Evaluation of humic acid embedded Chitosan/PVA composite performance in the removal of uranyl ions

In this study, the retention of uranyl ions on a novel, natural and cost-effective adsorbent, humic acid (HA) embedded chitosan/polyvinyl alcohol (Ch/PVA-HA) bio composite was investigated. The highest adsorption capacity reported in literature was achieved by Ch/PVA-HA in a column system in this study. Specific surface area of Ch/PVA-HA was found as 1.308 m2g-1 which is rather high comparing that of Ch/PVA (0.254 m2g-1). The maximum adsorption on Ch/PVA and Ch/PVA-HA were achieved in the range of 1 < pH < 5, and 1 < pH < 4, respectively. The batch tests showed that adsorption isotherm of uranyl ions was changed from Freundlich to Langmuir when the surface of Ch/PVA copolymer was covered with HA. The maximum uranyl adsorption capacity of Ch/PVA-HA was found as 37.8 mg/g while the column capacity was 1909 mg/g. The presence of HA enhanced the distribution ratio of uranyl ions between adsorbent phase and aqueous solution. Considering the results of the batch and column tests, it can be said that the Ch/PVA-HA may have high potential to use as alternative low-cost adsorbent for removal of uranyl ions. Also, this study will lead up synthesis of new adsorbents to provide higher and recoverable uranyl adsorption.