A new chelating agent, L-histidine-modified silica from rice husk (LHSRH), was prepared as a selective adsorbent for Pb(II). LHSRH was synthesized by immobilizing L-histidine on silica from rice husk modified with 3-aminopropyltrimethoxysilane. The LHSRH was used to adsorb Pb(II) ion. The pH range, amount of the adsorbent, and adsorption time were optimized by response surface methodology. We found the optimum condition for the adsorption of Pb(II) was at pH 5, adsorbent amount about 0.1 g, and adsorption time about 15 minutes. The adsorption capacity for Pb(II) ion was found to be 62.5 mg/g. The adsorption behavior of the matrix followed the Langmuir's model.

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