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本文采用两种六价铬还原剂,以不同掺量进行分析测试,并通过水泥大磨试验中的应用,研究其还原效果及化学稳定性,同时探讨了还原剂对水泥性能的影响。结果表明:水泥水溶性Cr6+含量随还原剂掺量的增加而降低,还原剂能够有效地降低水溶性Cr6+含量,0.1%掺量时可使Cr6+含量降至2 mg/kg以下,且产品R2还原能力优于R1;六价铬还原剂在大磨实验中呈现出较好的耐高温性能和化学稳定性,具有优异的还原效果和还原稳定性,同时对水泥生产工艺与水泥基本性能无较大影响,以期推动GB 31893—2015《水泥中水溶性铬(Ⅵ)的限量及测定方法》标准的强制性实施,促进水泥产业的绿色健康发展。 相似文献
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0引言水泥中水溶性六价铬污染是继粉尘污染之后水泥行业面临的重要污染之一,六价铬具有水溶性高和渗透性强的特点,易渗透到人体组织,造成皮肤炎、溃烂等疾病甚至会诱发癌变。2015年9月11日GB 31893—2015《水泥中水溶性六价铬(Ⅵ)的限值及测定方法》由国家质量监督检验检疫总局批准发布,并明确规定了水泥中六价铬含量不大于10mg/kg的限值要求。2019年国家市场监督总局下发《产品质量监督抽查管理暂行办法》,其中水泥中水溶性铬(Ⅵ)含量为重要的质量监督指标,对于抽检结论不合格的产品,被抽检生产者和销售者将立即停止生产及销售同类产品。 相似文献
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作为传统建筑材料,水泥在国内已经有一百多年的使用历史。随着高质量发展的要求,不仅在性能上需要持续提高,在绿色、安全环保层面也面临更加严格的要求。目前大部分水泥原料采用废物利用,虽然节约了成本,但是随之而来的毒性控制问题仍需要技术进步。而毒性的主要来源是水溶性铬,在水溶性铬家族中又以水溶性六价铬毒性最强,因此对水溶性六价铬源头研究和防治迫在眉睫。对国内业界水泥中水溶性六价铬的来源以及毒性防治措施研究作一评述,进而对水泥未来发展趋势进行展望。 相似文献
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水泥中水溶性六价铬是水泥重金属中毒性较大的元素之一,它可能通过皮肤接触、呼吸道吸入、食物摄入及环境接触等途径对人体及环境造成危害。在国家强制性标准GB 31893-2015《水泥中水溶性铬(VI)的限量及测定方法》正式实施之前,国家水泥质量监督检验中心联合中国水泥协会开展了《2015年全国水泥产品质量安全风险监测》工作,样本采集覆盖了全国31个省、直辖市及自治区,包括普通硅酸盐水泥、复合硅酸盐水泥、II类硅酸盐水泥、矿渣硅酸盐水泥等7类品种,强度等级标号包括32.5、32.5R、42.5和52.5等4类,共计100批次水泥样本。经过数据统计分析得出:全国约有20%的水泥产品中水溶性六价铬不满足标准限量要求,属于存在严重风险,应引起水泥行业和有关部门的重视。 相似文献
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熟料中水溶性六价铬离子严重超标,导致水泥中水溶性六价铬超标,给水泥质量管控造成严重风险.通过调整水泥原材料,在生料配料中利用钢铁厂收尘灰渣代替转炉渣作为铁质材料降低熟料中水溶性铬(V)离子,经多次反复验证效果理想,综合成本低,达到预期效果. 相似文献
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Removal of hexavalent chromium by nanofiltration 总被引:4,自引:0,他引:4
Removal of chromate CrO42− from water was investigated using nanofiltration as a possible alternative to the conventional methods of CrVI removal from aqueous solution. Retention measurements with single reference salt revealed that Donnan exclusion plays an important role. The phenomenological parameters σ and P were calculated using the Spiegler-Kedem equation. The rejection rate depends on the ionic strength and pH. The increasing of ionic strength decreases the retention. The effect of pH was clarified by using a stable diagram of the CrVI---H2O system. Better retention was obtained at basic pH. 相似文献
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BACKGROUND: A plate‐gap model interpretation of enzymatic reaction kinetics and rotating disc voltammetry were applied for evaluation of the nature of the reaction of the electroreduction of Cr(VI) (as dichromate ions) on a polyaniline (PANI)‐modified glassy carbon (GC) electrode. RESULTS: The kinetic parameters (the maximal current (Vmax) and Michaelis constant (KM)) for electroreduction of Cr(VI) on the PANI‐modified GC electrode were determined as Vmax = 0.34 × 10?7 mol cm?3 s?1 and KM = 0.47 × 10?6 mol cm?3. The reduction of dichromate is intensified by PANI film growth. CONCLUSION: To characterise the electroreduction of Cr(VI) on a PANI‐modified GC electrode, the kinetic parameters of the reaction were determined using a plate–gap model interpretation of enzymatic reaction kinetics and rotating disc voltammetry. The catalytic nature of Cr(VI) electroreduction on the PANI‐modified electrode has been shown. Copyright © 2009 Society of Chemical Industry 相似文献
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S. Goeringer N.R. de Tacconi C.R. Chenthamarakshan K. Rajeshwar 《Journal of Applied Electrochemistry》2000,30(8):891-897
The galvanic reaction of metallic copper in Cr(VI)-laden aqueous solutions of varying pH was examined by in situ u.v.–visible spectrophotometry, rotating disc electrode chronopotentiometry and cyclic voltammetry. The galvanic reaction in 0.2 M H2SO4 solutions was pseudo first order in Cr(VI) concentration. Experiments with both magnetically stirred solutions and a copper mesh or a copper film in a rotating disc electrode configuration revealed the reaction to be diffusion-controlled with respect to Cr(VI) transport to the copper surface. Finally, cyclic voltammetry data in Cr(VI)-laden media of varying pH underline the important role of protons in the galvanic reaction. 相似文献
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为了降低水泥中水溶性六价铬含量,采用大磨生产试验,测试了不同掺量下硫代硫酸钠对水泥中六价铬含量、水泥需水量、凝结时间、强度等影响。结果表明,掺加适量的硫代硫酸钠,可显著降低水泥中的六价铬含量,但超过1‰时,降铬效率趋于饱和;硫代硫酸钠的掺入,对水泥需水量和施工和易性无明显影响,会使水泥的凝结时间缩短12%,同时在一定程度上提高其早期强度。基于硫代硫酸钠特性,在实际生产过程中,需将其单独放置于堆棚中。 相似文献
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Reduction of hexavalent chromium (Cr(VI)) by zero-valent iron (Fe0) was investigated systematically in the present study. No change in Cr(VI) concentration occurs using untreated Fe0 powders even after a long contact time. The Fe0 powders treated with acid washing shows a weak activity and a poor long-term performance to reduction of Cr(VI). The activity and long-term performance of treated Fe0 powders is not effectively improved in the presence of citric acid. In contrast, introduction of photoirradiation not only dramatically increases the reduction rate of Cr(VI) in the presence of citric acid but also effectively stabilizes the activity of Fe0 powders and films. Such enhancement should be attributed to photoreductive dissolution of the oxide layer on Fe0 surface. For this newly developed system, effective reduction of Cr(VI) is favored at low pH values and oxalic and tartaric acid are also effective as complex reagents. 相似文献