Phytochemical analysis of OPW by various researches has revealed the presence of several important bioactive compounds such as carotenoids, phenolic compounds, sterols and polysterols, tocols, coenzyme Q10 and squalene whose pharmacological activities are beneficial for healthy body growth. Quantification and isolation of these phytonutrients have successfully been done through various technologies such as high performance liquid chromatography (HPLC). OPW phytochemicals are found to enhance the body’s immunity and promote would healing with most of them possessing antioxidant, anticariogenic and anti-hypertensive activities.

Various extracts from the OPW have been reported by Yap et al. (1991) to contain about 13 different types of carotenoids with the major ones being a-carotene, P-carotene, y-carotene lycopene and phytoene which help maintain healthy body tissues and prevent xerophthalmia (night blindness) (Choo et al. 1992; Ooi et al. 1994).

The residual oil from PPF contains almost six times the amount of carotenoids (4,000-6,000 ppm) found in CPO (500-800 ppm) (Choo et al. 1992, 1996). The carotenoid concentration is even higher in PPF residual oil from hybridised palm oil species (6,000-7,000 ppm) (Choo et al. 1996). This implies that, presently, due to technological advancement, most of the palm oil fresh fruits produced are from hybrid species hence more carotenoids from the PPF. Carotenoids from PPF have again been quantified and isolated by various recent authors with concentrations of about 2,922 mg/kg compared to 800-1,000 mg/kg for CPO (Lau et al. 2005, 2006, 2008; De Franca and Meireles 2000) using various separation and extraction tech­niques such as the HPLC. The presence of carotenoids in the membrane cell of PPF which could not be completely extracted during CPO extraction is said to account for the higher carotenoids in PPF. This could mean that the fibres of OPW present potential sources of carotenoids in large quantities. The tocols in PPF include a-tocopherols (55.3% and higher than that of CPO with 24.4%), a-tocotrienols (11.4%), y-tocopherols (3.5% and higher than that of CPO with 1.7%), y-tocotrienols (21.0%) and S-tocotrienols (8.8% and higher than that of CPO with 7.6%) (Ng et al. 2004; Choo et al. 2005; Han et al. 2004). The approximate concentrations of tocols found in PPF as reported by various authors are 2,000-4,000 ppm compared to 600-1,000 ppm for CPO (Choo et al. 1996; Ng et al. 2004) and 3.7-4.0 mg/ml (Sanagi et al. 2005). PPF contain about 500-1,000 ppm of squalene (Choo et al. 2005), about 1,000-1,500 ppm coenzyme Q10 compared to 10-100 ppm in CPO (Ng et al. 2004) and about 2.6 wt% and 3.0 wt% glycolipids and phospholipids, respectively (which is higher in chloroform/methanol extracts at 6 wt% and 10 wt%, respectively) of the total lipids extracted.

OPL extracts contain about 1,900 ppm carotenoids (Ng and Choo 2010),

I. 71 x 10 m3 tocols (mostly tocopherols) per kg dried OPL (Birtigh et al. 1995),

II, 229-14,805 pg a-tocopherol per g OPL (Kato et al. 1983) and 30-44 pg P-tocopherol per g OPL using the technologies of combined gas chromatography- mass spectrometry and thin layer chromatography (Kato et al. 1983). Flavonoid content of OPL extracts has antioxidant effects (analysed by 2,2-diphenyl-2- picrylhydrazyl (DPPH) assay) in the range of 56-93% OPL which help heal free radical-mediated diseases such as cancer (Ng and Choo 2010), anti-hypoglycaemic effect (against alloxan diabetic rats), anti-hyperlipidemia effect (Sasidharan et al. 2010, 2012; Syahmi et al. 2010) and antimicrobial activity (Sasidharan et al. 2010). In most parts of Africa, OPR and OPL water extracts have been used in treating malaria and typhoid fever. The OPW fibres are also milled and made into pastes which are used in treating boils, skin diseases and wounds.

The antioxidant effect of OPF extracts (203 pmol) is found to be higher com­pared to that of green chilli (43 pmol), papaya shoot (58 pmol) and lemon grass (22 pmol) (Abeywardena et al. 2002). PKS pyrolysate has been analysed by Ukoh et al. (2004) to exhibit high antibacterial effects hence the need to extract phyto­chemicals from PKS which is considered wastes in the palm oil industry.

