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首页> 外文期刊>Separation and Purification Technology >Recovery of chromium(III) from wastes of uncolored chromium leathers. Part I. Kinetic studies on alkaline hydrolytic decomposition of the wastes
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Recovery of chromium(III) from wastes of uncolored chromium leathers. Part I. Kinetic studies on alkaline hydrolytic decomposition of the wastes

机译：从无色铬皮废料中回收铬（III）。第一部分：废物碱性水解的动力学研究

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A series of experiments were performed on determination of some conditions under which chromium(III) passes from uncolored chromium-tanned leather wastes to an alkaline solution in the form of soluble hydroxocomplexes, and next, it could be removed from this hydrolyzate by the solvent extraction. The effect of time, temperature, and concentration of NaOH solution on the hydrolytic decomposition of the leather wastes was examined. Kinetic analysis of this process was made using some of the most important kinetic models which are usually applied for analysis of heterogeneous processes. The Arrhe-nius kinetic parameters were evaluated separately for the chromium(III) leaching and the collagen hydrolysis of the wastes under isothermal conditions at the different constant temperatures from 313 to 343 K. It was concluded that the fractions of chromium(III) and collagen dissolved in alkaline solution vs. time curves are deceleratory. The alkaline leaching of chromium(III) is probably limited by more than one of the factors which contribution changes with temperature. The diffusion and reaction at the phase boundary substrate-product (contracting volume and reaction order) may have a significant effect on kinetics of the dechromation of the leather wastes while the kinetics of the collagen hydrolysis may be described the best by the contracting volume and the first-order models. Average values of the activation energy (E) and the frequency factor (A) found for the both processes are as follows: E_(Cr) = 122 ± 2 kJ/mol; In A_(Cr) = 34.4 ± 1.8 s~(-1), and E_N = 96 ± 3 kj/mol; In A_N = 25.5 ± 0.4 s~(-1), respectively.
机译：在确定某些条件下进行了一系列实验，在这些条件下铬（III）从无色铬鞣革废料以可溶性羟基络合物的形式传递到碱性溶液中，然后可以通过溶剂萃取将其从水解产物中除去。研究了时间，温度和NaOH溶液浓度对皮革废料水解分解的影响。使用一些最重要的动力学模型对该过程进行动力学分析，这些模型通常用于分析异质过程。在313至343 K的不同恒温条件下，分别评估了等温条件下废物中铬（III）的浸出和胶原蛋白水解的Arrhe-nius动力学参数。结论是铬（III）和胶原蛋白的组分溶于碱性溶液的时间曲线是减速的。铬（III）的碱浸可能受到多种因素的限制，这些因素会随温度变化。在相界底物产物上的扩散和反应（收缩量和反应顺序）可能对皮革废料的脱色动力学有显着影响，而胶原蛋白水解的动力学可以用收缩量和收缩量来最好地描述。一阶模型。这两个过程的活化能（E）和频率因子（A）的平均值如下：E_（Cr）= 122±2 kJ / mol;在A_（Cr）= 34.4±1.8 s〜（-1），并且E_N = 96±3 kj / mol;在A_N = 25.5±0.4 s〜（-1）中。

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