The Screening of Extractants for the Separation of Zn(II) from Australian Hot-Dip Galvanizing Effluent

In this study, the most appropriate organic phase for the selective extraction of Zn(II) from Australian hot-dip galvanizing effluent streams has been determined. TBP (tributyl phosphate) and Hostarex A226 (diisotridecylamine) were identified as the most favourable for the extraction of zinc ions from a chloride matrix. Two alternatives, Hostarex A324 (tri-iso-octlyamine) and Hostarex A327 (tri-n-octyl/n-decylamine), were also tested. Laboratory scale shake tests were conducted using model solutions containing a range of acid concentrations and zinc concentrations up to 80 g/L. Industrial pickling effluent was used to test the effect of impurities present. The use of TBP was confirmed as the most appropriate extractant.     

改性沸石去除废水中Zn^2＋的试验

采用NaCl-MnO2联合的方式对天然斜发沸石进行改性,在静态条件下,对改性斜发沸石处理模拟含锌废水进行了试验研究,考察了吸附时间、吸附剂投量、Zn^2＋初始浓度和pH对改性斜发沸石吸附Zn^2＋的影响。结果表明：当温度为25℃、pH为5.0～6.0、Zn^2＋初始浓度≤50 m g/L时,按锌与改性斜发沸石质量比为1：40投加改性斜发沸石进行处理,Zn^2＋去除率可达90%以上,模拟含锌废水经改性沸石处理后,水中锌含量低于国家排放标准。改性斜发沸石对Zn^2＋的吸附规律符合Langm uir吸附等温线和准二级动力学模型,相关系数分别为0.927 5和0.999 2。     

Zinc-rich epoxy primers based on lamellar zinc dust

Conclusions  1. Lamellar zinc primers showed an apparent reduction in the effective pigment volume concentration; the levels from 50 to 55% were the best and they are estimated to be near the corresponding critical pigment volume concentration which is significantly lower than that for spherical zinc primers which was approximately 66%. 2. Taking into account both corrosion and blistering resistance, the best behaviour was obtained with a 75/25 spherical zinc/lamellar zinc ratio (series B) at pigment volume concentration near 60.0%. The sample with 50/50 ratio (series C) at a pigment volume concentration slightly less (approximately 57.5%) also displayed a very good performance at the end of all the tests concerned. 3. After six months storage, lamellar zinc incorporated in the epoxy base showed very slight sedimentation; after adding the curing agent, the primer can be applied after only light stirring. The spherical zinc primers, after the quoted period of storage, exhibited a heavy pigment settlement and consequently were very difficult to redisperse by hand stirring which may lead to more heterogeneous films with poor mechanical properties, high porosity, reduced corrosion-inhibitive properties, etc.     

乙酸锌改性稻壳生物炭电容及电吸附Cu2+性能

以稻壳为原料制备生物炭,利用不同浓度的乙酸锌对稻壳炭改性,制得产物分别命名为RHC和MRHC。通过SEM、BET、XRD对制备的生物炭理化特性进行表征。分析表明,改性炭孔隙结构丰富,比表面积较大,且锌以氧化物颗粒状存在于生物炭表面。将改性前后的稻壳生物炭制成电极,测试其电化学性能。结果表明,与未改性生物炭相比,改性后的炭电极比电容大大提高,电阻显著减小,循环性能和倍率性能均有提升。MRHC-0.3（乙酸锌浓度为0.3 mol/L时的改性生物炭）比表面积为495 m2/g,孔容为0.214 cm3/g,该电极在2 A/g下充放电2000次后,其电容保持率为92.16%。将MRHC-0.3电极用于电吸附Cu2+实验,发现在0.9 V,pH为5时吸附效果最好,吸附量为9.57 mg/g。在0.9 V,pH为5,Cu2+初始质量浓度为50 mg/L时,去除率可达63.82%。     

A new Zn2+ chemosensor based on functionalized 8-hydroxylquinoline

A new fluorescent Zn²⁺ chemosensor (3) based on functionalized 8-hydroxylquinoline has been synthesized and characterized. Compound 3 shows weak fluorescence in CH₃CN–HEPES buffer solution (50 mM, pH 7.2 v/v = 1:9), but the fluorescence is significantly enhanced upon binding to Zn²⁺ through a zinc(II)-catalyzed ester hydrolysis reaction to form a highly emissive zinc(II) complex. This suggests that 3 can be served as a typical “switch–on” chemosensor with high selectivity for Zn²⁺ over other metal ions.     

