Adsorption of Hg2+ from aqueous solution on functionalized MCM-41

Abstract

Mesoporous MCM-41 has been functionalized using 3-aminopropyltriethoxysilane (KH550) and 3-(2-aminoethylamino)propyldimethoxymethylsilane (KH602). The adsorption behavior of Hg²⁺ on functionalized MCM-41 was investigated systematically. The adsorption rates were very fast and agreed well with pseudo second-order kinetics. The adsorption isotherms fitted the Langmuir model well. The modified MCM-41 adsorbent functionalized using KH602 (NM2) displayed the greatest mercury adsorption efficiency and residual concentration of Hg²⁺ was able to achieve drinking water standards. The regeneration capacity maintained 99.75% performance when the initial solution concentration was 4 mg L⁻¹ (4000 ppb) at the tenth cycle, meeting the safe regulatory discharge standard for the first time. Meanwhile, regeneration by washing only with deionized water to remove residual surface Hg²⁺ can cut down the cost of traditional desorption agents and reduce damage to the structure of the adsorbent. Therefore, the adsorbent NM2 has potential and promising application in the field of water pollution control.