化学沉淀-吹脱法处理稀土精矿废水

为解决某稀土精矿分解厂在废水处理工艺中,NH3-N吹脱效率低(40%),吹脱塔内经常结垢的问题,采用化学沉淀法对废水进行预处理,再进一步考察吹脱法对NH3-N的去除.研究结果表明,化学沉淀试验中,在尽量不增加PO43-污染物的前提下,当pH=9.0、n(Mg2 ):n(PO43-)=10.975时,NH3-N浓度减少到2 148mg·L-1,处理效率为74%,Mg2 浓度减少到33.6 mg·L-1;吹脱试验中,当pH=11时,吹脱后NH3-N浓度进一步减少到420mg·L-1,总去除率为95.3%,且结垢问题大为改善.本研究为解决相关问题提供了参考.     

Effects of organic ligands on fractionation of rare earth elements (REEs) in hydroponic plants: an application to the determination of binding capacities by humic acid for modeling

Previous studies have revealed the fractionation processes of rare earth elements (REEs) in hydroponic plants, with a heavy REE (HREE, the elements from Gd to Lu) enrichment in leaves. In this study, effects on the HREE enrichment in soybean leaves with additions of carboxylic acids (acetate, malate, citrate, NTA, EDTA and DTPA) and two soil humic acids (HAs) were investigated. REE speciation in carboxylic acid and HA solutions was simulated using Visual MINTEQ and Model V, respectively. The results showed that the effects caused by carboxylic acids were strongly dependent on the differences between their binding strengths for light REEs (LREEs, the elements from La to Eu) and those for HREEs. A good correlation existed between these effects and the changes of free REE ions in solutions. This relationship was also observed for the HA treatments, provided that the intrinsic equilibrium constants of REEs for cation–proton exchange with HA (i.e., pK_MHA) in Model V were estimated using a free-energy relationship with the stability constants for REE complexation with lactic acid. It is suggested that this set of pK_MHA values is more suitable for use in Model V for the simulation of REE complexation with HA.     

Research and application of comprehensive electromagnetic detection technique in spontaneous combustion area of coalfields

Perplexed by severe disasters, spontaneous combustion areas of coalfields in China not only lose a large number of precious coal resources but damage the ecological environment badly. The premise of effective control against the disasters is investigations on the source position and scope of spontaneous combustion areas at coalfields so as to provide scientific basis for fire extinguishment design and construction of coalfields. Working principles, construction methods and detection effects of high resolution earth resistivity method, transient electromagnetic method (small loop-center probe device) applied in the detection of combustion areas at coalfields have been introduced. The application shows that the above mentioned methods can detect the accurate position of underground combustion areas, are effective ones in detecting the combustion center, combusted area and distribution scope of combustion areas at coalfields, and have broad application prospects.     

投加硅藻土对MBR处理校园生活污水影响的研究

实验研究了投加硅藻土对膜生物反应器处理校园生活废水效果的影响。两组膜生物反应器的对比实验结果表明:投加硅藻土有利于MBR工艺中活性污泥的培养和出水的稳定。投加硅藻土使MBR的出水COD质量浓度稳定在25 mg/L以下,BOD5质量浓度小于5 mg/L,NH3-N质量浓度0.4 mg/L左右,TP质量浓度小于0.5 mg/L,SS未检出,出水水质更加稳定。     

Reuse of spent bleaching earth by polymerisation of residual organics

Spent bleaching earth (SBE) is a waste generated by the edible oil industry that currently has limited options for beneficial reuse. In excess of ～2 million tonnes per year of SBE is generated world-wide with major quantities available in the middle-east where significant volumes of edible oils are produced. Low pressure compaction followed by heat treatment at 150 °C causes polymerisation of the residual organic components in SBE and this produces monolithic samples with high unconfined compressive strengths (54 MPa). SBE can therefore be used to manufacture novel clay blocks for use in construction that are bonded by polymerised vegetable oil. This represents a new, innovative and resource efficient application for SBE. In this research, commercial SBE has been characterised and the effects of key processing variables (temperature and compaction pressure) on the compressive strength, porosity and density of the SBE clay blocks are reported and the mechanisms responsible for strength development are discussed.     

Bond behaviour of bamboo splints in cement-stabilised rammed earth blocks

This paper represents an effort to study the bond characteristics of plain and noded bamboo splints embedded in cement-stabilised rammed earth (CSRE) blocks. A series of CSRE pullout test specimens and two species of bamboo, namely Melocanna Baccifera and Bambusa Balcooa having an average tensile strength of 384 and 310 MPa, respectively, were fabricated using 4–10% Portland cement. These bamboo species are commonly available and widely used for construction in the north-eastern part of India. Besides considering the effects of soil strength, cement content, splint size and type on bond force and slip, the effect of embedded area was also briefly considered as part of the test programme. The test result showed that pullout bond resistance is correlated to rammed earth compressive strength, splint size and type, and embedded area.     

