絮凝处理改善离子交换树脂对杨木预水解液中木素的吸附

Flocculation-induced Enhancement in Lignin Removal by Ion Exchange Resin from Prehydrolysis Liquor of Poplar

本文首先对预水解液中的木素进行絮凝沉淀,以期提升后续离子交换的处理效率。结果表明:聚合氯化铝(PAC)和阳离子聚丙烯酰胺(CPAM)用量分别为4000 mg/L和10 mg/L时,木素去除率达到最高值50.3%。经絮凝处理后的水解液用2%的阴离子交换树脂处理,残余木素的浓度与未絮凝处理的水解液用6%的树脂处理后的浓度持平,均达到75.8%的木素去除率,说明絮凝处理能够显著节约树脂用量。Freundlich模型的分析表明,未絮凝处理水解液木素的浓度变化对树脂吸附量的影响更为显著,而木素浓度相同时,树脂对絮凝处理后的残余木素具有更大的吸附量,这说明絮凝处理通过去除木素大分子,强化了残余木素在树脂内部的传质作用,进而提升树脂的处理效率。

In order to improve the lignin removal from prehydrolysis liquor （PHL）, flocculation was done to enhance the efficiency of the subsequent lignin removal by ion exchange resin. The results showed that the combination of PAC of 4000 mg/L and CPAM of 10 mg/L can achieve the highest lignin removal of 50.3%. Ion exchange resins were then applied to remove the residual lignin after floeculation. The flocculation induced reduction of resin dosage was reflected by the equal lignin removals of 75.8% that can be obtained either by 2% resin dosage for flocculation treated PHL or by 6% resin dosage for untreated PHL. Freundlich model indicated the adsorption of lignin in untreated PHL into resin was more susceptible to the variation of adsorbate concentration, while the adsorption capacity was relatively higher for flocculation treated PHL. It was then concluded that the enhanced adsorption was resulted from the improved mass transfer due to the elimination of macro - lignin molecules.