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During the production of beer large amounts of yeast waste are generated. This paper considers the possible making of environmentally friendly adhesive compositions from such wastes. Chemical treatment of yeast wastes increases their adhesive characteristics. Chemical cross-linking with glutaric aldehyde and biological cross-linking by enzyme trans...
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... are not strong. Adding glutaric aldehyde changed the color of the glue to a reddish one. Experiments in which glutaric aldehyde was added to the modified yeast pellets resulted in decreasing the content of the available amino groups as compared with a control experiment in which no cross-linking agent was used (Fig. 3). The quantity of the available amino groups on the modified yeast pellets before treatment with glutaric aldehyde was 0.77 μgeq/g of the mixture. After addition of 1.2 mL of glutaric aldehyde, the content of the available amino groups decreased by 43% to 0.44 μgeq/g. Increasing the amount of glutaric aldehyde added to the modified yeast pellets to 1.9 and 2.6 mL resulted in the decrease of the available amino groups to the minimal amount (Fig. 3). The IR spectra show that the presence of glutaric aldehyde reduces the intensity of the -1 -1 absorption bands at frequencies 3500 cm and 1640 cm caused by free amino groups. (Fig. 4). Glutaric aldehyde crosslinks protein to amino groups, thereby reducing the degree of hydration and water solubility of adhesive compositions. Both the treated and untreated (with glutaric aldehyde) modified yeast pellets were spherical in shape, and they were placed under water for 24 h to investigate the effect of the glutaric aldehyde on the water resistance of the resulting modified yeast pellets (Fig. 5). Changes in the structure and shape were observed visually. The samples that had not been treated with glutaric aldehyde collapsed in 2 h, but the samples treated with glutaric aldehyde maintained their structures for 10 to 24 h, depending on the amount of glutaric aldehyde that was ...
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... These materials emit phenol and formaldehyde into the environment. Different methods are currently used to reduce the toxicity level of these materials (Haag et al. 2004; Pan et al. 2006; Kadimaliev et al. 2012), but they do not fundamentally solve the problem. Therefore, an intensive search is underway for new natural compounds that can replace resins with a biological binder. ...
A prospective binder composed of a microbial polysaccharide levan present in the culture fluid was obtained. The synthesis of levan was carried out by an Azotobacter vinelandii bacteria strain using molasses, distillery stillage, and milk whey as the nutrient medium. The maximum amount of levan produced in these experiments was 14.5 g/L. Composite materials were obtained based on wood waste and biological binder. Depending on the pressing behaviour, materials were obtained within a density range of 1083 to 1443 kg/m3 and a tensile strength of 7.2 to 32.4 MPa. Water absorption and thickness swelling were 7.2% and 14.9%, respectively. During hot pressing, the resulting materials changed in their attenuated total reflection-frustrated total reflection (ATR-FTR) spectra at frequencies of 930, 1000, and 1750 cm-1, indicating the occurrence of chemical and structural changes in individual components of the lignocellulosic raw materials and changes in the composition of biological binding agent. Analysis of the physico-mechanical properties and other results of the composite materials using scanning electron microscopy (SEM) and X-ray microtomography suggested that composite materials based on the microbial polysaccharide levan-containing binder are advanced, new, and eco-friendly substances.
... Meanwhile, some literature data indicates that compositions prepared from modified bioorganic waste can be used as substitutes of natural adhesives. For example, the authors have shown that the yeast residues with appropriate modification acquire adhesive properties and can be used as bio-adhesives for bonding paper, fabrics, and wood (Zhang et al. 2011; Kadimaliev et al. 2012). Analysis of the literature and physico-mechanical tests suggest that bio-adhesives can be used as a binder (adhesive) for pressed materials production. ...
... Bio-adhesive was produced according to the procedure described in the articles of Kadimaliev et al. (2012a,b). Yeast waste (Saccharomyces cerevisiae var. ...
... In a previous study, it was shown that the introduction of glutaric dialdehyde 5% solution into adhesive composition increases moisture resistance (Kadimaliev et al. 2012). This is due to the formation of proteins cross-linked by amino groups with strong azomethine (Fernandez-Lorente et al. 2006; House et al. 2007). ...