POME extracts contain about 287-1,665 ppm carotenoids. Ahmad et al. (2009) have reported that about 284,000 tonnes of oil extractable from POME could produce about 140,000 kg carotenoids. The presence of significant amounts of phenolic compounds (mostly flavonoids) in POME has been reported by various authors (Rakamthong and Prasertsan 2011; Omayma et al. 2009), and their antioxidant activities are also analysed by Yun et al. (2008). A sustainable utilisation of POME for phytonutrients would be achieved through simultaneous production of POME and extraction of phytonutrients to supplement those in CPO by means of a series of innovative separation techniques which would iso­late specific compounds of interest on the basis of their molecular weights (Sundram et al. 2003).

Through molecular distillation process, PFAD is found to contain about 3.94% (Sarunya et al. 2006) and 2,000-8,000 ppm (Choo et al. 2005) of squalene, 6.63% tocotrienols, 2.20% a-tocopherol and 4.77% sterols (Posada et al. 2007). Chu et al. (2004) have also detected various sterols in PFAD including 13.7% ergogst-5-en-3- P-ol(2,2-dihydrobrassicasterol), 6.27% 2,2-stigmasta-5,2,2-dien-3-P-ol (stigmas — terol) and 80% stigmast-5-en-3-P-ol (sitosterol).

Cinnamic derivatives and flavones in OPR and palm oil fibre (which may include fibre from OPT, OPF and EFB) were detected at 280 nm (Akpan and Usoh 2004), whilst flavonones, chlorogenic derivatives and flavones were also detected at 350 nm (Diabate et al. 2009).

Extracts from PKC contain about 5.5 ppm sterols consisting of 7-a — and 7-P-hydroxy derivatives of p-sitosterol, stigmasterol, campesterol and phytosterol oxides (7-keto-P-sitosterol) (Bortolomeazzi et al. 2003) and 2.3 g/kg saponins which are higher than the saponins found in chickpea (2.3 g/kg) (Ogbuagu 2008).

D-Mannose (a hexose which is used as food additive or supplements in many applications in the pharmaceutical industry) has been isolated from PKS and puri­fied for the prevention of bacterial infections (Zhang et al. 2009).

Many types of organic acids have been produced from OPW including lactic acid from OPT (Kosugi et al. 2010; Chooklin et al. 2011), acetic, propionic, butyric and lactic acids from POME (Ali Hassan et al. 1996) and citric acid from EFB (Bari et al. 2009) which are used as additives in the food, pharmaceutical and cosmetics industries.

Ultrasound technology can be applied for transesterification of raw materials into biodiesel. It is known to be a useful tool for overcoming the hurdle of mass transfer limitation between reactants in the system. Ultrasonic irradiation of respective fre­quencies can have various effects on the chemical reactions. One of the most impor­tant effects is cavitation, where the ultrasound increased the interaction between the phases due to the collapse of cavitation bubbles and the ultrasonic jet that disrupts the phase boundary and causes emulsification (Brito et al. 2012). Aside from enhancing the mass transfer efficiency, this method also allows for shorter reaction times and less extreme operating conditions. Ultrasonication also provides the mechanical energy for mixing and the required activation energy for initiating the transesterification process.

Mahamuni and Adewuyi (2009) conducted in-depth study of biodiesel synthesis from soybean oil using ultrasound-enhanced base-catalyzed transesterification. KOH was used during the process. The introduction of ultrasound clearly improved the reaction, where the initial rate of biodiesel formation is very high and more than 80% biodiesel was formed within 30 min, but only 40% biodiesel produced in 60 min with the absence of ultrasound. Increase in the power of ultrasound enhances biodiesel formation rate. The same pattern was also observed for the frequency of the ultrasonic waves, but further increased does not significantly improved emulsi­fication and reaction rate. The increase in all other operating parameters such as cata­lyst loading, oil to methanol ratio, and temperature resulted in increased rate of biodiesel formation and biodiesel yield. The kinetic study proved that the trans­esterification of soybean in the presence of ultrasound is second order. Overall, the conversion of 90% FAME was achieved in <30 min at optimum conditions.

