不同钝化剂对微碱性土壤镉、镍形态及小麦吸收的影响

通过大田试验,研究生物炭、褐煤、鸡粪对土壤Cd、Ni形态变化及小麦植株对Cd、Ni富集吸收的影响.结果表明,生物炭可提高土壤pH,褐煤降低土壤pH,均未达显著水平,鸡粪可显著降低孕穗期、成熟期土壤pH,分别降低0. 23和0. 20个单位.生物炭、鸡粪和褐煤单一施用对可交换态Ni含量降低不显著,而对可交换态Cd降低效果显著,小麦不同生长期均以褐煤2%处理降幅最大,分别为30. 50%、43. 34%和31. 20%.小麦地上部、地下部重金属Cd、Ni的含量均有所下降,且降幅随钝化剂添加量的增加而增加,不同生长期均以褐煤2%处理小麦根部Cd含量降幅最大,分别达38. 35%、58. 00%和50. 20%.孕穗期、成熟期均以褐煤2%处理小麦根部Ni含量降幅最大,分别达41. 33%和51. 35%. 3种钝化剂均可降低微碱性土壤中Cd和Ni的有效性,且对镉的钝化效果优于镍;均可有效降低不同时期小麦植株不同器官中Cd和Ni的含量.对于重金属镉,3种钝化剂同等剂量水平下,小麦器官中镉的降低效果依次为褐煤生物炭鸡粪.     

多孔TiO2薄膜电极/泡沫镍硬模板制备及其光电催化性能

以泡沫镍为载体,活性炭为造孔剂,采用硬模板法制备泡沫镍负载多孔TiO2薄膜(Porous TiO,films/foam nicel,PTFN)电极,并利用XRD和SEM等测试手段对其结构进行表征.同时,通过亚甲基蓝溶液的光电催化降解反应,对其光电催化活性进行评价,并探讨阳极偏压、通气速率、亚甲基蓝初始溶液浓度和活性炭造孔剂量对降解效率的影响规律.结果表明:相对于未加模板造孔剂的TiO2薄膜电极的光电催化性能,泡沫镍负载多孔TiO2薄膜具有更好的光电催化性能,原因是高比表面积电极有利于为光电催化提供高浓度的亚甲基蓝分子,使反应速率加快;另外,存在最佳的光电催化降解条件,即当外加阳极偏压为3 V,通气速率为40 L·h-1,n(活性炭造孔剂最):n(前驱体中钛)(即C/Ti)为10％,亚甲基蓝溶液初始浓度为1mg·L-1时,光电催化降解效率最高.同时,研究发现,亚甲基蓝在光电催化降解过程中,通过自由基的氧化发生了C=N键的断裂去甲基化,最后被降解为H2O、CO2和SO42-、NO3-、Cl-离子.     

浅析某厂化学镀镍线的主要污染物及处理措施

某厂化学镀镍线产生的主要污染物为大气污染、水污染和固体废物污染。其中大气污染物主要为硫酸雾。水污染物为总镍、总铜、化学需氧量、悬浮物、总磷、氨氮等。固废废弃物均为危险废物,包括废包装材料、酸性废液、含镍废液。该文分析了化学镀镍线产生的废气、废水和固体废物的主要来源,并提出了防止污染的对策。     

Electro-oxidation of Ni (II)-citrate complexes at BDD electrode and simultaneous recovery of metallic nickel by electrodeposition

The simultaneous electro-oxidation of Ni (II)-citrate and electrodeposition recovery of nickel metal were attempted in a combined electro-oxidation-electrodeposition reactor with a boron-doped diamond (BDD) anode and a polished titanium cathode. Effects of initial nickel citrate concentration, current density, initial pH, electrode spacing, electrolyte type, and initial electrolyte dosage on electrochemical performance were examined. The efficiencies of Ni (II)-citrate removal and nickel metal recovery were determined to be 100% and over 72%, respectively, under the optimized conditions (10 mA/cm², pH 4.09, 80 mmol/L Na₂SO₄, initial Ni (II)-citrate concentration of 75 mg/L, electrode spacing of 1 cm, and 180 min of electrolysis). Energy consumption increased with increased current density, and the energy consumption was 0.032 kWh/L at a current density of 10 mA/cm² (pH 6.58). The deposits at the cathode were characterized by scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). These characterization results indicated that the purity of metallic nickel in cathodic deposition was over 95%. The electrochemical system exhibited a prospective approach to oxidize metal complexes and recover metallic nickel.     

