2018～2019年世界塑料工业进展(Ⅱ)

收集了2018年7月~2019年6月世界工程塑料和特种工程塑料工业的相关资料,介绍了2018~2019年世界工程塑料和特种工程塑料工业的发展情况,按工程塑料(尼龙、聚碳酸酯、聚甲醛、热塑性聚酯)和特种工程塑料(聚苯硫醚、液晶聚合物、聚醚醚酮、聚芳砜、聚邻苯二甲酰胺)不同品种的顺序,对树脂的产量、消费量、供需状况及合成工艺、产品应用开发、树脂品种的延伸及应用的进一步扩展等技术作了详细介绍。     

Cyanidation of Gold Associated with Silver Minerals in Sulfide Mineral Matrices

Lead salt stimulated the dissolution of gold when gold associated with silver minerals was interspersed in the silica or in the pyrite‐silica layer. Gold dissolution was likewise promoted through lead addition for chalcopyrite‐silica and the sphalerite‐silica systems. Lead addition did not boost gold dissolution and a recovery of 6.9 % was achieved for gold and silver minerals dispersed in stibnite. Lead pretreatment also enhanced gold recovery except for the stibnite‐silica system. Gold surface‐passivating films were observed for gold associated with silver minerals and stibnite.     

Effect of tube size on performance of a fixed-film tubular bioreactor for conversion of hydrogen sulfide to elemental sulfur

A fixed-film continuous-flow photobioreactor was used for the removal of hydrogen sulfide from synthetic industrial wastewater and conversion of it to elemental sulfur using sixteen 150 mm length Tygon tubes as the active part of the reactor. Three different tube sizes (internal diameters (ID) 6.4, 3.2, and 1.6mm) were used to investigate the effect of tube size on reactor performance. The reactor with 1.6mm tube attained a higher sulfide loading (1451 mg/Lh) than previously reported in the literature. High bacterial concentration, light to volume ratio and intimate contact between attached bacteria and influent sulfide resulted in excellent performance of the 1.6mm tube reactor.     

The contribution of biotic and abiotic processes during azo dye reduction in anaerobic sludge

Azo dye reduction results from a combination of biotic and abiotic processes during the anaerobic treatment of dye containing effluents. Biotic processes are due to enzymatic reactions whereas the chemical reaction is due to sulfide. In this research, the relative impact of the different azo dye reduction mechanisms was determined by investigating the reduction of Acid Orange 7 (AO7) and Reactive Red 2 (RR2) under different conditions. Reduction rates of two azo dyes were compared in batch assays over a range of sulphide concentrations in the presence of living or inactivated anaerobic granular sludge. Biological dye reduction followed zero order kinetics and chemical dye reduction followed second-order rate kinetics as a function of sulfide and dye concentration. Chemical reduction of the dyes was greatly stimulated in the presence of autoclaved sludge: whereas chemical dye reduction was not affected by living or gamma-irradiated-sludge. Presumably redox-mediating enzyme cofactors released by cell lysis contributed to the stimulatory effect. This hypothesis was confirmed in assays evaluating the chemical reduction of AO7 utilizing riboflavin, representative of the heat stable redox-mediating moieties of common occurring flavin enzyme cofactors. Sulfate influenced dye reduction in accordance to biogenic sulfide formation from sulfate reduction. In assays lacking sulfur compounds, dye reduction only readily occurred in the presence of living granular sludge, demonstrating the importance of enzymatic mechanisms. Both chemical and biological mechanisms of dye reduction were greatly stimulated by the addition of the redox-mediating compound, anthraquinone-disulfonate. Based on an analysis of the kinetics and demonstration in lab-scale upward-flow anaerobic sludge bed reactors, the relative importance of chemical dye reduction mechanisms in high rate anaerobic bioreactors was shown to be small due to the high biomass levels in the reactors.     

Electrochemical sulfide oxidation from domestic wastewater using mixed metal-coated titanium electrodes

Hydrogen sulfide generation is a major issue in sewer management. A novel method based on electrochemical sulfide oxidation was recently shown to be highly effective for sulfide removal from synthetic and real sewage. Here, we compare the performance of five different mixed metal oxide (MMO) coated titanium electrode materials for the electrochemical removal of sulfide from domestic wastewater. All electrode materials performed similarly in terms of sulfide removal, removing 78 ± 5%, 77 ± 1%, 85 ± 4%, 84 ± 1%, and 83 ± 2% at a current density of 10 mA/cm² using Ta/Ir, Ru/Ir, Pt/Ir, SnO₂ and PbO₂, respectively. Elevated chloride concentrations, often observed in coastal areas, did not entail any significant difference in performance. Independent of the electrode material used, sulfide oxidation by in situ generated oxygen was the predominant reaction mechanism. Passivation of the electrode surface by deposition of elemental sulfur did not occur. However, scaling was observed in the cathode compartment. This study shows that all the MMO coated titanium electrode materials studied are suitable anodic materials for sulfide removal from wastewater. Ta/Ir and Pt/Ir coated titanium electrodes seem the most suitable electrodes since they possess the lowest overpotential for oxygen evolution, are stable at low chloride concentration and are already used in full scale applications.     

