Recovery of silicon powder from kerf loss slurry waste using superconducting high gradient magnetic separation technology

A major challenge in recycling of silicon powder from kerf loss slurry waste is the complete removal of metal particles. The traditional acid leaching method is costly and not green. In this paper, a novel approach to recover high-purity Si from the kerf loss slurry waste of solar grade silicon was investigated. The metal impurities were removed with superconducting high gradient magnetic separation technology. The effects of process parameters such as magnetic flux density, slurry density, and slurry flow velocity on the removal efficiency were investigated, and the parameters were optimized. In one lot of control experiments, the silicon content was increased from 90.91 to 95.83%, iron content reduced from 3.24 to 0.57%, and aluminum content from 2.44 to 1.51% under the optimum conditions of magnetic flux density of 4.0 T, slurry density of 20 g/L, and slurry flow velocity of 500 mL/min. The result indicates that the superconducting high gradient magnetic separation technology is a feasible purifying method, and the magnetic separation concentrate could be used as an intermediate product for high-purity Si powder.

     

Effect of F,Cl, Br and I substitution on the BphB enzyme for the degradation of halogenated biphenyls,revealed by quantum and molecular mechanics

Halogenated biphenyls are worldwide persistent pollutants of great environmental concern. In particular, polychlorinated biphenyls and polybrominated biphenyls have been globally used for industrial purposes until they were found highly toxic, mutagenic and carcinogenic to humans. Therefore, ecological strategies to remove halogenated biphenyls, such as enzyme-catalyzed degradation, are needed. Here, we studied the effect of substitution of F, Cl, Br or I at the 4,4′-positions of 2,3-dihydro-2,3-dihydroxybiphenyl-2,3-dehydrogenase (BphB) on the degradation of halogenated biphenyls by quantum and molecular mechanics. Results show that Boltzmann-weighted average degradation barriers of substituted BphB are all lower than the unsubstituted biphenyl, except for chlorinated biphenyl. The roles of residues nearby the active site, e.g., isoleucine89, asparagine115, serine142, asparagine143, proline184, methionine187 and threonine189, were also investigated.

     

虫螨腈对斑马鱼的急性毒性及生物富集性研究

以斑马鱼(Brachydanio rerio)为试验生物,采用半静态法测定虫螨腈对斑马鱼的急性毒性和生物富集系数。试验结果表明,虫螨腈对斑马鱼96 h-LC50为0.015 mg·L-1,其95%的置信限为0.011 mg·L-1~0.12 mg·L-1,属于高毒。在两个处理浓度2.0×10-4mg·L-1和2.0×10-3mg·L-1下,连续暴露8 d,斑马鱼对虫螨腈的生物富集系数(BCF8d)分别为1 211.6和1 549.7,属于高富集性农药。     

唐山市空气中SO2与TSP污染状况分析

分析了唐山市从1988年至1992年大气中SO2和TSP的污染状况和变化规律，取得对该市环境管理的科学依据。     

耕地土壤铜、镉、锌形态及生物有效性研究

土壤重金属总量常被用来评估土壤质量安全,但是大量事实说明单纯用土壤重金属总量并不能完全说明土壤重金属的生物有效性及其环境风险。相对于国内外常用的Tessier的五态方法,欧共体标准物质局提出的三步提取法（BCR法1,中国地质调查局地质连续提取法的七态标准少见报道。本研究选取河南平原耕地样品,采用中国地质调查局地质连续提取法（DD2005．03）进行耕地中重金属元素（Cu、Cd、Zn）的形态分布,结果表明：Cu、Zn主要以残渣态存在,其残渣态分别占全量的55．80％和67．35％。Cd以离子交换态为主,占全量的27．30％。Cu、Cd、Zn各态含量占全量比例的顺序是,Cu：残渣态〉弱有机结合交换态〉铁锰氧化态〉碳酸盐结合态〉强有机结合态〉水溶态〉离子交换态。Cd：离子交换态〉弱有机结合交换态〉强有机结合态〉残渣态〉碳酸盐结合态〉铁锰氧化态〉水溶态。Zn：残渣态〉铁锰氧化态〉弱有机盐结合态〉离子交换态〉强有机结合态〉碳酸盐态〉水溶态。从生物可利用性系数k来看,Cd主要以活动性较大的状态存在,很容易被作物吸收。     

钙稳态失调与镉肝细胞毒性关系的研究

分别从细胞外钙对镉肝细胞毒性的影响.细胞内总钙和游离钙含量变化以及钙移位酶活力的变化等方面探讨了镉对肝细胞的毒性与细胞内钙稳态失调的关系.结果表明:镉对大鼠游离肝细胞的毒作用并非由于引起细胞外钙内流所致,也不是由于干扰了细胞内钙隔离系统功能所致.     

