title: Cellulose/chitin beads for adsorption of heavy metals in aqueous solution.
abstract: We successfully prepared the biodegradable cellulose/chitin beads by coagulating a blend of cellulose and chitin in 6 wt% NaOH/5 wt% thiourea aqueous solution with 5% H2SO4 as coagulant, and investigated the adsorption of heavy metals (Pb2+, Cd2+, Cu2+) from an aqueous solution on the beads by atomic absorption spectrophotometer. Batch adsorption experiments were carried out as a function of ion concentrations, initial pH, ionic strength, temperature, adsorption time and desorption time. The results revealed that the cellulose/chitin beads could adsorb effectively Pb2+, Cd2+ and Cu2+ ions, and the uptakes of Pb2+, Cd2+ and Cu2+ ions on cellulose/chitin beads were 0.33 mmol/g at pH0 4, 0.32 mmol/g at pH0 5 and 0.30 mmol/g at pH0 4, respectively. Experimental results also showed that the adsorption of these heavy metals was selective to be in the order of Pb2+ > Cd2+ > Cu2+ in a low ion concentration solution. The adsorption equilibrium time of these heavy metals on beads was 4-5 h, but the desorption time was 5-15 min. Moreover, these beads could be regenerated up to about 98% by treating with 1 mol/L HCl aqueous solution. The mechanisms for the removal of free heavy metal ions by cellulose/chitin beads was based on mainly complexation adsorption model, as well as a affinity of hydroxyl groups of the materials on metals. Therefore, we developed new environment-friendly beads prepared by a simple produce process for removal and recovery of heavy metals.
authors.affiliation: Department of Chemistry, Wuhan University, 4300072, China.
authors.forename: Dao
authors.initials: D
authors.lastname: Zhou
authors.forename: Lina
authors.initials: L
authors.lastname: Zhang
authors.forename: Jinping
authors.initials: J
authors.lastname: Zhou
authors.forename: Shenlian
authors.initials: S
authors.lastname: Guo
mesh_terms: D000327:Adsorption; D002104:Cadmium / Q000737:chemistry / Q000302:isolation & purification*; D002482:Cellulose / Q000737:chemistry*; D002686:Chitin / Q000737:chemistry*; D003300:Copper / Q000737:chemistry / Q000302:isolation & purification*; D006863:Hydrogen-Ion Concentration; D007854:Lead / Q000737:chemistry / Q000302:isolation & purification*; D014873:Water Pollutants / Q000302:isolation & purification*; D018508:Water Purification / Q000379:methods*
chemical_list: D014873:Water Pollutants; D002104:Cadmium; D002686:Chitin; D007854:Lead; D003300:Copper; D002482:Cellulose