可见分光光度检测离子色谱仪分析铬鞣液中铬含量

本文介绍了用可见分光光度检测离子色谱仪分析铬鞣液中铬含量,允其适用于大量样品的连续分析。实验证明,该方法精密度高,变异系数0.32%,线性关系好,回收率为98～100.25%,准确,快速,方便是该方法的特点。     

改性戊二醛及其在皮革工业中的应用

本文报道了改性戊二醛的合成方法,测定了其组成与结构,介绍了它的性质。在此基础上,研究了改性戊二醛的鞣制条件及其鞣制不同皮类的鞣制工艺。最后,介绍了改性戊二醛的分析方法。     

Techno-economic evaluation of membrane filtration for the recovery and re-use of tanning chemicals

The majority of pollution generated from leather manufacturing can be contributed to the inefficiency of chemical use in leather processing and to organic substances derived from the hides during processing. In particular, the overall tanning processes performed in drums can be characterized by a high consumption of water and chemicals, most of which are found in the final wastewater. To ensure full penetration and reaction of chemicals with collagen, chemicals are added in excess and are only partly up-taken by the leather. Significant savings of chemicals can be achieved by recovery and recycling of chemicals and water from part streams, thus reducing environmental impacts.This research formed an integrated approach to investigate and exploit the potential of a closed loop operation for various part streams of tanneries. Each of the process streams was separately collected, treated and purified by membrane technologies to obtain a recyclable liquor which can be re-used operationally. In this way a complete recovery of process liquors can be achieved for immediate operational re-use.Membrane technology has been applied to recover chemicals from un-hairing, vegetable tanning, chrome liquors and to polish saline part streams for re-use. By applying membrane filtration up to 90% of the treated liquors can be recovered giving a remaining concentrate volume of only 10%. The permeate obtained from several process areas contained to a high extent chemicals, which were re-used for leather processing.     

锌铝水滑石的制备及其在制革少铬鞣中的应用

通过共沉淀法制备了锌铝水滑石(ZnAl-LDH),采用XRD、FTIR、SEM对其结构进行了表征.将其配合用量为皮质量2％的铬粉(记为2％铬粉)应用于制革鞣制工艺中.考察了ZnAl-LDH制备时的金属源物质的量比、陈化时间对鞣制坯革收缩温度、鞣后废液中的Cr2O3质量浓度的影响.结果表明,ZnAl-LDH是尺寸在100～400 nm之间的片状材料.当n〔(Zn(NO3)2?6H2O)〕:n〔Al(NO3)3?9H2O〕=2.0:1.0,陈化时间为6 h时,制备的ZnAl-LDH-4具有优异的性能.与单独使用2％铬粉鞣制坯革相比,ZnAl-LDH-4(用量为皮质量的4％)配合2％铬粉鞣制坯革收缩温度由75℃提高到94℃,废液中的Cr2O3质量浓度由99.58 mg/L降低至46.98 mg/L,且加入ZnAl-LDH-4鞣制后,鞣后废液化学需氧量和生物需氧量均降低.     

Viability study of different reverse osmosis membranes for application in the tertiary treatment of wastes from the tanning industry

The tanning industry uses large quantities of water and produces a correspondingly large amount of wastewater with high levels of salts and organic materials. Before these wastewaters can be eliminated, they must be submitted to a suitable depuration treatment. However, conventional treatments such as those used for urban wastewater are not able to reduce the salt content sufficiently and new methods need to be studied in the light of new technologies. In this aspect, membrane technology is increasingly used as a separation technique in chemical and environmental engineering, including desalination, selective separation and wastewater treatment. In this paper, we describe a comparative study of six different reverse osmosis membranes, which were tested for their ability to reduce the salt content in the tertiary treatment after the elimination of chromium salts and organic matter of an effluent from a pilot plant for treating industrial wastewater from the tanning industry to reach the legal levels established for their safe disposal. The membranes were checked using a 3×10⁻³ m² flat cell, where the concentrated streams were recirculated to the feed reservoir.     

