Abstract
Water pollution caused by the highly toxic metal hexavalent chromium (Cr(VI)) creates significant human health and ecological risks. In this study, a novel adsorbent was used to treat Cr(VI)-containing wastewater; the adsorbent was prepared using red mud (RM) generated from the alumina production industry and the rare earth element lanthanum. This study explored adsorption performance, kinetics, and mechanisms. Results showed that the adsorption kinetics of the RM modified by lanthanum (La-RM), followed the pseudo-second-order model, with a rapid adsorption rate. Cr(VI) adsorption was positively associated with the absorbent dose, pH, temperature, and initial Cr(VI) concentration; coexisting anions had little impact. The maximum Cr(VI) adsorption capacity was 17.35 mg/g. Cr(VI) adsorption on La-RM was a mono-layer adsorption pattern, following the Langmuir isotherm model. Thermodynamic parameters showed the adsorption was spontaneous and endothermic. The adsorption of Cr(VI) on La-RM occurred as a result of LaOCl formation on the RM surface, which in turn further reacted with Cr(VI) in the wastewater. This study highlighted a method for converting industrial waste into a valuable material for wastewater treatment. The novel absorbent could be used as a potential adsorbent for treating Cr(VI)-contaminating wastewater, due to its cost-effectiveness and high adsorption capability.
Highlights
Rapid economic development has created significant environmental pollution in China, with heavy metal pollution becoming one of the most significant problems
Li H N et al reported that cobalt doped red mud was stable and toxicity free when it was used for catalytic ozonation of bezafibrate in wastewater [24]
This paper described Cr(VI) adsorption using a novel La-red mud (RM) material; adsorption was positively associated with the La-RM dose, pH, temperature, and initial Cr(VI) concentration
Summary
Rapid economic development has created significant environmental pollution in China, with heavy metal pollution becoming one of the most significant problems. Hexavalent chromium (Cr(VI)), a typical heavy metal, is one of the 25 most hazardous substances in the priority list of hazardous substances [1]. Cr(VI)-contaminated wastewater is generated in large volumes by many industries, such as leather tanning, plating, electroplating, anodizing baths, rinse waters, and other industrial activities [2]. Survey data indicate there are more than 10,000 electroplating factories in China, collectively discharging more than 4 billion cubic meters of Cr-contaminated wastewater annually [3]. Cr(VI) has a wide range of adverse impacts on plants, animals, and humans. Cr(VI) toxicity can lead to the function failure of liver, lung, kidney, and liver
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