Synthesis of lignin-base bead adsorbent and its application in removing Cr (VI) from aqueous solution

A novel spherical lignin-base adsorbent (L-BAA) was prepared by reversed phase suspension polymerization technique. The L-BAA was characterized by element analysis and FTIR spectra. The modified lignin beads (L-BAA) were used to adsorb Cr (VI) from aqueous solution. The effects of the contact time, the pH value, the initial concentration and the temperature on the adsorption were investigated. It was found that Cr (VI) adsorption was greatly dependent on the pH and temperature of the Cr (VI) aqueous solution. When the temperature was 25 °C, the maximum capacity of 417.26 mg/g was attained at 0.82 pH. The adsorption capacity is better than other reported adsorbents. All of the end pHs were higher than the initial pHs. The results indicated that the adsorption belongs in ligand exchange mechanism. High temperature promoted adsorption, the high capacity 473.80 mg/g was attained at 35 °C and the adsorption efficiency was up to 94.76 %. This result indicated that the adsorption was not only physical but also chemical, which could be proved more by the FTIR spectra, and the adsorption was an endothermic progress.