal contaminants, especially lead in the soil and ground water. The potential for plant and animal uptake, metabolism, and propagation into food-chain poses great health risks. World communities face a common need to a cheap, efficient, and effective technology to mitigate the growing problem of heavy metal contaminations. The present investigation was undertaken to evaluate the potential of using aqueous extracts of edible vegetables and fruits for the in-situ remediation of lead contaminated water (1300 PPM). The plants used in this study include Mustard Green (Brassica juncea), Spinach (Spinacea oleracea), Collard Green (Brassica Oleracea), Bitter leaf (Vernonia Amygdalina), Carrot (Daucus Carota Sativus), Red, Green, and Yellow Bell Pepper (Capsicum Annuum ), tomatoes (Lycopersicon esculentum), red and white grape (Vitis vinifera), and lime (Citrus aurantifolia). After shaking triplicate reaction mixtures lead contaminated water with each substrate for 22 hours at room temperature, lead removal by the substrates were analyzed by EPA Method 6010, using Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES). Results suggest that the order of lead removal is Collard Green (99.8%) >, Spinach (98.7%) > Mustard Green (98.2%) > Green Bell Pepper (97.8%) > Yellow Bell Pepper (97.75%) > White Grape (96.7%)> Carrot (95.5%) > Red Bell Pepper (94.28%) > Red Grape > 93.5% > Tomatoes (84%) > Bitter Leaf (61%). The study concludes that liquid substrates such as the supernatants from pureed edible tuberous, leafy, and fruity vegetables can effectively remove lead from contaminated water.
The present study investigates the use of different wastes such as blue Pine wood shavings, walnut
shell and chick pea testa in arsenic removal from aqueous solutions. Various conditions that affect the
adsorption such as pH, biosorbent dose, contact time, temperature and concentration of adsorbate were
investigated. Blue Pine wood shavings showed a tremendous potential as a remediation material for the
removal of arsenic from water samples (surface and ground water). Walnut shell pieces also showed
good biosorption (88%); however, the chick pea testa was not much effective. Experimental data were
modeled by Langmuir and Freundlich isotherms. It was observed that arsenic biosorption conformed to
both Langmuir and Freundlich isotherms. The Blue Pine biomass could be used as a low-cost biosorbent
for arsenic removal from water samples.
The increasing influx of heavy metals into water bodies from industrial, agricultural, and domestic activities is of global concern because of their well documented negative effects on human and ecosystem health. A recent study of streams in Blantyre and Zomba, Malawi revealed lead levels of up 0.118 mg/L, exceeding the World Health Organisation acceptable level of 0.01 mg/L. Our ongoing study on low cost effective heavy metal remediation techniques in developing countries has already demonstrated that Moringa oleifera , the well known source of natural water clarifiers, is effective in heavy metal detoxification of water. This paper presents the first reported use of a related species, the African moringa, Moringa Stenopetala for lead detoxification and preliminary investigation of the interaction of the metal with the polyelectrolytes of M. oleifera and stenopetala. The potential of M. stenopetala for lead removal was tested by means of jar tests. With an initial lead concentration of 7 ppm, M. stenopetala seed powder, at doses of 0.50, 1.00, 1.50, 2.00 and 2.50 g/100mL, reduced the concentration of lead by 20.00 ± 0.00, 46.19 ± 2.06, 71.19 ± 2.06 and 89.43 ± 0.60 and 96.23 ± 0.12 % respectively. M. stenopetala was more effective than M. oleifera in removing lead from water (p=0.001 at 95% confidence level). For oleifera, lead levels decreased exponentially during the first 5 h. of the reaction and then equilibrium was established; for stenopetala, a linear decrease was observed. The pH of the mixture rose from 2.30 to a maximum of 2.53 and 2.57 and then fell to an equilibrium value of 2.30 and 2.29 for oleifera and stenopetala respectively. Lead removal was also affected by pH, ionic strength, and water hardness. Our results show that M. stenopetala has potential in lead remediation of contaminated waters. Further studies are being carried out on remediation of other metals and the mechanism of the metal moringa interaction.