硫化钠沉淀法处理化学镀镍废液

采用化学沉淀法处理化学镀镍废液,以硫化钠为沉淀剂,将废液的镍离子以硫化镍的形式析出,从而达到净化废液和回收镍的目的。实验结果分析表明,在影响镍去除率效果的几个因素中硫化钠投加量的影响最大,pH值次之,反应时间影响最小。在pH为6,投加200 mL质量分数为20%的硫化钠溶液,反应时间为30 min,可以使200 mL化学镀镍废液中(镍质量浓度为5450 mg/L)的镍去除率达到99.8%,残余镍的质量浓度可以降至12 mg/L左右,对其余重金属离子的去除也有明显的效果。同时得到的沉淀致密,镍含量高(质量分数为21.6%),便于进一步回收利用。     

Application of ferrate（VI） in the treatment of industrial wastes containing metal-complexed cyanides ： A green treatment

Ferrate(VI) was employed for the oxidation of cyanide (CN) and simultaneous removal of copper or nickel in the mixed/complexed systems of CN-Cu, CN-Ni, or CN-Cu-Ni. The degradation of CN (1.00 mmol/L) and removal of Cu (0.095 mmol/L) were investigated as a function of Fe(VI) doses from 0.3–2.00 mmol/L at pH 10.0. It was found that Fe(VI) could readily oxidize CN and the reduction of Fe(VI) into Fe(III) might serve e ciently for the removal of free copper ions. The increase in Fe(VI) dose apparently favoured the CN oxidation as well as Cu removal. Moreover, the pH dependence study (pH 10.0–13.0) revealed that the oxidation of CN was almost una ected in the studied pH range (10.0–13.0), however, the maximum removal e ciency of Cu was obtained at pH 13.0. Similarly, treatment was carried out for CN-Ni system having the initial Ni concentration of 0.170 mmol/L and CN concentration of 1.00 mmol with Fe(VI) dose 2.00 mmol at various pH values (10.0–12.0). Results showed a partial oxidation of CN and partial removal of Ni. It can be observed that Fe(VI) can partially degrade the CN-Ni complex in this pH range. Further, Fe(VI) was applied for the treatment of simulated industrial waste/e uent waters treatment containing CN, Cu, and Ni.     

不同淋洗剂对镍污染砂土的柱淋洗研究

比较了去离子水、阴离子表面活性剂十二烷基硫酸钠（SDS）、盐酸和柠檬酸对模拟污染砂土中镍（Ⅱ）的柱淋洗作用。SDS浓度为500、1000、1750、2500和3250mg／L,盐酸溶液pH值为0．8、1、2和3,柠檬酸溶液浓度为0．01、0．04、0．1和0．4mol／L。结果表明,几种淋洗剂对土柱中镍的淋洗曲线规律相似,即在淋洗液孔隙体积数为0．5时开始有镍淋出,随着累计孔体积数目的增大,淋洗液中镍的浓度逐渐开始增大,迭到峰值时又开始减小。在去离子水淋洗过程中,镍最大淋出浓度为90．8mg/L;五种不同浓度SDS淋洗过程中,镍最大淋出浓度分别为92．4、90．2、94．1、51．0和53．7mg／L;四种不同pH值的盐酸溶液对应的镍最大淋出浓度分别为959．5、753．3、56．3和23．9mg／L;四种不同浓度的柠檬酸对应的镍最大淋出浓度分别为318．6、793．4、930．1和1464．4mg／L。pH=1的盐酸溶液对镍的淋洗去除率最高为87．3％,其次是浓度为0．1mol／L的柠檬酸溶液,去除率为83．2％;SDS的淋洗效率低,与去离子水相当。0．1mol／L的柠檬酸溶液可为污染土壤重金属镍淋洗用试剂。     

