Development of novel inorganic adsorbent for water treatment

It has been particularly interesting to develop an adsorbent demonstrating a high adsorption capacity and low cost for removing various pollutants from contaminated waters. Inorganic chemical adsorbents have thus been studied widely, aiming at providing an alternative to the activated carbon in the treatment of surface and ground water and industrial effluents. This article aims to review and provide new insight into the recent development of modified clays, zeolites and layered double hydroxides based sorbents for the removal of aqueous contaminants such as heavy metals, natural and synthetic organic matter and anion contaminants. A new type of sorbent, metal-organic frameworks (MOFs), is also introduced owing to its extremely high surface areas and promising adsorption capacity in treating emerging organic micro-pollutants.

► Clay minerals and zeolites have cation exchange capacity and can be used to adsorb cationic pollutants.
► Cationic surfactant modified clays and zeolites are to be applicable for adsorption of anionic and organic containments.
► Layered double hydroxides (LDHs) possess good anion exchange capacity and are to be used to remove various oxyanions.
► Detailed studies are needed to explore the feasibility of replacing activated carbon with low-cost inorganic adsorbent.
► Future work on the LDHs is suggested to resolve the limitations of using this inorganic adsorbent in practical water treatment.
► Granulated format of inorganic adsorbents needs investigated further via the column tests in order to use them in practice.