The objective of this study was to investigate the possibility of using maize tassel as an alternative adsorbent for the removal of chromium (VI) and cadmium (II) ions from aqueous solutions. The effect of pH, solution temperature, contact time, initial metal ion concentration and adsorbent dose on the adsorption of chromium (VI) and cadmium (II) by tassel was investigated using batch methods. Adsorption for both chromium (VI) and cadmium (II) was found to be highly pH dependent compared to the other parameters investigated. Obtained results gave an adsorption capacity of 79.1 % for chromium (VI) at pH 2, exposure time of 1h at 25 ºC. Maximum capacity of cadmium of 88 % was obtained in the pH range of 5-6 at 25 ºC after exposure time of 1 h. The adsorption capacities of tassel for both chromium (VI) and cadmium (II) were found to be comparable to those of other commercial adsorbents currently in use for the removal of heavy metals from aqueous wastes. These results have demonstrated the immense potential of maize tassel as an alternative adsorbent for toxic metal ions remediation in polluted water and wastewater.
Despite dramatic declines in children's blood lead concentrations and a lowering of the Centers for Disease Control and Prevention's level of concern to 10 microg per deciliter (0.483 micromol per liter), little is known about children's neurobehavioral functioning at lead concentrations below this level.
We measured blood lead concentrations in 172 children at 6, 12, 18, 24, 36, 48, and 60 months of age and administered the Stanford-Binet Intelligence Scale at the ages of 3 and 5 years. The relation between IQ and blood lead concentration was estimated with the use of linear and nonlinear mixed models, with adjustment for maternal IQ, quality of the home environment, and other potential confounders.
The blood lead concentration was inversely and significantly associated with IQ. In the linear model, each increase of 10 microg per deciliter in the lifetime average blood lead concentration was associated with a 4.6-point decrease in IQ (P=0.004), whereas for the subsample of 101 children whose maximal lead concentrations remained below 10 microg per deciliter, the change in IQ associated with a given change in lead concentration was greater. When estimated in a nonlinear model with the full sample, IQ declined by 7.4 points as lifetime average blood lead concentrations increased from 1 to 10 microg per deciliter.
Blood lead concentrations, even those below 10 microg per deciliter, are inversely associated with children's IQ scores at three and five years of age, and associated declines in IQ are greater at these concentrations than at higher concentrations. These findings suggest that more U.S. children may be adversely affected by environmental lead than previously estimated.
On a community basis, urban soil contains a potentially large reservoir of accumulated lead. This study was undertaken to explore the temporal relationship between pediatric blood lead (BPb), weather, soil moisture, and dust in Indianapolis, Indiana; Syracuse, New York; and New Orleans, Louisiana. The Indianapolis, Syracuse, and New Orleans pediatric BPb data were obtained from databases of 15,969, 14,467, and 2,295 screenings, respectively, collected between December 1999 and November 2002, January 1994 and March 1998, and January 1998 and May 2003, respectively. These average monthly child BPb levels were regressed against several independent variables: average monthly soil moisture, particulate matter < 10 microm in diameter (PM10), wind speed, and temperature. Of temporal variation in urban children's BPb, 87% in Indianapolis (R2 = 0.87, p = 0.0004), 61% in Syracuse (R2 = 0.61, p = 0.0012), and 59% in New Orleans (R2 = 0.59, p = 0.0000078) are explained by these variables. A conceptual model of urban Pb poisoning is suggested: When temperature is high and evapotranspiration maximized, soil moisture decreases and soil dust is deposited. Under these combined weather conditions, Pb-enriched PM10 dust disperses in the urban environment and causes elevated Pb dust loading. Thus, seasonal variation of children's Pb exposure is probably caused by inhalation and ingestion of Pb brought about by the effect of weather on soils and the resulting fluctuation in Pb loading.
