Exploring the insights and benefits of biomass-derived sulfuric acid activated carbon for selective recovery of gold from simulated waste streams.

The surging affluent in society, concomitant with increasing global demand for electrical and electronic devices, has led to a sharp rise in e-waste generation. E-wastes contain significant amounts of precious metals, such as gold, which can be recovered and reused, thus reducing the environmental impact of mining new metals. Selective recovery using sustainable and cost-effective materials and methods is therefore vital. This study undertook a detailed evaluation of low-cost biomass-derived activated carbon (AC) for selective recovery of Au from simulated e-waste streams. Utilizing high-performance synthesized H2SO4-AC, the adsorption mechanisms were explicated through a combination of characterization techniques, i.e., FE-SEM, BET, TGA, XRD, FTIR, XPS, and DFT simulations to conceptualize the atomic and molecular level interactions. Optimization of coordination geometries between model H2SO4-AC and anionic complexes revealed the most stable coordination for AuCl4- (binding energy, Eb = -4064.15 eV). The Au selectivity was further enhanced by reduction of Au(III) to Au(0), as determined by XRD and XPS. The adsorption reaction was relatively fast (∼5h), and maximum Au uptake reached 1679.74 ± 37.66 mg/g (among highest), achieved through adsorption isotherm experiments. Furthermore, a mixture of 0.5 M thiourea/1 M HCl could effectively elute the loaded Au and regenerate the spent AC. This study presents radical attempts to examine in detail, the synergistic effects of H2SO4 activation on biomass-derived ACs for selective recovery of Au from complex mixtures. The paper therefore describes a novel approach for the selective recovery of Au from e-wastes using multifunctional biomass-derived H2SO4-AC.

Modelling the Survival of Acid-Adapted and Nonadapted Escherichia coli O157:H7 in Burkina: A Western African Traditional Fermented Milk Product.

Burkina, a traditional fermented dairy product, is consumed in most parts of West Africa, including Ghana. Studies on the microflora of Burkina have indicated the presence of Escherichia coli and other pathogenic organisms. Thus, predicting the survival of E. coli in the product will inform the best manufacturing and handling practices. This study investigated the combined effect of storage temperature and time on the survival of acid-adapted and acid-non-adapted E. coli O157:H7 in Burkina. Samples were pasteurised and inoculated with acid-adapted or acid-non-adapted E. coli O157:H7. They were stored at 5, 15, and 30°C for 0, 2, 4, 6, 8, 10, 12, 14, 18, and 48 h, and the bacteria colonies were enumerated. Growth rate (survival versus time) models were developed using MATLAB software. Observed data were fitted to the Baranyi model using the DMFit curve fitting software. The E. coli O157:H7 strain appeared inherently tolerant to acid, with storage time having the most significant effect on the response parameter, survival (log CFU/mL). A negative correlation was observed for the primary models (survival versus time), which accounted for 79-97% of the relationship (p < 0.05). Although E. coli survived, its growth was inhibited over time regardless of acid adaptation.

Effect of xanthan gum and carboxymethyl cellulose on structure, functional and sensorial properties of yam balls.

Yam and its products can be modified during processing to reduce losses and ensure food security in the developing world. Xanthan gum (XG) and carboxymethyl cellulose (CMC) were added at different concentrations to yam balls and their effect on the structural, functional, and sensory properties of frozen yam balls were investigated in this study. Freeze-thaw stability and oil absorption capacity of yam ball mix were determined. Sensory evaluation and instrumental texture profile analysis (TPA) were done on samples of deep-fried yam balls using TA-XT Texture Analyser. Yam balls mixture containing XG and CMC had significantly (p < 0.05) lower oil uptake and water migration rates of 0.19 g/g and 4.10% as compared to control products 0.25 g/g and 11.05% respectively. Deep-fried yam balls samples containing 1 g of both XG and CMC obtained higher scores for their sensory attributes, while samples containing 2 g of both hydrocolloids were the chewiest. The findings suggest that the addition of hydrocolloids; XG and CMC enhances the freeze-thaw stability and reduces the oil absorption potential of the yam balls mix, and improve the sensory and texture properties of deep-fried yam balls.