Use of peat-based sorbents for removal of arsenic compounds

It is important to apply sorbent materials for purification of water from arsenic contamination due to serious arsenic pollution worldwide. We have developed new sorbents based on natural materials that provide a cheap and environmentally friendly alternative. For the first time, peat modified with iron compounds and iron humates were tested for sorption of arsenic compounds. The highest sorption capacity was found in peat modified with iron compounds. We have found that sorption of different arsenic speciation forms was strongly dependent on solution pH, reaction time and temperature. Calculations of the sorption process using thermodynamic parameters indicate the spontaneity of sorption process and its endothermic nature. Sorption kinetics showed that most arsenates are removed within 2 hours, and the kinetics of arsenate sorption on modified peat can be described by the pseudo-second order mechanism.