Synthesis of adsorbent materials from FELDSPAR for removal of ammonium in water

Abstract

In this study, adsorbent materials from natural feldspar were fabricated for application in +NH4 removal. Raw, pretreated by HCl 3M, and modified feldspar by NaOH and aluminum (Al powder, Al(OH)3, and AlCl3.6H2O) were used. Feldspar was modified under different experimental conditions including without calcination and calcinated at 500ºC and 700ºC. The influence of various operating parameters consisting of material size, adsorption time, +NH4 initial concentration and material dosage were investigated. Adsorbent materials < 0.1 mm in size showed the highest adsorption efficiency. Subsequently materials with size of < 0.1 mm were used for the following studies to investigate the affect of other parameters on +NH4 adsorption process. The highest removal efficiency (31.10%) and removal capacity (21.80 mg/g) were obtained by modified feldspar by NaOH and AlCl3.6H2O with calcination at 700ºC at +NH4 initial concentration of 5 ppm. Results from the scanning electron microscope (SEM) showed the differences on surfaces of adsorption materials. Modified feldspar had a clean surface and more tiny pores compared to those of raw and pretreated feldspar resulting in an increased surface area. Consequently +NH4 adsorbent efficiency and removal capacity were increased. By BET (Brunauer, Emmett and Teller) the specific surface areas of adsorbent materials were analyzed and the surface areas of raw, pretreated and modified feldspar were 0.484 m2/g, 0.988 m2/g and 2.024 m2/g, respectively. +NH4 adsorbent mechanisms of all raw, pretreated, and modified feldspar materials were found to follow the Langmuir adsorption isotherm with the correlation coefficient R2 = 0.989 which described the monolayer type of the adsorption.