Heavy metal contamination has become a worldwide problem through disturbing the normal functions of rivers and lakes. Sediment, as the largest storage and resources of heavy metal, plays a rather important role in metal transformations. This paper provides a review on the geochemical forms, affecting factors and remediation technologies of heavy metal in sediment. The in situ remediation of sediment aims at increasing the stabilization of some metals such as the mobile and the exchangeable fractions; whereas, the ex situ remediation mainly aims at removing those potentially mobile metals, such as the Mn-oxides and the organic matter (OM) fraction. The pH and OM can directly change metals distribution in sediment; however oxidation-reduction potential (ORP), mainly through changing the pH values, indirectly alters metals distribution. Mainly ascribed to their simple operation mode, low costs and fast remediation effects, in situ remediation technologies, especially being fit for slight pollution sediment, are applied widely. However, for avoiding metal secondary pollution from sediment release, ex situ remediation should be the hot point in future research.
The use of arsenic in agriculture, industry, and domestic endeavors since the last century has increased the concentration of arsenic in the environment.
During cleanup activities at a former pesticide facility, water that was collected during various operations was contaminated with arsenic and required treatment before discharge. Chemical precipitation was identified as being the most effective means of treatment.
Bench‐scale treatability testing was completed to determine the effectiveness of various coagulants, including ferric chloride, hydrated lime, sodium sulfide, and alum. A combination of hydrated lime and ferric chloride was able to remove more than 99% of the original arsenic concentration.
Contaminated water to be treated by the full‐scale system had arsenic concentrations up to 48 mg/L. The discharge limitation required that the arsenic concentration be reduced to less than 1 mg/L. More than 605 000 L (160 000 gal) of water were treated using a combination of chemical precipitation, filtration, and carbon absorption.
Garden soil and housedust samples, from households in a Derbyshire village closely associated with historic lead mining, have highly elevated lead levels. Handwipe samples from children also have relatively high lead concentrations suggesting that elevated levels of lead are transferred to the child by the soil-dust-hand-mouth pathway. However, this is not reflected in their blood lead concentrations which are within normal UK ranges and less than predicted by some lead exposure models. SEM analysis of soil grains has revealed that many are composed of pyromorphite [Pb5(PO4)3Cl], a stable soil-lead mineral. This mineral is formed from the weathering of galena [PbS] but it is not clear to what extent weathering has occurred in the soil. Pyromorphite has an extremely low solubility which may contribute to a low human bioavailability of lead in these soils, resulting in the lower than expected blood lead concentrations.
Conventional pump-and-treat technologies are among the most widely used systems for the remediation of contaminated ground-water. Within recent years it has become recognized that these systems can require protracted periods of time to make significant reductions in the quantity of contaminants associated with both the liquid and solid phases which constitute the subsurface matrix. Evaluating the effectiveness of pump-and-treat remediations at Superfund sites, as well as attempting to improve this effectiveness, are issues identified by the Regional Superfund Ground Water Forum as a concern of Superfund decision makers. The Forum is a group of ground-water scientists and engineers, representing EPA's Regional Superfund Offices, organized to exchange the most recent information related to ground-water remediation at Superfund sites. Recent research has led to a better understanding of the processes involved in the transport and transformation of contaminants in the subsurface. While some of these processes are not readily amenable to enhance removal by ground-water extraction, others suggest that there are available techniques to increase the efficiency of these types of remediation systems. The intent of the document is to explore the use of chemical enhancement to improve ground-water remediation efficiencies using pump-and-treat technologies, and point out arenas of contamination where such techniques are not practical.
