Removal of anionic pollutants from liquids by biomass materials: A review

The industrialization development has delivered a number of anionic species (nitrate, nitrite, cyanide, phosphate, perchlorate, and fluoride), as well as anionic metal complexes (chromate, arsenate/arsenite, vanadate and selenate/selenite) into ecosystems, which have received increasing concerns of environmental and human health risks. Increasing R&D emphasis has been placed on the development of cost-effective treatment technologies to remove these anionic pollutants. Among the advanced treatment technologies, sorption process has offered significant advantages like availability, profitability, simplicity in operation and efficiency. To exploit and use a low cost and high efficiency sorbent is the center of an industrial process. We present the current state of research on the preparation and utilization of biomaterials based activated carbons/anion exchange resins for removal of various anions. We report activation methods, especially recent chemical technologies to functionalize surface characteristics, specificity and selectivity of the biomass materials, and to enhance their sorption capacities and rates. The sorption as well as recovery capacities of the biomass sorbents studied in laboratory scale and pilot plant systems are summarized. It is evident that these biomaterials based sorbents have shown significantly low costs and comparable sorption capacities for various anions as those of commercial sorbents; this makes the biomaterials promising for the development of technically and economically feasible technology for removal anionic pollutants.