Removal of natural organic matter (NOM) from an aqueous solution by NaCl and surfactant-modied clinoptilolite Mehdi Vosoughi Niri, Amir Hosein Mahvi, Mahmoud Alimohammadi, Mohammad Shirmardi, Hafez Golastanifar, Mohamma Javad Mohammadi, Abolfazl Naeimabadi and Maria Khishdost ABSTRACT Zeolitic tuffs are found in different parts of the world. Iranian zeolite is a low-cost material that can be frequently found in nature. Surfactant-modied zeolite (SMZ) can be used for the adsorption of natural organic matter (NOM) from aqueous solutions. The adsorption study was conducted to evaluate the adsorption capacity of SMZ; furthermore, the effects of contact time, initial pH, and the initial adsorbent dose on the adsorption process were investigated in a batch system. The kinetic studies showed that the adsorption of NOM on SMZ was a gradual process. The optimum initial pH values for the adsorption of NOM on SMZ were in the acidic ranges. The batch kinetic experiments showed that the adsorption followed the pseudo-second-order kinetic model with good correlation coefcients. The equilibrium data were well described by the Langmuir isotherm model. The results show that the natural zeolite being modied with NaCl and hexadecyltrimethylammonium bromide as a cationic surfactant was an appropriate adsorbent for the removal of NOM. Mehdi Vosoughi Niri Mohammad Shirmardi Mohamma Javad Mohammadi Maria Khishdost Department of Environmental Health Engineering, School of Public Health, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran Mahmoud Alimohammadi Department of Environmental Health Engineering, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran Amir Hosein Mahvi (corresponding author) National Institute of Health Research, Tehran University of Medical Sciences, Tehran, Iran E-mail: mvn_20@yahoo.com Hafez Golastanifar National Exploration Directorate Oil Company, NIOC, Iran Abolfazl Naeimabadi Department of Environmental Health, School of Public Health, North Khorasan University of Medical Sciences, Bojnourd, Iran Key words | adsorption isotherm, adsorption kinetics, hexadecyltrimethylammonium bromide, natural organic matter, zeolite INTRODUCTION Natural organic matter (NOM) is considered a complex matrix of organic compounds present in many water resources, especially surface water (Wang et al. ; Zazouli et al. ; Brigante et al. ). NOM causes a wide variety of problems in drinking water treatment operations. The presence of NOM in water may be carci- nogenic as a result of reactions between NOM and disinfectants. The presence of NOM in raw water sources is unfavorable and has long been a problem for water supply systems in industries. In particular, NOM affects the quality of drinking water in several ways. For example, color, taste, and odor are important esthetic drinking water quality problems caused by such compounds (Mahvi et al. ; Li et al. ; Ben- Sasson et al. ). In addition, NOM can bind with syn- thetic organic pollutants (such as pesticides) and heavy metals and result in their transport through treatment units and the distribution network (Anirudhan & Rama- chandran ; Mahvi et al. ; Imyim & Prapalimrungsi ). Also, as a consequence of the pres- ence of high concentrations of NOM in raw water, the chlorination of raw water can result in disinfection by- products such as trihalomethanes during the chlorination process (Anirudhan & Ramachandran ; Chiang et al. ). Therefore, the removal of NOM from drinking water resources is very important. 394 © IWA Publishing 2015 Journal of Water and Health | 13.2 | 2015 doi: 10.2166/wh.2014.088