Category Archives: Microbes and biochemistry of gas fermentation

Acid value

The acid value measures the content of free acids in the sample, which have influence on fuel ag­ing. It is measured in terms of the quantity of KOH required to neutralize sample. The base cata­lyzed reaction is reported to be very sensitive to the content of free fatty acids, which should not exceed a certain limit recommended to avoid deactivation of catalyst, formation of soaps and emulsion [Sharma et al., 2008, Meher et al., 2004]. The feedstock acid values obtained in this study differed significantly ranging from 1.86 to 3.31 mg KOH/g oil. Thus, in the light of the previous discussion on the requirements for the feedstock acid values, it could be concluded that frying oil had the values above the recommended 2 mg KOH/g. However, these values did not turn out to be limiting for the efficiency of the applied two-stage process, as it will be discussed along to the obtained product yields and purity later on. Acid values of MEs were less than 0.5 mg KOH/ g specified as the maximum value according to JUS EN14214 (Table 4), Sharma et al. (2008) re­viewed the literature and found that acid value of the feedstock for alkaline transesterification has to be reduced to less than 2 mg KOH/g (i. e. 1%), while only few examples of transesterifica­tion with feedstock acid value of up to 4.0 mg KOH/g (i. e. 2%) were found. They also reported that when waste cooking oil is used as feedstock, the limit of free fatty acids is a bit relaxed and the value a little beyond 1% (i. e. 2 mg KOH/g) did not have any effect on the methyl ester conver­sion. Acid values of MEs produced from frying oil was 1.16 mgKOH/g when compared with 0.5 mg KOH/g specified as the maximum value according to JUS EN14214 [JUS EN 14214:2004].

Bagasse-thermoplastic biocomposites

Bagasse has been used as reinforcing filler in different thermoplastic matrices such as poly(eth — ylene-co-vinyl acetate) (or EVA) [152153], polyolefins [154155] and starch-based biodegrad­able polyester [140141, 156157]. The effect of cultivar type and surface cleaning of the bagasse fiber on the tensile properties of the bagasse-EVA composites have been investigated [152]. The results suggested that blends of bagasse from various cultivars can be used for commercial applications of these composites. Also, the surface cleaning of the bagasse obtained from sugar mill was good enough to use the bagasse without further surface treatment. Another study on the impact behavior of the bagasse-EVA composites showed that the mechanical performance of this type of composites could be tailored by varying the bagasse volume fraction in order to reproduce the behavior of wood-based particleboards [153]. Luz et al. [154] explored the efficiency of two different processing methods, injection molding and compression molding, to produce bagasse-polypropylene (PP) composite. They found that the injection molding under vacuum process was more efficient and created homogeneous distribution of fibers without blisters. It was observed that bagasse incorporation into PP improved the flexural modulus. High density polyethylene (HDPE) was used as the matrix for incorporation of cellulose obtained from bagasse [155]. It has been reported that modification of bagasse cellulose with zirconium oxychloride helped in improving the tensile strength of the biocom­posite.

Bagasse fibers have been used to produce biocomposites from bagasse and biodegradable corn starch-based polyester which is reported as a blend of starch and polycaprolactone (PCL). The effects of volume fraction and fiber length were investigated and an optimum value for both factor were reported beyond which the decrease in mechanical performance was observed [140]. Also, it was reported that after alkali treatment of the bagasse fibers the improvement in fibre-matrix adhesion occurred that resulted in enhancement of mechanical properties [141]. Moreover, incorporation of bagasse fiber into the polyester matrix improved tensile as well as impact strength. Acetylated starch has been reinforced with bagasse fiber [156157]. The matrix in that case was a blend of starch, PCL and glycerol. It was observed that incorporation of alkali-treated bagasse fiber up to 15 wt% increased the tensile strength while it decreased when bagasse content was more than this value. Also, the water absorption of the composite was improved as the bagasse content increased due to hydrophobic nature of bagasse compared to acetylated starch.

OPEFB torrefaction

Torrefaction is a thermal conversion method of biomass in the low temperature range of 200-300 °C. Biomass is pretreated to produce a high quality solid biofuel that can be used for combustion and gasification [1617]. It is based on the removal of oxygen from biomass to produce a fuel with increased energy density. Different reaction conditions (temperature, in­ert gas, reaction time) and biomass resources lead to the differences in solid, liquid and gas­eous products.