Most industrial waste streams contain a number of different heavy metals. The feasibility of selective electrodeposition of cadmium, cobalt and nickel as their pure metals (99%) from binary mixtures has been investigated. Single cation linear sweep voltamograms and nucleation potential measurements have been made and used to predict the optimum potentials and conditions for selective electro-deposition from the mixed-cation solutions. The anions used in this work are SO4
2–, Cl– and BF4 . The optimum potential for removal by electrodeposition of Cd from a solution containing Cd(ii) and Co(ii) or Ni(ii) without codepositing Co or Ni has been evaluated from a simple diagram constructed from nucleation potential measurements. It is shown that the [Cd(ii)] remaining in the solution after exhaustive electrolysis at a fixed potential is determined by the Nernst equation, and not by the electrolysis time provided that a critical minimum time has been exceeded.
Lead from gasoline has played a major role in the geochemical distribution patterns of Pb within U.S. cities. Since 1950, ~75,000 and 89,000 t of Pb were consumed as a gasoline additive in Louisiana and Minnesota, respectively. Previously, a survey was conducted in five cities in Minnesota that showed a relation between soil Pb and city size. New empirical data are presented on the geochemical pattern of Pb in soils within six cities of Louisiana. Soils were collected from within 1 m of the sides (foundations) of residences, within 1 m of the street, and from open spaces (yards or parks) within each city. The data show that soil Pb is a function of city size and that the inner city of the largest town had the highest Pb accumulation. Remarkable statistical differences (exact p-values as low as 10−80) between street-side soils of central New Orleans and adjacent communities, and other cities of Louisiana, were demonstrated. The Louisiana results are similar to those of five cities in Minnesota. The median of foundation and street-side soil samples within inner city communities of New Orleans and Minneapolis were >840 and 265 ppm Pb, respectively, whereas the median soil Pb for foundations and street-sides of the small towns of Natchitoches, Louisiana, and Rochester, Minnesota, were <50 and 58 ppm Pb, respectively.
The use of low-cost sorbents has been investigated as a replacement for current costly methods of removing heavy metals from solution. Natural materials or waste products from certain industries with a high capacity for heavy metals can be obtained, employed, and disposed of with little cost. Modification of the sorbents can also improve adsorption capacity. In this review, an extensive list of sorbent literature has been compiled to provide a summary of available information on a wide range of potentially low-cost sorbents, including bark, chitosan, xanthate, zeolite, clay, peat moss, seaweed, dead biomass, and others. Some of the highest adsorption capacities reported for cadmium, chromium, lead and mercury are: 1587 mg Pb/g lignin, 796 mg Pb/g chitosan, 1123 mg Hg/g chitosan, 1000 mg Hg/g CPEI cotton, 92 mg Cr(III)/g chitosan, 76 mg Cr(III)/g peat, 558 mg Cd/g chitosan, and 215 mg Cd/g seaweed.
Metals including lead, chromium, arsenic, zinc, cadmium, copper and mercury can cause significant damage to the environment and human health as a result of their mobilities and solubilities. The selection of the most appropriate soil and sediment remediation method depends on the site characteristics, concentration, types of pollutants to be removed, and the end use of the contaminated medium. The approaches include isolation, immobilization, toxicity reduction, physical separation and extraction. Many of these technologies have been used full-scale. This paper will review both the full-scale and developing technologies that are available. Contaminants can be isolated and contained to minimize further movement, to reduce the permeability of the waste to less than 1×10−7 m/s (according to U.S. guidelines) and to increase the strength or bearing capacity of the waste. Physical barriers made of steel, cement, bentonite and grout walls can be used for isolation and minimization of metal mobility. Another method is solidification /stabilization, which contains the contaminants in an area by mixing or injecting agents. Solidification encapsulates contaminants in a solid matrix while stabilization involves formation of chemical bonds to reduce contaminant mobility. Another approach is size selection processes for removal of the larger, cleaner particles from the smaller more polluted ones. To accomplish this, several processes are used. They include: hydrocyclones, fluidized bed separation and flotation. Addition of special chemicals and aeration in the latter case causes these contaminated particles to float. Electrokinetic processes