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There has been a considerable amount of research in the development of sustainable water treatment techniques capable of improving the quality of water. Unavailability of drinkable water is a crucial issue especially in regions where conventional drinking water treatment systems fail to eradicate aquatic pathogens, toxic metal ions and industrial w...
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Due to the toxicity effects and endocrine disrupting properties of many organic compounds, their removal from water and wastewater has gained widespread global attention. This review summarizes photocata-lytic degradation of different organic molecules present in wastewaters. This is an overview of photocatalytic deg-radation with the goal of prese...
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... There are lots of studies conducted for the removal of different pollutants such as heavy metals, dyes, pharmaceuticals by nano metal oxides based composite materials with/without using any supporting materials [6][7][8]. Titanium and iron oxides are the most applied nanoparticles in these studies [2,9]. For example, Spirulina (microalgae) based iron oxide [10] and titanium oxide [11] nanoparticles were found efficient in removing Cr 6+ and dyes (methyl orange and malachite green), respectively. ...
Heavy metal toxicity is a known problem and various methods are used for treatment. Adsorption has some advantages and it would be promising if environmentally friendly and cheap materials were utilized. Alginate and zinc oxide nanoparticles were selected and composite alginate beads were used for the removal of mixed metals from aqueous solutions. Batch and column experiments were conducted to determine some parameters’ effects and the adsorbent’s real application potential. According to the batch experiments, zinc oxide nanoparticles to alginate ratio of 0.5 g g⁻¹, and pH levels nearby to the neutral range led to better metal removals. 0.5 ml min⁻¹ of flow rate supplied better metal removal efficiencies in columns, with the highest treatment as 86% of Pb²⁺. Acid treatment can be successfully applied for the regeneration of the adsorbent, at least three times only with a 4% reduction in the adsorption efficiency. Heavy metal uptake was compatible with the pseudo 2nd order model indicating chemisorption as a dominant mechanism. Also, the intraparticle diffusion model illustrated adsorption might govern more than one step. The Langmuir model had the best fit and suggested monolayer covering for Pb²⁺, 76.3 mg g⁻¹. Alginate-based nanocomposite beads were useful for mixed metal removal and could be used.
... Photocatalytic degradation under visible light irradiation is a feasible technique for removing stubborn contaminants from water. It is one of the most common and well-studied method for eliminating harmful contaminants from water [27][28][29]. Numerous semiconductors, particularly transition metal oxides, have been extensively investigated for their photocatalytic capabilities. ...
The present work reports the synthesis of pure V2O5 and Ni-doped V2O5 nanoparticles via co-precipitation method, exploring diverse concentrations of Ni²⁺ in V2O5 system. The valent reduction of V, Ni, Oxygen stabilization and formation of V2O5 and Ni-doped V2O5 nanoparticles were evident by characterization techniques such as X-ray diffraction, Fourier transform infrared spectroscopy, Photoluminescence and UV–Visible Diffuse Reflectance Spectroscopy. Bandgap variations and Crystallite size of pure V2O5 and Ni-doped V2O5 nanoparticles confirmed the reduction of Ni⁺ and V⁺ their difference was found to be ∆Eg = 1.52 eV and 24–43 nm, respectively. X-ray Photoelectron Spectroscopy analysis examined oxidation states and binding energies which is vital for understanding structural and compositional aspects. Evaluation of bacterial endurance against gram-positive (S. aureus) and gram-negative bacteria (E.coli), coupled with antioxidant activity measurements via 2,2-Diphenyl-1-picrylhydrazyl (DPPH) method, indicate the successful utilization of the synthesized nanoparticles for biomedical and wastewater treatment applications. In contagious diseases, Ni/V2O5 nanoparticles showed superior activity against both S. aureus and E. coli. Photocatalytic activity against MB (98%) and Rh–B (88%) dyes under visible light irradiation was also evaluated with Ni/V2O5 nanoparticles which is exhibiting enhanced performance. Pseudo-first-order kinetics revealed accelerated dye degradation upon Ni ion incorporation, suggesting improved electron–hole pair activity and ROS formation. The AOP facilitated by the photocatalyst holds promise for wastewater treatment, with advantages such as absence of secondary product formation and presence of activated electrons. The in-depth investigation about the properties of Ni²⁺ into V2O5 lead us towards the cost effective and multifunctional applications of these nanoparticles at industrial level.
... This light irradiation prompts the excitation of electrons from the valence band (VB) to the conduction band (CB), simultaneously creating holes in the VB. 137,138 Subsequently, these electrons and holes, stimulated by the light radiation, migrate to the surface of the semiconductor particles through various interactions. Once there, they react with water or organic substances adsorbed on the surface of the semiconductor catalyst particles, thereby producing a photocatalytic effect., 139,140 as shown in Fig. 7. ...
