Search

Fly ash is a significant pollutant in thermal power stations. Although this waste harms the environment and humans, it is badly removed and managed, and only a few studies are interested in this waste. For that, this study aims to valorise fly ash into potential adsorbents to treat tannery effluents for the first time. The physicochemical characterisation showed that fly ash has a pHpzc of 9.78, a very porous structure, a high specific surface area of 3127.2 m 2 /g with a total pore volume of 3.27 cm 3 /g, and a high silica and aluminium percentage. SEM showed that the fly ash studied has a small particle size ranging between 32 nm and 100 μm. Batch adsorption experiments were done, and the effects of adsorption parameters were investigated. The kinetics and isotherms models indicate that the equilibriums were achieved in 30 min, where the maximum uptake capacity was 2496, 223.7 and 106.8 mg/g for Chemical Oxygen Demand (COD), chromium (VI) and sulfide ions, respectively. The kinetic data were well fitted to the pseudo-second-order model and showed that adsorption onto fly ash may be chemical and physical simultaneously. Freundlich's model gave a better fit for the experimental adsorption equilibrium data and displayed multilayer adsorption. The thermodynamic isotherm showed that the adsorption onto fly ash is thermodynamically spontaneous (ΔG° < 0) and endothermic (ΔH° > 0). In conclusion, fly ash, which is a free material, has a more robust adsorption capacity than other expensive materials. Thus, it can be a promising, eco-friendly, attractive adsorbent for industrial wastewater treatment., Competing Interests: The authors declare no conflict of interest., (© 2022 Published by Elsevier Ltd.)

This study investigates the performance of soil and OMW microfloras in OMW organic matter humification in soil. In order to highlight the role of OMW and soil microfloras in the processes of OMW organic matter humification, either OMW or soil was sterilized with autoclaving. The study was carried out in microcosms of 1l containing 500 g of raw or sterilized soil, to which was added 200 ml of raw or sterilized OMW. After 24 months of incubation, the amount of phenolic compounds in the different microcosms was statistically indifferent compared to the control. However, TG-DTA and FTIR analysis of soil humic acids showed that recalcitrant OMW phenolic compounds remain in soil humus in the microcosm: sterilized OMW + raw soil, even after 24 months. Results show that humic acids detected in presence of OMW microflora are loaded with proteins and carbonated compounds and deprived of phenolic compounds and aliphatics with long chain, while humic acids detected in absence of OMW microflora are loaded with phenolic compounds., (© 2020 Published by Elsevier Ltd.)