Evaluation of the Adsorption Potential of Synthesized Anatase Nanoparticles for Arsenic Removal

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Evaluation of the Adsorption Potential of Synthesized Anatase Nanoparticles for Arsenic Removal Z. Özlem Kocabaş and Yuda Yürüm Faculty of Natural Science and Engineering, Sabanci University, Orhanlı 34956 Tuzla, Istanbul/Turkey ABSTRACT Titanium dioxide has been extensively tested in environmental applications, especially in separation technologies. In the present study, anatase nanoparticles were synthesized by using a sol-gel method, and batch adsorption experiments were carried out to analyze arsenic removal capacity of the anatase nanoparticles from water. The maximum arsenic removal percentages were found ~ 84 % for As(III) at pH 8 and ~98% for As(V) at pH 3, respectively, when 5 g/l anatase nanoparticles were used at an initial arsenic concentration of 1 mg/l. The results of the sorption experiments, which take into consideration the effects of equilibrium concentration on adsorption capacity, were analyzed with two popular adsorption models, Langmuir and Freundlich models. From the comparison of R2 values, the adsorption isotherm for As(III) was fitted satisfactorily well to the Langmuir equation (R2 > 0.996) while the adsorption behavior of As(V) on anatase nanoparticles was described better with Freundlich equation (R2 > 0.991). This study proposes the potential adsorbent material for water which is contaminated with arsenic species. INTRODUCTION Arsenic, classified as 20th in natural abundance and 14th in seawater, is a well-known toxic contaminant that co-exists in nature with other metals like Fe, Cu, Ni, Zn as sulfide or oxide ores [1]. The excessively high arsenic concentration especially in drinking water, is a challenging water pollution problem for many countries such as USA, China, Chile, Bangladesh, Taiwan, Mexico, Argentina, Poland, Canada, Hungary, Japan, and Turkey [2]. Arsenic is severely harmful to human health and long term exposure to arsenic can lead to cancer of the lungs, skin, kidney and liver [3]. Therefore the maximum contamination level of arsenic in drinking water has been adopted at 10 µg/L by the World Health Organization (WHO) [4]. The existing technologies for removal of arsenic species from water can be classified as coagulation, electrolysis, ion exchange, membrane processes, and adsorption [4-7]. Nowadays, removal of arsenic by adsorption has acquired importance due to its technical simplicity and applicability in rural areas, where people are more subjected to polluted drinking water with arsenic [8]. Titanium dioxide possesses a great potential for the environmental application due to its physical and chemical stability, lower cost, nontoxicity and resistance to corrosion. The main objective of this study is to investigate an effective and inexpensive water purification system by using anatase nanoparticles. With this aim, this experimental study evaluates arsenic removal efficiency of anatase nanoparticles from water by the adsorption process under various

experimental conditions, including pH and contact time, to determine the optimum process parameters. EXPERIMENTAL D