Abstract

BACKGROUND AND OBJECTIVE: Removal of trihalomethanes (THMs) due to carcinogenic effects in liver, bladder, kidney and central nervous system dysfunctions is very crucial. Elimination of THMs precursors from drinking water resources is the most important step for inhibition of THMs formation. The aim of this study was to investigate the adsorption of humic acid (HA) onto modified pumice with Hexadecyl Trimethyl Ammonium Bromide (HDTMABr). METHODS: This experimental study was carried out in chemistry laboratory of water and wastewater of Hamadan University of Medical Sciences, Hamadan, Iran. Apparent characteristics and chemical structure of pumice was determined via scanning electronic microscope (SEM), X-Ray diffraction (XRD) and X-Ray fluorescent (XRF) techniques. HA concentration was determined by photometry on 254nm. Langmuir, Freundlich and Temkin models and pseudo-first and pseudo second-order kinetics were used for adsorption isotherm and kinetics studies. FINDINGS: Elevation of preliminary concentration of HA, adsorbent dosage and contact time led to increasing of HA adsorption. Increasing of pH in the range of 3 to 12 led to decreasing of adsorption and the experimental maximum adsorption occurred in pH: 3. Adsorption of HA onto modified pumice complies with Langmuir (R2=0.99) and pseudo second-order kinetic (R2=0.99). Maximum experimental (Qexpmax) and theoretical adsorption (QCalmax) was 22.5 mg/g and 29 mg/g, respectively. Langmuir constant (b) was 0.8 L/mg. CONCLUSION: The results of this study showed that in acidic condition the modified pumice with HDTMA-Br has an appropriate efficiency on HA adsorption.