Innovative treatment of industrial effluents through combining ferric iron and attapulgite application.

The escalation of industrial activities has escalated the production of pharmaceutical and dyeing effluents, raising significant environmental issues. In this investigation, a hybrid approach of Fenton-like reactions and adsorption was used for deep treatment of these effluents, focusing on effects of variables like hydrogen peroxide concentration, catalyst type, pH, reaction duration, temperature, and adsorbent quantity on treatment effectiveness, and the efficacy of acid-modified attapulgite (AMATP) and ferric iron (Fe(III))-loaded AMATP (Fe(III)-AMATP) was examined. Optimal operational conditions were determined, and the possibility of reusing the catalysts was explored. Employing Fe3O4 as a heterogeneous catalyst and AMATP for adsorption, CODCr was reduced by 78.38-79.14%, total nitrogen by 71.53-77.43%, and phosphorus by 97.74-98.10% in pharmaceutical effluents. Similarly, for dyeing effluents, Fe(III)-AMATP achieved 79.87-80.94% CODCr, 68.59-70.93% total nitrogen, and 79.31-83.33% phosphorus reduction. Regeneration experiments revealed that Fe3O4 maintained 59.48% efficiency over three cycles, and Fe(III)-AMATP maintained 62.47% efficiency over four cycles. This work offers an economical, hybrid approach for effective pharmaceutical and dyeing effluent treatment, with broad application potential.

Novel combination of iron-carbon composite and Fenton oxidation processes for high-concentration antibiotic wastewater treatment.

The research presented herein explores the development of a novel iron-carbon composite, designed specifically for the improved treatment of high-concentration antibiotic wastewater. Employing a nitrogen-shielded thermal calcination approach, the investigation utilizes a blend of reductive iron powder, activated carbon, bentonite, copper powder, manganese dioxide, and ferric oxide to formulate an efficient iron-carbon composite. The oxygen exclusion process in iron-carbon particles results in distinctive electrochemical cells formation, markedly enhancing wastewater degradation efficiency. Iron-carbon micro-electrolysis not only boosts the biochemical degradability of concentrated antibiotic wastewater but also mitigates acute biological toxicity. In response to the increased Fe2+ levels found in micro-electrolysis wastewater, this research incorporates Fenton oxidation for advanced treatment of the micro-electrolysis byproducts. Through the synergistic application of iron-carbon micro-electrolysis and Fenton oxidation, this research accomplishes a significant decrease in the initial COD levels of high-concentration antibiotic wastewater, reducing them from 90,000 mg/L to about 30,000 mg/L, thus achieving an impressive removal efficiency of 66.9%. This integrated methodology effectively reduces the pollutant load, and the recycling of Fe2+ in the Fenton process additionally contributes to the reduction in both the volume and cost associated with solid waste treatment. This research underscores the considerable potential of the iron-carbon composite material in efficiently managing high-concentration antibiotic wastewater, thereby making a notable contribution to the field of environmental science.

Facile preparation of novel nickel sulfide modified KNbO3 heterojunction composite and its enhanced performance in photocatalytic nitrogen fixation.

This work was designed to prepare a novel NiS/KNbO3 p-n heterojunction composite for efficient photocatalytic nitrogen fixation under simulated sunlight. The NiS/KNbO3 photocatalyst was prepared through a two-step hydrothermal method. X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy analyses proved that NiS nanoparticles were closely decorated on the surface of KNbO3 nanorods, to facilitate the migration of electrons between the two semiconductors. Mott-Schottky analysis indicated that the Femi level of KNbO3 is higher than that of NiS. Thus, the electron migration from KNbO3 to NiS occurs naturally. This migration elevates the band potential of NiS, makes NiS/KNbO3 form a type-II photocatalyst, and generates an internal electric field in the composite. The synergetic effect of the internal electric field and the type-II band structure endows NiS/KNbO3 with high efficiency in the spatial separation of photogenerated electron-hole pairs, verified by electrochemical impedance spectroscopy and transient photocurrent experiments. Therefore, NiS/KNbO3 presents good efficiency in photocatalytic N2 reduction with an NH3 production rate of 155.6 µmol·L-1·g-1·h-1, which is 1.9 and 6.8 times higher than those of KNbO3 and NiS, respectively. UV-visible diffuse reflectance spectroscopy and N2-adsorption experiments were also performed to investigate the effect of light absorption and surface area on the photocatalytic reaction. Nevertheless, compared with the great promotion effect in charge separation, the contribution of the two factors can be ignored.