| Drinking water sources pollution prevention and safe water supply protection is the current hot problems urgently to be solved in water treatment. In this paper, a safety, non-toxic and effective water treatment technology of eliminating the water supply plant chromium pollution was studied by using iron-carbon micro-electrolysis process aimed at the heavy metal chromium pollution in drinking water sources.In this study, the redox reaction of hexavalent chromium of iron-carbon micro-electrolysis was researched with the non-toxic, odorless activated carbon and metallic iron as the processing media. The pre-treatment process was lunched to remove chromium for meeting the basic requirements of quick start of the emergency plans and ensuring the normal operation of subsequent treatment and water quality. In this article, the iron-carbon micro-electrolysis was used to treat Cr(VI) in drinking water sources. The influence of single factor for iron-carbon micro-electrolysis treating Cr(VI) in drinking water was studied and the best process conditions was determined. The thermodynamic and dynamic researches of iron-carbon micro-electrolysis treating Cr(VI) was did and the reaction mechanism was discussed. The continuous tests were took to study the dynamic reaction process of iron-carbon micro-electrolysis treating Cr(VI).The experimental results are as follows:(1) The optimum conditions of iron-carbon micro-electrolysis treating Cr(VI) were determined by single factor experiment when the concentration of Cr(VI) was lmg/L:the iron-carbon weight ratio was 7:3, the solid/liquid (iron-carbon/water) ratio was 14g:100mL, the reaction time was 40min, the temperature was 25-30℃ and the removal rate was more than 95%.(2) In this paper, the adsorption model researches of iron-carbon micro-electrolysis treating Cr(VI) were at the temperature of 30℃,40℃ and 50℃. It concluded that the adsorption of iron-carbon micro-electrolysis treating Cr(VI) was in line with the Langmuir equation and mainly based on chemical adsorption, and the correlation coefficients R2 were 0.9965,0.9952 and 0.9973. The process of iron-carbon micro-electrolysis treating Cr(Ⅵ) was a process that was spontaneous exothermic and the confusion reduced according the ΔH0, ΔS0 and ΔG0.(3) The dynamics experiments showed that the second-order dynamic equations were the best fitting dynamics model of iron-carbon micro-electrolysis treating Cr (Ⅵ) and the correlation coefficients R2 were 0.9812,0.9992 and 0.9999. According to adsorption model and kinetics, the process of iron-carbon micro-electrolysis treating Cr (VI) was mainly redox reactions and chemical adsorption simultaneously.(4) The experimental results of continuous feed water showed that the optimal experimental conditions of iron-carbon micro-electrolysis treating Cr (Ⅵ) continuously were as follows:the flow rate was 8mL/min, the initial concentration of chromium was 1mg/L, the iron-carbon was cross-mixing for 5 times, the iron-carbon ratio was 7:3 and the total weight of carbon-iron was 350g. Under the above condition, the time of the experiment to achieve the breakthrough point was long, the effect of treatment was good and the effluent was up to the standard.(5) The chromium that were prepared with tap water and distilled water was studied and the result showed that the time to achieve the breakthrough point of tap water and distilled water were 13d and 47d, respectively, because the tap water contained some other materials. The pH and total iron of effluent reached the standard of "life drinking water health standards" (GB 5749-2006) (the pH was 6.5-8.5 and the limitation of total iron was 0.3mg/L).(6) According to the penetration curve of iron-carbon micro-electrolysis treating Cr (Ⅵ) the time of penetration was 312h, the concentration of penetration was 0.0493mg/L, the reaction reached saturated pole at about 768h and the iron-carbon processing capacity was 0.046mg/g. The Thomas model and Yoon-Nelson model could fit the data of dynamic breakthrough curve properly and its equation fitting parameter provided reference data for application.The method of iron-carbon micro-electrolysis treating Cr (Ⅵ) has obtained an ideal effect and has a certain guiding significance for actual engineering design. |
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