Recent advances on pollutants removal by rice husk as a bio-based adsorbent: A critical review

Rice husk is an attractive bio-based adsorbent material for pollutant removal since it is one of the low-cost and renewable resources. The objective of this review is to give a summary of the key scientific features related to pollutants removal using rice husk, with a specific emphasis on the effect of factors on adsorption capacity of rice husk. According to the results, rice husk has the removal potential of various pollutants and it can be more used in the wastewater treatment. On the other hand, untreated bio-based adsorbent in large-scale application can usually cause some difficulties and selection of appropriate pretreatment method for rice husk is also one of the major challenges. Therefore, this review studies different pretreatment methods as well as regeneration of adsorbent and the fate of adsorbed contaminants. According to the literature, pretreatment methods increase the rice husk capability and adsorption capacity and the chemical treatments have been more used than thermal treatments. Also, regeneration of rice husk adsorbent and adsorbed contaminants is applicable. Finally, examples of some applications and possibility of biocatalyst immobilization on the rice husk as a promising approach are presented. Results confirmed that rice husk has an excellent prospective potential for biocatalysts immobilization.