The experiment involving transesterification from soybean oil with ethanol was conducted, assisted by low-frequency ultrasound and KOH catalyst (Brito et al. 2012). A full two-level factorial design was applied to determine the significance of operating variables. Increase in all variables (oil:ethanol molar ratio, catalyst con­centration, reaction time) enhanced biodiesel yield, with catalyst concentration as the most significant parameter. Ninety-seven percent biodiesel yield was obtained when the transesterification was assisted by ultrasonication in a period of 6 min. The formation of stable microemulsion from the ultrasonic cavitation allows for good conversion of soybean oil.

Mootabadi et al. (2010) demonstrated the ultrasonic-assisted transesterification of palm oil using metal oxide catalysts (CaO, SrO, BaO) at different operating con­ditions. BaO was the most active catalyst compared to the other two catalysts for all operating conditions. However, the catalytic activity of BaO decreased faster than SrO when it was used repeatedly. Generally, ultrasonic amplitude can enhance the biodiesel productivity as the power of the ultrasonic irradiation is directly propor­tional to biodiesel yield. About 95% biodiesel yield was obtained in 60 min, which proved that the transesterification with the application of ultrasonic cuts reaction time involving heterogeneous catalyst.

The ultrasonic technology is also suitable for the process utilizing acid catalyst. The esterification of palm fatty acid distillate (PFAD) was done using concentrated H2SO4 in an ultrasonic bath (Deshmane et al. 2008). The conversion of PFAD into biodiesel was enhanced as ultrasound waves are introduced, whereas lower conver­sion was achieved when only mechanical agitation was applied. The currents gener­ated by the stirrer were not sufficient to eliminate the mass transfer limitations. On the other hand, ultrasound-generated cavitation produced intense turbulence at microscale and uniform mixing at the microlevel, hence overcoming the mass transfer resistance. Increase in catalyst concentration enables the reaction to achieve almost 100% con­version and at a faster rate. The optimum operating parameters were 7:1 molar ratio of PFAD to methanol, 5% catalyst concentration, and temperature of 40°C.

The esterification of FFAs with different short-chain alcohols was performed under ultrasonic irradiation (Hanh et al. 2009). Acid catalysts (H2SO4 and CH3COOH) were used to induce the process. Higher catalyst concentration and reaction time increased oleic acid conversion. The same trend was also observed when the esterification was conducted using palmitic acid and stearic acid as the feed. The conversion to ethyl esters was almost the same irrespective of the kind of FFAs. Normal-chain alcohols lead to higher reaction rate in shorter time than sec­ondary alcohol. This behavior is due to the sterical hindrance that limits the access to the reaction center, thus dampening the reaction rate of biodiesel conversion com­pared to normal-chain alcohols.

B. cepacia lipase was immobilized by the following method. At first, the lipase was cross-linked using 25% glutaraldehyde solution in the following way. 1 g of lipase powder was dissolved in 1 ml of phosphate buffer (pH = 7); to this, 500 pl of 25% glutaraldehyde solution was added and stirred for 3 h at 25°C for cross-linking. On the contrary, 1.5% w/v solution of к-carrageenan in water was prepared by dissolv­ing it at 80°C for an hour, and later, the temperature was brought down to 35°C. To this, an equal weight of sodium alginate (1.5% w/v) was added and stirred for an hour more to obtain uniform distribution. Later, the cross-linked lipase was mixed into this and stirred for another 15 min. The mixture was then dropped into 0.1 M solution of calcium chloride (CaCl2) by using a syringe pump (Thermo Model TE-331, Japan) of 50 ml/h flow rate to form the desired beads. The beads in the collection flask were stirred for ten minutes and later stored in 0.1 M CaCl2 solu­tion overnight at 4°C for hardening. Later, the beads were filtered, washed with distilled water, and dried in room temperature for further stability studies. Figure 12.2 shows the overall process of immobilization. The immobilized beads (Fig. 12.3) were also dried under reduced pressure, and their scanning electron micrographs were obtained with ZEISS (EVO MA 10, UK) scanning electron microscope (Fig. 12.4a, b).

