State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, China.
State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, China; Research Center for Environmental Nanotechnology (ReCENT), Nanjing University, Nanjing 210023, China.
Chemosphere. 2018 Nov;211:867-874. doi: 10.1016/j.chemosphere.2018.07.159. Epub 2018 Aug 4.
The efficient removal of Se(VI) from sulfate-rich water is challenging as most reported processes last for hours to days. In this study, a combined sulfite/UV/Fe(III) coagulation process was proposed for efficient Se(VI) removal from sulfate-rich water within a short time (∼1 h). In the presence of sulfate (1000 mg L), over 99% of Se(VI) (initially at 10 mg L) could be reduced by sulfite (5.0 mM) with a UV dose of 16 J cm (within 20 min) into Se(IV) as the sole observed product. An alkaline pH (>9) was required for the reduction process, which was naturally obtained with the addition of sulfite. Scavenging experiments with NO and NO both indicated that hydrated electrons (e) were responsible for Se(VI) reduction by sulfite/UV. The presence of chloride, sulfate, phosphate, and carbonate (up to 10 mM) showed negligible influence on Se(VI) reduction, whereas nitrate and humic acid inhibited Se(VI) reduction to different extents depending on their concentrations. By Fe(III) coagulation, Se(IV) in the co-presence of sulfite and sulfate was efficiently removed at an OH/Fe molar ratio of 1.8-2.8. The removal of Se(IV) by Fe(III) coagulation responded insignificantly to chloride, nitrate, or sulfate (up to 10 mM), whereas it was adversely affected at high levels of carbonate (10 mM) and phosphate (1 mM). The combined sulfite/UV/Fe(III) coagulation process was validated for the efficient removal of Se(VI) from synthetic sulfate-rich solution, simulated wastewater, and authentic smelting wastewater (in 1.1 h). The introduced sulfite underwent minor consumption during UV irradiation and was almost (∼90%) removed after coagulation.
从富含硫酸盐的水中高效去除硒（VI）具有挑战性，因为大多数报道的过程需要数小时到数天。在这项研究中，提出了一种亚硫酸盐/UV/Fe(III)联合混凝工艺，可在短时间内（约 1 小时内）从富含硫酸盐的水中高效去除硒（VI）。在硫酸盐（1000mg/L）存在的情况下，超过 99%的硒（VI）（初始浓度为 10mg/L）可被亚硫酸盐（5.0mM）在 16J/cm 的 UV 剂量下还原为 Se(IV)，这是唯一观察到的产物。还原过程需要碱性 pH 值（>9），亚硫酸盐的加入自然会产生这种碱性 pH 值。用 NO 和 NO 进行的清除实验均表明，亚硫酸盐/UV 还原硒（VI）的是水化电子(e)。氯离子、硫酸盐、磷酸盐和碳酸盐（高达 10mM）的存在对硒（VI）的还原几乎没有影响，而硝酸盐和腐殖酸则根据其浓度不同程度地抑制硒（VI）的还原。通过 Fe(III)混凝，在亚硫酸盐和硫酸盐共存的情况下，硒（IV）在 OH/Fe 摩尔比为 1.8-2.8 时可被有效地去除。Fe(III)混凝对氯离子、硝酸盐或硫酸盐（高达 10mM）的去除效果不明显，但在高浓度的碳酸盐（10mM）和磷酸盐（1mM）时受到不利影响。该联合亚硫酸盐/UV/Fe(III)混凝工艺已在合成富含硫酸盐的溶液、模拟废水和真实冶炼废水中验证了从硒（VI）的高效去除（1.1 小时内）。在 UV 照射过程中亚硫酸盐的消耗量较小，在混凝后几乎（约 90%）被去除。