碳羟磷灰石对废水中Zn2+的去除及机理探讨

利用废弃的鸡蛋壳为主要原料合成碳羟磷灰石(CHAP),用以去除废水中的Zn2+。分别考查了废水中Zn2+的初始浓度、CHAP的用量、pH值、温度及作用时间等因素对CHAP去除Zn2+的吸附效果的影响以优化吸附条件。结果表明,用2.5g/L的CHAP处理Zn2+的质量浓度为100mg/L的废水,40℃条件下,处理45min,Zn2+的去除率可达98.67%,最佳pH值为6～7。同时探讨了CHAP对重金属离子Zn2+的吸附机理,吸附机理研究表明,CHAP对Zn2+的主要吸附形式为离子交换吸附和表面吸附。     

Sonophotocatalytic treatment of methyl orange dye and real textile effluent using synthesised nano‐zinc oxide

In this work, experiments were carried out by combining the sonication technique with the photocatalytic technique (ultraviolet light source) for the degradation of methyl orange dye and real textile effluent. Studies were performed with variation in parameters such as oxidant (sodium persulfate), commercially available zinc oxide, methyl orange concentration, and sonochemically synthesised zinc oxide. Fourier transform infrared spectroscopy, scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, and X‐ray diffraction analysis of synthesised zinc oxide showed that the particle size was in the nano range. Near‐complete colour removal by sonophotocatalytic treatment was observed for a concentration of 10 mg l^?1 of methyl orange with 1 g l^?1 of synthesised zinc oxide and 1500 mg l^?1 of sodium persulfate. For 100 mg l^?1 of methyl orange, the colour removal was 77% for 1 g l^?1 commercially available zinc oxide and 84% for 1 g l^?1 synthesised zinc oxide respectively, with 1500 mg l^?1 sodium persulfate. Similar experimental conditions were applied for the sonophotocatalytic treatment of real textile effluent with different dilutions (1:100, 1:10, and 1:1) and raw effluent. For real textile effluent, sonophotocatalytic treatment was found to be highly effective both in colour and chemical oxygen demand removal. The chemical oxygen demand removal was 88, 65, 63, and 41% for 1:100, 1:10, and 1:1 dilutions and raw effluent respectively.     

PART 3. THE EXTRACTION OF Co2+, Ni2+, Cu2+ AND Zn2+ USING NOVEL DITERTIARY-AMINEEXTRACTANTS

The syntheses of N-N-octyl-2-2'-pyridylimidazole and N,N'-di-n-octyl-(a)-aminopicoline are presented. Their extraction properties are compared with that of an aliphatic diamine N,N,N',N'-tetraoctylethylene-diamine. The reagents, dissolved in chloroform, were used to extract divalent cobalt, nickel, copper and zinc from aqueous chloride medium. Two extraction mechanisms are postulated for the extraction of these metals, and extraction data are discussed in terms of these postulates.

Extraction of the copper(II) ion at low pH values with amines is best effected by the inclusion of aromatic nitrogen atoms into a diamine extractant.     

Dynamic Modelling and Process Control of ZnS Precipitation

Abstract

This paper presents the dynamic modelling and design of a control strategy for the ZnS precipitation process. During lab‐scale experiments, the sulfide concentration in a precipitator was controlled at a prespecified pS value by manipulating the flow from a buffer vessel. Batch tests showed that the optimal condition for zinc sulfide precipitation is at a sulfide concentration of 10^?15 mole/l (pS 15). Experiments with the precipitator showed that the sulfide concentration highly deviates from a given setpoint when proportional (P) control is used, but this deviation can be decreased using a Proportional Integral (PI) controller. Moreover, the PI controller was able to handle sudden disturbances in the process conditions (pH, influent flow rate, or zinc and sulfide concentration). Additional precipitation experiments were conducted using effluent from a sulfate reducing gas‐lift reactor to determine if the compounds present in the effluent influence the control process. With the gas‐lift reactor effluent and a PI controller, the desired sulfide concentration was reached almost instantaneously (within 15 minutes) within acceptable margins (2–5%).     

