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Microwave-assisted pretreatment of eucalyptus waste to obtain cellulose fibers
Cellulose ( IF 5.7 ) Pub Date : 2020-02-07 , DOI: 10.1007/s10570-020-03019-7
Paulo H. Camani , Beatriz F. Anholon , Rick R. Toder , Derval S. Rosa

Abstract

This work aims to evaluate the impact of microwave-assisted methodology in the pretreatments of the eucalyptus waste (Eucalyptus citriodora), to remove non-cellulosic components. Two pretreatments, without and with microwave, were used: (a) mercerization using sodium hydroxide, and (b) bleaching using hydrogen peroxide. The times (15 and 30 min) and power (100 W, 400 W, and 800 W) of microwave varied in order to find out the best conditions to obtain cellulose fibers. Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy, thermogravimetric analysis (TGA), lignocellulosic contents (TAPPI), and statistical analysis (bivariate analysis) were used to evaluate the delignification of the obtained cellulose fibers. Life Cycle Impact Assessment (LCIA) analyses were used to evaluate environmental impacts [Cumulative Energy Demand (CED), Agricultural Land Occupation, and Climate Changes (CC)] from two processes: non-microwave and microwave-assisted pretreatment. FTIR results show an increase in the intensity of the cellulose bands and a decrease in bands of non-cellulosic components, corroborating with photomicrographs, which show the fiber opening. FTIR, TGA, TAPPI, and statistical analysis results show that the best condition for mercerization was 30 min, with 400 W and 800 W and the bleaching process with 400 W, the last condition presenting 99.1% of cellulose purity. From LCIA analyses, it was observed a decrease of environmental impacts as CED and CC for microwave-assisted pretreatment compared to non-microwave, being more intensified for CED, both at the laboratory scale and industrial scale. Therefore, the use of microwave promoted an increase in the removal of non-cellulosic compounds of the eucalyptus waste, which reduced reaction time, energetic expenditure, and reagent quantities.

Graphic abstract



中文翻译:

微波辅助预处理桉树废料以获得纤维素纤维

摘要

这项工作旨在评估微波辅助方法在桉树废料(Eucalyptus citriodora)预处理中的影响。),以去除非纤维素成分。使用了两种不带微波和带微波的预处理:(a)使用氢氧化钠的丝光处理,和(b)使用过氧化氢的漂白。改变微波的时间(15分钟和30分钟)和功率(100 W,400 W和800 W),以便找到获得纤维素纤维的最佳条件。使用傅里叶变换红外光谱(FTIR),扫描电子显微镜,热重分析(TGA),木质纤维素含量(TAPPI)和统计分析(双变量分析)来评估所得纤维素纤维的脱木质素性。使用生命周期影响评估(LCIA)分析从两个过程(非微波和微波辅助预处理)评估环境影响[累积能量需求(CED),农业用地和气候变化(CC)]。FTIR结果表明,纤维素带的强度增加,非纤维素组分的带减少,这与显微照片相吻合,显微照片显示了纤维的开度。FTIR,TGA,TAPPI和统计分析结果表明,丝光化的最佳条件是30分钟(400 W和800 W)以及漂白过程中的400 W(最后一个条件是99.1%的纤维素纯度)。根据LCIA分析,与非微波相比,微波辅助预处理的CED和CC降低了对环境的影响,在实验室规模和工业规模上,CED和CC的强化程度都更高。因此,微波的使用促进了桉树废料中非纤维素化合物的去除增加,这减少了反应时间,能量消耗和试剂数量。

图形摘要

更新日期:2020-04-20
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