• journal_title：Clays and Clay Minerals
• Contributor：Mingshan Wang ; Libing Liao ; Xiuli Zhang ; Zhaohui Li ; Zhiguo Xia ; Weida Cao
• Publisher：Clay Minerals Society
• Date：2011-
• Format：text/html
• Language：en
• Identifier：10.1346/CCMN.2011.0590503
• journal_abbrev：Clays and Clay Minerals
• issn：0009-8604
• volume：59
• issue：5
• firstpage：459
• section：Articles

Vermiculite is a common layered silicate clay mineral which has good adsorption and ion-exchange properties, and which is used to remove pollutants from groundwater. The adsorption by vermiculite from Heibei Province, China, of low-concentration ammonium in water was assessed here to evaluate the effects of adsorption time, particle size, adsorbent dose, pH, and temperature. Using Fourier-transform infrared spectroscopy, the concentration of NH₄⁺ at 1430 cm⁻¹ was evaluated after ammonium was adsorbed by vermiculite. Based on Langmuir-model analysis, the adsorption capacity of the Chinese vermiculite (in the particle-size range 0.025–0.075 mm) for ammonium was 18 mg/g after 3 h of equilibration. Optimal adsorption occurred at pH 6–7 and 60°C, which is different from that at high ammonium concentrations. Smaller particle-size fractions showed greater degrees of adsorption. Increase in Mg²⁺, K⁺, or Na⁺ concentrations influenced ammonium adsorption and, therefore, indicated that cation exchange was the mechanism for ammonium uptake from low-concentration solutions.