Preparation of Natural Bio-Adsorbent from Green Tea Extract Powder and Its Application for Selective Removal of Cs(I) from Water

Abstract

The present study investigates a new adsorbent for Cs(I) removal from green tea extract. An extract of green tea rich in polyphenolic compounds was simply cross-linked using concentrated sulfuric acid to reduce aqueous solubility and improve Cs(I) adsorption. Dissolution of total organic carbon (TOC) from non-modified tea extract (TE, 4,324 mg/L) was drastically suppressed in cross-linked tea extract (CLTE, 13.6 mg/L). The adsorption performance of CLTE for Cs(I) was compared with TE, the feed material, using the batch-wise method. Kinetic study showed that the adsorption equilibrium can be reached within 4 h for native TE and 12 h for CLTE. The maximum adsorption capacity of Cs(I) using non-modified tea extract (TE, 0.20 mmol/g) was drastically increased after cross-linking (CLTE, 1.23 mmol/g). The Cs(I) ion was selectively adsorbed onto CLTE from a mixture containing a trace amount of Cs(I) and a high concentration of Na(I). Therefore, the CLTE adsorbent investigated in this study can be expected to be a potential efficient; and environmentally benign adsorbent for the treatment of water polluted with Cs(I) ion.