双室微生物燃料电池对电解锰废水中Cr(VI)的去除及其产电性能研究

构建以F026为阳极产电菌和含Cr(VI)电解锰废水为阴极液的双室微生物燃料电池(MFC)。考察电解锰模拟废水pH、Cr(VI)初始质量浓度、MFC运行温度等因素对废水中Cr(VI)的还原率及MFC产电效果的影响规律,并对最优条件下MFC处理实际电解锰含铬废水的效果和Cr(VI)的还原产物进行研究。结果表明:当废水pH为2、MFC运行温度为303K时,MFC对含Cr(VI)废水具有最佳的处理效果。在此条件下,MFC对Cr(VI)质量浓度为124 mg/L的电解锰废水处理80 h后,92.1%的Cr(VI)可有效还原为α-Cr_2O_3,而155h处理后还原率可达100%,产电功率达到914.7 mW/cm~2,表明MFC是一种发展前景良好的含Cr(VI)电解锰废水处理工艺。     

铂的萃取分离技术研究进展

溶剂萃取法分离提纯铂相比于传统的沉淀法具有工艺简单、高效、操作安全等优势,本文从胺类萃取剂、中性磷类萃取剂、离子液体萃取剂、新型萃取剂四个方面综述了近年来溶剂萃取分离铂的技术研究进展,并对各种溶剂萃取法存在的优缺点进行了评述。胺类萃取剂和中性磷类萃取剂萃取效率高,成本低,已成熟应用于铂的分离提纯,但选择性相对较差。离子液体的研究起步较晚,其选择性好但造价高昂,距离工业化应用还有很长的距离。随着对铂分离提纯技术的要求越来越高,进一步开发高效清洁的新型萃取剂、研究协同萃取体系、简化萃取流程以及改进萃取设备是未来铂萃取分离技术的发展方向。     

预分散溶剂萃取法处理Cr(Ⅲ)废水(英文)

以2-乙基己基膦酸单2-乙基己基酯(HEHPEHE)为萃取剂,以及与其它萃取剂形成酸加酸、酸加碱、酸加中性混合萃取剂,通过考察萃取剂对废液中的Cr3+萃取分配比的影响,筛选出萃取Cr3+的适宜萃取剂HEHPEHE;采用预分散溶剂萃取技术对含Cr3+废液进行分离研究,以煤油为稀释剂,HEHPEHE为萃取剂,十二烷基苯磺酸钠(SDBS)为水性表面活性剂,吐温20(Tween-20)为油性表面活性剂,制备胶质液体泡沫CLAs。同时,为了研究预分散溶剂萃取技术萃取Cr3+废液的效果,考察了废液中的Cr3+浓度、胶质气体泡沫CGAs体积、萃取剂浓度、相比、阳离子表面活性剂十六烷基三甲基溴化铵(HTAB)浓度、阴离子表面活性剂SDBS浓度、表面活性剂Tween20浓度以及Cr3+废液的pH值等影响因素对Cr3+的萃取率影响,得到了萃取Cr3+的适宜条件;并用实际的含Cr3+废液进行检验,结果表明,在获得的适宜工艺条件下,经过二级萃取后,废水可以直接排放,Cr3+的萃取率超过99.9%。     

固定相络合萃取剂处理水中六价铬性能研究与应用

采用固定相络合萃取剂回收处理水中六价铬,考察了接触时间、废水起始pH、废水浓度、流速、再生次数等因素对六价铬回收处理的影响,初步探讨了其应用.实验结果表明,在废水起始pH为1.0～2.0时,络合萃取剂能快速络合萃取废水中的六价铬,且易被NaOH溶液再生,再生率达到98.7%,明显优于活性炭,可在单级或多级振动床或固定床中回收处理较宽浓度范围的含铬废水.络合萃取-碱沉淀法可用于同时含有六价铬和三价铬的电镀废水的处理.     