The application of a membrane contactor for the carbonation of the microalgae culture was reported in the late of 1990s for the purpose of utilizing CO2 emissions to prevent them from entering the atmosphere. The hydrophobic membrane is capa­ble of enhancing CO2 transfer per area of membrane surface by a factor of 10 com­pared to silicone tubing (Ferreira et al. 1998) and 1.48 x 10-2 min-1 compared to 7 x 10-3 min-1 of plain bubbling and higher by a factor of two (Carvalho and Malcata 2001).

Membrane hydrophobic is also capable to enhance CO2 fixation rate from 80 to 260 mg L-1 h-1 or more than three times greater than a reactor without a membrane (Cheng et al. 2006; Fan et al. 2007). The DO dropped by a factor of 30 (Cheng et al. 2006) and the O2 evolution was enhanced (Fan et al. 2007). Besides their use for carbonation and deoxygenation, membrane contactors also can be used to integrate with the microalgae harvesting system (Bayless and Stuart 2009), thus could reduce the production cost of microalgae biomass.

The effectiveness of membrane contactors for sequestering CO2 is affected mainly by the microalgae density in the reactor, feed gas flow rate, light intensity (in the case of using microalgae), and the properties of the membrane. The property ranges that suitable to be applied to achieve the maximum capability of the membrane to sequester CO2 are listed in Table 14.3 (Ferreira et al. 1998; Carvalho and Malcata 2001; Cheng et al. 2006; Fan et al. 2007). These are the values that are used in the membrane contac­tor research field when using microalgae for the bio-mitigation of CO2.

Matlal Fajri Alif, Kozo Matsumoto, and Kuniyuki Kitagawa

Abstract Biomass/biowaste gasification using supercritical water is a new way to produce hydrogen gas, a clean and renewable energy. This method besides produc­ing hydrogen will also produce heteroatomic compounds, substances that can be a burden to the environment; therefore, it is important to clarify the mechanisms of these compounds. A newly developed online mass spectrometry determination of the sulfur compounds released during hydrothermal reaction from L-cysteine as model compound and durian fruit as practical sample was done. The effect of alka­line Ca(OH)2 addition on the formation of sulfur heteroatom compounds has been studied in detail.

Keywords Biomass • L-Cysteine • Durian • Hydrothermal • Heteroatom • Sulfur

4.1 Introduction

Dependence on fossil fuels as the main energy sources has led to serious energy crisis and environmental problems, i. e., fossil fuel depletion and pollutant emission. The increasing energy demands increases the rate of exhaustion of the finite fossil fuel. Combustion of fossil fuel produces greenhouse and toxic gases, such as CO2, SOx, NOx, and other pollutants. To resolve the problems mentioned above, effort has been made to find clean, renewable alternatives sources of energy for sustainable development. Biomass is one of the most abundant renewable resources. In this regard, hydrogen is among promising clean gas fuels.

M. F. Alif (*)

Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, Nagoya, Japan e-mail: matlal_falif@hotmail. com

K. Matsumoto • K. Kitagawa

EcoTopia Science Institute, Nagoya University, Nagoya, Japan

R. Pogaku and R. Hj. Sarbatly (eds.), Advances in Biofuels,

DOI 10.1007/978-1-4614-6249-1_4, © Springer Science+Business Media New York 2013

Figure 6.5a, b shows the 2D distributions of temperature in the combustion flames obtained with the thermal video camera for sunflower and soybean oils, respec­tively. The average of 100 frames was depicted. The results indicate that the

Fig. 6.4 The schematic diagram of CO2 visualization using IR-camera

temperature ranges between 400 and 1,400°C. The temperature of sunflower oil combustion flames is slightly higher than that of soybean oil due to its higher enthalpy during combustion (see the orange color area). Moreover, before the com­bustion, vegetable oil is likely dissociated to produce two sorts of components such as fatty acids and glycerols at the inner part of flame cone. Consequently, the onset of micro-explosion takes place shortly before the second step combustion of glyc­erol (Wardana 2010). We also assumed that the difference in fatty acid composition of oils influences the combustion temperature (Freedman and Bagby 1989).

