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Cellulose Mediated Reduction and Immobilization of Cr(VI) in Chromite Ore Processing Residue.
Journal of Hazardous Materials ( IF 12.2 ) Pub Date : 2020-03-20 , DOI: 10.1016/j.jhazmat.2020.122538
Qianzhe Sun 1 , Feng Liu 1 , Yanjie Yuan 2 , Weizhen Liu 3 , Weifang Zhang 4 , Jing Zhang 4 , Zhang Lin 3
Affiliation  

It is a great challenge to find an effective method for the treatment of chromite ore processing residue (COPR), due to the highly toxic and mobile characteristic of Cr(VI) in the sludge. This work reported a facile strategy to thoroughly reduce and immobilize Cr(VI) that was encapsulated in COPR by biomass-assistant hydrothermal treatment. After hydrothermal treatment at 160 °C for 180 min, the leaching of Cr(VI) in COPR decreased from 138.6 mg/L to 2.31 mg/L, well below the disposal standard limit (5 mg/L). It was found that in-situ produced volatile synthesis gas (H2, CO and CH4) by cellulose under hydrothermal condition, was responsible for Cr(VI) reduction. The reduction kinetics were temperature-dependent and the rate constants increased from 7.8 × 10-3 min-1 at 120 °C to 77.9 × 10-3 min-1 at 180 °C. Further simulation experiments revealed that (i) Fe-hydrotalcite in COPR acted as the catalyst for the decomposition of cellulose, and (ii) cellulose can hydrothermally produce reductive gas with a high efficiency, where 0.1 g of cellulose can realize the reduction and immobilization of Cr(VI) equivalent to 14 g of COPR by 14 cycles of treatment. This study provided a promising strategy for one-step remediation of COPR by the coupled reduction-stabilization process.

中文翻译:

纤维素介导的铬铁矿加工残渣中六价铬的还原和固定化。

鉴于污泥中六价铬的高毒性和移动性,寻找一种有效的处理铬铁矿矿石加工残渣(COPR)的方法是一项巨大的挑战。这项工作报告了一种简便的策略,可以通过生物量辅助水热处理彻底还原和固定化封装在COPR中的Cr(VI)。在160°C下进行水热处理180分钟后,COPR中Cr(VI)的浸出量从138.6 mg / L降至2.31 mg / L,远低于处理标准限值(5 mg / L)。发现纤维素在水热条件下原位产生的挥发性合成气(H2,CO和CH4)是导致Cr(VI)还原的原因。还原动力学与温度有关,速率常数从120°C时的7.8×10-3 min-1增加到180°C时的77.9×10-3 min-1。进一步的模拟实验表明,(i)COPR中的铁水滑石是纤维素分解的催化剂,(ii)纤维素可以高效水热生产还原性气体,其中0.1 g纤维素可以实现纤维素的还原和固定化。通过14个治疗周期,Cr(VI)相当于14 g COPR。这项研究为通过耦合的还原稳定化过程一步修复COPR提供了一种有希望的策略。
更新日期:2020-03-21
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