Uemura et al. [16] studied the effect of torrefaction on the basic characteristics of oil palm emp­ty fruit bunches (EFB), mesocarp fibre and kernel shell as a potential source of solid fuel. It was found that mesocarp fibre and kernel shell exhibited excellent energy yield values higher than 95%, whereas OPEFB, on the other hand, exhibited a rather poor yield of 56%. Torrefaction can also be done in the presence of oxygen. Uemura and his colleagues [17] carried out OPEFB tor — refaction in a fixed-bed tubular reactor in the presence of oxygen at varied oxygen concentra­tion. The mass yield decreased with increasing temperature and oxygen concentration, but was unaffected by biomass particle size. The energy yield decreased with increasing oxygen concentrations, however, was still between 85% and 95%. It was found that the oxidative torre — faction process occurred in two successive steps or via two parallel reactions, where one reac­tion is ordinary torrefaction, and the other is oxidation.

Second step transterification

The production methodology followed in this study was according to Tomosevic and Si — ler-Marinkovic [2003] with some modification, where the alkali-catalyzed transesterifica­tion was applied. Basically, methanol was the alcohol of choice and KOH was used as the catalyst. Potassium methoxide solution (PMS) was prepared freshly by mixing a pre­determined amount of methanol (« 12 wt % of oil) with KOH (« 1.0 wt % of oil) in a container until all the catalyst dissolved. The PMS was then added to 200 g of oil and

stirred vigorously for 30 min at 30oC. Then after, the mixture was carefully transferred to a separating funnel and allowed to stand for 4 h. the lower layer (glycerol, methanol and most of the catalysts) was drained out. The upper layer (methyl esters MEs, some methanol and traces of the catalyst) was transferred into another flask containing fresh­ly prepared PMS mixed at 60 rpm under reflux at 60oC for 30 min. afterwards; the mix­ture was carefully transferred to a separating funnel and allowed to stand there over night. The glycerol was removed by gravity settling, whereas the obtained crude esters layer was transferred into water bath to remove excess methanol at 65oC and 20 kPa. The obtained crude methyl esters were then cleaned thoroughly by washing with warm (50oC) deionized water, dried over anhydrous Na2SO4, weighted and applied for further analy­sis (Shalaby and Nour, 2012; Shalaby, 2011).

Biodiesel Proteineous meal

The major biodiesel feedstocks are vegetable oils which are generally produced by crushing oil seeds, leaving significant quantity of proteineous meals as coproducts. The global con­sumption of proteineous meal in 2011/12 as reported by USDA Economic Research Services [97] is depicted in Figure 7 indicating soybean as the predominant crop producing proteineous meal with 67 % contribution. According to the FAOSTAT database [98], US, Brazil and Argentina were the global premiers of soybean production in 2010 with 35, 26 and 20% contribution, respectively. The next largest producer is China with almost 6% share in the global soybean production. In this context, biodiesel production of the US, as for example, has increased, during 2006-11 period, 340% from 250 to 1100 millions of gallons [99], which promoted the proteineous meal production. Soybean meal is traditionally used as a filler in animal feed including poultry, swine, beef, dairy, pet and other animals due to its concentrated protein content (Table 1).

Other examples of plant-based feedstock potentially suitable for oil extraction and biodiesel production can be listed as canola and linseed [100], palm [101], karanja [102] and jatropha [103]. Jatropha is a non-edible seed from a large shrub commonly found throughout most of the tropical and subtropical regions of the world. As shown previously in section 2.1, jatropha is projected to have a 3.2 % contribution in biodiesel production by 2020. The growing utilization of plant-based feedstocks other than soybean meal in biodiesel production also brings new streams of proteineous meal as coproducts.

Iodine value

The iodine value of the feedstocks used in this study, which is a measure of unsaturation degree, was in the range of 70-78 mg I2/100 g. According to JUS EN 14214 [JUS EN 14214:2004], MEs used as diesel fuel must have an iodine value less than 120 g I2 per 100 g of sample. Methyl esters obtained in this study had iodine value in the range 72-80g I2/100 g and this finding is in accordance to the fatty acid composition, i. e. the calculated total unsa­turation degree of MEs (see Table 4). Iodine value depends on the feedstock origin and greatly influences fuel oxidation tendency. Consequently, in order to avoid oxidation.

1.5.2. Saponification value

The saponification value represents milligrams of potassium hydroxide required to saponify one gram of fat or oil. The obtained results indicated that in general, esters had higher sapo­nification values than the corresponding oils. Saponification values of the feedstocks and products analyzed here, ranged from 199 to 207 mg KOH/g oil. However, knowing that a triglyceride has 3 fatty acid chains associated and each triglyceride will give 3 methyl esters, stoichiometrically it may be expected that the same amount of fatty acid carbon chain in neat feedstock oil and the biodiesel will react with the same amount of KOH giving the soaps, i. e. their saponification values will be the same. But, could this assumption be also applied on the waste frying oils knowing that their properties differ significantly from the neat oils as a consequence of cyclization, polymerization and degradation of fatty acids.

