Removal of nickel from spent electroless nickel-plating bath with nickel foam cathode

The electrochemical method was used to remove nickel ion from spent electroless nickel plating bath (pH=5 3). An electrolytic cell was composed of a porous nickel foam cathode and an inert RuO 2/Ti anode. Nickel ions were reduced and deposited on the surface of the nickel foam cathode. The effect of current density (i), linear velocity of wastewater(v), gap between cathode and anode(d C/A) and reaction time(t) on nickel removal rate and current efficiency were studied. As reaction time prolonged, nickel removal rate increased while current efficiency decreased. And larger v and smaller d C/A can enhance nickel removal rate and increase current efficiency by promoting mass transfer and dropping concentration polarization. The effect of current density on nickel removal by electrochemistry was related to other parameters. After three hours’ electrolysis with i=1 0 A/dm2, v=18 5 cm/min and d C/A=0 5 cm, nickel removal rate and current efficiency reached 85 6% and 29 1%, respectively.

Nickel electrodeposition from novel citrate bath

A new type of electroplating bath suitable for nickel electrodeposition was developed. Trisodium citrate was used as a complexing agent and a buffer in the bath. The buffering capacity between trisodium citrate and boric acid were compared. The effects were investigated under different conditions of bath composition, current density, pH and temperature on the potentiodynamic cathodic polarization curves, cathodic current efficiency and throwing index, as well as the electrical conductivity of these baths. The optimum conditions for producing sound and satisfactory nickel deposits were: NiSO4·6H2O 350 g/L, NiCl2·6H2O 45 g/L and Na3C6H5O7 30 g/L at pH=4 and 55 ℃. The surface morphology of the as-plated Ni deposit was examined by SEM. The results reveal that the nickel deposition obtained from the optimum conditions are composed of compact, non-porous fine grains covering the entire surface. X-ray analysis shows that nickel deposits obtained from the citrate bath have a fine crystal structure compared with deposits from the Watts bath.

Comparison Between Electrolysis and Reduction for Treatment of Spent Electroless Nickel Plating Bath

There are lots of residual nickel and organic compounds in the spent electroless nickel plating bath. It not only wastes resource but also causes environmental pollution if the wastewater is discharged without treatment. In this paper, electrolytic method and reduction method for treating spent electroless nickel plating bath were compared. The factors studied included reaction time, pH, temperature, effectiveness and cost. It was found that the recovery rate of nickel by reduction was 99.9% under the condition ofpH 6, 50℃ for 10 min. The purity of reclaimed nickel was 66.1%. This treatment needed about 16 g NaBH4 for a liter spent solution, which cost RMB 64 Yuan. For electrolysis method, with pH 7.6, 80℃, 0.45 A （current intensity） for 2 h, the recovery rate reached 97.3%. The purity was 88.5% for the reclaimed nickel. Moreover, it was found that through electrolysis, the value of TOC （Total Organic Carbon） decreased from 114 to 3.08 g·L^-1 with removal rate of 97.3%. The main cost of electrolysis came from electric energy. It cost about 0.09 kWh （less than RMB 0.1 Yuan） per liter wastewater. Compared with reduction, electrolysis had more advantages, so the priority of selection should be given to the electrolysis method for the treatment of spent electroless nickel plating bath.

Purification and Regeneration of Spent Electroless NickelPlating Baths by Electrodialysis

A method using electrodialysis to seperate phosphite from spent electroless nickel (EN) plating solution was studied. The major working parameters for the electrodialyzer with our selected membranes such as voltage, current and the flow rate of spent EN bath and condensed solution were optimized. Under the optimum operating conditions, spent EN bath could be effectively purified. And then the purified solution was replenished and reused for EN plating. The life of the EN bath was prolonged for more than 17 metal turnovers (M.T.Os). It showed that the electrodialysis method was one of the most effective means for purification and regeneration of spent EN plating baths and for saving resources and reducing waste.