Pressed composites can be produced from wood sawdust waste using modified yeast biomass, waste as a bio-adhesive, ultra-dispersed bacterial cellulose (UBC) as a binder, and preliminary chemical cross-linking. The materials obtained were not inferior to traditional materials based on the required levels of toxic phenol-formaldehyde resin and physical and mechanical parameters. Physical and mechanical properties of the materials depended on the amount and viscosity of the binder, as well as on the chemical structure and conditions of chemical cross-linking and modified UBC application. The strengths of the best examples of the materials obtained were approximately 17 to 20 MPa, the densities were in the range of 1207 to 1255 kg/m3, and the water absorption was less than 20%. During hot pressing, notable changes were observed in the wood particles at FTIR-ATR spectra frequencies of 3620 cm -1, 3600 to 3000 cm -1, 2920 cm -1, 2850 cm-1, 1770 cm-1, 1650 cm-1, 1560 cm-1, and 1089 cm-1. This is mainly due to the chemical and structural changes in lignin, hemicellulose, and binder.
The environmental crisis and the safeguarding of the population's health has led to research into different ways of mitigating harmful gases. Among the emissions that the wood industry has sought to reduce are those of formaldehyde, which is why new green adhesive methods for wood panels have been investigated in recent years. In this research, particleboard with two bio-based wood adhesive (PB-bbwa) formulations. The first PB-bbwa formulation, based on proteins obtained from compounds from the alcoholic beverage industry, and the second PB-bbwa formulation, based on proteins from a mixture of compounds from the alcoholic beverage and food industries, were manufactured and tested to evaluate the physical–mechanical, thermal and formaldehyde emission properties of untreated and UV-treated formulations at a laboratory scale. The results of the physical properties obtained in the PB-bbwa were similar or even better than those of the control PB. Additionally, PB-bbwas improve on the control PB sample’s Janka hardness by least 28%, and a decrease in thermal conductivity in the edgewise position and formaldehyde emissions by 12% and 88%, respectively, in comparison to the control PB. The tests performed evidenced that PB-bbwas showed comparable performance against the control PB made with urea-formaldehyde and satisfied international standard requirements.
The change in the strength of particle boards made using nontoxic-modified residual brewer's yeast as a biobinder during thermal aging was studied. It was shown that the strength of the particle boards increased during the first 24 h when the boards were exposed to temperatures of + 50 and + 80 °C, and then the strength decreased. Through the approximation of the experimental results for the changes in strength during thermal aging using polynomial and power functions, the aging period (durability) of the particle boards under accelerated testing conditions was determined. The calculated values for the activation energy of the thermal degradation processes and the values of the actual (equivalent) operating temperature of the pressed products were used to calculate the durability of the wood composites under operating conditions. It was found that the estimated durability of particle boards made with brewer's yeast as a biobinder was 11 months and slightly lower than that of particle boards made with toxic synthetic resins.
The possibility of preparing Molding-Bioengineered materials, such as woodchip boards (WCB), from sawdust using technical lignosulfonate (LGS), a wood waste product, and a culture liquid (CL) of levan microbial polysaccharide producer by Azotobacter vinelandii D-08 is explored in this article. The parameters of the derived materials are comparable to those of traditional materials made from toxic Phenol-Formaldehyde resins. The various physical and mechanical characteristics of the materials depend on the quantity of the bonding agent used for the preparation. Adding a culture liquid increases the humidity resistance of the molding materials. Using electron microscopy and X-Ray Micro-Tomography, it is clear that the structure of woodchip boards become more homogeneous without microcracks with the addition of CL. The strength of the best samples prepared was approximately 24 to 29 MPa with a density of 1170 to 1255 kg/m3 and a swell on wetting of 6.7%. During hot pressing, noticeable changes were observed by Fourier transform infrared spectroscopy (FTIR) at frequencies typical of LGS Sulfonic-Acid groups, levan fructose fragments, and skeletal vibrations of a syringal/guaiacyl core in lignin and of C-H groups of hemicelluloses. This indicates the involvement of these functional groups in the process of binding wood particles with hot pressing.