离子液体Cyphos IL104的溶剂浸渍树脂的制备及其在铬(VI)回收中的应用(英文)

采用XAD-7树脂浸渍离子液体二(2,4,4三甲基戊基)亚膦酸三己基十四烷基烷基鏻(Cyphos IL104)。研究该种溶剂浸渍树脂(SIR)的制备过程及其在Cr(VI)分离中的应用,并对树脂的表面形貌和热稳定性进行表征。研究平衡时间和初始pH值对Cr(VI)吸附的影响,讨论溶剂浸渍树脂的吸附等温线、吸附和解吸附过程以及浸渍树脂的选择性。结果表明,萃取剂Cyphos IL104浸入了树脂的内部孔道中,溶剂浸渍树脂吸附Cr(VI)的最佳pH范围为0-2。当CyphosIL104作为解吸附溶液时,Cr(VI)可以从树脂上有效地脱附。     

采用萃取剂[Omim][BF_4]分离提取铬渣中的Cr_2O_7~(2-)

铬渣是重要的工业固体废物,具有极其严重的环境危害性,分离提取铬的资源化利用是减少铬渣环境污染和资源浪费的有效途径。以1-辛基-3-甲基咪唑四氟硼酸盐离子液体([Omim][BF_4])为萃取剂,戊醇为稀释剂,对铬渣酸浸液进行萃取和反萃取实验。在萃取实验过程中,分别考察萃取剂浓度、时间、pH等条件的影响作用。采用斜率法及红外光谱分析进行了萃取机理研究,最后进行了反萃取实验研究。结果表明:在萃取剂浓度ρ([Omim][BF_4])=50.0 g/L、6.0 min、pH为1.408~2.006条件下,Cr_2O_7~(2-)的萃取率达到94.81%;[Omim][BF_4]对Cr_2O_7~(2-)的萃取主要是根据软硬酸碱理论通过离子缔合形成萃合物达到较高的萃取率;在pH=10、反萃取剂为0.5mol/L NaBr+0.5 mol/L(NH_4)_2SO_3、15.0 min的条件下,铬的反萃率达到99.35%。实现了铬渣中铬资源的分离提取。     

用CH-1菌从铬渣中选择性回收铬

提出CH-1菌解毒铬渣及回收铬资源的新工艺.采用扫描电镜、透射电镜以及能量弥散X 射线分析(EDXA)和电子顺磁共振(EPR)等分析手段对还原反应前后细菌细胞形貌进行观察,并对还原反应沉淀产物的元素组成进行定性分析,研究并计算了示范工程中铬的回收率及平衡.结果表明Cr(VI)的还原反应在细菌体外发生,反应产物的主要组成元素为Cr3+,反应产物成分为Cr(OH)3.铬渣中90%以上的Cr(Ⅵ)以Cr(OH)3淤泥的形式得以回收,20 t/批规模的示范工程可回收Cr(OH)3 (含量32.8%) 淤泥694.2 kg,实现铬的再生,并从根本上消除铬渣的污染问题.     

紫外-可见光催化活性的硫酸铵改性含钛高炉渣光催化剂的制备(英文)

以含钛高炉渣和硫酸铵为原料,利用高能球磨法制备硫酸盐掺杂的含钛高炉渣(STBBFS)光催化剂。利用X射线光电子能谱(XPS)、X 射线衍射(XRD)、扫描电镜(SEM)、紫外-可见吸收光谱(UV-Vis)、热重(TGA)分析以及暗态吸附 Cr(VI)废水、光催化还原 Cr(VI)废水实验对 STBBFS 催化剂的物相、表面结构、光吸收能力、吸附容量以及光催化活性进行表征。结果表明:Cr(VI)在 STBBFS 催化剂表面上的吸附遵循 Langmuir 吸附等温线模型;掺杂硫酸盐后,STBBFS 催化剂的吸附容量增大为 8.25 mg/g;在 300 °C煅烧后,STBBFS 催化剂由于存在较高的钙钛矿含量、吸附容量及表面酸性,从而具有较高的光催化活性。     

聚乙二醇双水相体系中铼、钼萃取性能研究

研究在不同双水相体系中,Mo(VI)与Re(VII)的萃取行为。实验结果表明：在6 mol/L的NaOH碱液体系中,通过加入掩蔽剂的方法,可实现Mo(VI)与Re(VII)的萃取分离。     

T12钢盐浴渗铬工艺对渗层组织和性能的影响

采用正交实验方法优化T12钢的低温盐浴渗铬工艺。正交实验表明,以BaCl2-CaCl2为基盐,以Cr2O3 铬盐(Cr3 ) 铬粉 NaF为渗铬剂,在0.15MPa氩气保护下,经850℃×6h渗铬,可获得与基体结合良好的48μm的渗铬层,渗层表面铬浓度约86.9wt%,表面硬度可达1750HV。渗铬表层主要物相为Cr7C3、Cr2C、Cr和(Cr,Fe)2O3组成。渗铬层具有优良耐蚀性,阳极极化曲线的测定分析证明渗铬层的耐腐蚀性能优于1Cr18Ni9Ti不锈钢。     