流变相法合成稀土水杨酸配合物的研究

采用流变相法合成了6种稀土水杨酸配合物,即将稀土氧化物RE<,2>O<,3>(RE=La,Nd,Sm,Eu,Gd,Dy)与水杨酸以1:3的摩尔比例混合研磨均匀,加适量去离子水配制成流变体.通过元素分析、热重分析和红外光谱分析对产品进行了表征.实验结果表明,反应最佳时间为12h,热重分析证明放热峰是由配合物氧化分解为稀土的氧化物所致,红外谱图分析得知稀土和水杨酸主要通过羧基进行配位,苯环上的羟基未参与配位.实验误差小,证明了流变相法合成稀土水杨酸配合物的可行性和实际应用价值.     

Fractionation of rare earth and other trace elements in crabs, Ucides cordatus, from a subtropical mangrove affected by fertilizer industry

Fractionation of rare earth elements (REE) and other trace metal concentrations (Th, U, Cd, Cr, Cu, Ni, Pb, and Zn) between mangrove sediments and claw muscles and shells of male crabs (Ucides cordatus) from a subtropical estuary highly impacted by fertilizer industry activities was investigated. This is the first record of REE distribution in these organisms, and the results showed higher accumulations of these metals, U and Th in shells, probably related to the replacement of Ca during molting. Contents of Cd, Cr and Ni were similar in both tissues, but Cu, Zn and Pb were mostly accumulated in the claw muscle with concentrations above those considered safe for human consumption according to the Brazilian legislation. REE fractionation was different in the analyzed tissues being softer in the shells. The results provided evidences that the water absorbed during molting controls the chemistry of REE in shells. In contrast, the chemistry of REE in the claw muscle, in which was observed preferential absorption of light REE, is controlled by diet. REE fractionation obtained for the claw muscles was closely correlated to the observed in the contaminated substrate and in materials related to the production of phosphate fertilizers (contamination source), which supports their transference to this Ucides cordatus tissue without fractionation by the ingestion of sediments. Our results showed the potential use of crab tissues for monitoring REE and trace element sources in mangrove areas, with claw muscle exhibiting the contaminant source fingerprint.     

丛枝菌根真菌对稀土尾矿中大豆生长和稀土元素吸收的影响

采用温室盆栽试验的方法,研究了接种丛枝菌根(arbuscular mycorrhiza,AM)真菌Glomus versiforme对稀土尾矿上大豆(Glycine max)生长、矿质营养吸收、C∶N∶P生态化学计量比、重金属和稀土元素吸收的影响,旨在为稀土尾矿废弃地的生态重建和植被恢复提供基础依据.结果表明,AM真菌G.versiforme与大豆成功建立了互惠共生关系,具有较高的菌根侵染率,平均为67%.接种G.versiforme显著增加了大豆植株地上部和根部的干重,显著提高了大豆植株中P和K的含量,降低了C∶N∶P计量比,符合生长速率假设.接种G.versiforme显著降低了大豆地上部Fe和Cr的浓度,增加了根部Cd的浓度,未显著影响其它重金属的浓度;同时,显著降低了大豆植株地上部和根部轻稀土元素La、Ce、Pr和Nd的浓度.试验初步证明AM真菌对于大豆适应稀土尾矿复合逆境,以及在稀土尾矿上重建植被具有潜在的作用,应进一步验证自然条件下AM真菌的作用潜力.     

声电氧化处理扑热息痛的研究

采用电沉积法制备了新型稀土和氟树脂共掺杂二氧化铅电极,并用于声电氧化体系处理扑热息痛(APAP)废水.结果表明,采用稀土掺杂电极后,APAP的去除效率及矿化效率大幅度增加,显示出催化效率的显著提升.工艺因素作用规律结果表明,Ce-PTFE共掺杂PbO2电极在电解质14.2 g.L-1、功率为49.58 W.cm-2、频率50 Hz、pH为3、电流密度为71.43 mA.cm-2的条件下去除APAP效果最佳.反应进行2 h后,500 mg.L-1APAP去除率为92.20%,COD和TOC的去除率分别为79.95%和58.04%,电流效率高达45.83%.结合GC-MS、HPLC、IC等分析手段,检测到了主要中间产物包括苯醌,苯甲酸、乙酸、顺丁烯二酸,乙二酸、甲酸等,推测了APAP的可能降解途径.