化学镀镍废液中硫酸根增值化为硫酸钡试验研究

化学镀镍废液排放量大、成分复杂,其合理处置有利于减轻环境污染和提高资源回收利用率,目前该废液的处置工艺缺少对硫、钠、磷、碳等元素的回收。本研究以除镍后化学镀镍废液和醋酸钡为原料,利用废液中柠檬酸根离子对钡离子的络合作用,采用共沉淀法制备了BaSO_(4)粉体。研究了溶液pH值、柠檬酸根离子与钡离子摩尔比、反应温度和反应时间对硫酸根离子去除率、BaSO_(4)产率及其形貌的影响。结果表明,在溶液pH=9、柠檬酸根离子与钡离子摩尔比为1∶3、反应温度55℃、反应时间10 h的条件下,硫酸根离子去除率达到99.7%以上,BaSO_(4)产率达到98.9%以上;所得BaSO_(4)粉体呈类球形,粒径分布范围窄,纯度高。该工艺实现了化学镀镍废液中硫酸根的增值化利用,符合绿色循环经济发展理念。

化学沉淀法去除化学镀镍废液中磷的工艺研究

[目的]对化学镀镍废液中的含磷物质进行正确处理和有效回收是实现可持续发展的有效策略。[方法]采用化学沉淀法处理化学镀镍废液,使其中的磷以羟基磷灰石(HAP)沉淀形式得以回收。研究了反应温度、初始pH及Ca/P比(指硝酸钙与废液中磷的质量比)对磷去除率的影响,通过正交试验优化工艺参数。[结果]在温度为75℃、初始pH为12及Ca/P比为1.67的条件下处理后,化学镀镍废液的磷去除率达到了99.998%,并且所得沉淀为HAP。[结论]采用本工艺可有效去除化学镀镍废液中的磷,并且随之产生的HAP有望得以回收利用。

化学镀镍废液处理中磷物种的转化及去除研究

以化学镀镍废液中难处理的高浓度磷为目标,监测并分析了催化氧化还原、H2O_(2)氧化、次氯酸钙氧化、Fenton氧化处理工艺中磷物种形态的转化趋势,之后进一步采用絮凝/沉淀工艺去除废液中的TP,考察最终TP的去除效果。实验结果表明,H2O_(2)氧化、次氯酸钙氧化和Fenton氧化3种氧化处理均无明显的选择性,反应后废液中仍残留着一定浓度难以处理的H2PO_(2)-,后续处理后TP去除率分别可达81.9%、92.2%和96%。而催化氧化还原处理后,化学镀镍废液中的磷物种基本全转化为了HPO32-,再经氯化钙沉淀处理后TP的去除率可达到99.7%。同时,HPO32-也是一种可利用的高价值资源,通过向经催化氧化还原处理后的废液中添加Al2(SO4)3·18H2O,可回收得到亚磷酸铝产品,在污水处理绿色环保及资源化利用方面具有重大意义。

不同体系电镀锌−镍合金的性能对比

[目的]对比不同体系电镀Zn-Ni合金镀层的性能差异,为实际生产中的工艺选择提供参考。[方法]分别采用碱性锌酸盐−硫酸镍体系、硫酸盐体系和氯化物体系在Q235低碳钢上电镀Zn-Ni合金,对比了所得镀层的外观、厚度、结合力、耐蚀性和表面形貌。[结果]氯化物体系Zn-Ni合金镀层在耐蚀性和结合力方面表现最佳;碱性体系Zn-Ni合金镀层的外观和结合力较好;硫酸盐体系Zn-Ni合金镀层的外观较好,但结合力有待提高。[结论]不同体系电镀Zn-Ni合金镀层各有优缺点,在实际生产中可按需选择合适的镀液。

碱性锌镍合金电镀溶液中氢氧化钠、锌、镍的测定

研究了碱性锌镍合金电镀溶液中氢氧化钠、镍及锌含量的分析方法。以0.1mol/L盐酸标准溶液,采用自动电位滴定法测定氢氧化钠含量;在过硫酸铵存在下,采用丁二酮肟分光光度法在碱性条件下测定镍含量;采用EDTA络合滴定法测定锌和镍的合量,减去分光光度法测得的镍含量,得到锌含量。试验结果表明,方法的相对标准偏差均小于2%,加标回收率接近100%。