镍钴转运酶NiCoT基因的克隆表达及基因工程菌对镍离子的富集

利用PCR技术从Staphylococcus aureus/ ATCC6538基因组中扩增出大小为1?053 bp的镍钴转运酶基因NiCoT gene,将其连接到pET-3c载体上构建重组质粒,并转化至E.coli BL21.筛选阳性菌并经酶切分析和PCR扩增双重鉴定.核苷酸序列测定及分析结果与GenBank中报道的同类基因相似性高达97%以上,表明其具有正确的NiCoT基因核苷酸序列.重组菌的SDS-PAGE结果图谱中,在相对分子量为39?000附近有特异性蛋白条带,大小符合预测值,表明NiCoT基因在E.coli BL21中成功表达.基因工程菌在IPTG用量为1.00 mmol·L^-1,诱导时间为4 h的条件下培养对镍离子的富集能力最高.在不同镍离子浓度时,基因工程菌对溶液中Ni²⁺的平衡富集量为11.33 mg·g^-1,与原始宿主菌相比提高了3倍.对基因工程菌吸附镍和钴的实验表明,Staphylococcus aureus ATCC6538的NiCoT对镍具有较高的特异性和富集容量,属于第Ⅲ类镍钴转运酶.     

Phosphine functionalised multiwalled carbon nanotubes: A new adsorbent for the removal of nickel from aqueous solution

Synthesised triphenylphosphine-linked multiwalled carbon nanotubes (Tpp-MWCNTs) were used to study the adsorption of nickel in aqueous solutions and their adsorption capabilities were compared with purified MWCNTs. The adsorption capacity increased with an increase in pH for all adsorbents. The adsorption equilibrium was reached in 40 and 30 min for purified MWCNTs and Tpp-MWCNTs, respectively. Both Freundlich and Langmuir isotherms used to investigate the adsorption process fitted the experimental data well with the correlation coefficient R² close to 1 for all adsorbents. On the other hand, the experimental data fitted well with a pseudo second-order model. The speciation of nickel also influenced the adsorption on the purified and Tpp-MWCNTs. The adsorbents used in this study showed superior adsorption capacity when compared to other adsorbents reported in the literature.     

Poly[β-(1→4)-2-amino-2-deoxy-D-glucopyranose] based zero valent nickel nanocomposite for efficient reduction of nitrate in water

Chemical reduction of nitrate using metal nanoparticles has received increasing interest due to over-dependence on groundwater and consequence health hazard of the nitrate ion. One major drawback of this technique is the agglomeration of nanoparticles leading to the formation of large flocs. A low cost biopolymeric material, poly [β-(1 → 4)-2-amino-2-deoxy-D-glucopyranose] (β-PADG) obtained from deacetylated chitin was used as stabilizer to synthesize zero valent nickel (ZVNi) nanoparticles. The β-PADG-ZVNi nanocomposite was characterized using infra red (IR), UV-Vis spectrophotometric techniques and Scanning Electron Microscope (SEM). The morphology of the composite showed that β-PADG stabilized-ZVNi nanoparticles were present as discrete particles. The mean particle size was estimated to be (7.76 ± 2.98) nm and surface area of 87.10 m²/g. The stabilized-ZVNi nanoparticles exhibited markedly greater reactivity for reduction of nitrate in water with 100% conversion within 2 hr contact owing to less agglomeration. Varying the β-PADG-to-ZVNi ratio and the ZVNi-to-nitrate molar ratio generally led to a faster nitrate reduction. About 3.4-fold difference in the specific reaction rate constant suggests that the application of the β-PADG-stabilizer not only increased the specific surface area of the resultant nanoparticles, but also greatly enhanced the surface reactivity of the nanoparticles per unit area.