Focus on the removal of lead and cadmium ions from aqueous solutions using starch derivatives: A review

Lead and cadmium are typical heavy metals that poses series of environmental and health risks when discharged indiscriminately. Starch is an abundant, renewable, physicochemically versatile and environment friendly biopolymer. Consequently, application of starch derivatives adsorbents (SDAs) in the removal/adsorption (as used interchangeably hereafter) of aqueous heavy metal ions (AHMIs) from water constitutes economical and sustainable water treatment techniques. Starch derivatives are developed to offset the intrinsic limitations of native starch, and impact requisite functional and structural properties. SDAs have been extensively studied for the removal of AHMIs, and this review is focused on the removal of Pb2+ and Cd2+, using SDAs categorized as single modified starch (SMS), dual modified starch (DMS), multiple modified starch (MMS), and graft copolymer/composite starch (GCS). This review also discuss the methods used in the synthesis of the SDAs, their affinity for the removal of Pb2+ and Cd2+, and the mechanisms involved in the processes.