A REVIEW OF GOLD LEACHING IN ACID THIOUREA SOLUTIONS

Since the initial report of thiourea as a complexing reagent for gold leaching, considerable research has been directed toward the use of thiourea as an alternative to cyanide for gold extraction from different auriferous mineral resources. At the same time, some fundamental investigations of the system have been reported. In this article, a review of both applications and fundamental research is made, including a review of the recent results from laboratory studies at the University of Utah. Recent research results demonstrate that thiourea decomposition is quite slow in the presence of ferric sulfate for simple solutions. Ferric sulfate and formamidine disulfide (FDS) are effective oxidants with fast kinetics. No passivation of the gold surface is observed in simple acidic solutions. However, in actual leaching systems, some sulfide minerals significantly catalyze the redox reaction between thiourea and ferric ion, causing high thiourea consumption if ferric ion is present in excess. The presence of copper has a deleterious influence on this leaching system.     

A Highly Efficient Palladium‐Catalyzed One‐Pot Synthesis of Unsymmetrical Aryl Alkyl Thioethers under Mild Conditions in Water

A palladium‐catalyzed, one‐pot synthesis of unsymmetrical aryl alkyl thioethers involving aryl halides (aryl bromides and chlorides), thiourea and alkyl bromides has been realized under mild conditions (room temperature to 50 °C) in water with polyoxyethanyl α‐tocopheryl sebacate (PTS) as amphiphile. The PTS/water could be recycled in up to eight runs without an obvious change in its activity.     

多元硫醇胺的合成与表征

由三乙醇胺,二氯亚砜合成三氯乙基胺盐酸盐,再与硫脲反应制得四异硫脲乙基胺盐酸盐,最后在氢氧化钠作用下与水反应后,采用二氯甲烷萃取得到了多元硫醇胺,通过红外、核磁、液相色谱对各阶段产物结构进行了表征,并通过化学分析计算了多元硫醇胺的官能度,为其固化研究提供了可靠依据。     

硫脲在酪氨酸酶催化中的抑制动力学

研究了硫脲对蘑菇酪氨酸酶活力的抑制效应。实验结果表明,硫脲与酪氨酸酶催化氧化产物醌反应,形成了无色的L-DOPA衍生物,从而阻断了多巴色素的形成。硫脲导致酪氨酸酶活力下降50%时的浓度(IC50)为1.37 mmol·L-1,在降低酶活的同时,硫脲能明显延长该酶的延滞时间,表现为不可逆反竞争性抑制。     

苎麻纤维NaOH/尿素/硫脲低温柔化处理研究

在现有NaOH／尿素体系低温柔化处理苎麻纤维的基础上,通过加入助溶剂硫脲,来提高苎麻纤维低温柔化处理的温度。研究了经NaOH／尿素／硫脲溶液处理后苎麻纤维性能的变化,通过对溶液配比、处理温度、处理时问和浴比等影响因素的研究,得出结论为：在-10℃时,溶液对纤维的最大溶解度配比为NaOH／尿素／硫脲=7：10：6．5;苎麻纤维处理温度越低、处理时问越长、浴比越大,纤维的断裂强度和初始模量越小,断裂伸长率越大;温度为I℃,处理时间为10min,浴比为l：10是较佳的处理工艺。     

代森锰锌在烟草中的残留分析

建立了用气相色谱法和高效液相色谱法分别测定烟草中代森锰锌及其代谢物乙撑硫脲(ETU)残留量的方法,在0.1~10mg/kg添加浓度范围内,鲜烟叶、干烟叶中代森锰锌和ETU的平均回收率各为82.99%~97.99%和81.60%~86.17%,变异系数分别为1.4%~7.01%和0.9%~4.2%。     

Antiviral activity and mechanism of action of novel thiourea containing chiral phosphonate on tobacco mosaic virus

Using half-leaf method O,O'-diisopropyl (3-(L-1-(benzylamino)-1-oxo-3- phenylpropan-2-yl)thioureido)(phenyl)methyl phosphonate (2009104) was studied for its activity on tobacco mosaic virus (TMV). It showed good curative activity in vivo and the curative activity at 500 μg/mL was found to be 53.3%. In vivo treatment with the control agent Ningnanmycin at 500 μg/mL resulted in 51.2% inhibition and curative inhibition rates respectively. Dot-ELISA test was employed to verify the efficacy of activity of compound 200910 for anti-TMV activity. The mechanism of action of compound 2009104 to resist TMV was also studied. The results showed that the resistance enzymes PAL, POD, SOD activity and chlorophyll content after TMV inoculation K(326) (Nicotiana tabacum K(326)) of tobacco plants followed by treatment with compound 2009104 were significantly enhanced. The study of the effect of compound 2009104 on TMV capsid protein (CP) showed that it inhibited the polymerization process of TMV-CP in vitro.     

Adsorption of selenite and selenate ions onto thiourea‐formaldehyde resin

In the present work, thiourea‐formaldehyde (TUF) chelating resin was synthesized and used in the adsorptions of selenite (SeO) and selenate (SeO) ions. The effects of initial acidity and initial selenium concentrations on the adsorptions were examined by batch technique. The synthesized resin was applied to the elemental analysis to determine its composition. FT‐IR spectra and SEM/EDS were also recorded before and after selenite adsorption. It was found that selenite and selenate ions were adsorbed onto TUF resin at strong acidic conditions (3–5M HCl). The adsorption capacities of the resin were calculated as 833.3 mg g^?1 TUF resin for selenite ions and 526.3 mg g^?1 TUF resin for selenate. All the adsorption data obtained for both selenite and selenate ions fitted well to the Langmuir isotherm. It was seen that the adsorption mechanisms in the both adsorptions were governed by the reduction of selenite or selenate to elemental selenium, Se⁰. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

Selective separation and concentration of Pd(II) from Fe(III), Co(II), Ni(II), and Cu(II) ions using thiourea‐formaldehyde resin

Thiourea‐formaldehyde (TUF), a well‐known chelating resin, has been synthesized and it was used in the adsorption, selective separation, and concentration of Pd(II) ions from Fe(III), Co(II) Ni(II), and Cu(II) base metal ions. The composition of the synthesized resin was determined by elemental analysis. The effect of initial acidity/pH and the adsorption capacity for Pd(II) ions were studied by batch technique. The adsorption and separation of Pd(II) were then examined by column technique. FTIR spectra and SEM/EDS analysis were also recorded before and after the adsorption of Pd(II). The optimum pH was found to be 4 for the adsorption. The adsorption data fitted well to the Langmuir isotherm. The maximum adsorption capacity of the TUF resin for Pd(II) ions was found to be 31.85 mg g⁻¹ (0.300 mmol g⁻¹). Chelating mechanism was effective in the adsorption. Pd(II) ions could be separated efficiently from Fe(III), Cu(II), Ni(II), and Co(II) ions using TUF resin. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

添加硫脲的稀土热稳定剂性能的研究

以硫脲、稀土镧为主要原料,制备了新型的稀土复合热稳定剂,并利用稀土热稳定剂与其他热稳定剂之间的协同效应,使它们按一定比例配合使用,以达到延长稳定时间的目的。实验结果表明,添加硫脲的稀土复合热稳定剂与传统热稳定稳定剂相比可以更显著地提高PVC的热稳定性能。将其与Zn（C17 H35 COO）2和Ca（C17H35COO）2按一定比例配合后,其热稳定效果更佳。