Removal of Zn(II) from chloride medium using a porous electrode: current penetration within the cathode

An electrolytic process for the removal of zinc from aqueous solutions using a flow-through cell with a reticulated vitreous carbon cathode is proposed. The operational conditions for the reactor were optimized as a function of the electrolyte pH, the cathode porosity and the solution flow rate. Both a synthetic solution and a real effluent from an industrial electroplating plant were processed until zinc concentration dropped from 50 to 0.1mg dm^–3 and from 152 to 0.5mg dm^–3, respectively. After the processing of the real effluent, tomographic images of the cathode were taken in order to investigate the current depth penetration during electrolysis. Results have shown that the current density decreases from the outer surface to the centre of the RVC cathode.     

The spatial distribution of Zn during galvanic corrosion of a Zn/steel couple

The spatial distribution of Zn²⁺ during galvanic corrosion of a model Zn/steel couple in 0.01 M NaCl was investigated using a scanning zinc disk electrode. The couple had a coplanar arrangement of a steel substrate with an electroplated zinc layer at the center. During galvanic corrosion, the marked changes in the Zn²⁺ concentration were confined to a thin solution layer ca. 1.0 mm thick above the couple surface. In this thin solution layer above the zinc layer, a higher concentration region of Zn²⁺ in the range of 5-18 mM extended around the zinc layer in the solution during galvanic corrosion. Conversely, above the steel surface distant from the zinc layer, the surface concentration of Zn²⁺ was almost zero during galvanic corrosion. On this surface, the precipitation of zinc corrosion products due to the hydrolysis reaction of Zn²⁺ was observed. The distribution of the Zn²⁺ concentration supported that Zn²⁺ acted as a buffer that suppressed the increased pH due to the cathodic reaction on the steel surface near the zinc layer and almost no corrosion products formed there. The spatial distribution of Zn²⁺ is discussed in relation to the distributions of potential and pH and the surface morphology of the galvanic couple.     

Synergistic extraction and separation of Fe(III) and Zn(II) using TBP and D2EHPA

Waste chloride pickle liquors from hot-dip galvanizing plants, steel plants and flue dust contain reasonable amounts of heavy metals such as Zn, Cr, Ni, etc. Iron is invariably associated with most of these materials and comes into solution during leaching. Thus, the synergistic extraction of zinc(II) and iron(III) from leach solutions in tri-n-butyl phosphate (TBP)–di(2-ethylhexyl) phosphoric acid (D2EHPA) system diluted in kerosene was investigated. The Zn and Fe concentrations in the leach liquor used in the present study were 2 g/L. Experiments were carried out in the pH range of 0.5–4.0, temperature of 25°C, using sole D2EHPA, sole TBP and D2EHPA–TBP mixtures at different ratios. Results showed that the co-extraction of zinc(II) and iron(III) increased with increasing equilibrium pH using D2EHPA. It is demonstrated that the mixtures of TBP and D2EHPA are more efficient and selective than D2EHPA alone. At low pH values, the separation factor is low when pure D2EHPA is used as an extractant; however, using TBP as a synergist, the separation factor increases and results in a better separation of zinc from iron. Increasing TBP to D2EHPA ratios in the organic phase caused a slight shift to the right in the extraction isotherm of iron and a marked shift to the right in the extraction isotherm of zinc, and the maximum separation factor of 13.3 × 10³ was achieved at a TBP to D2EHPA volume ratio of 4:1 (0.58 M TBP: 0.12 M D2EHPA). Furthermore, the effect of equilibrium pH, organic to aqueous phase ratio and Cl^? concentration on the selective extraction was investigated. Using two extraction stages at the O/A ratio of 2:1 and pH_e (equilibrium pH) of 3 and 1 for zinc and iron, respectively, 99% of zinc(II) and 96.25% of iron(III) were extracted.     

