Evaluation of iron-coated ZSM-5 zeolite for removal of As(III) fromaqueous solutions in batch and column systems

摘要

Influential parameters to produce iron-coated ZSM-5 zeolite including iron loading concentration, calcination temperature and time, synthesis temperature and mixing intensity were investigated. Results showed that the optimized iron-coated ZSM-5 nano-adsorbent is produced if 40 wt.% iron loading concentration at 30 degrees C synthesis temperature under 60 rpm mixing intensity and 400 degrees C calcination temperature for 3 h are applied. Also, optimization of some parameters such as pH, adsorbent dose, contact time and temperature for removal of arsenite from aqueous solution with 400 mu g/L initial concentration was considered. Evidently, the highest adsorption of arsenite occurred under pH 7, adsorbent dose 2.5 g/L, contact time 30 min and temperature 40 degrees C. Kinetic and isotherm models studied showed that arsenite adsorption by iron-coated ZSM-5 follows a pseudo-third-order equation and well fitted with the Langmuir isotherm model. Evaluation showed that the optimized iron-coated ZSM-5 zeolite is able to remove up to 98.37% of arsenite under the best conditions in a batch reactor. For the column system, arsenite concentration range of 0.04-97.53 mu g/L in output at 1-35 min interval was confirmed and the breakthrough curve showed that iron-coated ZSM-5 nano-adsorbent was saturated after 215 min whereas Fe, pH and EC measured in output solution were 0.90 mg/L, 6.65 and 148.40 mu s/cm, respectively.