Modelling the kinetics of toxic metal desorption in sediment affected by a dam breakdown disaster in Doce River - Brazil

On November 5$^{th}$, 2015, Brazil's biggest socio-environmental disaster occurred. The mining dam spilled a huge brown plume of mining waste in the Doce River. Considering the hypothesis that each metal travels in a different way, the question is, how long will a toxic metal remain in the basin until the natural balance is achieved? Therefore, samples of sludge, sediment, and water were collected along the Doce River Basin, to characterise physical and chemically the sludge and assess the elements' total leaching by kinetic modelling. The sludge is composed mainly of quartz, hematite, and goethite. Toxic elements such as Al, Mn, Ag, Cd, Pb, Cu, and As were also found in the sediments. Manganese concentration and turbidity exceeded the maximum allowed by the Brazilian regulation for freshwater. A proposed sorption/desorption factor (F$_{SD}$) indicated that Mn$^{2+}$, Ag$^{+}$, and Cd$^{2+}$ can be mobilised about 80, 90, and 57 times more than its initial concentration. However, Pb, Al, As, Fe, and Cu ions remained immobilised on the sediments. The desorption kinetics showed lower rate constant (k) and higher initial desorption constant (h) for Mn$^{2+}$ than Cd$^{2+}$ and Ag$^{+}$, which can suggest both high- and low-affinity interaction sites for Mn$^{2+}$. The exponential decay from half-life demonstrated that metals can leach for months or years. The long-lasting releasing metal-rich tailing waste, in concentrations that endanger ecosystem and human health, makes it clear that long-term monitoring is required. It's worth mentioning that is necessary to strengthen the laws and Brazilian regulation on environmental issues

Modelling the kinetics of toxic metal desorption in sediment affected by a dam breakdown disaster in Doce River - Brazil

On November 5$^{th}$, 2015, Brazil's biggest socio-environmental disaster occurred. The mining dam spilled a huge brown plume of mining waste in the Doce River. Considering the hypothesis that each metal travels in a different way, the question is, how long will a toxic metal remain in the basin until the natural balance is achieved? Therefore, samples of sludge, sediment, and water were collected along the Doce River Basin, to characterise physical and chemically the sludge and assess the elements' total leaching by kinetic modelling. The sludge is composed mainly of quartz, hematite, and goethite. Toxic elements such as Al, Mn, Ag, Cd, Pb, Cu, and As were also found in the sediments. Manganese concentration and turbidity exceeded the maximum allowed by the Brazilian regulation for freshwater. A proposed sorption/desorption factor (F$_{SD}$) indicated that Mn$^{2+}$, Ag$^{+}$, and Cd$^{2+}$ can be mobilised about 80, 90, and 57 times more than its initial concentration. However, Pb, Al, As, Fe, and Cu ions remained immobilised on the sediments. The desorption kinetics showed lower rate constant (k) and higher initial desorption constant (h) for Mn$^{2+}$ than Cd$^{2+}$ and Ag$^{+}$, which can suggest both high- and low-affinity interaction sites for Mn$^{2+}$. The exponential decay from half-life demonstrated that metals can leach for months or years. The long-lasting releasing metal-rich tailing waste, in concentrations that endanger ecosystem and human health, makes it clear that long-term monitoring is required. It's worth mentioning that is necessary to strengthen the laws and Brazilian regulation on environmental issues

Crosslinkers for polysaccharides and proteins: Synthesis conditions, mechanisms, and crosslinking efficiency, a review

info:eu-repo/semantics/publishe

Caffeine Release from Magneto-Responsive Hydrogels Controlled by External Magnetic Field and Calcium Ions and Its Effect on the Viability of Neuronal Cells

Caffeine (CAF) is a psychostimulant present in many beverages and with rapid bioabsorption. For this reason, matrices that effectuate the sustained release of a low amount of CAF would help reduce the intake frequency and side effects caused by high doses of this stimulant. Thus, in this study, CAF was loaded into magnetic gelatin/alginate (Gel/Alg/MNP) hydrogels at 18.5 mg/ghydrogel. The in vitro release of CAF was evaluated in the absence and presence of an external magnetic field (EMF) and Ca2+. In all cases, the presence of Ca2+ (0.002 M) retarded the release of CAF due to favorable interactions between them. Remarkably, the release of CAF from Gel/Alg/MNP in PBS/CaCl2 (0.002 M) at 37 °C under an EMF was more sustained due to synergic effects. In PBS/CaCl2 (0.002 M) and at 37 °C, the amounts of CAF released after 45 min from Gel/Alg and Gel/Alg/MNP/EMF were 8.3 ± 0.2 mg/ghydrogel and 6.1 ± 0.8 mg/ghydrogel, respectively. The concentration of CAF released from Gel/Alg and Gel/Alg/MNP hydrogels amounted to ~0.35 mM, thereby promoting an increase in cell viability for 48 h. Gel/Alg and Gel/Alg/MNP hydrogels can be applied as reservoirs to release CAF at suitable concentrations, thus forestalling possible side effects and improving the viability of SH-SY5Y cells