蛋清蛋白热絮凝脱除麦草秸秆碱预处理水解液中木质素的研究

Study on Removing Lignin from Wheat Straw Alkali Pretreatment Hydrolysate by Thermal Flocculation of Egg White Proteins

中文关键词:  蛋清蛋白  絮凝  麦草秸秆碱预处理液  可生化降解

Key Words:egg white proteins  flocculation  wheat straw alkali pretreatment hydrolysate  biodegradability

中文摘要:

      为提升麦草秸秆碱法预处理水解液（简称碱预处理液）的可生化降解性能，本研究利用蛋清蛋白（Egg White Proteins，EWPs）热絮凝工艺脱除碱预处理液中的木质素，并与EWPs常温絮凝工艺，以及分别以氯化铁（FeCl₃）和聚氯化铝（PAC）为絮凝剂的传统絮凝工艺进行比较。结果表明，在碱预处理液浓度（以COD_Cr计）为8 g/L时，经EWPs热絮凝工艺处理，碱预处理液中大分子胶体木质素（以浊度计）去除率达70.6%±2.2%，小分子可溶性木质素（以总酚计）去除率达20.7±1.4%，与EWPs常温絮凝、FeCl₃及PAC絮凝工艺相比均有所提高。EWPs热絮凝脱除木质素的机理探究结果表明，高温会引发EWPs变性，导致其蛋白结构发生变化，促进EWPs通过疏水及氢键作用与木质素絮凝结合；在加热过程中，EWPs通过分子间氢键作用及巯基-二硫键转换反应，进一步与木质素形成大分子絮体，促进了碱预处理液中大分子木质素及其衍生物的絮聚脱除。

Abstract:

      In order to improve the biodegradability of the alkali pretreatment hydrolysate， the lignin of the alkali pretreatment hydrolysate was removed by egg white proteins （EWPs） thermal flocculation process in this study. The method was compared with the EWPs flocculation processes at room temperature， and the traditional flocculation processes using FeCl₃ and polyaluminum chloride （PAC） as flocculants， respectively. The results showed that when the concentration of the alkali pretreatment hydrolysate （calculated by COD_Cr） was 8 g/L， the removal rate of macromolecular colloidal lignin （calculated by turbidity） in the alkali pretreatment hydrolysate was 70.6%±2.2%， and the removal rate of small molecule soluble lignin （calculated by total phenol content） reached 20.7%±1.4% after EWPs thermal flocculation treatment. Compared with EWPs flocculation process at room temperature， FeCl₃ and PAC flocculation processes， the removal rate of lignin increased. Investigation about the mechanism of lignin removal by EWPs thermal flocculation showed that high-temperature-induced denaturation of EWPs led to protein structural changes， promoting the bindings between EWPs and lignin resulted from the hydrophobic flocculation and hydrogen bonding. During the heating process， macromolecular flocs were further formed through hydrogen interaction and sulfhydryl-disulfide conversion reaction of EWPs protein molecular with lignin， which promoted the flocculation and removal of macromolecular lignin and its derivatives in the alkali pretreatment hydrolysate.