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首页> 外文会议>Progress in environmental science and technology.;vol. 3. >Treatment of a Model HA Compound (Resorcinol) by Potassium Manganate
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Treatment of a Model HA Compound (Resorcinol) by Potassium Manganate

机译：锰酸钾处理HA模型化合物（间苯二酚）

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Current work is exploring the feasibility of using potassium manganate (K2MnO4) in drinking water treatment. The manganate species (MnO4 2-) can act as both an oxidant and a coagulant/adsorbent arising from the formation of insoluble manganese dioxide from the chemical reduction of Mn(VI) to Mn(IV). Extensive tests have been undertaken to investigate the treatability of humic acids by manganate, with and without the co-addition of ferrous sulphate. In these tests solutions of commercial humic acid (HA) have been reacted at varying concentrations of K2MnO4 and FeSO4 and pH. A high degree of HA removal has been demonstrated, particularly at low pH (pH 5), as expected from conventional theories of charge interaction and solid phase adsorption. In attempting to understand the mechanisms of HA reaction and separation by manganate, given the heterogeneous nature of HA, laboratory tests have been undertaken also with resorcinol as a model compound of HA. Since manganate disproportionates during its aqueous reaction to permanganate and MnO2, the comparative reactivity and separation of resorcinol by manganate (Mn(VI)) and permanganate (Mn(VII)) have been considered. During the chemical reduction of potassium manganate and potassium permanganate insoluble manganese dioxide (Mn(IV)) is produced which can adsorb un-reacted resorcinol and reaction products. The adsorption of resorcinol by MnO2 was studied by pre-forming MnO2 by the reaction of the Mn(VI) and Mn(VII) with sodium thiosulphate, prior to the addition of the resorcinol. The influences of adsorption time and MnO2 dose have been investigated. The combined effects of chemical oxidation by manganate or permanganate and MnO2 adsorption, on resorcinol have been studied in detail. In particular, the influence of the ratio of oxidants to resorcinol, oxidation time and adsorption time on resorcinol removal have been evaluated. The tests were undertaken at pH 5, which is a preferred treatment pH for low turbidity, high humic waters in practice, and also allowed comparison with the results from experiments involving HA. The changes in resorcinol concentration were measured in both absolute terms by HPLC, and indirectly as NPDOC. The results have shown that resorcinol can be removed to a moderate degree by MnO2 adsorption where the adsorbent was formed in solution from the two Mn oxidants immediately prior to interaction with resorcinol. The adsorption/contact time had only a minor effect on compound removal with a greater removal at a longer contact time. In reaction with both Mn oxidants, the ratio of oxidant to resorcinol had a significant effect on compound removal, with the removal increasing substantially at higher ratios of oxidant to resorcinol. During the chemical oxidation and MnO2 adsorption experiments with the two Mn oxidants, varying the respective periods of oxidation and adsorption had only a moderate effect on the compound removal efficiency; in the former case compound removal increased with the period length. Comparatively, the treatment performance of potassium manganate was superior to that of potassium permanganate.
机译：当前的工作正在探索在饮用水处理中使用锰酸钾（K2MnO4）的可行性。锰酸盐物种（MnO4 2-）既可以作为氧化剂，又可以作为氧化剂和凝结剂/吸附剂，它们是由Mn（VI）还原为Mn（IV）形成不溶性二氧化锰而产生的。已经进行了广泛的测试，以研究在有或没有共同添加硫酸亚铁的情况下锰酸盐对腐殖酸的可处理性。在这些测试中，商用腐殖酸（HA）溶液在K2MnO4和FeSO4的不同浓度和pH下反应。正如电荷相互作用和固相吸附的传统理论所预期的，已证明高度去除HA，尤其是在低pH（pH 5）下。为了了解HA反应和锰酸盐分离的机理，鉴于HA的异质性，还使用间苯二酚作为HA的模型化合物进行了实验室测试。由于锰在其与高锰酸盐和MnO2的水反应过程中歧化，因此考虑了比较反应性和间苯二酚通过锰酸盐（Mn（VI））和高锰酸盐（Mn（VII））的分离。在化学还原锰酸钾和高锰酸钾的过程中，产生了不溶性二氧化锰（Mn（IV）），它可以吸附未反应的间苯二酚和反应产物。通过在添加间苯二酚之前，通过Mn（VI）和Mn（VII）与硫代硫酸钠的反应预生成MnO2，研究了MnO2对间苯二酚的吸附。研究了吸附时间和MnO2用量的影响。详细研究了锰酸盐或高锰酸盐化学氧化和MnO2吸附对间苯二酚的综合作用。特别地，已经评估了氧化剂与间苯二酚的比率，氧化时间和吸附时间对间苯二酚去除的影响。测试是在pH 5下进行的，这在实践中是低浊度，高腐殖质水的首选处理pH，并且还可以与涉及HA的实验结果进行比较。间苯二酚浓度的变化是通过HPLC绝对值测量的，也可以通过NPDOC间接测量。结果表明，间苯二酚可以通过MnO2吸附除去，其中吸附剂是在与间苯二酚相互作用之前由两种Mn氧化剂在溶液中形成的。吸附/接触时间对化合物的去除只有很小的影响，而在较长的接触时间下去除率更大。在与两种锰氧化剂的反应中，氧化剂与间苯二酚的比例对化合物的去除具有显着影响，在氧化剂与间苯二酚的比例较高时，去除率显着增加。在使用两种Mn氧化剂进行化学氧化和MnO2吸附实验期间，改变各自的氧化和吸附时间仅对化合物的去除效率产生中等程度的影响。在前一种情况下，化合物去除量随着周期的延长而增加。相比之下，锰酸钾的处理性能优于高锰酸钾。

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