Modified biomass adsorbents for removal of organic pollutants: a review of batch and optimization studies

Modification of the adsorbent surfaces has been considered a fascinating strategy that enhances biomass-based adsorption properties for efficient removal of organic pollutants. This is based on the attempt to replace the cost-ineffectiveness of the commercial activated carbon. The present study discusses different modification strategies and a review on modified biomass materials for the sorption of organic contaminants. Unlike previous literatures in the field, wider range of these pollutants are discussed in this study under different categories including pesticides (such as insecticides, herbicides, fungicides), pharmaceutical (e.g. analgesic and antipyretic drugs, antibiotic drugs, non-steroidal anti-inflammatory drugs and antimalaria drugs), and dyes (e.g. azo, xanthene, miscellaneous diagnostic, tri-aryl methane, and phenol-derived polymeric dyes). It was observed that the acid-activated Posidonia oceanica and HNO3-modified rice husk displayed the highest and lowest adsorption capacities of 2681.9 and 0.35 mg/g for removing Rhodamine B dye and methyl parathion pesticide, respectively. The mechanistic aspects of organic pollutants adsorption, their corresponding regeneration studies, and environmental challenges with chemical modifications are also discussed. The use of computational (optimization) models for modified biomass-based adsorbents to remove organic pollutants is devoid in previous reviews but discussed in the present study. To foster more advancement in this field, the concluding part presents various challenges and knowledge gaps for furthering research towards more realistic industrial implementations.