Enhance the luminescence properties of Ca14Al10Zn6O35:Ti4+ phosphor via cation vacancies engineering of Ca2+ and Zn2+

Ti⁴⁺-activated zinc calcium aluminate phosphors, owing to their excellent luminescence properties, nontoxicity, environment friendliness and low price, have a certain prospect in the field of plant cultivation. In this study, we have successfully synthesized a series of Ca_14-yAl_10-xZn_6-zO₃₅:xTi⁴⁺ (CAZO:Ti⁴⁺) phosphors through a high-temperature solid-state method. Furthermore, the emission spectrum of CAZO:Ti⁴⁺ located in bluish violet-emitting band, and has an emission peak at 378?nm upon the excitation of 268?nm due to the charge transfer of Ti⁴⁺-O^2-. Moreover, the luminescence intensity of as-synthetized phosphors can be improved by cation vacancies engineering to compensate for charge unbalance. Especially, the luminescence intensity could be further improved when the Ca²⁺ vacancy is 0.35?mol or the Zn²⁺ vacancy is 0.275?mol. Furthermore, the X-ray powder diffraction (XRD) analysis and crystal structure are checked and confirmed that the synthesized material is pure phase. The concentration quenching mechanism, FT-IR spectra, UV–vis absorption properties, lifetimes and electron transition process of Ca_14-yAl_10-xZn_6-zO₃₅: xTi⁴⁺ were discussed in detail. From the above, the phosphor has a potential application for plant growth field due to its broad bluish violet emission.     

Solvent‐crazed PET fibers imparting antibacterial activity by release of Zn2+

Poly(ethylene terephthalate) fibers containing zinc chloride in the fiber bulk were prepared by solvent crazing. Fibers containing 6 g/Kg and 13 g/Kg Zn²⁺ were investigated. SEM‐EDX analyses and the formation of the pink bis(1,5‐dithiocarbazonato‐N,S) complex inside the fibers confirm the presence of zinc. UV‐Vis spectroscopy indicates a slow release of zinc ions into the aqueous media and, thus, the fibers serve as a release system to inhibit the growth of Escherichia coli during the first exposure. Thermal annealing of the freshly prepared fibers above T_g was shown to modify the release profile so that bacterial growth was also inhibited during repetitive and prolonged exposures. The washing fastness is fair and after 10 washing cycles, ～ 30% of the original zinc content still remains in the fiber. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

用TMOS为原料合成Zn_2SiO_4∶Mn~(2+)荧光粉的工艺研究

采用四甲氧基硅(TMOS)、硝酸锌和硝酸锰为原料,用sol-gel法合成了Zn2SiO4∶Mn2+荧光粉。XRD分析确定试样均为a-Zn2SiO4晶体结构。利用荧光分析测定试样的发射光谱和激发光谱,分析了所合成的Zn2SiO4∶Mn2+荧光粉材料发光强度,最强峰位等与初始原料用量、Mn2+粒子取代Zn2+程度、热处理温度等的相互关系,结果显示,首先采用TMOS过量1%的配比;其次,采用(2~3)℃/min的缓慢升温速度在1 120,1 150,1 050℃分别保温1,2,4 h;最后在空气中急冷获得的Zn2SiO4∶Mn2+荧光粉具有良好的发光性能。     

Electrochemical studies of Zn underpotential/overpotential deposition on a nickel electrode from non-cyanide alkaline solution containing glycine

In this work we present an electrochemical study of the underpotential deposition (UPD) and overpotential deposition (OPD) of zinc onto nickel electrode (NE) from a non-cyanide alkaline solution containing glycine. The studied parameters were zinc concentration, glycine concentration and scanning rate. The analysis of the experimental data clearly showed the presence of UPD and OPD processes that started at −0.8 V vs. SCE and −1.4 V vs. SCE, respectively. The voltammetric studies also indicate diffusion control of the zinc UPD and OPD processes onto the NE. From the potentiostatic transients we found instantaneous nucleation (2D) mechanisms, which agree to that observed in the AFM study. In order to compare the effect of zinc/glycine concentration, we calculate thermodynamic parameters for the OPD process.     