室内空气污染的探讨

据有关部门检测，现在室内空气中挥发性有机化合物达300多种，其中易对人体造成伤害，甚至致癌的就有20多种。研究证实，建筑的装修材料是导致室内空气污染的主要根源。随着我国经济的迅速发展以及人民生活水平的不断提高，室内装修频频出现，装修产生的室内空气污染问题日趋严重。装修产生的室内空气污染，其主要污染物与装修材料有极大的关系。装修一个环保的室内环境，只有选材、建材环保，装修才能环保。 近几年，中国房地产市场不断升温，建材生产的销售量也随之快速增加。于是，各种不合格装修材料充斥市场，许多不具备生产资质的厂商生产的建材产品有害物质超标，严重危害着消费者的人身健康。     

耕地土壤铜、镉、锌形态及生物有效性研究

土壤重金属总量常被用来评估土壤质量安全,但是大量事实说明单纯用土壤重金属总量并不能完全说明土壤重金属的生物有效性及其环境风险。相对于国内外常用的Tessier的五态方法,欧共体标准物质局提出的三步提取法(BCR法),中国地质调查局地质连续提取法的七态标准少见报道。本研究选取河南平原耕地样品,采用中国地质调查局地质连续提取法(DD2005-03)进行耕地中重金属元素(Cu、Cd、Zn)的形态分布,结果表明:Cu、Zn主要以残渣态存在,其残渣态分别占全量的55.80%和67.35%。Cd以离子交换态为主,占全量的27.30%。Cu、Cd、Zn各态含量占全量比例的顺序是,Cu:残渣态弱有机结合交换态铁锰氧化态碳酸盐结合态强有机结合态水溶态离子交换态。Cd:离子交换态弱有机结合交换态强有机结合态残渣态碳酸盐结合态铁锰氧化态水溶态。Zn:残渣态铁锰氧化态弱有机盐结合态离子交换态强有机结合态碳酸盐态水溶态。从生物可利用性系数k来看,Cd主要以活动性较大的状态存在,很容易被作物吸收。     

Using multi-integrated biomarker indexes approach to assess marine quality and health status of marine organism: a case study of Ruditapes philippinarum in Laizhou Bay,China

With the progress of technology and the deepening of understanding of biological monitoring, much more attention has been paid to the multiple evaluation of marine pollution monitoring. In view of this, our study aimed at establishing a multi-integrated biomarker indexes approach to evaluate marine condition systematically and comprehensively. In the current study, sampling was conducted in Laizhou Bay, China (S1, S2, and S3) in May, August, and October of 2015. And then, multi-integrated biomarker indexes approach was applied to assess marine PAHs pollution, select appropriate biomarkers, and evaluate marine environmental quality and health status of the clams of Ruditapes philippinarum. As the results showed, S2 was the most PAHs-polluted site while S1 was the least polluted site, and the levels of tPAHs in seawater and sediments ranged from 69.78 to 315.30 ng/L and 163.19 to 565.17 ng/g d.w., respectively. And all three sampling sites had different sources of PAHs. IBR represented DNA damage (F value), the expression of SOD, EROD activity, GST activity, and LPO could be served as biomarkers to monitor the PAHs pollution in Laizhou Bay. And MPI suggested the quality of all three sites: S1 was generally favorable, S2 was moderately polluted, and S3 was lightly polluted. BRI values showed that the order of health status of R. philippinarum was S1?>?S3?>?S2.

     

淹水对菖蒲(Acorus calamus)根际氧环境的影响

为研究淹水对湿地植物根际氧环境的影响,选择典型湿地植物菖蒲幼苗(株高约15 cm、根长约6 cm)和成株(株高约40 cm、根长约11 cm)在沉积物中培养并完全淹没,利用微型电机控制氧气微光极对菖蒲根中部根际氧浓度及组织内部氧浓度原位测定3周. 结果表明:短期(7 d) 淹水,菖蒲幼苗及成株根际氧扩散层厚度及氧浓度比对照组均显著下降;在淹水第14天,在幼苗根际未检出氧扩散层;在淹水第21天,成株根际氧扩散层厚度及平均氧浓度仍分别为0.34 mm和11.18%,并保持至淹水试验结束. 淹水组菖蒲的根际氧扩散层厚度、平均氧浓度均随根组织内部氧浓度的下降而降低,其中幼苗3个指标分别由初始的0.22 mm、1.4%和50.3%降至0 mm、0%和32.9%,成株分别由0.64 mm、19.3%和64.6%降至0.34 mm、11.2%和55.3%,表明前2个指标的下降程度显著超过后者;淹水组菖蒲幼苗、成株根组织内部氧浓度主要受植株光合作用的影响,而对照组则受光合作用及气体交换作用的共同影响,淹水能在短期(7 d)内促进菖蒲成株根通气组织的发育,使其孔隙率从28.45%升至32.44%,并有助于维持根组织内的氧浓度水平,根组织内部氧浓度淹水组(65.6%)与对照组(67.1%)无显著差异. 研究表明,淹水胁迫下,根组织内部氧浓度水平是影响菖蒲根氧扩散的核心因素,其中幼苗根组织内部氧浓度显著下降并威胁到自身存活时,其已无氧扩散效应,而成株根组织内部较高的氧浓度使其仍能保持一定程度的氧扩散.