The combustion shape of sunflower oil is bigger than that of soybean oil due to the lower viscosity of sunflower oil compared to soybean oil. It is clearly visualized that (see Fig. 6.5, right) the flames of two SVOs are stable in inner part and unstable in outer part due to the secondary and peripheral convection airflow from the ambient causing the peripheral fluctuation.

Figure 6.6 shows the spontaneous emission intensity profiles ofNO emitted from sunflower oil and soybean oil combustion flames obtained with ICCD camera. The NO emission of sunflower oil is higher than that of soybean oil due to its higher temperature.

Figure 6.7 shows the result of in situ monitoring of infrared emission spectrum emitted from sunflower oil and soybean oil combustion flames. The presence of C=O stretching (2,300 cm-1), C-O stretching (2,120 cm-1), O-H stretching (4,000­3,100 cm-1), O-H bending (2,000-1,200 cm-1), and NO rovibration (1,800­1,500 cm-1) is obviously seen for two oils. The O-H bending suspected arises not only from H2O presence but also from OH radical.

Figure 6.8 shows the visualization of spontaneous CO2 emission emitted from sunflower oil and soybean combustion flames obtained with the infrared camera. The CO2 emissions emitted from both of oil combustions are giving almost the same result flame which has high intensities, especially the inner part due to the high temperature.

6.2 Conclusion

The temperature distributions of sunflower and soybean oil combustion flames using the semawar burner have been investigated in this research using spectro­scopic method. The 2D temperature distribution of combustion flames has been successfully in situ monitored with the video thermal camera. The result has shown that the flame temperatures ranged from 400 to 1,400°C. The spontaneous NO emission has also visualized by ICCD camera. It has obviously seen that NO emis­sion of sunflower oil is more significant than soybean oil due to the higher tempera­ture of sunflower oil combustion flames. The presence of CO2 , CO, H2O, and NO from sunflower and soybean oil combustion flames has been observed using FT-IR, and CO2 has been also visualized using infrared camera. The presence of O-H stretching and bending suspected not only comes from H2 O but also comes from OH radical emission. NO rovibration of sunflower oil combustion flame has been shown in high level compared to soybean oil combustion flame due to higher carbon content in sunflower oil.

Various processes for the conversion of low-grade feedstock (Jatropha oil) to bio­diesel were discussed. Although the process that mentioned in this section is for Jatropha-based biodiesel production, these techniques can be used for other low — grade feedstock with high FFA content in order to produce high-grade biodiesel product. Researchers have been reporting several techniques for converting Jatropha oil to biodiesel: that is via catalytic transesterification reaction using alkaline cata­lyst (Helwani et al. 2009; Kulkarni and Dalai 2006), acid catalyst, and enzyme (Kumari et al. 2009; Tamalampudi et al. 2008) or via non-catalytic approaches in supercritical alcohol (Hawash et al. 2009). Table 10.5 summarized the transesterifi­cation techniques for Jatropha oil to biodiesel. In the case of catalytic reaction, the catalyst was categorized into two groups based on its mobility which can be categorized as homogeneous and heterogeneous. These catalysts and transesterifi­cation technology are very much dependent on the quality (FFA content) of Jatropha oil (Juan et al. 2011).

The well established conventional transesterification reaction is utilizing homo­geneous alkaline-catalyzed (KOH or NaOH) reaction. However, the presence of FFA content (>1 wt%) in Jatropha oil will react with alkaline catalyst to form saponified products. The side reaction of saponification process led to the formation of emulsion that create difficulties in downstream recovery and purification process, which require exhaustive and costly purification of the biodiesel products (Berchmans and Hirata 2008; Karmee and Chadha 2005; Nazir et al. 2009).