involve passing a low intensity electric current between a cathode and an anode imbedded in the contaminated soil. Ions and small charged particles, in addition to water, are transported between the electrodes. This technology have been demonstrated in the U.S. full-scale, in a limited manner but in Europe, it is used for copper, zinc, lead, arsenic, cadmium, chromium and nickel. The duration of time that the electrode remains in the soil, and spacing is site-specific. Techniques for the extraction of metals by biological means have been not extensively applied up to this point. The main methods include bioleaching and phytoremediation. Bioleaching involves Thiobacillus sp. bacteria which can reduce sulphur compounds under aerobic and acidic conditions (pH 4) at temperatures between 15 and 55°C. Plants such as Thlaspi, Urtica, Chenopodium, Polygonum sachalase and Alyssim have the capability to accumulate cadmium, copper, lead, nickel and zinc and can therefore be considered as an indirect method of treating contaminated soils. This method is limited to shallow depths of contamination. Soil washing and in situ flushing involve the addition of water with or without additives including organic and inorganic acids, sodium hydroxide which can dissolve organic soil matter, water soluble solvents such as methanol, nontoxic cations, complexing agents such as ethylenediaminetetraacetic acid (EDTA), acids in combination with complexation agents or oxidizing/reducing agents. Our research has indicated that biosurfactants, biologically produced surfactants, may also be promising agents for enhancing removal of metals from contaminated soils and sediments.In summary, the main techniques that have been used for metal removal are solidification/stabilization, electrokinetics, and in situ extraction. Site characteristics are of paramount importance in choosing the most appropriate remediation method. Phytoremediation and bioleaching can also be used but are not as well developed.
Adsorption of copper and lead ions onto tea waste from aqueous solutions was studied to enable comparison with alternative commonly available absorbents. Batch experiments were conducted to determine the factors affecting adsorption and kinetics of the process. Fixed bed column experiments were performed to study practical applicability and breakthrough curves were obtained. Tea waste is capable of binding appreciable amounts of Pb and Cu from aqueous solutions. The adsorption capacity was highest at solution pH range 5–6. The adsorbent to solution ratio and the metal ion concentration in the solution affect the degree of metal ion removal. The equilibrium data were satisfactorily fitted to Langmuir and Freundlich isotherms. Highest metal uptake of 48 and 65 mg/g were observed for Cu and Pb, respectively. Pb showed higher affinity and adsorption rate compared to Cu under all the experimental conditions. Kinetic studies revealed that Pb and Cu uptake was fast with 90% or more of the adsorption occurring within first 15–20 min of contact time. The kinetic data fits to pseudo second order model with correlation coefficients greater than 0.999. Increase in the total adsorption capacity was observed when both Cu and Pb ions are present in the solution. Higher adsorption rate and the capacity were observed for smaller adsorbent particles. Tea waste is a better adsorbent compared to number of alternative low cost adsorbents reported in literature.
Although enormous effort has been focused over the past two decades on examining the potential adverse effects of exposure to environmental lead on human health, there has been a debate over the persistence and dynamic pattern of these effects. Methodology: Articles relevant to this issue which were published between January 1982 and December 1996 were retrieved from Medline and adjunct searching methods (i.e. hand searching of key journals, review of the bibliographies of reports known to be relevant, consulting with experts, and use of Science Citation Index).
Currently available epidemiological evidence suggests that 'low' level exposure to lead in early childhood is likely to cause a moderate but real and detectable effect on cognitive development, and this effect appears to persist into later childhood. The findings from four long-term prospective studies seem to support the constant decrement model which assumes that cognitive deficits resulting from early lead exposure persist over an extended period of time even when exposure decreases.
From a public health perspective, it is highly desirable and prudent to reduce the dispersive uses of lead. Since lead is ubiquitous and persistent in the environment and may have a subtle and persistent effect on cognitive development, how to set the environmental standards for lead exposure is an important scientific issue still open for debate.