溶剂萃取分离钯研究进展

溶剂萃取法是分离富集贵金属有效方法,近年来国内外展开了许多研究报道,本文对溶剂萃取分离钯的研究进展进行综述,主要从传统含硫萃取剂、喹啉、肟类萃取剂、含磷萃取剂、含氮萃取剂以及新型“绿色溶剂”离子液体和疏水低共熔溶剂等几个方面进行了综述,重点介绍近年合成的新型萃取剂对钯的萃取进展,并对一些新的方法做了评述以及在溶剂萃取分离钯的应用方面做了展望。     

Corrosion behavior of Cr electrodeposited from Cr(VI) and Cr(III)-baths using direct (DCD) and pulse electrodeposition (PED) techniques

A comparison was made between the electrochemical corrosion behaviors of chromium deposited from hexavalent [Cr(VI)] and trivalent [Cr(III)] chromium baths using direct current (DCD) and pulse electro deposited (PED) techniques. Chromium coatings were deposited on mild-steel (MS) substrate. The corrosion behavior of both DCD and PED chromium from Cr(VI) and Cr(III)-baths in 3.5%NaCl solution was studied using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results indicated that PED chromium from Cr(VI) and Cr(III)-baths have higher charge-transfer resistance R_ct and very low I_corr than that of DCD chromium on mild-steel substrate.     

Surface Characterisation Studies of CrVI and CrIII Electroplated Carbon Steel Samples

Conventional Nickel-Chromium (VI) electroplating has played an important role for corrosion protection of carbon steel blades used in ice-skating for many decades. However, in recent years, the exposure limits for humans to chromium (VI) compounds have been further reduced due to their toxicity and carcinogenic nature, which makes the use of hexavalent chromium electroplating less likely in the future.

It is envisaged that environmentally acceptable Nickel-Chromium (III) electroplating will be a suitable replacement. In this study, Nickel-Chromium (VI) and Nickel-Chromium (III) electroplating have been applied to carbon steel blades. Electrochemical tests were carried out on both Cr(VI) and Cr(III) electroplated blades to evaluate their anti-corrosion performance. In addition, Atomic Force Microscopy and Scanning Electron Microscopy were used to investigate the surface characteristics of the electroplated samples before and after accelerated corrosion tests. It was found that Cr(III) deposits had the lower surface roughness but exhibited higher corrosion rates than Cr(IV). This difference was attributed to multiple pit formation and coalescence in the Cr(III) coating.     

Self-assembling molecules as corrosion inhibitors for 1050 aluminum

Whether it contains hexavalent chromium, chromium (VI), or simply Cr(VI), chromating has been largely used for surface preparation of aluminum aimed at corrosion protection due to its effectiveness and easy application. The most used among these processes are those that contain toxic and carcinogenic substances, which generate environmental backlash concerning the disposal of used baths with toxic elements. The high costs involved in the treatment of the disposal solutions prior to being discarded, besides the increasing restrictions concerning the environment, have encouraged research in the search for alternatives with lower toxicities than chromating processes but with high effectiveness for corrosion protection. Surface treatments with alkane diphosphonate molecules (ADM) have been investigated as potential substitutes for chromating. However, their effectiveness in the corrosion protection of aluminum alloys still needs further investigation. In the present study, the corrosion resistance of 1050 aluminum with various surface treatments was investigated by electrochemical techniques and salt spray testing. The corrosion performance of 1050 aluminum samples with a surface treatment that consisted of immersion in ADM was compared with that of the same alloy chromated by immersion in baths of Cr(III) or Cr(VI). The results showed that surface treatment with ADM was effective on samples that had been exposed to boiling water for oxide growth prior to treatment with ADM. The results also showed the superior corrosion performance for samples with the oxide-hydroxide + ADM surface treatment compared to those with both chromating treatments, either with Cr(III) or with Cr(VI). Cr(III) chromating treatment also provided better corrosion performance than chromating with Cr(VI), suggesting that both surface treatments (oxide-hydroxide + ADM and Cr(III)) are potential candidates for substitution for Cr(VI)-containing processes. However, for effective corrosion protection, the ADM treatment has to be carried out on surfaces previously exposed to treatments that favor oxide growth.     