Attapulgite clay, due to its unique crystalline hydrated magnesium–aluminium silicate composition and layer-chain structure, possesses exceptional adsorption and catalytic properties, which enable it or its composites to be utilized as adsorbents and catalysts for wastewater treatment. But the drawbacks of attapulgite are also very obvious, such as relatively low specific surface area (compared to traditional adsorbents such as activated carbon and activated alumina), easy aggregation, and difficulty in dispersion. In order to fully utilize and improve the performance of attapulgite, researchers have conducted extensive research on its modification, but few specialized works have comprehensively evaluated the synthesis, applications and challenges for attapulgite-based composite materials in refractory organic wastewater treatments. This paper provides a comprehensive review of controllable preparation strategies, characterization methods and mechanisms of attapulgite-based composite materials, as well as the research progress of these materials in refractory organic wastewater treatment. Based on this review, constructive recommendations, such as deep mechanism analysis from molecular level multi-functional attapulgite-based material developments, and using biodegradable materials in attapulgite-based composites, were proposed.
... While industrialization is essential for strengthening the economy of any country, it also has significant adverse effects on the delicately balanced natural environment. The fabric, cosmetic, printing, and leather industries are estimated to annually use 3 × 10 5 metric tons of different dyes [1,2]. The industrial effluents containing toxic organic dyes are discharged into waterbodies during different stages of the manufacturing process, leading to severe water contamination [3][4][5]. ...
... * Shams ur Rahman shamsur_rehman@comsats.edu.pk 1 ...
The release of industrial effluents into fresh water is a major contributor of water contamination. Therefore, it is highly desirable to develop a viable solution to this alarming issue to improve the quality of clean water. To enhance the photocatalytic efficiency and hence utilization ratio of CuO, a series of CuO–FeSe2 composites with different varying contents of FeSe2 were prepared through facile synthetic methods. X-ray diffraction (XRD) and energy-dispersive X-rays (EDX) analysis verified that the samples were successfully prepared without any contaminating phases. The average crystallite sizes of CuO and FeSe2 were computed to be 29 and 21 nm respectively. For the CuO–FeSe2 composites, the crystallite sizes varied between 25 and 27 nm. The morphology of CuO was comprised of needle-shaped structures, whereas that of FeSe2 was observed to be flower-shaped structures comprising of irregular crystals. A red shift in the bandgap of CuO–FeSe2 composites was observed with the increase in FeSe2 concentration. The prepared photocatalysts were utilized to evaluate their efficiency under visible light against Rhodamine B (RhB). Among all the prepared composites, CuO–75% FeSe2 revealed a remarkable performance and degraded 96% RhB in 180 min. Rate constants for the degradation of the dye were determined by applying the Langmuir–Hinshelwood model.
... However, these conventional oxidation processes are characterized by some limitations such as byproduct formation, the use of expensive oxidants, and sludge production [11]. To overcome these drawbacks, alternative oxidation processes are preferred, such as heterogeneous photocatalysis, which is widely used for the removal of water pollutants [20][21][22][23][24][25]. In particular, the TiO 2 photocatalyst is shown particularly performing for As(III) oxidation without the addition of chemicals other than dissolved O 2 [26]. ...
Arsenic in drinking water is one of the most concerning problems nowadays due to its high toxicity. The aim of this work is the photocatalytic oxidation of As(III) to As(V) under visible light. This study is focused on the use of gadolinium-doped bismuth ferrite as a photocatalyst active under visible light. Different gadolinium amounts were evaluated (0, 0.5, 1, 2, 5, 10 mol%), and 2 mol% resulted in the best gadolinium amount to reach higher photocatalytic efficiency in terms of As(V) production. The samples were thoroughly characterized in their optical, structural, and morphological properties. The results allowed us to identify an optimal concentration of gadolinium equal to 2 mol%. The reactive oxygen species most responsible for the photocatalytic mechanism, evaluated through the addition of radical scavengers, were O2−● and e−. Finally, a photocatalytic test was performed with a drinking water sample polluted by As(III), showing photocatalytic performance similar to distilled water. Therefore, gadolinium-doped bismuth ferrite can be considered an efficient catalytic material for the oxidation of As(III) to As(V) under visible light.
... Many physical, chemical, and biological techniques for decontamination and depolarization have been investigated by researchers, owing the past three decades [15][16][17]. The purification of wastewater may be accomplished using a variety of processes, some of the more frequent includes, chemical precipitation [18], coagulation and flocculation [19], gelling reagents [20] and photo-catalysis [21]; however, broad implementation of these innovative approaches of water purification has been limited by their high initial cost, limited water treatment volume, and high chemical usage [22]. ...