Concentrations of five metals (Cd, Cu, Mn, Fe, Zn) were determined in tree leaves collected from an area with large coal-fired plants in Ptolemais, Macedonia, Greece. The analyses were carried out with flame atomic absorption spectroscopy. Mean heavy metal content in the tree leaves is, in descending order, Fe>Mn>Zn>Cu>Cd. In Populus nigra and Salix babylonica the dense piled leaves and the widespread root system are the reasons for high heavy metal uptake. Conifer trees Pinus nigra and Juniperus arizona, which have a rough leaf surface, also had elevated concentrations. Leaves with a smooth surface were less contaminated. The presence of one metal within leaf cells may reduce the uptake or toxicity of other metals. Fruits accumulated less heavy metal than the corresponding leaves. The most damaged areas are those in the direct vicinity of the coal power plants, and the rate of damage caused in the environment is affected by the main wind direction. All sampling sites in Ptolemais basin are generally more or less polluted when compared with the control site.
Remediation of sites contaminated with toxic metals is particularly challenging. Unlike organic compounds, metals cannot be degraded, and the cleanup usually requires their removal. However, this energy-intensive approach can be prohibitively expensive. In addition, the metal removing process often employs stringent physicochemical agents which can dramatically inhibit soil fertility with subsequent negative impacts on the ecosystem. Phytoremediation has been proposed as a cost-effective, environmental-friendly alternative technology. A great deal of research indicates that plants have the genetic potential to remove many toxic metals from the soil. Despite this potential, phytoremediation is yet to become a commercially available technology. Progress in the field is hindered by a lack of understanding of complex interactions in the rhizosphere and plant-based mechanisms which allow metal translocation and accumulation in plants. In this paper, four research areas relevant to metal phytoextraction from contaminated soil are reviewed. The review concludes with an assessment of the current status of technology deployment and suggestions for future phytoremediation research.
The disease burden from exposure to lead resulting in mild mental retardation (due to IQ point decreases) and cardiovascular outcomes (due to increases in blood pressure) was estimated at a global level. Blood lead levels were compiled from the literature for 14 geographical regions defined by the World Health Organization according to location and adult and child mortality rates. Adjustments were applied to these levels, where appropriate, to account for recent changes relating to the implementation of lead-reduction programs and the lower levels seen in rural populations. It is estimated that mild mental retardation and cardiovascular outcomes resulting from exposure to lead amount to almost 1% of the global burden of disease, with the highest burden in developing regions. This estimate can be used to assess the magnitude of the benefits that could be accrued by increasing the global coverage of lead-reduction programs.
We have investigated adsorption of Cd(II) and Pb(II) at pH 2-6.7 onto the biomaterials chitosan, coffee, green tea, tea, yuzu, aloe, and Japanese coarse tea, and onto the inorganic adsorbents, activated carbon and zeolite. High adsorptive capabilities were observed for all of the biomaterials at pH 4 and 6.7. In the adsorption of Cd(II), blend coffee, tea, green tea, and coarse tea have comparable loading capacities to activated carbon and zeolite. Although activated carbon, zeolite, and chitosan are utilized in a variety of fields such as wastewater treatment, chemical and metallurgical engineering, and analytical chemistry, these adsorbents are costly. On the other hand, processing of the test biomaterials was inexpensive, and all the biomaterials except for chitosan were able to adsorb large amounts of Pb(II) and Cd(II) ions after a convenient pretreatment of washing with water followed by drying. The high adsorption capability of the biomaterials prepared from plant materials is promising in the development of a novel, low-cost adsorbent. From these results, it is concluded that heavy metal removal using biomaterials would be an effective method for the economic treatment of wastewater. The proposed adsorption method was applied to the determination of amounts of Cd(II) and Pb(II) in water samples.
The removal of heavy metals from wastewater using olive cake as an adsorbent was investigated. The effect of the contact time, pH, temperature, and concentration of adsorbate on adsorption performance of olive cake for Pb(II) and Cd(II) ions were examined by batch method. Adsorption of Pb(II) and Cd(II) in aqueous solution onto olive cake was studied in single component. After establishing the optimum conditions, elution of these ions from the adsorbent surface was also examined. The optimum sorption conditions were determined for two elements. Maximum desorption of the Pb(II) and Cd(II) ions were found to be 95.92 and 53.97% by 0.5M HNO(3) and 0.2M HCl, respectively. The morphological analysis of the olive cake was performed by the scanning electron microscopy (SEM).
