Prospects for Irradiation in Cellulosic Ethanol Production

Table 2

Effects of electron beam on lignocellulosic biomass.

Biomass	Treatment conditions	Structural alterations	Results	References
Waste papers	Electron beam treatment integrated with gamma irradiation		Increased rate of hydrolysis	[43]
Wood chips	30 kGy electron beam pretreatment		Reduced strength, reduction in energy consumption to 20–25% for high yielding pulp	[44]
Rice straw	NaOH assisted electron beam pretreatment	Reduction in size of rice straw	Increased sugar content compared to that in individual methods	[45]
Rice straw	Electron beam irradiation	Surface changes in biomass	Increased digestibility, 65.5% of theoretical sugar yield, and no inhibitory products formation	[46]
Rice Straw	Alkali-electron beam irradiation	Reduction in lignin content, increase in cellulose content from 19.5% to 64%	Enhanced sugar yield in hydrolysis	[47]
Rice straw	Beam irradiation combined with 3% dilute acid treatment followed with autoclaving		80% total sugar yield	[48]
Rice straw	80 kGy beam irradiation		52.7% ethanol yield after simultaneous saccharification and fermentation with Mucor  indicus	[49]
Wheat and rice straw	Electron beam treatment at 200 Gy		More delignification by Phanerochaete  chrysosporium, more cellulase production	[50]
Wheat straw	Electron beam treatment comparison: single irradiation at 100 kGy and divided irradiation at 25 kGy in 4 tandem doses	Reduction in cellulose crystallinity from 43% to 38.8%, removal of hemicellulose, and lignin modification	74.9% saccharification yield upon single irradiation compared to 40.9% in control and 51.1% in divided irradiation	[51]
Wheat straw	Electron beam pretreatment	Reduction in dry matter	Increased degradability	[52]
Sugarcane bagasse	Electron beam irradiation at 50 kGy followed with dilute acid and hydrothermal treatment		30% enhancement in enzymatic saccharification by irradiation in hydrothermal treatment compared to 20% in acid treatment	[53]
Sugarcane bagasse	Electron beam irradiation	Breakage of bonds in lignocellulosic matrix	Dose-dependent increase in fibre degradation and increased rumen digestibility	[54]
Kenaf core	500–1000 kGy beam irradiation and autoclaving for 5 hrs		Increase in crystallinity index from 50.65 to 555 at 500 kGy, gradual increase in sugar concentration from 100 to 500 kGy being 83.9% at 500 kGy	[55]
Kenaf core (Hibiscus  cannabinus)	Combined alkaline-electron beam method		72.4% total sugar recovery in hydrolysis with 63.9% glucose	[56]
Spruce wood	2 Mgy beam irradiation	90% cellulose recovery	80% recovery of glucose with Trichoderma cellulase	[57]
Sawdust & chaff	100 Mrad beam irradiation		Linear increase in enzymatic hydrolysis rate with irradiation dose, reduced time of pretreatment	[58]
Hybrid poplar	Beam irradiation followed with mild alkali extraction	Xylan degradation	Enhancement in extraction and enzymatic hydrolysis with commercial cellulase	[59]
Oil palm empty fruit bunch	Electron beam irradiation at 400 kGy	Biomass degradation; cellulose, hemicellulose, and linin deformation	Reduced crystallinity index, increased solubility in water, benzene, and NaOH	[38]
Bamboo	Beam irradiation from 0 to 50 kGy	Cellulose structure alteration	Gradual decrease in crystallinity index with increasing dose	[42]
Switchgrass (Panicum  virgatum L.)	1000 kGy beam irradiation followed with hot water extraction	Decreased cellulose crystallinity, decrease in hemicellulose content from 32.2% to 16.9%	Decrease in molecular weight, 4-fold increase in glucose yield	[60]
Pistachio byproduct	Beam irradiation at 30–40 kGY	Reduction in ADF, NDF and increase in ADL	Decreased tannin content,; enhanced fermentation	[61]
Miscanthus sinensis	Beam irradiation at 500 kGy Beam irradiation with aqueous ammonia treatment		1.26-fold increase in saccharification compared to control,; 2.4-fold increase in combined treatment, and production of 96.8% ethanol from hydrolysate	[62]