Abstract: To study the adsorption of phosphorus by lemon residues,the lemon residues was modified by H₂SO₄ and CaCl₂ solution,and the L₁₆(4⁵) orthogonal design was used to optimize the modification conditions.The specific surface area,pore volume and pore size of the adsorbent were tested.The adsorbent were characterized by SEM/EDS.The result showed that the optimal combination of modification conditions was CaCl₂ mass concentration of 20%,pH 8.5,adsorption time of 120 min and adsorption temperature of 25 ℃.Under these conditions,the absorption rate of phosphorus reached 93.6%.The significance of influencing factors was in the sequence of CaCl₂ mass concentration,adsorption time,adsorption temperature,pH.Tthe influence of CaCl₂ mass concentration was significant.After modification,the specific surface area increased by nearly 4 times,but the change of pore volume,pore size and iodine adsorption were little,and the ash rate reduced by nearly 70%.After adsorption,the elements of P were detected in the lemon residue,but its peak was not high.

Key words: lemon residue, modification, adsorption, phosphorus