Abstract：
In recent years, numerous attempts have been made to develop a low-cost adsorbent for selectively recovering industrially important products from fermentation broth or complex mixtures. The current study is a novel attempt to selectively adsorb esterase from Trichoderma harzianum using cheap adsorbents like bentonite (BT), activated charcoal (AC), silicon dioxide (SiO2), and titanium dioxide (TiO2). AC had the highest esterase adsorption of 97.58% due to its larger surface area of 594.45 m3/g. SiO2 was found to have the highest selectivity over esterase, with an estimated purification fold of 7.2. Interestingly, the purification fold of 5.5 was found in the BT-extracted fermentation broth. The functional (FT-IR) and morphological analysis (SEM-EDX) were used to characterize the adsorption of esterase. Esterase adsorption on AC, SiO2, and TiO2 was well fitted by Freundlich isotherm, demonstrating multilayer adsorption of esterase. A pseudo-second-order kinetic model was developed for esterase adsorption in various adsorbents. Thermodynamic analysis revealed that adsorption is an endothermic process. AC has the lowest Gibbs free energy of -10.96 kJ/mol, which supports the spontaneous maximum adsorption of both esterase and protein. In the desorption study, the maximum recovery of esterase from TiO2 using sodium chloride was 41.34 %. Unlike other adsorbents, the AC-adsorbed esterase maintained its catalytic activity and stability, implying that it could be used as an immobilization system for commercial applications. According to the kinetic analysis, the overall rate of the reaction was controlled by reaction kinetics rather than external mass transfer resistance, as indicated by the Damkohler number.
摘要：
近年来,已经进行了许多尝试来开发用于从发酵液或复杂混合物中选择性地回收工业上重要的产物的低成本吸附剂。当前的研究是一种新颖的尝试，使用廉价的吸附剂如膨润土（BT）从哈茨木霉中选择性吸附酯酶，活性炭（AC），二氧化硅（SiO2），和二氧化钛(TiO2)。由于其594.45m3/g的较大表面积，AC具有最高的酯酶吸附率，为97.58％。发现SiO2比酯酶具有最高的选择性，估计纯化倍数为7.2。有趣的是,在BT提取的发酵液中发现5.5的纯化倍数。采用功能化(FT-IR)和形态分析(SEM-EDX)对酯酶的吸附进行表征。酯酶在AC上的吸附，SiO2和TiO2很好地拟合了Freundlich等温线，证明了酯酶的多层吸附。建立了各种吸附剂中酯酶吸附的伪二级动力学模型。热力学分析表明，吸附是一个吸热过程。AC具有最低的吉布斯自由能-10.96kJ/mol，这支持酯酶和蛋白质的自发最大吸附。在解吸研究中，使用氯化钠从TiO2中提取酯酶的最大回收率为41.34%。不像其他吸附剂,AC吸附酯酶保持了其催化活性和稳定性，暗示它可以用作商业应用的固定系统。根据动力学分析,反应的总速率由反应动力学而不是外部传质阻力控制，如Damkohler数字所示。
