Study on the removal of Cr(vi) from ethylene wastewater using stabilized nanoscale zero-valent iron based on porous basalt material

Abstract

In this research, the authors prepared stabilized nanoscale zero-valent iron based on natural basalt material and used it to remove Cr(VI) from ethylene wastewater. SEM, TEM, FTIR, XRD, BET and other means were used to characterize the material (BM-nZVI-CMC) before and after loading. The results showed that under the action of CMC, the Fe⁰ particles after loading were all nano-sized (particle size between 43 and 119 nm), and FTIR and XRD results show that compared with BM-nZVI, Fe⁰ in the stabilized material (BM-nZVI-CMC) is more likely to remain in the form of zero valence without being oxidized, that is, the stability is significantly enhanced. BM-nZVI-CMC had a large specific surface area (433.29 m² g⁻¹) and suitable pore size (51.05 nm). In the experiments of Cr(VI) removal by adsorption, the acidity experiment results show that, except under strong acidic conditions, BM-nZVI-CMC has good adsorption effect on Cr(VI); the isotherm experiment results show that BM-nZVI-CMC's adsorption of Cr(VI) more fits the Langmuir model (Langmuir R² = 0.991), indicating a tendency towards chemical adsorption; the kinetic experiment results show that BM-nZVI-CMC's porous structure and large specific surface area are conducive to improving the adsorption rate, and the adsorption of Cr(VI) by BM-nZVI-CMC is the result of both physical and chemical processes (pseudo first order R² = 0.997; pseudo second-order R² = 0.995); BM-nZVI-CMC has a high removal rate for Cr(VI) in different types of ethylene wastewater (quench water and ground oil-bearing water, more than 87%; DS discharge water, more than 73%), and after 120 hours of storage, the adsorption effect of BM-nZVI-CMC for Cr(VI) remains at a high level.