Effectiveness of nanozeolite modified by cationic surfactant in the removal of disinfection by-product precursors from water solution

Aim: In this study the performance of a natural nanozeolite, modified with a cationic surfactant, on the adsorption of humic acid from water was investigated in a batch system. Materials and Methods: Clinoptilolite as a natural nanozeolite was modified with different doses of a cationic surfactant solution, hexadecyltrimethylammonium bromide (HDTMA-Br), at dosages from 0.5 to 10 g/l. The modified adsorbents were individually added to synthetic water samples containing a known amount of humic acid and put on the shaker for two hours, at room temperature. Humic acid (HA) concentrations, turbidity, and pH were measured before and after the adsorption process. Results: According to the results obtained, and based on the statistical analysis (Pearson correlation statistical test), there was a clear correlation between the cationic surfactant dosage and HA removal (P_value <0.001, r=0.87). By increasing the HDTMA-Br dosage, the ratios of turbidity/turbidity _initial and UV ₂₅₄ /UV _254-initial adsorbance by HA (after/before adsorption process) were decreased. In HDTMA-Br dosages of 7 and 10 g/l, the maximum removal efficiency for HA was 96 and 86%, respectively, with a slight variation in the pH value and turbidity unit. Conclusions: This study showed that modification of nanozeolite by cationic surfactants, to reduce its negative surface charge, could markedly improve its efficiency in the adsorption of disinfection by-product precursors from an aqueous solution. The HDTMA-Br/Clinoptilolite nanozeolite (CNZ) ratio of 0.07, pH have to coincide in iso-electric point, can be an optimum ratio for the modification.