Polymeric blends and composites from lignin Lignin in thermoplastics

In polymers, lignins have been used as low-cost fillers aiming to retain their mechanical properties. Nitz et al. [164] reported the influence of various types of lignin reinforcement with the thermoplastics on their mechanical properties. Their results indicate that they are able to incorporate ~40 wt% lignin in to polyamide 11 (PA11), polyester (Ecoflex®) and polyestera — mide (BAK®) systems without impairing their mechanical properties [164]. Generally lignin shows high cross-linking/intramolecular interactions, which limits their application in solid material systems. This can be overcome through polymer blending; however, achieving miscibility is very essential to develop a material system with superior properties [165]. This is possible in lignin-based blends by manipulating the chemistry of hydrogen bonding between the OH groups and interacting sites of polymers, either polar or semi polar [165]. Moreover, the hydrogen bond with a polymer varies with lignin to lignin since the monomer combinations of the lignins are unique [166].

Lignin-thermoplastic blends can be classified into two categories and they are (i) lignin — petro — based polymer blends and (ii) lignin-renewable resources based polymer blends. Blending the lignin with polyethylene and polypropylene is well known [166169]. Alexy et al. [166] reported the effect of lignin concentration in the fabrication of polymeric blend with PP and PE. They measured the tensile strength as the measure of mechanical properties over the various lignin compositions. For both the polymer systems they identified that the mechanical properties decrease with increasing lignin content [166]. In addition to mechanical properties, Canetti et al. [169] and Mikulasova et al. [170] reported the fabrication of lignin/PP blends and investigated their thermal and biodegradable properties respectively. Poly(vinyl chloride) (PVC) is the next popular thermoplastic, which has been produced globally and exhibits a wide range of applications [171]. Raghi and coworkers [171] reported the fabrication of lignin/PVC blend and studied their mechanical/weathering properties. Their research investigation confirmed that the addition of lignin to PVC enhanced their tensile strength and not influenced their weathering behavior. Banu et al. [172] reported the fabrication of PVC/lignin blends and investigated the effect of plasticizer in their formulations. They concluded that the specific thermal and mechanical properties are feasible in some formulations with the addition of plasticizer. In addition to that, lignin/ poly(vinyl alcohol) (PVA) and lignin/ poly(ethylene oxide) (PEO) blend systems with various types of lignins are also investigated for the effective electrospinning performance [173176]. Sahoo et al., [92] reported the fabrication of polybuty­lene succinate (PBS) reinforced with renewable resource-based lignin employing a melt extrusion process. They found that lignin reinforcement in PBS enhances their properties synergistically and also achieved the incorporation of high fraction of lignin of about 65%. In addition to that, they also reported the fabrication of PBS-based composite materials with the hybrid reinforcement of lignin and other natural fibre [93]. They found that the hybrid reinforcement is more beneficial over individual reinforcement for the better flexural strength.

The research on lignin-based polymer blends with renewable resource-based biopolymer is very limited. Only few publications are available in this content. Camargo et al. [177] reported the melt processing of poly(3-hydroxybutyrate-co-hydroxyvalerate) (PHBV) with lignin, in which they used the lignin isolated from sugarcane bagasse. They found that the addition of lignin to PHBV caused a reduction in their mechanical properties, which is due to the zero integration of lignin and PHBV [177]. Mousavioun et al. [178] performed the processing of poly(hydroxybutyrate) (PHB)-soda lignin blend and studied its thermal behavior. They found that the addition of soda lignin formed the miscible blend and improved their overall thermal stability. However, they have not reported their mechanical properties [178]. Vengal et al. [179] investigated the blending effect of lignin with starch and gelatin for the fabrication of biode­gradable polymeric films. They found that the addition of lignin into starch can create better film with the composition of 90:10 (lignin: starch) and further increment of lignin content decreases their properties. Casetta et al. [180] fabricated the PLA and lignin blend and investigated their flame retardant behavior. They observed that the addition of lignin to PLA enhanced their flame retardant property comported to virgin PLA.


The analysis of thermo-chemical conversion of OPEFB suggests that gasification is the most suitable thermo-chemical route for OPEFB conversion to biofuels. It has the highest carbon conversion (>90%) and biofuel yield. Due to the high viscosity and high water content of py­rolysis products, application of bio-oil as a biofuel is still very challenging. Compared to other oil palm residues, such as oil palm kernel, due to its high water content, OPEFB may not be a good candidate for solid fuels even after torrefaction pretreatment.

