RESUMEN
In this study, we report on the synthesis of ternary photocatalysts comprising TiO2/SnO2/g-C3N4 for the degradation of ciprofloxacin (CIP) in water. SnO2 nanoparticles were synthesized via the sol-gel method, while g-C3N4 was obtained through melamine calcination. Commercial TiO2 and SnO2 nanopowders were also used. The heterojunctions were synthesized via the wet impregnation method. The photocatalysts were characterized via various techniques, including XRD, TEM, STEM, FTIR, N2 adsorption, UV-Vis DR, and hole tests. Photocatalytic degradation tests of CIP were carried out under UV, visible, and solar radiation. The P25/npA/g-C3N4 (90/10) material exhibited the best performance, achieving CIP degradation of over 97%. The synthesized materials demonstrated excellent initial adsorption of CIP, around 30%, which facilitated subsequent degradation. Notably, the CIP photocatalytic degradation tests performed under solar radiation showed a synergistic effect between the base materials and carbon nitride in highly energetic environments. These results highlight the effectiveness of ternary photocatalysts TiO2/SnO2/g-C3N4 for CIP degradation, particularly under solar radiation.
RESUMEN
The use of natural zeolite clinoptilolite to reduce the leaching rate of potentially toxic elements such as Cd, Pb, and Mn in soil from mine tailings was studied. Soil from the surroundings of the mine El Bote in Zacatecas, Mexico, was analyzed, and the zeolite was characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, and nitrogen physisorption. An ammonium-exchange method for the zeolite was employed. Leaching experiments using packed columns with polluted soil and zeolite mixtures were carried out and the effect of the pH of the carrier solutions was studied. Incorporation of zeolite in the soil achieved a beneficial increase in pH, from 5.03 to 6.95. The concentration of Cd and Mn was reduced when zeolite was present in the column and the ammonium-modified zeolite with ammonia also enhanced the concentration reduction of metallic species in leachates in a range of 28 to 68%. The first-order model best fits the experimental data, suggesting that the leaching rate is controlled by concentration difference between the liquid and the soil matrix. These results demonstrate the potential for using natural zeolite clinoptilolite to reduce the leaching rate of potentially toxic elements in soil from mine tailings.
RESUMEN
The significant amounts of agriculture residues such as bean straw (BS) in rural areas, advises its valorisation for energy recovery. The feasibility of using BS for biogas production through anaerobic digestion was assessed. Prior to this, a fungal pre-treatment to hydrolyse BS with Pleutorus ostreatus was studied at 30°C and 100â rpm in orbital incubators with 1, 10 and 30â mg fungus/g straw for 14, 21 and 28 days. Then, anaerobic digestion experiments were performed in batch with cow manure (CM) as co-substrate and pre-treated BS at ratios (g/g total solids) of 1/2, 1/3, 1/5 and 0/1. Maximum lignin (18%) and hemicellulose (44%) degradation occurred at 30â mg fungus/g straw and 28 days, along with the highest total methane yield (38â mL CH4/g VS loaded). The total amount of methane decreased when increasing CM in the experiments (701.4-191.5â mL CH4), suggesting inhibition owed to a component of CM. Self-sustained biogas production of BS occurred due to the presence of bacteria (i.e. Bacilli and Bacteroidia) and archea (i.e. Methanobacteria and Methanomicrobia). However, the usage of a full-active inoculum should be studied for higher biogas production rates.