A Comparative Study on the Sorption of BTEX and Cr (VI) in Drinking Water by Anionic and Cationic Sorbents
- PDF / 395,648 Bytes
- 7 Pages / 595.22 x 842 pts (A4) Page_size
- 4 Downloads / 178 Views
A Comparative Study on the Sorption of BTEX and Cr (VI) in Drinking Water by Anionic and Cationic Sorbents S. O Flores-Valle*, S. P. Paredes Carrera, M. A.Valenzuela-Zapata, M. L. Hernández Pichardo Instituto Politécnico Nacional, ESIQIE, Laboratorio de Catálisis y Materiales, Av. IPN S/N Zacatenco, 07738, D. F., México. *Corresponding author, Email: [email protected] Abstract A comparative study of different sorbent materials was performed in order to propose an integrated system to eliminate both, anionic and cationic contaminant ions in drinking water, such as Cr (VI) and BTEX (benzene, toluene, ethylbenzene and xylenes). The adsorption process was studied using several adsorbents: activated carbon, cationic clays (bentonite) and natural zeolite as well as anionic clays (Al-Mg/Nitrate hydrotalcites). The activated carbon and natural zeolites were commercial samples, while hydrotalcite-like compounds were synthesized by an ultrasound-assisted method. It was found that although activated carbon showed a good performance in the cationic sorption, the calcined hydrotalcites presented the highest sorption capacity of chromates compared with activated carbon which had a good performance only up to 100 ppm. For higher concentrations (>100 ppm) activated carbon is saturated rapidly and its sorptive capacity is practically null. Keywords: Water decontamination, Cationic Sorbents, Anionic Sorbents, Nitrated hydrotalcitelike compounds. 1. INTRODUCTION Increasing water contamination caused by toxic compounds is a matter of great concern. Particularly, the reduction of drinking water quality due to the contamination of soils and groundwater by volatile organic petroleum hydrocarbons and some other contaminants has been extensively documented [1-2]. This pollution is in part originated during the stages of extraction and distribution, as well as a result of continuous leaking of fuels from underground storage tanks in gas stations [3]. Recent studies [4] have shown that in the particular case of Mexico City some of the main contaminants founded in drinking water are: benzene, toluene, ethylbenzene and xylenes (BTEX in low concentration) as well as some traces of Cr (VI), among others. These pollutants are considered hazardous substances because of their high toxicity, confirmed carcinogenicity, and environmental persistence [5]. Then, the development of an efficient technology to remove these substances from drinking water is absolutely necessary. Photocatalysis and advanced oxidation processes (AOPs) based on the photocatalytic destruction of organic pollutants and the removal of some toxic ions, in combination with basic procedures of filtration are novel proposal for the decontamination and/or final disinfection of drinking water. However, these processes must be complemented by other technical approaches such as sorption methodologies with new materials, which have not been exploited in such applications. Sorption studies of chemical species with cationic clays (bentonite and zeolite), silico aluminates and activated carbon
Data Loading...
