ABSTRACT
In this study, to simultaneously dispose of sludge and wastewater containing heavy metals, sludge biochar loaded with nano zero-valent-iron (nZVI) was prepared at 700 °C (nBC700) to remove Cr(VI) and Cu(II). The results showed the removal capacity of biochar was greatly improved by loading nZVI, and the adsorption capacities of biochar for Cu(II) and Cr(VI) increased by 251.96% and 205.18%. Pseudo-second-order kinetic and Sips isotherm models were fitted to the removal processes. Intraparticle diffusion models showed the removal process was controlled by surface diffusion and intraparticle diffusion. Competitive experiments showed Cr(VI) can compete with Cu(II) for active sites, but Cr(VI) was more easily removed by nBC700 through cation bridge. The removal mechanism illustrated removing Cu(II) mainly depended on complex precipitation, followed by reduction reaction, while Cr(VI) was on the contrary. This work provided effective data for sludge disposal and heavy metal removal.
Subject(s)
Carbonated Water , Metals, Heavy , Water Pollutants, Chemical , Adsorption , Charcoal/chemistry , Chromium/chemistry , Deuterium Oxide , Iron/chemistry , Sewage , Steam , Wastewater , Water/chemistry , Water Pollutants, Chemical/chemistryABSTRACT
A series of g-C3N4/SrTiO3 (CN/SrTiO3) composites with the different mass ratio of g-C3N4 were prepared by facile in situ hydrothermal growth method, which was utilized to degrade tetracycline antibiotics (TC) under the visible light. The obtained samples were characterized by XRD, SEM, XPS, FT-IR, and UV-vis DRS. The photocatalytic performance was also investigated in detail. The obtained 20% CN/SrTiO3 composite is sixfold of the pure SrTiO3 and twofold of the pristine g-C3N4 under the visible light irradiation. This impressive performance of the heterojunction is ascribed to the effective restraint of the charge carrier recombination and expanded light absorption region. Moreover, the stability of the composite is also researched in detail. At last, a possible photocatalytic mechanism and charge carrier transfer pathway were further discussed.