Sulfide-iron interactions in domestic wastewater from a gravity sewer

Interactions between iron and sulfide in domestic wastewater from a gravity sewer were investigated with particular emphasis on redox cycling of iron and iron sulfide formation. The concentration ranges of iron and total sulfide in the experiments were 0.4-5.4mgFeL(-1) and 0-5.1mgSL(-1), respectively. During anaerobic conditions, iron reduction kinetics were investigated and reduction rates amounted on average to 1.32mgFeL(-1)d(-1). Despite the very low solubility of iron sulfide, the reduced iron reacted only partly with sulfide to produce iron sulfide, even when dissolved sulfide was in excess. When a ferric chloride solution was added to sulfide containing anaerobic wastewater, the ferric iron was quickly reduced to ferrous forms by oxidation of dissolved sulfide and the ferrous iron precipitated almost completely as iron sulfide. During aerobic conditions, iron sulfide was oxidized with a half-life period of 11.7h. The oxidation rate of iron sulfide was significantly lower than that reported for the oxidation of dissolved sulfide.     

Characterization of activated sludge exocellular polymers using several cation-associated extraction methods

Evaluation of prior research and preliminary investigations in our laboratory led to the development of an extraction strategy that can be used to target different cations in activated sludge floc and extract their associated extracellular polymeric substances (EPS). The methods we used were the cation exchange resin (CER) procedure, base extraction, and sulfide addition to extract EPS linked with divalent cations, Al, and Fe, respectively. A comparison of sludge cations before and after CER extraction revealed that most of Ca(2+) and Mg(2+) were removed while Fe and Al remained intact, suggesting that this method is highly selective for Ca(2+) and Mg(2+)-bound EPS. The correlation between sludge Fe and sulfide-extracted EPS was indicative of selectivity of this method for Fe-bound EPS. The base extraction was less specific than the other methods but it was the method releasing the largest amount of Al into the extract, indicating that the method extracted Al-bound EPS. Concomitantly, the composition of extracted EPS and the amino acid composition differed for the three methods, indicating that EPS associated with different metals were not the same. The change in EPS following anaerobic and aerobic digestion was also characterized by the three extraction methods. CER-extracted EPS were reduced after aerobic digestion while they changed little by anaerobic digestion. On the other hand, anaerobic digestion was associated with the decrease in sulfide-extracted EPS. These results suggest that different types of cation-EPS binding mechanisms exist in activated sludge and that each cation-associated EPS fraction imparts unique digestion characteristics to activated sludge.     

硫化氢对氢化丁腈橡胶性能的影响

就硫化氢与丁腈橡胶和氢化丁腈橡胶的不饱和双键,以及与丙烯腈侧基的老化反应的机理作了介绍。研究表明:氢化丁腈橡胶具有优异的耐硫化氢性能,适合用来生产石油钻探领域的相关橡胶制品。     

Enhanced H2 evolution and the interfacial electron transfer mechanism of titanate nanotube sensitized with CdS quantum dots and graphene quantum dots

Synergistic the modulation of photon absorption capability and interfacial charge transfer of the photocatalyst are highly required for developing high-performance heterojunction photocatalysts. The ternary CdS-graphene quantum dots-titanate nanotubes (CdS-GQDs-TNTs) nanocomposite have been prepared by an in situ growth method. The physicochemical characterization reveals that the GQDs are firmly decorated on both inner and outer surface of TNT through the formation of Ti–O–C chemical bonding, and CdS QDs are loaded on the outer surface of TNTs through strong interfacial interaction. The intimate integrated CdS-GQDs-TNTs nanocomposite exhibits much superior photocatalytic performance toward H₂ production compared with binary GQDs-TNTs and pure TNTs photocatalyst, which can be attributed to the combined interaction of the stronger visible light harvesting, the longer lifetime of photogenerated electron−hole pairs, faster interfacial charge transfer rate, fast and long-distance electron transport pass. The interfacial charge transfer mechanism of CdS-GQDs-TNTs ternary composite are proposed based on photoelectrochemical measurements.     

镍矿的处理工艺现状及进展

镍矿是国民经济中一种重要的金属矿产资源,随着经济的发展,人们对镍矿资源的消耗呈逐年上升趋势。目前所查明的镍矿资源中,有近70%的镍矿资源都是硫化镍矿,近30%的镍矿资源属于红土镍矿。随着镍矿资源查明储量的下降,其镍矿资源的综合利用受到越来越多国家的重视。在查阅大量文献的基础上,简要的论述了镍矿资源的总体情况,概述了硫化镍矿常规的处理方法,以及近年来浮选法的一些实际应用及发展。最后,介绍了当前状况下红土镍矿的火法和湿法处理工艺现状及进展,以及一些其他处理镍矿石的方法。为以后镍矿石资源的综合利用和处理工艺的研究提供了一定的参考价值。