The Effect of Acid Hydrolysis Parameters on the Properties of Nanocellulose Extracted from Almond Shells

ABSTRACT

The effects of acid hydrolysis parameters (acid type, acid concentration, reaction time, and temperature) on the properties of nanocellulose (NC) extracted from almond shells were investigated. The highest percentage yield of NC obtained from each type of acid was 71.8% using 25% w/v sulfuric acid at 50°C for 60 min, followed by 71.1% with 50% w/v perchloric acid at 35°C for 15 min, and finally 67% with 50% w/v methane sulfonic acid at 25°C for 10 min. The hydrolysis treatment using sulfuric and perchloric acids greatly affect the NC particle size and length. The extracted NCs show different thermal degradation profiles due to the difference in the crystallinity index and types of acid used. Hydrolysis with strong acids (sulfuric and perchloric acids) produce NC with lower crystallinity due to the degradation of both amorphous and crystalline regions in the cellulose. Furthermore, BET analysis revealed the NCs from the hydrolysis using sulfuric acid possesses the highest surface area, desorption/adsorption pore diameter, desorption, and adsorption cumulative pore volume compared to other acids.

摘要

研究了酸水解参数（酸类型、酸浓度、反应时间和温度) 对从杏仁壳中提取的纳米纤维素（NC) 性能的影响. 使用25%w/v硫酸在50°C下60分钟，从每种类型的酸中获得的NC的最高百分比产率为71.8%，其次是使用50%w/v高氯酸在35°C下15分钟，最后是67%，使用50%w/v甲烷磺酸在25°C下10分钟. 使用硫酸和高氯酸的水解处理极大地影响NC颗粒尺寸和长度. 由于结晶度指数和所用酸类型的差异，提取的NCs显示出不同的热降解曲线. 强酸（硫酸和高氯酸) 水解产生结晶度较低的NC，这是由于纤维素中无定形和结晶区域的降解. 此外，BET分析表明，与其他酸相比，使用硫酸水解的NCs具有最高的表面积、解吸/吸附孔径、解吸和吸附累积孔体积.

KEYWORDS:

• Nanocellulose
• natural fiber
• acid hydrolysis
• crystallinity
• thermal degradation
• surface area

KEYWORDS:

• nanocellulose
• 纳米纤维素，natural fiber
• 天然纤维，acid hydrolysis
• 酸水解，crystallinity 结晶度
• thermal degradation
• 热降解，surface area 表面积

Acknowledgements

Mr. Mohammed Alhaji acknowledges the Federal Government of Nigeria and Management of Federal University of Lafia for providing the financial support for his postgraduate studies. The authors gratefully acknowledge financial support from the Universiti Malaya SATU Grant (ST043-2021).

Disclosure statement

No potential conflict of interest was reported by the authors.