Role of oxygen vacancies in long persistent phosphor Ca2Ga2GeO7: Zn2+

Acting as the electron trap, oxygen vacancies can strongly influence the long persistent luminescence (LPL) properties were verified in Ca₂Ga₂GeO₇: Zn²⁺ (CGGZ) phosphor. The existence of oxygen vacancies in this self‐excitation material was confirmed by a simple fluorescence probe method. The introduction of zinc ions promotes the generation of oxygen vacancies, as well as optimizes its LPL properties. Thermoluminescence (TL) analysis revealed that electrons in deep trap will effectively transfer to the shallow one via the bridge of interstitial zinc. Accordingly, a mechanism for PL and LPL in this Gallogermanates was provided.     

紫菜吸附铜、锌离子的研究

本文采用紫菜作为吸附剂吸附溶液中Cu^2 和Zn^2 。结果表明，紫菜对Cu^2 的吸附性能大大优于Zn^2 ，对Cu^2 的吸附2min就近乎达到平衡，适宜的pH为4-6，对Zn^2 需要2h才能达到平衡，适宜的pH为3-6。初始浓度即使高达30mmol／L时，Cu^2 的吸附率仍在90％以上，吸附量高达13．9mmol／g，而Zn^2 的吸附率只有12％，吸附量只有1．7mmol／g，紫菜对Cu^2 、Zn^2 的吸附等温线用Langmuir方程均能得到较好的表达。     

“O3+GFH+BF”再生水处理工艺不同阶段出水中藻类的生长特征研究

采用"O3+GFH+BF"工艺作为再生水回用景观水体水质维持措施,为了考察该组合工艺的有效性及确定起决定作用的处理单元,将各工艺段出水置于气候培养箱,模拟外界自然条件开展藻类生长试验,结合水质变化规律,考察不同处理单元出水对藻类生长的影响。结果表明,试验开始前"O3+GFH+BF"保障工艺出水相较于二级出水,BOD5、COD、TP、NH4+-N和NO3--N的去除率分别为71.8%、49.4%、96.6%、93.7%和15.3%。经过一个藻类的生长周期(约1个月)的培养后,各处理单元出水中均出现丝状绿藻;人工湖叶绿素-a的质量浓度53 mg.m-3,远低于二级出水中的220 mg.m-3。"O3+GFH+BF"保障工艺能有效抑制再生水景观回用过程中藻类的生长。试验中磷是主要限制因子,确定了GFH工艺是防止景观湖防富营养化的决定性工艺。     

CONTINUOUS FOAM SEPARATION OF HEAVY METAL IONS FROM ELECTROPLATING INDUSTRIAL EFFLUENT

Process industries generate a large amount of waste materials during either production or downstreaming operations. Among many methods available for their separation, foam separation plays a major role, especially when the concentration of undesirable components involved is very low. The success of this technique depends on the stability and characteristics of the foam. This operation is simple with less maintenance as there are no moving parts. In the present study, simultaneous removal of metal ions such as chromium (VI), copper (II), and zinc (II) from electroplating industrial effluent was carried out with sodium lauryl sulfate (SLS) as surfactant in continuous foam column. Enrichment ratios of 3.94, 4.05, and 7.96 with a percentage removal of 59.0%, 63.0%, and 99.2% were obtained for chromium (VI), copper (II), and zinc (II) ions respectively at the optimum operating parameters of 23 cm liquid pool height in column, 0.1 liter per minute (Lpm) of airflow rate, feed flow rate of 4 liters per hour (Lph), 0.1% (w/v) of SLS concentration, pH of 6.0, and at feed concentrations of 32.5, 27.0, and 23.0 ppm for chromium (VI), copper (II), and zinc (II) ions respectively. Enrichment ratio was found to increase with an increase in feed flow rate. With a decrease in concentration of the bulk solution, the separation factor was found to increase. The study indicates the feasibility of continuous foam separation for treating industrial effluents.