Advances in adsorption technologies for hexavalent chromium removal: Mechanisms, materials, and optimization strategies

In the realm of environmental engineering and water treatment, significant attention has been devoted to the removal of hexavalent chromium Cr (VI) from wastewater. Delving into the mechanisms of adsorption reveals a complex interplay of ion exchange, surface complexation, and electrostatic interactions dictating the binding of Cr (VI) to various adsorption materials. Utilizing diverse adsorbents like 2-D materials, metal oxides, and bio-based substances is driven by their exceptional absorptive capacity and specificity. Key parameters such as pH, temperature, initial concentration, and dosage are scrutinized to optimize the efficiency of adsorbent removal and ascertain the absorptive nature of the adsorbate. Beyond natural sources, human activities have exacerbated chromium contamination across ecosystems, posing a threat to food chains due to chromium's non-biodegradable nature and persistence. Chromium affects a wide range of life forms, including humans, aquatic organisms, and terrestrial species, through the accumulation and repercussions of chromium discharge. The leaching of chromium into ground and surface water triggers various health issues such as dermatitis, allergic reactions, skin ulcerations, bronchial carcinoma, asthma, and gastroenteritis. This review intended to list different treatment technologies for chromium removal along with their mechanism. Different types of sensors used for chromium detection have also been explored.