压延铜箔的无氰电镀镍铜黑化处理工艺

为了研究出相较于电镀纯镍黑化工艺成本更低的电镀镍铜黑化工艺,以NiSO_(4)·6H_(2)O、CuSO_(4)·5H_(2)O、H_(3)BO_(3)、(NH_(4))_(2)S_(2)O_(8)和C_(6)H_(15)NO_(3)为镀液基本成分,通过加入添加剂,使金属在铜箔表面沉积形成光陷阱结构,从而实现电镀镍铜使铜箔黑化的目的。研究了镀液成分及工艺参数对黑化箔镀层亮度的影响,对黑化箔镀层的成分进行了测试,并对黑化箔镀层结构进行了观察分析。研究结果表明:电镀镍铜的黑化箔镀层中Cu代替Ni形成镀层,黑化箔镀层成分为NiCu;通过加入添加剂可以使电镀时使用的电流密度降低,达到了降低成本的目的。

Relationship between the Corrosion and Cr-Ni Content of Stainless Steel in Borax Bath

The corrosion of stainless steel was experimentally investigated and analyzed to improve the service-life of the crucible and fixture clamps. Through the experiment, stainless steel was found to satisfy the crucible and fixture clamps materials. As the chromium element mass percentage of the stainless steel increased, the corrosion decreased rapidly at first and then slowly increased. With the corrosion time prolonging, the corrosion growth rate is generally a downward trend. With Chromium 20%, the corrosive were the least. With Nickel element mass percentage increased, the corrosion increased rapidly at first and then decreased rapidly, flatten at the last. It was special that the corrosion had little relationship with the Chromium and Nickel mass percentage when the Nickel percentage is more than 35%. The most remarkable corrosion is corresponding with the Nickel element 12%, the least corrosion with Nickel element 80%. So Nickel element 35% is the most optional.

化学镀镍−硼合金工艺和镀液稳定性

以铁片为基材进行化学镀Ni–B合金。研究了镀液中主盐、还原剂和配位剂用量及稳定剂种类对镀速、镀液稳定性,以及Ni–B合金镀层外观和显微硬度的影响,得到的较佳配方为:SF-815镍盐A 60 mL/L,SF-815配位剂B 200 mL/L,SF-815还原剂C 20 mL/L,含巯基化合物(用作稳定剂)5 mg/L。采用该体系镀液在pH 6.2~7.2、温度60~70℃的条件下化学镀1 h所得Ni–B合金镀层均匀,呈半光亮,结晶细致,B质量分数为1.62%~3.23%,显微硬度为683.0~753.1 HV。该体系镀液性能稳定,连续工作10个周期后镀液保持澄清,镀层外观和各项性能保持合格。

DTC类重捕剂在化学镀镍浓废液深度除镍中的应用研究

以催化氧化还原预处理后的化学镀镍浓废液为对象,通过使用DTC(二硫代氨基甲酸盐)类复合重捕剂对其进行深度除镍,研究了重捕剂用量、反应时间、初始pH、反应温度和初始镍浓度对处理效果的影响。结果表明,在重捕剂用量为600 mg/L、初始pH为7、反应温度为25℃的条件下,反应3 min后即可将镍浓度从24.5 mg/L稳定降低至0.05 mg/L,镍去除率高达99.8%,符合电镀废水中重金属镍的排放要求。

H2O2氧化/CaO沉淀预处理化学镀镍废槽液及其FO浓缩减量效果研究

为了降低高浓度化学镀镍废槽液处理成本,采用氧化-沉淀预处理-正渗透(FO)组合工艺对废槽液进行常温浓缩减量.FO膜为水通道蛋白膜(AQP),汲取液为4 mol·L^(-1)NaCl溶液,FO过程采用活性层朝向原料液(AL-FS)的模式.当采用H2O2加CaO进行预处理时,废液电导率、TP、TOC和Ni的去除率远高于其他预处理方案.当CaO添加量为5%时,系统水通量可达到5.89 L·(m^(2)·h)^(-1);浓缩后污染物TP、Ni和TOC的截留率分别达到73.97%、92.90%和84.65%.三维荧光图谱(EEM)结果显示,有机物类腐殖酸组分比酪氨酸或色氨酸蛋白类物质更容易透过半透膜从原料液进入到汲取液中.适量的CaO预处理不仅可以有效的降低污染物的浓度和渗透压,有利于后续FO工艺浓缩减量,而且节约了经济成本.

