Novel insights into adsorption of heavy metal ions using magnetic graphene composites

Abstract

Anthropogenic activities have detrimental consequences on global water pollution and freshwater availability. Unsustainable use of hazardous materials and inorganic chemicals in the environment can lead to contamination of water resources, and consequently, create health issues. Adsorption process has been deliberated as an affordable technique for the removal of heavy metals during water treatment using chemically functionalized and oxidized graphene-based materials. Therefore, the present work has summarized the adsorption of different heavy metals i.e., arsenic (III)/(V), lead (II), chromium (III)/(VI), and selenium (IV)/(VI) onto magnetic graphene-based composites. Further, this paper discusses the different synthesis techniques, surface morphological characteristics, and physio-chemical behaviour of magnetic graphene composites with diverse applications. Adsorption of heavy metals are significantly affected by morphology and structure of graphene-based oxides/composites as well as solution chemistry, viz., pH, adsorbent concentration, contact time, initial contaminant concentration, and adsorbent doses. Surface complexation, due to the inner-spherical complex functional groups (like –OH, –OH2+, NH3+, etc), encourages the adsorption and electrostatic interactions for removal of arsenic (III)/(V), lead (II), chromium (III)/(VI), and selenium (IV)/(VI) by using magnetic graphene-based composites at low pH (< 7). Sustainability needs to be achieved via novel functionalized magnetic graphene-based composites with the potential for enhanced adsorption capacity and reusability. Thus, investigation and advances on novel magnetic graphene composites for sustainability can have substantial implications via commercialization and environment-friendly application.