Performance characteristics of peel of Artocarpus nobilis fruit can be enhanced by the treatment of the biosorbent with aqueous NaOH solutions under stirred conditions, followed by thorough washing of the treated biosorbent with water. A series of experiments performed within a wide range of solution pH demonstrates that the optimum pH for Cr(III) removal is pH 5.0, while it is 2.0 for Cr(VI) by peel of Artocarpus nobilis fruit after treatment with aqueous NaOH solutions of concentrations varied from 0.0050 to 0.15 M. Adsorption of Cr(III) and Cr(VI) from individual aqueous solutions on the above biosorbent treated with 0.010 M NaOH solution, which provides the highest extent of removal of 4.89 × 10³ mg kg⁻¹ (pH = 5) and 4.94 × 10³ mg kg⁻¹ (pH = 2), respectively, follows pseudo-first-order kinetics at the ambient temperature of 27.5 °C when the concentration of adsorbate concentration is kept relatively constant. The order of the reaction is unchanged when the solution temperature is increased up to 40.0 °C for Cr(III) although the reaction becomes pseudo-second order for Cr(VI). Further, the energy of activation for adsorption of Cr(III) is determined to be 66.82 kJ mol⁻¹, suggesting a strong attraction between the adsorbate and the biosorbent. Application of the intraparticle diffusion model to kinetics data within the early stages of the adsorption process of Cr(III) suggests that boundary layer-retarded diffusion be valid at both solution temperatures, while no retardation be possible for Cr(VI) at the warmer temperature.

中文翻译：

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Cr（III）和Cr（VI）物种在NaOH修饰的面包果果皮上的生物吸附。1.动力学研究

通过在搅拌条件下用NaOH水溶液处理生物吸附剂，然后用水彻底洗涤处理过的生物吸附剂，可以增强面包果的果皮性能特性。在宽范围的溶液pH值范围内进行的一系列实验表明，用浓度较高的NaOH溶液处理后的面包果皮去除Cr（III）的最佳pH为pH 5.0，而Cr（VI）的最佳pH为2.0。从0.0050到0.15 M.Cr（III）和Cr（VI）在上述用0.010 M NaOH溶液处理过的生物吸附剂上的水溶液中Cr（III）和Cr（VI）的吸附，去除率最高，为4.89×10 ³  mg kg ^-1（ pH = 5）和4.94×10当吸附剂浓度保持相对恒定时，在27.5°C的环境温度下，分别具有³  mg kg ^-1（pH = 2）的伪一级动力学。当Cr（III）的溶液温度升至40.0°C时，反应的顺序不变，尽管Cr（VI）的反应变为伪二级。此外，确定吸附Cr（III）的活化能为66.82kJ mol ^-1，表明被吸附物和生物吸附剂之间有很强的吸引力。在Cr（III）吸附过程的早期阶段将颗粒内扩散模型应用于动力学数据表明，边界层延迟扩散在两种溶液温度下均有效，而Cr（VI）在较热温度下无阻滞作用。