RESUMEN
Plant-mediated synthesis of nanoparticles is a sustainable approach that has gained widespread scientific acceptance due to its numerous benefits and applications. In this study, a zinc oxide-doped activated carbon (ZAC) derived from palm kernel shells (PKS) was synthesized via a bioreduction route using a water-based extract of Nymphaea lotus leaves as a reducing agent. The synthesized ZAC nanocomposites were characterized using microscopic (TEM, SEM) and spectroscopic (FTIR, EDS, XRD, and UV-Vis) analyses. The adsorptive properties of ZAC and efficiency in scavenging a phenothiazine derivative (methylene blue) from an aqueous solution were investigated. Results reveal that nano-scale ZAC particles were crystalline, exhibited irregular shapes, with an average size of 45 nm, and were highly dispersed. The optimum quantity adsorbed was 248 mg/g at a methylene blue concentration of 140 mg/L for 60 min using 0.02 g/100 mL of ZAC. Adsorption and kinetics data closely aligned with the Freundlich isotherm and the pseudo-second-order model, respectively indicating heterogeneous surface adsorption and chemisorption as the dominant mechanisms. The regeneration study of ZAC shows that over five cycles, thermal regeneration maintained high adsorption capacity with minimal decline and chemical regeneration significantly led to reduction in the adsorption capacity but solvent washing offered a balance between efficacy and structural preservation.
RESUMEN
Anaerobic codigestion (AcD) of agroindustrial residues was investigated. Granular sludge from bench-scale bioreactors digesting different manure were acclimated and recycled as microbial seed sludge to demonstrate inoculum-type influence on digestion performance. The biomethane potential (BMP) assay was operated for 30 days at 40 ± 2 °C in batch-type laboratory-scale reactors (100 mL). In inoculum amended reactors, codigestion showed significant, yet distinctive, biomethanation than monodigestion with a 5-fold increase (p < 0.05) in average biogas (248.3 ± 5.30 mL gVS-1) and CH4 yield (207.5 ± 4.15 mL gVS-1). The pH, soluble chemical oxygen demand (sCOD) and volatile fatty acids (VFAs) concentrations were within limits for stable AcD process with elevated total solids (TS) and volatile solids (VS) removal efficiencies. This study reinforces advancements in the recycling of digestate in biodigesters and suggests the appropriate selection of inoculum, preferably cow manure, to essentially boost methane production from these wastes.
RESUMEN
In this study, bamboo impregnated with nanoscale zero-valent iron (nZVI) and nanoscale manganese (nMn) were prepared by the aqueous phase borohydride reduction method and characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and PIXE analysis. The synthesized nMn-bamboo and nZVI-bamboo composites were subsequently applied to the sorption of methylene blue (MB) dye from aqueous solution. The adsorption of MB dye was investigated under various experimental conditions such as pH, contact time, initial concentration of MB dye and adsorbent dosage. The results showed that the synthesized nZVI-bamboo composite was more effective than nMn-bamboo composite in terms of higher MB dye adsorption capacity of 322.5 mg/g compared to 263.5 mg/g of nMn-bamboo composite. At a concentration of 140 mg/L MB dye, 0.02 g of nZVI-bamboo and nMn-bamboo composites resulted in 79.6% and 78.3% removal, respectively, at 165 rpm, contact time of 120 min and at a solution pH of 7.6. The equilibrium data was best represented by Freundlich isotherm model and the pseudo-second order kinetic model better explained the kinetic data for both nZVI-bamboo and nMn-bamboo composites.