The rapid advancement of technical advancements has resulted in the generation of substantial amount of electronic trash (e-waste). The volume of e-waste created, as well as the presence of both dangerous and beneficial elements, enhances the business potential of recovery and recycling significantly. Waste printed circuit boards (PCBs) include a number of hazardous heavy metals, including copper (Cu), tin (Sn), lead (Pb), and others (Zn, Ni, Fe, Br, Mn, Mg etc.). These discarded metals without treatment threaten the economy, the environment, and human health. Heavy metal recovery from PCBs is a big difficulty for researchers. The present review focuses on technological advances in the recovery of toxic, precious metals from PCBs.
To mitigate the negative effects of pollution produced by the growing levels of pollutants in the environment, research and development of novel and more effective materials for the treatment of pollutants originating from a variety of industrial sources should be prioritized. In this research, a UV-irradiated nano-graphene oxide (UV/n-GO) was developed and studied for methylene blue (MB) adsorption. Furthermore, the batch adsorption studies were modelled using response surface modelling (RSM) and artificial neural networks (ANNs). Investigations employing FTIR, XRD, and SEM were carried out to characterize the adsorbent. The best MB removal of 95.81% was obtained at a pH of 6, a dose of 0.4 g/L, an MB concentration of 25 mg/L, and a period of 40 min. This was accomplished with a desirability score of 0.853. A three-layer backpropagation network with an ideal structure of 4-4-1 was used to create an ANN model. The R2 and MSE values determined by comparing the modelled data with the experimental data were 0.9572 and 0.00012, respectively. The % MB removal predicted by ANN was 94.76%. The kinetics of adsorption corresponded well with the pseudo-second-order model (R2 > 0.97). According to correlation coefficients, the order of adsorption isotherm models is Redlich–Peterson > Temkin > Langmuir > Freundlich. Thermodynamic investigations show that MB adsorption was both spontaneous and endothermic.
The municipal wastewater may be treated using a number of different types of fixed beds that have a larger surface area. Since the fibrous materials have such a large specific surface area, they are frequently considered to be the best option for greater microbiological support and treatment efficacy. In this research, natural fibre materials such as coir fibre and areca husk were investigated for their potential to function as fixed aerated beds for the treatment of municipal wastewater. During the experiment, variations in the chemical oxygen demand (COD), biological oxygen demand (BOD), total dissolved solids (TDS), and total suspended solids (TSS) of the effluent were used to determine how well the aerated fixed bed work in treating the wastewater. The most efficient operating parameters for the successful treatment of wastewater were determined to be a contact period of 72 hrs, a filter medium depth of 5 cm, and a packing density of 10 kg/m3. The reductions in BOD, COD, TDS, and TSS for coir fibre are 55%, 58.8%, 57.8%, and 51.89%, respectively, whereas the reductions for areca husk are 38.3%, 37.78%, 31.76%, and 30.56%, respectively. In the course of this experiment, the coir fibre was discovered to be marginally more effective in comparison to the areca husk.
Electronic garbage is one of the fastest-growing waste streams. Its disposal and appropriate management are a worldwide concern. Printed circuit boards (PCBs) are critical components in contemporary electronic gadgets that contain toxic elements. Bioprocessing of PCBs for metal recovery employing microbial methods has evolved as a green solution in metallurgical operations. Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans were used in this study to leach metals from powdered waste PCBs. The RSM is used for optimizing the leaching conditions. The optimal conditions obtained were a bacterial activation period of 28 days, a pulp density of 23 g/L, and a temperature of 31°C. A confirmatory experiment under these optimal circumstances yielded recovery rates of Cu2+, Sn2+, Pb2+, and Zn2+ of 95.62%, 96.27%, 95.6%, and 98.25%, respectively.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.