Qualitative analysis of glycerol

The Borax/phth test is special test for detection on the compound contain two neighboring hydroxyl group as in glycerol organic compound as the following:

1 ml glycerol layer mix with 1 ml of Borax/phth (red color) if the red color disappear in cold and appearing after heating (direct) this positive control. Fourier transforms infrared spectroscopy (FTIR) analysis

FTIR analysis was performed using instrument, Perkin Elmer, model spectrum one, for de­tection of transesterification efficiency of oil by determination of the active groups produced from these process.

The results obtained by Shalaby and Nour (2012) found that, two step transterification of oil led to 100 % disappearance of hydroxyl group but this was less than 100 % in case of one step transterification as shown in Figure (4).

1.4. Bioethanol

Crude glycerol

Biodiesel is chemically known as methyl esters, which is produced through transestrification reaction by reacting a vegetable oil or animal fat with an alcohol under a strong base catalysis environment [104]. Along with biodiesel, such transestrification reaction produces significant


quantity of glycerol (also called as glycerin), which is normally collected with other ingredients such as catalysis, water and unreacted alcohol and it is termed as crude glycerol [105]. Normally biodiesel industries utilize excess amount of methanol as required for the completion of reaction, which leaves unreacted methanol to the glycerol after the reaction. With every 3 gallons of biodiesel, 1kg of crude glycerol is produced and it shows very low value because of its impurity [106]. As the global biodiesel production increases exponentially, the resulting crude glycerol is extensively high and become issues due to their disposal or effective utiliza­tion. On the other hand, pure glycerol has found a wide range of applications that includes food, cosmetics, and drugs. In order to upgrade the crude glycerol to those high end applica­tions, it should undergo various purification stages such as bleaching, deodoring, and ion exchange. Normally, this is not affordable nor economically feasible for most of the small/


Figure 7. World protein meal consumption(milliontonnes)in2011(drawnfromdata reportedin[97]).

medium ranged industries. Hence, it is necessary toinvestigatethevalue-addedusesofcrude glycerol in various applications.

Prior to that, it is necessary to understandldierelationship between time oilfeedstosk end tha eouife glycerol. Thompson and He [105] performed a research on the characterization of crude glycerol samples from various feedstocks. Theirresearchsho ws that the compositions of different crude glycerol are highly varying wirh rheir feedstocks. Shieereates thechallenge le ados>tauniver — sal protocol to fabricate value-added arodunCffsom oruaeglyrerolfrom vae-Ges Seedstacke. Crude glycerol has been ueed to produce varioui prnduots mcludingl-3/l, a-propenediol, dihydroxyacetones, polyestenr andOydrogen [і.7]. Mu el: aS. —i(rn] repoeted tha r^jmSCtef:^гз1Гl, iCn propanediol using crude glyeerel produced during biodfeselptepapationrheough fermenta­tion process using Klebsiell apneumoma. Theyusedtirecruda gtyoero1 nbtained °uring soybean oil-based biodiesel producttongmolooingalkalicatolysis. Tgeyulfimatelycompepedtheproduct of 1,3-propanediol obtainedbrometirefdyt-erolanafoundthaeiheyarecimiSar toaachnthor]aeaC. Soares et al. [109] demonstr afeg thegenerationofseerthenii gaeorsgngar (hydrooen andcasdng monoxide) from glycerol at vaoy low temperatuiebeeween225-300 °С emploningaPd-nared catalyst. Further it can be converted into nuelrOchemicalcbyPisohae-Trons tli mathano! son-he. sis. They also suggest this paneess fos ahe effettive utilizationotvarloue cmaegiyrerca Ceed — stocks for the fabrication of high vatue fuefe/chemfealr. Mothec e — ai.[r dOt repocendl the synlherlc of poly (3-hydroxybutyrate) ^HB. uaingcrudegiycesol (ropeseldoil-barodiar She feedstockvia biotechnological process empioyind Peracoscue demlrillcanr anl Cupriaoldusnecatoemi — crobes. They compared the propertiecof hre eyntiraeized йгогпРігоіИіїєгєп1 feedetocke add

found that the properties areviryalmi lnr:ZhoueCeLiniO(rev-ewedtheehemn-peleetiveox idslion of crude glycerol into various prodncts suchacgleoeric add, Sydroaypyenvio асЮ grid meeoox, alic acid which can be used a sprecurrnrforvariourfmerhemicalrandpoh^iericmaterialr. Theso reports indicate the emergm. oppostumtierfor erude glnceroeforoaciousapnUcahonomclud — ing chemical, fuel and mate rials.