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The work aims to synthesize and characterize vegetal charcoal (or biochar) from Syzygium cumini (AC-SC), evaluating the adsorption capacity for dexamethasone drug (DEX) removal, using the kinetic and equilibrium adsorption. The samples were characterized by N

The present work aims to evaluate the removal capacity of Rhodamine B dye (RhB) using nano-porous chitosan (NC) from shrimp shells. NC was characterized by XRD, SEM-EDS, N

The pollution of wastewater with dyes has become a serious environmental problem around the world. In this context, the work aims to synthesize and characterize a supported nanocatalyst (NZ-180) from rice husk (RH) and alum sludge (AS) incorporating silver (AgNPs@NZ-180) and titanium nanoparticles (TiNPs@NZ-180) for Rhodamine B (RhB) dye degradation, under UV and visible irradiation. Central rotatable composite design (CRCD) was used to determine ideal conditions, using nanocatalyst and dye concentration such as input variables and degradation percentage like response variable. Samples were characterized by XRD, SEM-EDS, N2 porosimetry, DLS, and zeta potential analyses. TiNPs@NZ-180 showed the best photocatalytic activity (62.62 and 50.82% under UV and visible irradiation, respectively). Specific surface area has increased from 35.90 to 418.90 m2 g−1 for NZ-180 and TiNPs@NZ-180, respectively. Photocatalytic performance of TiNPs@NZ-180 has reduced to 8 and 10% after 5 cycles under UV and visible light irradiation. Ideal conditions found by CRCD were 2.75 g L−1 and 20 mg L−1 for nanocatalyst and RhB concentrations, respectively. Therefore, (agro)industrial waste present such an alternative material for application in the removal of wastewater with dyes, which helps in the reduction of the impact of chemicals/pollutants on human and animal health.

The disposal of solid waste containing toxic metals in the composition is a problem of environmental and human contamination. The amount of waste as printed circuit boards has been increasing year by year. New processes that aim at recycling and subsequent application implementing a circular economy of this waste have been gaining importance. This study proposes the printed circuit boards characterization for the copper recycling by acid leaching in two steps, green synthesis of copper nanoparticles using ascorbic acid (vitamin C), and later application of nanoparticles into surfactant degradation through the Fenton-like process. Acid leaching proved a possible methodology for recycling copper, obtaining over 90% recovery. The printed circuit boards show to be a copper secondary source with a weight percentage of about 26 and recovery of 97% in two leaching stages. The synthesis of CuNPs was inferred through UV–Vis with absorption peak in 585 nm and modification of the coloration over time of solutions to dark brown. The syntheses were performed at 70 °C, 80 °C, and 90 °C and in 0.17, 0.5, 0.83, 1, 2, and 3 h, and the stability of copper nanoparticles was verified in 168, 720, and 960 h after syntheses. Stable nanoparticles were produced with different diameters, and they were applied as a catalyst in the Fenton reaction to degrade an amine-based surfactant used in the mining industry. The total carbon degradation found was 57%. It was possible to observe that the recycling of printed circuit boards is strategic to obtain copper from a secondary source, and the synthesis of copper nanoparticles could be used as a product to applicate in the circular economy using the Fenton process.