Phosphorus-containing carbon sorbents for water purification

Abstract

Background. Activated carbon is a non-selective adsorbent. Therefore to increase of selectivity different modifications are used which leads to increasing production costs. Topical is one-pot preparation and modification of carbons from agricultural or wood processing (lignin) waste materials. Purpose – review of modern research on developing new modified adsorbents based on agricultural waste materials and their use for purification of water from the heavy metals ions - iron and copper.
Material and methods. Carbon sorbents were prepared by chemical activation with phosphoric acid of polymer (copolymer of styrene and divinyl benzene) and lignocellulosic precursors (waste of the processing of agricultural products – corn and fruit stones). Iron and copper adsorption was investigated from aqueous solutions using method spectrophotometry and iodometry, respectively.
Results. Phosphorus-containing carbon materials (sorbents) with adjustable performance were obtained by chemical activation with phosphoric acid of polymer (copolymer of styrene and divinyl benzene) and lignocellulosic precursor materials (by-products of the processing of agricultural products – corn cobs, and fruit stones) at 400 °C. Increasing the number of added phosphoric acid and the use of air during the carbonization of carbon enhanced development of microporosity and mesoporosity having bottle like shape with preferred size of the neck 3.1–3.4 nm. Steam activation without addition of phosphoric acid does not lead to the development of mesopores with size 3.1–3.4 nm.
The studies of iron ions and copper sorption by phosphorus-containing carbon adsorbents showed their high adsorption ability and advantage over ion exchange materials in adsorption of heavy metal ions from aqueous solutions in a dynamic mode.
Conclusion. Developed phosphorus-containing carbon sorbents are selective and effective for adsorption of heavy metal ions from aqueous solutions. The sorbents are superior to ion exchange materials for adsorption of heavy metal ions from aqueous solutions in a dynamic mode. High chemical resistance and high adsorption capacity of phosphorus-containing carbons makes them promising for water purification from heavy metal ions and drinking water. Phosphorus-containing carbon sorbents can be obtained from the by-products of agricultural (corn and fruit stones) and wood industry (lignin), which leads to the reduction of production costs and solving the problem of waste disposal.