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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.

This work investigated the potentiality of Hypnea musciformis algae as a biosorbent for the removal of indigo carmine dye from synthetic solution. The sorption experiments were performed in batch mode under different parametric conditions like pH, contact time, the average particle size of biosorbent and its dosage, dye solution initial concentration, and temperature. The experimental results confirmed the optimum contact time is at least 25 min and favorable pH of 5 for the biosorption of carmine dye. Langmuir, Freundlich, and Temkin isotherms have been used to test the equilibrium data and found the best fit with the Freundlich isotherm with a regression coefficient (R2) of 0.992 followed by Langmuir (R2 = 0.979) and Temkin isotherm (R2 = 0.94). The analysis of kinetic data revealed Pseudo first order as the best fit. The thermodynamic parameter evaluated confirmed the endothermic nature of indigo carmine dye biosorption process. [ABSTRACT FROM AUTHOR]

Considering the toxicity, the removal of heavy metals from the liquid effluent is of great significance. This article addresses the impact of the adsorbent bed height and flowrate on the adsorption performance and breakthrough curves in column studies. To explore the potential of Liagora viscida biosorbent, adsorption experiments were conducted in a packed column at various bed heights in the range of 2 to 6 cm and flow rates in the range of 10 to 20 ml/min. The maximum uptake of 53.90 mg/g has been achieved at the flow rate of 20 ml/min for an initial metal solution concentration of 20 ppm and pH and bed height of 6 and 2 cm, respectively. In the current study, the breakthrough (tb) and exhaust times (ts) correspond to 0.1 and 0.9, respectively. To predict the breakthrough characteristics, the experimental data were tested using Bohart‐Adam (B‐A), Bed Depth Service Time (BDST), Thomas, and Yoon‐Nelson (Y‐N) models. The experimental results confirmed that all three models except the Bohart‐Adams model were suitable for the experimental data with a good correlation coefficient. [ABSTRACT FROM AUTHOR]