含Cr低合金钢的CO2腐蚀产物膜形成及机理研究进展

针对含Cr低合金钢石油专用管的CO₂腐蚀产物膜,介绍了CO₂腐蚀产物膜的形成机理,总结了含Cr低合金钢的CO₂腐蚀产物膜的影响因素,其中包括Cr含量、温度、CO₂分压、pH值、腐蚀时间、Cl^-浓度、流速等对其腐蚀产物膜的影响,并对腐蚀产物膜的结构与成分进行总结,归类了缓蚀剂对含Cr低合金钢石油专用管的保护办法,以期为今后含Cr低合金钢的CO₂腐蚀产物膜的研究提供借鉴。     

Research and prospect on extraction of vanadium from vanadium slag by liquid oxidation technologies

A series of innovative green metallurgical processes using novel reaction media including the NaOH/KOH sub-molten salt media and the NaOH–NaNO₃ binary molten salt medium, for the extraction of vanadium and chromium from the vanadium slag have been developed. In comparison with the traditional sodium salt roasting technology, which operates at 850 °C, the operation temperatures of these new processes drop to 200–400 °C. Further, the extraction rates of vanadium and chromium utilizing the new approaches could reach 95% and 90%, respectively, significantly higher than those in the traditional roasting process, which are 75% and approximate zero, respectively. Besides, no hazardous gases and toxic tailings are discharged during the extraction process. Compared with the conventional roasting method, these new technologies show obvious advantages in terms of energy, environments, and the mineral resource utilization efficiency, providing an attractive alternative for the green technology upgrade of the vanadium production industries.     

Chromium electrodeposition from Cr(III) aqueous solutions

The aim of this work is to study an alternative plating process to obtain chromium coatings through electrodeposition from baths containing trivalent chromium, as aqueous solutions of Cr (III) are significantly less dangerous, in terms of human health and environmental impact, as compared to the traditional Cr (VI) baths employed for this purpose. In order to overcome problems regarding the reduction of Cr (III) in aqueous solution, two approaches were followed: i) the possibility of co-depositing chromium along with a second metal, which could help the process of discharge of Cr³⁺ on the substrate; ii) the use of a specific ligand for the Cr³⁺ ion, which can generate easily reducible complexes at the metal-solution interphase. Both approaches led to interesting results: in particular, the co-deposition enabled us to obtain NiCr alloy with a high percentage of chromium, and the deposition using specific complexing agents allowed optimal bath compositions to be developed both for decorative and hard chromium plating.     

Oxidation of green rust suspensions containing different chromium ion species

The oxidation of hydrosulphate green rust (GR2(SO₄²⁻)) suspension containing different chromium ion species was investigated by X-ray diffraction, X-ray absorption spectroscopy and transmission electron microscopy. The pH, oxidation-reduction potential and amount of dissolved oxygen in aqueous solutions were measured during the reactions. The results show that the addition of Cr(III)₂(SO₄)₃ solution suppresses the transformation of GR2(SO₄²⁻) into iron oxyhydroxides and oxides in aqueous solution, while the addition of Na₂Cr(VI)O₄ solution promotes the transformation of GR2(SO₄²⁻) in which Cr(VI) is reduced to Cr(III); α-FeOOH particles were refined by the addition of the chromium ions.     

C、Cr、Si、Mn对低铬白口铸铁组织和力学性能的影响

应用湿砂铸型浇注低铬白口铸铁，采用正交试验研究了C、Cr、Si、Mn对低铬白口铸铁组织和力学性能的影响。结果表明：含碳量2．4％和2．7％时碳化物基本上是呈网状分布的，形成了离异共晶的网状碳化物组织；而含碳量3．0％时，离异共晶组织不再出现。高碳、低硅、高铬和低锰有利于提高硬度；低碳、低硅、中铬和高锰有利于提高冲击韧度；高碳、低硅、低铬和高锰有利提高耐磨性。新开发的低铬白、口铸铁的硬度、冲击韧度和耐磨性远高于目前在生产排沙潜水泵过流部件中所使用材料的各项性能，使用寿命是其5倍左右。