These problems make conventional alkaline transesterification reaction much less efficient. The homogeneous acid-catalyzed reactions are capable to transesterify oil with high FFA content and reduce amount of FFA content in Jatropha oil to <1 wt% during esterification reaction. However, acid-catalyzed reactions are not feasible for biodiesel synthesis due to the slow reaction rate and high reaction temperature. Saponification phenomenon is avoided by applying acid catalyst, but the catalytic effect on the transesterification was then decreased (Goff et al. 2004). Neither NaOH nor H2SO4 is suitable as catalyst for biodiesel production. Thus, a more efficient method would be via two-step transesterification approach that consists of acid-catalyzed reaction before proceeding the transesterification with alkaline catalyst. At first step, an acidic catalyst (H2SO4) will be utilized to reduce the FFA content in Jatropha oil to less 1 wt% via esterification reaction. Meanwhile, at the second step, alkaline catalyst was used to transesterify the low acid oil into biodiesel. This two-step pro­cess was found to be very effective with the yield of biodiesel in the overall process reaching up to above 90% (Berchmans and Hirata 2008; Karmee and Chadha 2005; Nazir et al. 2009; Ramadhas et al. 2005).

Optimization reactions were performed for transesterification of Jatropha oil by varying the amount of water concentration from 0 to 2.0 g at optimum oil-to-ethanol molar ratio obtained from above experiment. The other baseline reactions and conditions were maintained as mentioned above.

The results shown in Fig. 12.7b depict a low enzyme activity at lesser water concentration. These observations are in accordance with the supporting fact that a minimum amount of water is required to activate the enzyme. There was consider­able increase in ethyl ester formation with increase in addition of water. A maxi­mum yield of 92% was obtained at 1 g water concentration and with 1:10 oil-to-ethanol molar ratio. Subsequent addition did not result in further increase in ester yield. The increase in the activity of transesterification of lipase upon addition of water has been reported previously (Noureddini et al. 2005).

Although palm biodiesel is a potential RE, its use in the transport sector is not

favourable as issue of food vs. fuels arises. There are several issues which can be

challenged such as:

1. Technology that is able to meet EN 14214/ASTM D 6751 specification, e. g. cold soak test and high CFPP.

2. Environmental concerns on sustainability of palm oil production for biodiesel with allegations of destruction of orangutans, rainforests, loss of biodiversity and potential net emissions of GHG in oil palm cultivation on peatland.

3. Market risks concerning fluctuation of crude oil and crude palm oil (CPO) prices; cheaper sources of raw material, e. g. jatropha and hydro-treated vegetable oils; change in biodiesel specification; overcapacity causing dumping of prices; and foreign exchange risk.

4. Trade barriers.

OPLs are mostly referred to as the leaflets which are attached to the petioles of the OPF. OPLs are pinnate shaped of about 3-5 m in length with spines. OPL is composed of three parts, namely, the blade, the petiole and the base (Dransfield et al. 2008). An palm oil tree produces an average of 20 kg of dry leaflets yearly as wastes. As the age of the palm oil tree increases, the ratio of lengths of the OPL to OPF petioles decreases (Dransfield et al. 2008). For example, a 6-year-old palm oil tree has the ratio of OPL/OPF to be about 1.7 compared to 0.3 for a 21-year-old tree. This implies that the leaves of an older tree may have higher nutritional value com­pared to that of the petioles of the OPF (Dahlan et al. 2000).

The OPLs are found to have a better nutritive value compared to the OPF. They contain about 13% DM crude protein, more than 4% fat (Aim-oeb et al. 2008), 3.8% DM silica (Dahlan et al. 2000) , about 60-68% holocellulose and 14% glucose (Abdul Khalil et al. 2006). OPL is found to contain more cellulose (35%) compared to that of neem tree (30%) and close to the same amount in wood (40-45%). The cell wall of the OPL contains moderate amount of crystalline cellulose mainly poly­saccharides in the form of acetylated arabinoxylans (Abdul Khalil et al. 2006). The mineral contents of OPL as detected by Abdul Khalil et al. (2006) are about 2.62% nitrogen, 0.16% phosphorus, 1.25% potassium, 0.24% magnesium, 0.6% calcium, 0.55% chlorine and 0.22% sulphur. The vitamins A and E contents of OPL range from 1,900 ppm and 11,229-14,805 pg/g, respectively. These chemical characteris­tics of the OPL suggest a better option of its transformation into value-added pro­ducts such as sugar and phytochemicals. However, after harvesting of the FFB, they are usually left in the plantation together with the OPF for only nutrient recycling.