... Photocatalysis has received much more attention for environmental treatment owing to its pollution-free nature as it uses solar energy [9][10][11]. Recent work reveals that heterogeneous photocatalysts are the most promising material due to their higher stability, facile separation of products, and easier recyclability for photocatalytic treatment of wastewater [12][13][14][15][16][17][18][19]. Transition metal oxides (TMO) are promising materials among all the heterogeneous catalysts for faster and recyclable water treatment [20][21][22][23][24][25][26][27][28][29][30]. ...
... This makes them particularly useful for air and water purification applications, where they can be incorporated into filters or coatings to remove pollutants and create cleaner, safer environments. In addition to their pollution reduction capabilities, photocatalytic nanomaterials also have potential for waste treatment, carbon dioxide reduction, soil remediation, disinfection and environmental monitoring applications (Ahmed and Haider 2018, Kandy and Fuels 2020, Mamba and Mishra 2016, Nahar et al. 2017, Perović et al. 2020, Wang et al. 2021a, Zhao et al. 2021. For example, they can be used to break down organic waste into simpler, less harmful compounds, convert carbon dioxide into useful chemicals, and detect pollutants in air, water and soil. ...
... Indeed, photocatalysis has become a versatile and promising technology with extensive uses in a range of sectors [58,59]. Photocatalysts enable chemical reactions that can break down toxic pollutants and transform them into less harmful or useful chemicals, providing an ecofriendly method for ensuring the sustainability of the environment [58,59]. ...
... Indeed, photocatalysis has become a versatile and promising technology with extensive uses in a range of sectors [58,59]. Photocatalysts enable chemical reactions that can break down toxic pollutants and transform them into less harmful or useful chemicals, providing an ecofriendly method for ensuring the sustainability of the environment [58,59]. Due to its promise in multiple practical uses, photocatalysis has recently been applied and explored in a wide range of areas and domains. ...
Sillenite materials have been the subject of intense investigation for recent years due to their unique characteristics. They possess a distinct structure with space group I23, allowing them to exhibit distinctive features, such as an electronic structure ideal for certain applications such as photocatalysis. The present research delves into the structure, synthesis, and properties of sillenites, highlighting their suitability for photocatalysis. It explores also advanced engineering strategies for designing sillenite-based photocatalysts, including heterojunction formation, morphology modification, doping, and hybrid processes. Each strategy offers advantages and limitations that are critically discussed. The review then lists and discusses the photocatalytic performance of various sillenite-based systems recently developed for common applications, such as removing hazardous organic and inorganic contaminants, and even infrequent applications, such as microbial inactivation, H2 generation, CO2 reduction and N2 fixation. Finally, valuable insights and suggestions are put forward for future research directions in the field of sillenite-based photocatalysis. This comprehensive overview would provide a valuable resource for the development of efficient photocatalytic systems to address environmental and energy challenges.
... In water treatment, contaminant sensing, and in energy production nanomaterials have many applications (Hashim et al., 2018). The recent method that is used for the treatment of wastewater is the heterogeneous photocatalysis process (Ahmed & Haider, 2018). During this process oxide semiconductor which is mostly titanium oxide (TiO2) used in the form of rutile or anatase, emits photoexcited electrons and generates holes which is positively charged. ...
Water pollution is the main problem in the current scenario which is being faced by mankind due to the industrial and commercial effects. Industrial effluents contain heavy metals and inorganic ions like nitrates and phosphate ions. These ions are being included in waterways through industrial runoff. When the concentration of these hazardous pollutants increases in aquatic flora and fauna causes severe health problems. So remediation of these toxicants from water reserves is of chief importance. Conventional processes along with modern processes are being used for the treatment of industrial wastes. Photo-degradation is a modern method used for the degradation of inorganic ions due to its environmentally friendly nature and cost-effectiveness. In a recent study Aluminum oxide (Al2O3) nanoparticles were synthesized via a green approach at different pH by using Cymbopogan citratus (lemongrass) plant extract and these nanoparticles were used for the removal of inorganic ions from wastewater. The nanoparticles of different pH showed different % degradation of the inorganic ions in acidic medium removal of inorganic waste was less, in basic media % degradation was more as compared to acidic media but maximum % degradation was observed in neutral media like that average % degradation 91% and 81% was observed for nitrate and phosphate ions. The maximum absorbance occurred at 212nm and Al2O3 nanoparticles showed absorbance from 210nm-217nm. The R2 values of pseudo1st, 2nd, and BMG models were 0.956, 0.837, 0.7007 0.95, 0.896, and 0.756 for the nitrate and phosphate ions. Characterizations of synthesized particles were investigated by using UV-visible spectroscopy and other analytical methods like X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The statistical analyses were done using Simple Linear regression (SLR).
