Rice husk and rice straw based materials for toxic metals and dyes removal: a comprehensive and critical review

This review investigated depth literature survey on the removal of various heavy metals and dyes contamination. The current study is a broad review of the different methods of preparation of biowaste adsorbent from rice husk and rice straw that has been implemented for the adsorption of many hazardous heavy metals and dyes in order to reduce their harmful effect on the environment. The selection of rice waste-based material for the adsorption process was considered due to its cost-effectiveness, easy availability, high adsorption efficiency, and reusability. This study is a comprehensive review of the adsorption of toxic heavy metals and dyes using rice husk and rice straw-based adsorbents either in bare or in modified forms under different physicochemical processes. In addition, some parameters affecting adsorption capability like pH, initial dye concentration, equilibrium time, temperature, adsorbent dosage, and shaking or stirring speed influence the adsorption mechanism have been discussed thoroughly. The applicability of various adsorption isotherm models and adsorption kinetic models for dye adsorption by various rice husk and straw biomass adsorbents is also reported here. Finally, from the literature reviewed conclusions have been drawn and also proposed a few future research suggestions.