Preparation of Amino-Functionalized Silica for Adsorption of Ammonium Ions

• Main Authors: Hsieh, Yo-Tsung, 謝侑璁
• Other Authors: Chang, Sue-Min
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/kbceg5

碩士 === 國立交通大學 === 環境工程系所 === 106 === In this study, amino-functionalized silica (NH2-SiO2) was prepared as the adsorbent for NH4+ removal for the first time. Tetraethyl orthosilicate (TEOS) and 3-Aminopropyltriethoxysilane (APTES) were used as the precursor for SiO2 and the source of -NH2 functional groups, respectively. From the FTIR spectra, the wavenumber of 798 cm-1 in the pure SiO2 sample represented the Si-O-Si bonding, while in the NH2-SiO2 powders with different APTES：TEOS ratios, additional N-H bonds at 694cm-1 indicates that -NH2 was successfully modified on the SiO2 particles. When the APTES：TEOS ratio increased from 0：5 to 20：5, the NH4 + adsorption amount increased from an undetectable value to 9.85 mg/g, implying that -NH2 is an active adsorption site for NH4+ ions. The adsorption behavior and mechanism of NH2-SiO2 were investigated through kinetic adsorptions, isothermal adsorptions, and FTIR characterization. The kinetics was better fitted by the pseudo-second-order model with R2= 0.997. Adsorption isotherm was better fitted by the Langmuir model with R2= 0.984 and the maximum adsorption capacity of 11.53 mg/g. These results reveal that the rate-limiting step is the chemical reaction between NH4+ and -NH2. Most of -NH2 are in the form of -NH3+ in the solution, and the H+ ions on the -NH3+ groups were exchangeable with NH¬4+ ions. In the aspect of regeneration, the NH4+ desorption can be achieved by simple heating at 100℃ and the regeneration efficiency was 74.5%.