A comprehensive review on emerging natural and tailored materials for chromium-contaminated water treatment and environmental remediation

The effluent discharge containing chromium, which is toxic and potentially carcinogenic, will lead to serious environmental problems. The removal of chromium is usually carried out by ion exchange, precipitation, membrane filtration, adsorption, and photocatalytic reduction. This paper focuses on the adsorption method to remove chromium. For decades, the rapid development of adsorbent materials, including natural minerals, synthetic polymers, metal oxides, layered double hydroxides, mesoporous silica, carbon materials and porous framework materials, etc. In this review, we provide a systematic and comprehensive overview of the research on chromium removal by these emerging materials. The different determination methods of chromium and adsorption mechanisms, including macroscopic experiment methods, microscopic spectrum methods and calculation methods, are summarized in brief. Finally, we summarized the current problems according to the performance comparison of various adsorbents, and proposed the development direction of adsorbents used in the treatment of chromium-containing wastewater in hopes of fueling more dramatic advancements in the material and environmental remediation fields.