Modified clays as adsorbent in filter system for medium or small scale water depuration
The pesticide contamination of water is increasing as a result of intensive farming (Hermosin et al., 2013) and it makes necessary to develop low-cost systems for water purification, as to be used at farm houses and small agroindustries. Clays are good adsorbents for pesticides. Due to their small size, expansive properties reactive surfaces and modification or “tunning” ability (Hermosin & Cornejo, 1992; Socias-Viciana et al., 1998; Cruz-Guzmán et al., 2005; Gámiz et al., 2015) and thus they have been proposed for water treatment (Beall 2003). In this work we assay and propose clays as adsorbent component in a filter to remove pesticides from water. The modified clays were prepared from a low value clay (CTI, smectite content, 30%) located in Bailén (Jaen, Spain) by saturation with Fe3+ (CTI-FE) and hexadecyltrimethyllammonium (CTI-HDTMA). A commercial organo-clay, Cloisite 10A (Clo, from BKG) was also used for comparison. The pesticides tested re those used in olive crops, as terbuthylazine, tebuconazole and MCPA (Hermosin et a l., 2013). The clays were granulated to pellets with carnauba wax (car) as binder through a ram extruder. Powder clay and car were mixed (30% wt car) at 90ºC. Anthracite (Antra 170, AstralPool) was mixed at rate of 40% with the clay pellets as filtering bed in the tank with artificially contaminated water, Antracite helps to avoid clay swelling and to increase the bed porosity and improve the conditions of the water flow. Experiment set-up has a minimum flow of 30 ml/min to obtain pressures of 1 bar. The adsorption tests were carried out using a solution containing the three pesticides at initial concentration of 1 ppm in 40 liters of water. The adsorption kinetics was measured at selected times (15 min, 30 min, 1 h, 2 h, 4 h, 6 h, 8 h, 24 h). This work reveals that the pelletization process did not affect significantly the pesticide sorption capacity of clays (37-96%) and the pellets were not altered in terms of size showing an excellent water resistance at the end of the experiment. We obtained a high adsorption of the three pesticides tested for the cases of the commercial clay (Clo10) and for CTI-HDTMA, removing from 40-100% of pesticide from water after 24 h of treatment in the filter system. In contrast, the CTI-Fe sample did not perform as a good adsorbent, removing only between 15-42% of the herbicides from water after 24 h of treatment in the filter. CTI-HDTMA reveals as a very promising adsorbent derived from a low cost material to be used in filter systems for removing pesticides from contaminated waters. Hence the development of a small company devoted to the processing of low value clay sample would have to be considered. Beall, G.W. (2003): The use of organo-clays in water treatment. Appl. Clay Sci., 24, 11-20. Cruz-Gúzman, M., Celis, R., Hermosín, M.C., Koskinen, W.C., Cornejo, J. (2005): Adsorption of pesticides from water by functionalized organobentonites. J. Agr. Food Chem., 53, 7502-7511. Gámiz, B., Hermosín, M.C., Cornejo, J. (2015): Hexadimethrine-montmorillonite nanocompo-site: Characterization and application as a pesticide adsorbent. Appl. Surf. Sci., 332, 606-613. Hermosín, M.C. & Cornejo, J. (1992): Removing 2.4-D from water by organo-clays. Chemosphere, 24, 1493-1503. Hermosín, M.C., Calderón, M.J., Real, M., Cornejo, J. (2013): Impact of herbicides used in olive groves on waters of the Guadalquivir river basin (southern Spain). Agr. Ecosyst. Environ., 164, 229-243. Socías Viciana, M.M., Hermosín, M.C., Cornejo, J. (1998): Removing prometrone from water by clays and organic clays. Chemosphere, 37, 283-300.
| Main Authors: | , , , , |
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| Format: | póster de congreso biblioteca |
| Published: |
Società Italiana di Mineralogia e Petrologia
2016-09-11
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| Subjects: | Contamination, Pesticides, Pelletization, |
| Online Access: | http://hdl.handle.net/10261/159393 http://dx.doi.org/10.13039/501100003339 http://dx.doi.org/10.13039/501100003329 http://dx.doi.org/10.13039/501100000780 |
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