Standard for soil lead limitations in the United States
- R Chaney
- H Mielke
Chaney R, Mielke H. Standard for soil lead limitations in the United States,
Trace
Substance. Environmental Health. 1986;20:357-377.
Re-examination of lead and arsenic contamination in New Orleans Parish School Soils
- L Agwaramgbo
- J Smith-Hopkins
- A Hawkins
- D Wilson
Agwaramgbo L, Smith-Hopkins J, Hawkins A, Wilson D. Re-examination of lead and
arsenic contamination in New Orleans Parish School Soils. American Chemical
Society, Chemical and Engineering News, American CHED-TECH. 2008;17:33.
Bone lead levels in adjudicated delinquents: A case control study
- H Needleman
- C Mcfarland
- R Ness
- S Fienberg
- M Tobin
Needleman H, McFarland C, Ness R, Fienberg S, Tobin M. Bone lead levels in
adjudicated delinquents: A case control study. Neurotoxicology and Teratology.
2003;24:711-717. DIO:dx.dio.org/10.1016/50892-0362(02)00269.
The relationship between lead exposure and homicide. Archives of Pediatric and Adolescent Medicine
- P B Strerteky
- M J Lynch
Strerteky PB, Lynch MJ. The relationship between lead exposure and homicide.
Archives of Pediatric and Adolescent Medicine. 2001;155(5):579-582.
Global approach to reducing lead exposure and poisoning
- P A Meyer
- M J Brown
- H Falk
Meyer PA, Brown MJ, Falk H. Global approach to reducing lead exposure and
poisoning. Mutat. Res. 2008;659(1-2):166-175. DOI: 10.1016/j.mrrev.
Hydrogeochemical analysis of water samples from Nworie River, Owerri Southeastern Nigeria
- J O Nwagbara
- S I Ibeneme
- E E Dim
- U K Iroegbu
- A O Selemo
- B C Ejiogu
- S O Onyekuru
Nwagbara JO, Ibeneme SI, Dim EE, Iroegbu UK, Selemo AO, Ejiogu BC, Onyekuru
SO. Hydrogeochemical analysis of water samples from Nworie River, Owerri
Southeastern Nigeria. The International Journal of Engineering and Sciences.
2013;2(9):58-67.
Extraction of Pb(II) from water samples by ionic liquid modified silica sorbents. Desalination and Water Treatment
- S Seleema
- Ans Saqiba
- A Mujahidb
- M Hanifa
- G Mustafac
- T Mahmooda
- A Wassem
- A R Khan
Seleema S, Saqiba ANS, Mujahidb A, Hanifa M, Mustafac G, Mahmooda T, Wassem
A, Khan AR. Extraction of Pb(II) from water samples by ionic liquid modified silica
sorbents. Desalination and Water Treatment. 2014; In Press.
Adsorption kenetics and intraparticulate diffusivities of
- J C Igwe
- A A Abia
- C A Ibeh
Igwe JC, Abia AA, Ibeh CA. Adsorption kenetics and intraparticulate diffusivities
of
As and Pb Ions on Un-Modified and Thiolated Coconut Fibre
- Hg
Hg, As and Pb Ions on Un-Modified and Thiolated Coconut Fibre. Int. J. Environ. Sci.
Tech. 2008;5(1):83-92.
Removal of chromium from industrial effluents by absorptions on sawdust
- Hcp Srivastava
- R P Marthus
- I Mehrotra
Srivastava HCP, Marthus RP, Mehrotra I. Removal of chromium from industrial
effluents by absorptions on sawdust. Environ. Technol. Lettrs. 1986;5:55-63.