**2. Biomass and biofiber**

Renewable biomass and biofiber are a carbon based biological material derived from living organism. It is composed of a mixture of organic molecules containing hydrogen, oxygen, nitrogen, and small quantities of other atoms such as alkali, alkaline earth, and heavy metals. These materials are abundant, eco-friendly, low cost, and sustainable biomaterials. The biomass and biofiber produced from various industries and manufacturing can be used in composite, textile, food, and chemical industries. On the other hand, these materials have also gained a great attention as a liquid biofuel feedstock due to low cost feedstock materials and environment friendly conversion process.

The renewable biomass and biofiber materials can be categorized into five major categories based on its origin as presented in **Figure 1**. Five distinct biomass and biofiber categories includes: (1) Wood and non-wood (softwood, hardwood, and residue), (2) animal fiber (wool, silk, hair) (3) aquatic plant (algae and hyacinth) (4) plant fiber (cultivated, residue), and (5) other renewable resource (animal residue, municipal solid waste [MSW], industrial residue, sewage).

**Figure 1.** Schematic classification of renewable resources for biofuel production.

petroleum reverse. To overcome this problem, production of biofuel from renewable resour‐ ces such as biomass and biofiber has gain great attention to partially replace fossil fuels in the future.Productionofbiofuelfromthesematerials isenvironmentfriendlyandsustainable.Mass production of biomass and biofiber as waste residue from agriculture and forestry industry has createdagreat concernfor environment sustainabilityglobally.Generally,biomassandbiofiber can be generated from various origin either direct cultivation, or as residue from agro-waste and forestry industries. The biomass and biofiber residue generated from these industries including sugarcane, bagasse, rice straw, empty fruit bunch (EFB), oil palm trunk (OPT), oil palm frond (OPF), and sago bark. Meanwhile,the examples forthe cultivated biofiber are kenaf

In order to produce biofuel from these materials, it has to undergo few processes such as biomass production, pretreatment, saccharification, and fermentation. Pretreatment of biomass has been reported to contribute substantial portion of liquid biofuel production cost. There are four established pretreatment methods such as thermal, chemical, biological, and physical pretreatment that have been applied to pretreat biomass and biofiber. However, among of the pretreatments mentioned, physical pretreatment method especially irradiation method is considered as one of the promising approaches applied to reduce the recalcitrant of biomass and biomaterials. Generally, this method utilizes both thermal and non-thermal effect generated by intermolecular collision during the realignment of biomass molecule. Irradiation pretreatment offers great advantages such as having very selective process, and it is energy efficient. Since there are wide ranges of tropical biomass types renewably available in tropical

country, thus, exploring the potential of this pretreatment is really much needed.

pretreatment approach for biofuel production.

environment friendly conversion process.

**2. Biomass and biofiber**

This chapter discusses comprehensively on irradiation pretreatment of tropical biomass prior to the subsequent enzymatic saccharification and fermentation processes. The emphasis is given on the type of irradiation pretreatments and mechanism that could be beneficial for scientists and researchers to understand the process, which can be applied as an alternative

Renewable biomass and biofiber are a carbon based biological material derived from living organism. It is composed of a mixture of organic molecules containing hydrogen, oxygen, nitrogen, and small quantities of other atoms such as alkali, alkaline earth, and heavy metals. These materials are abundant, eco-friendly, low cost, and sustainable biomaterials. The biomass and biofiber produced from various industries and manufacturing can be used in composite, textile, food, and chemical industries. On the other hand, these materials have also gained a great attention as a liquid biofuel feedstock due to low cost feedstock materials and

The renewable biomass and biofiber materials can be categorized into five major categories based on its origin as presented in **Figure 1**. Five distinct biomass and biofiber categories includes: (1) Wood and non-wood (softwood, hardwood, and residue), (2) animal fiber (wool,

and hemp.

330 Radiation Effects in Materials

These biomass and biofiber are natural biomaterials and can be described as lignocellulosic materials comprised of cellulose, hemicellulose, and lignin. These materials can be further categorized into five categories based on which part it comes from. The five categories are (1) leaf, (2) seed-hair, (3) coir, (4) bark or stem, and (5) other than part mentioned above [1].

Most of the biomass and biofiber generally have a very low economic value. However, due to a broad range of characteristics especially in chemical composition, distribution has provided a variety of applications (**Table 1**).

The biomass and biofiber produced from agro-industry can be used in the plywood, hybrid composite, and animal feed. In any case, the biomass generated from the industry also can be converted into bioenergy and other chemicals, for instance acid and solvent, and liquid biofuel. Due to environmental concern and reduction of fossil fuel reserve, production of liquid biofuel from biomass has gained a great attention because the process is environment friendly. In order to produce biofuel from biomass, it has to go through several processes such as biomass production, pretreatment, followed by enzymatic saccharification, and fermentation (**Fig‐ ure 2**).


**Table 1.** Chemical composition of various types of renewable biomass and biofiber.

Production of liquid fuel and value-added chemicals from biomass is believed to be one of the approaches to increase the value of biomass and biofiber generated. However, one of the main huddles to ensure the success of this process is the pretreatment process. Pretreatment process has been reported to contribute substantial portion in biofuel production cost. Thus, selecting the most efficient and low cost production could reduce biofuel production cost.

**Figure 2.** Process flow diagram for biofuel production from biomass and biofiber through biochemical conversion.