镁合金化学镀镍溶液稳定性

为了开发出长寿命高稳定性镁合金化学镀镍溶液,通过添加硫脲、碘酸钾等稳定剂,研究了pH值、温度对镀液的稳定性能、镀速、镀层质量等因素的影响。采用称重法测定镀层的沉积速率,沉积到镀件上的镍量占溶液中消耗镍量的百分比来表示溶液的稳定性,NaCl溶液浸泡实验评定镀层的覆盖度,热震实验评定镀层的结合力,极化曲线表征镀层的耐蚀性。结果表明,沉积速率随硫脲、碘酸钾浓度的增大先升高后降低,碘酸钾对镀速的影响不如硫脲显著。添加硫脲0.5 mg·dm-3时稳定常数最大值达89.25%,添加碘酸钾5 mg·dm-3时,稳定常数达82.45%。采用pH值为5.0的含硫脲的镀液,(82±1)℃施镀,获得的Ni-P镀层和镁合金基体之间没有缝隙,结合紧密,而且Ni-P镀层均匀致密。硫脲不仅能提高沉积速率,而且也催化镁合金表面,提高沉积效率。

镁合金化学镀镍工艺的研究

研究了镁合金硫酸镍化学镀镍工艺 ,得到了最佳的酸洗、活化及镀镍液配方。通过研究发现 ,镁合金在化学镀镍液中不会受到腐蚀 ,并初步探讨了化学镀镍的沉积机理。

镁合金硫酸镍体系化学镀镍工艺及镀层性能研究

采用酸性钼酸盐酸洗、碱性钼酸盐活化工艺，研究了AM60镁合金上硫酸镍溶液体系化学镀镍的方法。采用扫描电子显微镜（SEM）观察镀层表面形貌，电子探针（EDX）分析镀层成分，电化学方法研究镀层腐蚀性能，锉刀试验测试镀层与基体结合力。结果表明，所得镀层为Ni-P合金镀层，磷质量分数为10％～14％；镀层均匀致密，无明显缺陷；镀层的自腐蚀电位接近-0．4V（VSSCE），阳极极化曲线有明显的钝化区；Ni-P镀层耐蚀性好，与基体结合牢固。

化学镀镍老化液的处理及资源回收利用

参考了 2 7篇国内外有关化学镀镍老化液处理及资源回收利用的有关资料 。

电渗析脱除化学镀镍老化液中亚磷酸盐的研究

本文研究了电渗析处理化学镀镍老化液的工作电压、工作电流、流量对亚磷酸盐去除效果的影响，得到了优化的工艺参数，分析了对老化液主要成份的脱降情况。处理后的老化液可重新回用。

方波溶出伏安法测定镀镍液中的微量铜

为建立镀镍液中微量铜的测定方法 ,用方波溶出伏安法测定了镀镍液中的微量铜 (Ⅱ )。研究了最佳的测定条件 ,确立了测定方法。试验结果表明 ,在 pH值为 4 .0～ 4 .5的NH4Cl Na2 SO4底液中 ,Cu2 + 于 - 0 .15 6V(vsSCE)出现灵敏溶出峰 ,峰电流在铜 (Ⅱ )浓度为 5 .0× 10 -7～ 1.0× 10 -5mol/L时呈现良好的线性关系 ,回归方程Ip(μA) =1.0 6 +1.0 8C(× 10 -6mol/L) ,相关系数为 0 .9994。方法的变异系数为 2 .7% ,检出限为 2 .8× 10 -7mol/L ,回收率为 94 %～ 10 6 %。该方法应用于现场镀镍液中微量Cu2 + 的测定 。