Conversion of Lignocellulosic Biomass to Nanocellulose: Structure and Chemical Process

Table 2

Degree of biomass degradation by using various types of chemical treatments.

Chemical pretreatment	Type of biomass	Concentration	Ratio of BM : chemical	Temperature (°C)	Time (h)	C^a	H^b	L^c	Monomeric sugar
Acid hydrolysis
(i) Dilute acid
Phosphoric acid [25]	Rapeseed	0.32% (w/w)	12 : 100	202	0.08	++	++	+	Recovered from hydrolysis of hemicellulose and cellulose
Sulphuric acid [26, 27]	Switch grass	1.2% (w/w)	3 : 100	160	4.3	++	++	+	Recovered from hydrolysis of hemicellulose and cellulose
(ii) Concentrated acid
Sulphuric acid [28]	Bamboo	75% (w/w)	2.4 : 4.4	59	0.5	++	++	+	Saccharification of BM
Sulphuric acid [29]	Corn stover	65–80% (w/w)	1 : 20	121	1	++	++	+	Saccharification of BM
Alkaline hydrolysis
Sodium hydroxide [30]	Wheat plant	8% (w/v)	5 : 95	75	1	+	+	++	Recovered from hydrolysis of hemicellulose and cellulose
Calcium hydroxide [31]	Switch grass	0.1 g	1 : 04	121	0.5	+	+	++	Recovered from hydrolysis of hemicellulose and cellulose
Organosolv
Ethyl acetate, ethanol-water [32]	Prairie cordgrass, corn stover, and switch grass	ND	1 : 10	140	0.33	−	−	++	Limited degradation of sugar
Ionic liquid
1-Ethyl-3-methylimidazolium acetate ([C2mim][OAc]) [26]	Switch grass	9.7 g	0.3 : 0.97	160	3	+	+	++	Recovered from hydrolysis of cellulose
1-Butyl-3-methylimidazolium chloride (BMIMCl) [33]	Sugarcane bagasse	ND	1 : 10	130	0.5	+	+	++	Recovered from hydrolysis of cellulose
Oxidative delignification
Peracetic acid [34]	Cotton	40 ml/L	1 : 30	30–70	0.25–4	++	+	++	Recovered from hydrolysis of hemicellulose and cellulose
Peracetic Acid [35]	Aspen Wood	115 mM	1.3 : 40	60	6	++	+	++	Recovered from hydrolysis of hemicellulose and cellulose

++: hydrolysis towards cellulose, hydrolysis towards hemicellulose, and efficient removal of lignin;
+: less effect towards cellulose hydrolysis, less effect and removal of hemicellulose, and solubilisation of lignin;
−: minor effect toward cellulose, minor effect towards hemicellulose, and less efficient in removal of lignin;
BM: biomass.
^aCellulose.
^bHemicellulose.
^cLignin.