Heavy metal pollution in the environment and effects on human health is within the most important issues. Because of continuous deterioration of water quality and persisting contamination level it has been observed and concerned by the scientists. Recently, to remove heavy metals from water/wastewater using various methods has been extensively studied. In conventional technologies, heavy metal removal/remediation is provided expensive because of non-regenerable materials used and high costs. Adsorption processes are being widely performed by several researchers for this purpose and various materials have been frequently used as adsorbent. It has been proved that adsorption is an effective method for purification, because of significant advantages including stability, utility, low-cost, ease of operation and performance. As adsorption technology is reduce the heavy metal ions concentrations to very low levels and because of using various low-cost adsorbent materials including biosorbents, clays, activated carbons, zeolites, metal oxides, it has major advantages. Metal adsorption onto adsorbent material, especially on agricultural wastes is a rather complex process because it is controlled by various factors. This process includes complexation, chemisorption, adsorption-complexation on surface and pores, micro precipitation, ion exchange. When used biological materials for adsorption process, some functional groups including sulphydryl, amido, hydroxyl and carboxyl, attach metal ions from water. This paper reviews the available adsorbent materials that have been used to heavy metal removal from water/wastewater and evaluates this technique advantages. Herein, the biosorbents such as banana peel, astragalus, chestnut sheel, natural adsorbents including clay also some artificial materials, like carbon-nanomaterials, zeolites, metal oxides, are reviewed as adsorbent materials for removal of different heavy metal ions like As(V), Pb(II), Cd(II), Cr(VI), Th(IV) and Eu(III) from water/wastewater.