皮革鞣制机理特点及进展探讨

本文对传统的鞣制理论和特点作了扼要的分析和评述，根据对合成鞣剂和油鞣剂的应用研究结果并结合近年来提出的有关制革理论新观点，指出了油鞣剂的实际油鞣作用、共聚物树脂鞣剂的填充（沉积）对改变纤维的分散状态、氢键数量下降和纤维分子趋于晶形化的影响。     

CrOx/SiO2 catalysts prepared using chromium recovered from tanning sewage

Catalysts at different Cr loading (x, in the range 0.18–3.8 wt% Cr) were prepared by (i) impregnation of SiO₂ Aerosil directly with the waste water (SCx(I) samples); or (ii) mixing Aerosil with chromium oxo-hydroxides, precipitated from the waste water to eliminate the sulphate and sodium ions (SCx(II) and SCx(III) samples). Preparations (II) and (III) only differ for the accuracy in sulphate and sodium ions elimination. Catalyst surface characterization was performed by FT-IR spectroscopy using CO, adsorbed at room temperature, as test molecule, and by UV-Vis-NIR DR spectroscopy. Their activity towards ethylene polymerization were tested by FT-IR spectroscopy, monitoring the time dependence of the CH₂ stretching modes intensity. The obtained results were compared with those obtained for simplified Phillips catalysts with comparable chromium contents, SCx(R). SCx(I) catalysts were not active in the ethylene polymerization, while the SCx(II) and SCx(III) ones showed lower activity (1/10 at maximum) compared to that of simplified Phillips catalysts with comparable chromium contents. SCx(II) and SCx(III) catalysts were active in the isobutane dehydrogenation reaction and showed activity in the range of those of standard catalysts, while SCx(I) ones showed activity at 873 K, but very low at the usual temperatures (773–823 K).     

Vegetable tannin composition and its association with the leather tanning effect

Abstract

The increasing environmentally friendly approach of using renewable materials has led to vegetable tannins having an important role as tanning agents in the leather industry. Tannins are complex phenolic structures, and the literature shows that a considerable amount of chemical parameters measured through analytical techniques can be associated with their tanning ability. In the present study, five types of vegetable tannins highly used in the tanning industry were chosen for the evaluation of some of their relevant chemical parameters and the correlation with their cross-sectional penetration in the hide. Black wattle (Acacia mearnsii), quebracho (Schinopsis lorentzii), chestnut (Castanea sativa), tara (Caesalpinia spinosa), and myrobalan (Terminalia chebula) were tested. The chemical properties of the total tannin polyphenols, non-tannin polyphenols, insoluble solids, soluble solids, total solids, total phenols, non-tannin polyphenols:total phenols ratio, and residual tanning float concentration were measured and associated with the leather cross-sectional penetration results. The statistical Mann–Whitney-U test showed that the insoluble solids, non-tannin polyphenols, soluble solids, and total tannin polyphenol percentages distinguished the groups of tannins that crossed the hide from those that did not well. Hence, since the analysis of insoluble solids is the simplest and the most direct among them, it would be recommended to use this parameter to define a cutoff to distinguish the performance of tannins for leather application.     

一种新型制革用树脂鞣剂的合成

以三聚氰胺,甲醛,甲醇为主要原料,经羟基化反应,缩反应制备新型皮革鞣剂,产品性能优于目前通用的树脂鞣剂。经二年多工业生产表明,工艺技术可行,经济效益较好。     

Synergistic effects of hydrophilic nano-SiO2/graphene oxide @ copolymer nanocomposites in tanning leather

The near-spherical silica nanoparticles with polyvinyl alcohol (denoted as PVA-SiO₂) or polyethylene glycol (denoted as PEG-SiO₂) as surface modifiers were loaded onto graphene oxide nanosheets (denoted as GO) to prepare PVA(PEG)-SiO₂-GO nanocomposites. The nanocomposites well dispersed in water were then compounded with maleic anhydride (MA) - acrylic acid (AA) copolymer (denoted as PMAAA) to prepare new nanocomposite tanning agents (denoted as PVA(PEG)-SiO₂-GO/PMAAA). The hydrothermal stability, thickness increase, mechanical properties, flame retardancy and antistatic property, etc. of the leather tanned with PVA(PEG)-SiO₂-GO/PMAAA were founded to be improved in a significant way compared with those of the leather tanned with the commercial acrylic resin (CHINATAN OM) and pure PMAAA copolymer tanning agents. The acquired excellent tanning properties may be related to the synergistic tanning effects of near-spherical silica nanoparticles and thin-layered graphene oxide nanosheets in leather tanning process. Especially, the highest shrinkage temperature of the wet-white sheepskin tanned with PVA-SiO₂-GO/PMAAA reached 71 ^◦C and the thickness increase reached 190% without chrome tanning agents.