Lignocellulosic biomass (LB) sources which are readily available in abundance are widely considered as a potential future sustainable raw materials for biofuel production. Typically, biofuel production involved several chemical and mechanical steps consisting of pretreatment, hydrolysis, fermentation and separation. The pretreatment step is considered as one of the most vital part of the whole processing scheme due to the impact it had on the efficiency of the subsequent processing steps. In this study we reviewed the mechanical pretreatment of LB focusing mainly on the size reduction technique by grinding process. Grinding is one of the proven preliminary pretreatment techniques employed in biomass conversion to liquid biofuel. However, this technique is known to be costly due to high energy consumption. In view of this, an efficient and cost effective pretreatment technology is required in order for the biofuel to be produced at a competitive level. At the same time, the impact on environment caused by the conventional pretreatment processes can be minimized. Thus, a new combined chemical-mechanical pretreatment is considered whereby a green ionic liquid (IL) solvent is introduced.

Ionic liquid (IL) has been shown to affect cellulose crystalline structure in lignocellulosic biomass (LB) during pretreatment. This research was carried out with two different experimental design involving IL to observe the effect of dissolution in IL on: (A) the crystallinity of cellulose and (B) the dissolution efficiency of LB. For experiment A, the types of IL used in this research were 1-ethyl-3-methylimidazolium Acetate [EMI[A, 1-allyl-3-methylimidazolium Chloride [AMI[C, 1-butyl-3-methylimidazolium Chloride [BMI[C and 1-ethyl-3-methylimidazolium Chloride [EMI[C. The crystallinity degree of LB was investigated before and after pretreatment with IL. The microcrystalline cellulose (MCC) was used as the simulated LB (cellulose content) was dissolved in IL and the crystallinity after the dissolution was analyzed. The temperature (70°C, 80°C, 90°C, 99°C) and concentration ratio of IL with volume/volume (v/v: 10%, 25%, 50%) were varied while the dissolution time remained constant. The crystallinity was analyzed by using Fourier Transform Infrared Spectroscopy (FTIR). The results showed that the dissolution temperature and IL concentration ratio affects the intensity of the FTIR peaks. In experiment B, the dissolution of LB with 1-butyl-3-methylimidazolium Chloride [BMI[C and 1-Ethyl-3-methylimidazolium Chloride [EMI[C as ILs were investigated. Four types of LB involved were Elaeis guineensis species of Oil Palm Trunk (OPT) and Oil Palm Frond (OPF) and Pennisetum purpureum species (elephant grass) originated from Taiwan and India. From the results obtained, the [BMI[C gave better dissolution to biomass.

Due to rapid growth in population and industrialization, worldwide ethanol demand is increasing continuously. The abundant sources of lignocellulosic biomass (LB) from agricultural wastes are attractive feed stocks to become a sustainable source for bioethanol production. There are many crucial engineering steps involved in the bioethanol production route especially on the pretreatment which comprises of chemical, mechanical and biological approaches. In this study we reviewed the various pretreatment involved in biofuel production. By considering the all steps required which may incur costs then influence the price of bioethanol an effective pretreatment technology is required for minimizing the cost and concurrently minimizing other problem especially environmental pollution caused by the pretreatment process. Therefore, a compact step combining all or some of the steps and with additional application of green technology with ionic liquid (IL) will be beneficial to the future direct production of liquefied biofuel with chemical-mechanical-biological based techniques starting from the pretreatment study which therefore lessen cost incurred and process time.

This work study the effect of empty fruit bunch (EFB) fiber on mechanical properties (tensile, flexural and impact) of different formulation of HDPE/EVA/MMT/EFB nanohybrid biocomposite with present of 1.5 phr compatibilizer. The ratio of HDPE and EVA are fixed at 80 wt% and 20 wt% respectively. However, the nanoclay montmorillonite (MMT) was varied from 0, 0.5, 1.0 and 1.5 phr. Meanwhile EFB fiber was varied from 0, 10, 20, 30, 40 and 50 wt%. The HDPE/EVA/MMT/EFB blends were prepared by melt extrusion blending technique using a single screw extruder. Generally, the result found that by increasing of EFB fiber content, the tensile strength of HDPE/EVA/MMT/EFB nanohybrid biocomposite was declined. The highest tensile strength was given by formulation of HDPE/EVA/1 phr MMT without EFB fiber loading which is 29.064 MPa. Meanwhile the lowest tensile strength is given by formulation of HDPE/EVA/0.5 phr MMT with 50 wt% of EFB fiber which is 9.673 MPa. Similar trend also showed by the result of flexural strength obtained. In contrast, the value of tensile modulus is progressively increased with further increasing of EFB fiber content. The highest tensile modulus given by formulation of HDPE/EVA/1 phr MMT with reinforced of 50 wt% EFB fiber loading (694.53 MPa) whereas the lowest is given by HDPE/EVA/0.5 phr MMT with 10 wt% EFB fiber loading (290.76 MPa). Similar trend for the flexural modulus where further increasing of EFB fiber content, the flexural modulus is directly increasing. Unfortunately, for impact properties, reinforced of EFB fiber give resulted on the reduction of impact strength.

This work study the mechanical properties (tensile, flexural and impact) of four different formulation of HDPE/EVA/MMT nanocomposite with present of 1.5 phr compatibilizer as a preliminary study before further development of HDPE/EVA/MMT/EFB nanohybrid biocomposite. The ethylene vinyl acetate (EVA) was varied from 0, 10, 20 and 30 wt%. Meanwhile the nanoclay montmorillonite (MMT) was varied from 0, 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0 phr. HDPE/EVA/MMT ternary blends were prepared by melt extrusion blending technique using a single screw extruder. The result found that in absent of nanoclay MMT, the tensile and flexural properties (strength and modulus) of HDPE/EVA/1.5 phr compatibilizer were decreased as EVA amount are increased. Meanwhile in absent of EVA gave the highest tensile and flexural strength which are 38.53 MPa and 35.02 MPa respectively. However the trend is reciprocal for impact strength. The Izod impact test found that 30 wt% EVA give the highest impact strength which is 103.88 J/m , followed by 20 wt% EVA, 10wt % EVA and 0 wt% EVA which are 59.91 J/m, 38.11 J/m and 30.63 J/m respectively. This is because EVA plays a role as impact modifier. Meanwhile incorporation of nanoclay MMT improved the tensile and flexural properties but reducing the impact properties.