Degradation of chlorinated phenols by nanoscale zero-valent iron

Chlorophenols (CPs), as important contaminants in groundwater, are toxic and difficult to biodegrade. Recently nanoscale zero-valent iron received a great deal of attention because of its excellent performance in treating recalcitrant compounds. In this study, nanoscale zero-valent iron particles were prepared using chemical reduction, and the reductive transformations of three kinds of chlorinated phenols (2-CP, 3-CP, and 4-CP) by nanoscale zero-valent iron under different conditions were investigated. The transformation process of the CPs was shown to be dechlorination first, then cleavage of the benzene ring. The removal efficiency of the CPs varied as follows: 2-CP > 3-CP > 4-CP. The reactivity of CPs was associated with their energy of lowest unoccupied molecular orbit (E _LUMO). With the increase in initial concentrations of CPs, removal efficiency decreased a little. But the quantities of CPs reduced increased evidently. Temperature had influence on not only the removal efficiency, but also the transformation pathway. At higher temperatures, dechlorination occurred prior to benzene ring cleavage. At lower temperatures, however, the oxidation product was formed more easily. __________ Translated from China Environmental Science, 2006, 26(6): 698–702 [译自: 中国环境科学]     

Arsenic and chromate removal from water by iron chips-Effects of anions

The purpose of this study is to estimate the removal efficiency of As and Cr (VI) by one kind of industrial waste — iron chips, as well as to estimate the effects of typical inorganic anions (sulfate, phosphate, and nitrate), and typical organic anions (citrate, oxalate, and humate) on As or Cr (VI) removal. The results showed that 98% of As (V) and 92% of As (III) could be removed from aqueous phase by the iron chips within 60 min. Compared with As species, Cr (VI) was removed much more rapidly and efficiently with 97% of Cr (VI) being removed within 25 min. The removal efficiency for arsenic was in the order: As (III) (sulfate), As (III) (nitrate) or As (III), As (III) (humate), As (III) (oxalate), As (III) (citrate), As (III) (phosphate), and for chromate was in the order: Cr (VI) (sulfate), Cr (VI) (phosphate) or Cr (VI) (nitrate) or Cr (VI) (oxalate), Cr (VI), Cr (VI) (citrate), Cr (VI) (humate). In all the treatments, pH level increased with time except for As (III), the removal of which was either without anions or in the presence of humate or nitrate.     

我国废钢加工设备发展中的问题及管理建议

我国钢铁工业的快速发展,带动了废钢回收及废钢加工设备产业的发展。介绍了我国废钢加工设备的生产规模及现状,对废钢加工设备制造企业多元化发展现象进行分析,并对废钢加工设备制造企业的规范化管理提出合理化建议。     

纳米铁强化的混凝-沉淀-过滤工艺对典型印染废水中有机物去除

以东江流域某典型印染企业尾水为研究对象,将混凝剂与少量的纳米铁进行复合投加,再结合多介质过滤器对印染尾水进行深度处理实验研究.结果表明,新型混凝剂HPAC-9对极性有机物具有较强的去除能力,但对非极性或弱极性有机物去除效果不很理想.通过将纳米铁与HPAC-9复合投加并结合多介质过滤工艺,对印染企业尾水中的有机污染物进行...     

铁屑对低浓度含铬地下水的处理研究

以某铬渣污染场地上抽提上来的低浓度含铬地下水作为实验研究对象。选用铁屑对含铬废水进行处理。通过静态试验考察了影响六价铬去除率的因素:pH、铁屑用量、反应时间,得到了较好的反应工艺参数。并在静态试验的基础上,用铁屑填充自制的反应柱研究了动态试验的效果。结果表明:六价铬的出水浓度低于0.05 mg/L,达到GB/T 14848-93《地下水质量标准》Ⅲ类排放标准。     

Preparation and coagulation efficiency of polyaluminium ferric silicate chloride composite coagulant from wastewater of high-purity graphite production

The aim of the present work was to produce a polyaluminium ferric silicate chloride (PAFSiC) coagulant from acidic and alkaline wastewater of purifying graphite by roasting, and subsequently to evaluate coagulation efficiency of the reagent by treating surface water from the Yellow River as well as municipal wastewater in comparison with the conventional coagulant polyaluminium chloride (PAC). The PAFSiC coagulant was prepared by co-polymerization. The effects of (Al+Fe)/Si molar ratio, OH/(Al+Fe) molar ratio (i.e., value), coagulant dosage and pH value of test suspension on the coagulation behavior of FAFSiC and the stability of the PAFSiC were also examined. Results showed that PAFSiC performed more efficiently than PAC in removing turbidity, chemical oxygen demand (COD), and total phosphate (TP). The PAFSiC with a value of 2.0 and (Al+Fe)/Si ratio of 5 (PAFSiC 2.0/5) showed excellent coagulation effect for both turbidity and COD, while PAFSiC 1.0/5 was the best for TP. The optimum coagulation pH range of PAFSiC 2.0/5 was 5.0–9.0, slightly wider than that of PAC (6.0–8.0). The process can be easily incorporated into high-purity graphite production plants, thereby reducing wastewater pollution and producing a valuable coagulant.     

改性膨润土处理污水处理厂二级出水的实验研究

研究基于再生水回灌地下、补充地下水水源的目的,使用河南信阳某膨润土厂生产的钠基膨润土,通过酸改性、铝柱撑改性和微波-硫酸亚铁改性制得三种改性膨润土,用于处理城市污水处理厂的二级出水.实验结果显示,经XRD衍射分析可知,三种方法制备的改性膨润土,其矿物结构都有不同程度上的变化,膨润土层间距都较膨润土原矿有所增大,可见其改...     

钱塘江杭州段沉积物中铁锰的分布特征

针对钱塘江杭州段水污染现状,对钱塘江杭州段12个采样断面的沉积物进行了系统研究。结果表明,沉积物Fe、Mn的平均含量分别为2.05%,449 mg/kg,变异系数分别为16%、27%。主成分分析结果表明,Fe、Mn、K具有一定的同源性,代表沉积物的自然来源,Fe、Al的分布情况反映两者之间可能存在一定的同源性。相关性分析结果表明,Fe、Al、K均与粘粒显著或极显著相关,反映了地球化学作用和水文条件相互作用的结果;Mn与有机污染(OM)呈显著负相关,说明Mn的污染源与OM不存在同源性,相反,有机质污染导致沉积物锰含量有所降低,两者可能存在密切关系。     

河南遂平石寨铺铁矿区地球物理特征及找矿远景

遂平石寨铺铁矿区位于河南省隧平县境内,属于沉积变质型铁矿,含铁层位是太古界太华岩群。依据地球物理特征及物探高精度磁法工作结果,与舞阳铁矿成矿条件对比,预测西北部找矿远景较好。     

钢铁企业节水评价指标体系的构建

针对中国钢铁行业尚未建立节水评价指标体系的现状,在广泛查阅资料的基础上,遵循科学合理性、目标导向性、实用性和可比性的原则,构建了钢铁企业节水评价指标体系。指标体系的建立使钢铁企业的节水成效具有横向和纵向可比性,有利于调动企业的节水积极性,促进节水技术的发展和推广,为钢铁企业开展节水工作指明目标和方向。