Biomass and Bioenergy 27 (2004) 265–275

Bio oil from pyrolysis of cashew nut shell-characterisation andrelated properties

Piyali Dasa, T. Sreelathab, Anuradda Ganesha;∗

aEnergy Systems Engineering, Indian Institute of Technology, Mumbai-400076, IndiabDepartment of Chemistry, Indian Institute of Chemical Technology, UPPAL Road, Hyderabad, 500 007, India

Received 7 February 2003; received in revised form 4 December 2003; accepted 15 December 2003

Abstract

Biomass in the form of cashew nut shell represents a renewable and abundant source of energy in India. Cashew nut shell(CNS) was pyrolysed in a 1xed bed pyrolysis reactor under vacuum. The CNS on heating upto 175◦C produced dark brownoil (oil CO1), which was extracted, and the CNS, after the removal of oil CO1, was pyrolysed under vacuum. The pyrolysisvapours were condensed to get a combustible oil fraction (oil CO2) as well as a noncombustible aqueous fraction. Thedetailed chemical compositional analysis of both the oils as well as aqueous fractions were carried out by various techniqueslike liquid column chromatography 1HNMR, 13CNMR, FTIR, GC-MS. The CNS oils (CO1 and CO2) were found to bea renewable natural resource of unsaturated phenols with long linear chains and marked absence of anacardic acid. Unlikeother bio oils, the CNS oils have been found to be fairly stable. The oils were completely miscible in diesel and were foundto have low corrosivity towards Copper and Stainless steel, and thus promise to be a potential fuel.? 2004 Elsevier Ltd. All rights reserved.

Keywords: Pyrolysis oil; Characterisation; Stability; Composition; Anacardium occidentale

1. Introduction

India is the largest producer, processor, and ex-porter of cashews (Anacardium occidentale Linn.)in the world. Cashew cultivation now covers a totalarea of 700 kha of land, producing over 400 kt of rawcashew nuts [1]. The cashew tree is cultivated glob-ally in tropical areas like in East Africa, South andCentral America, and Far East. The hard cashewnut shell has a honeycomb structure, which containsCashew nut shell liquid, commercially known asCNSL. The CNSL is reported to be 15–20% by weight

∗ Corresponding author. Tel.: +91-22-576-7886; fax: +91-22-572-6875.

E-mail address: aganesh@me.iitb.ac.in (A. Ganesh).

of the unshelled nut in Africa, 25–30% by weight inIndia and 25% overall [2]. About 30–35% CNSL ispresent in the shell where the shells amount to ap-proximately 67% of the nut. CNSL is obtained as abyproduct of cashew processing industries. The worldavailability of CNSL is in the region of 50 kt per year.Commercially, CNSL is extracted by various meth-

ods [3] like drum roasting of nuts and collecting ex-pelled liquids, extraction with hot CNSL without char-ring the kernels, superheated steam treatment method,solvent extraction method, etc. The traditional methodof removing CNSL in East Africa involves roastingthe nut in drums or baths. The roasting process notonly removes the corrosive CNSL but also makesthe shell brittle, thereby aiding the cracking process.This method results in the loss of most of CNSL.

0961-9534/$ - see front matter ? 2004 Elsevier Ltd. All rights reserved.doi:10.1016/j.biombioe.2003.12.001

266 P. Das et al. / Biomass and Bioenergy 27 (2004) 265–275

To extract the retained CNSL the nuts are roasted inbaths at a temperature of 180–185◦C. Vents in theequipment dispel the unpleasant fumes. This methodrecovers 85–90% of the liquid [4]. Method of ex-tracting CNSL in India involves roasting the nuts ina shallow pan over open charcoal 1res. Constant ag-itation is required to prevent the nuts from becomingscorched. This method is extremely unpleasant as theshells burst releasing CNSL and fumes with resultinglosses [5]. An improved method involves roasting thenuts in perforated cylinders inclined at an angle abovea heat source. As the nuts fall downward the shell liq-uid Gows through the holes and is collected in troughs.In an Italian patent [6], the shells are scraped in arotary apparatus with sand and steel wool, heated at100–300◦C for 1 h and then roasted at 400–700◦C inan inert atmosphere, when the oil again oozes out. Ina Swiss patent [6], the cashew nuts are roughened in arotary drum coated with an abrasive material. They arethen treated with moisture, heated in an infrared ovenand 1nally passed through a high-frequency electric1eld when the liquid Gows out.Gedam et al. has reported that JeJeries, W. M. and

Peirce Leslie and Co. Ltd. [6] were the 1rst to in-troduce hot oil process for the extraction of CNSL,in which a single layer of whole nuts is passed fora few minutes through CNSL heated at 187–194◦C.In this process about 50% of the total CNSL is ex-tracted from the shell. This method has been furtherimproved, wherein the dry nuts are 1rst subjected tosurface wetting and then passed through the hot oil[6]. The excess moisture content of about 7–10% ofthe weight of the nuts causes the cells to burst, result-ing in the oil oozing into the bath. In the hot oil pro-cess of Sociedade Imperial De Caju E Oleos LDA [6],the nuts are wetted by dipping in water followed bysteam pretreatment to open up the pores of the shells.Then they are dipped in hot CNSL at 170–185◦Cfor a predetermined period. Several other hot oil pro-cesses are also employed for the extraction of CNSfrom the whole nuts [6,7]. Hot oil bath method appearsto be another common method of commercial extrac-tion of CNSL in Quilon and other areas of Kerala, anIndian state. In this method the nuts are conditioned bytreatment with water for 24 h before extraction. Thenthey travel a single submerged layer over a belt, situ-ated in a tank containing CNSL maintained at 180◦C.The conveyer belt is guided by two sprocket wheels,

and has rods on its outer surface. A false bottom isprovided a little above the bottom of the tank, fromwhich they are discharged. Other extraction processeshave also been reported. Oil from CNS was extractedby solid–liquid and spray-type process. The extractiontemperatures (30◦C, 35◦C and 40◦C) and the ratiosof CNS to hexane (1:8, 1:10, and 1:12) were the fac-tor of study. Initially CNS was partially dried in theoven to remove some moisture by reducing 4–10% ofits weight. From the experimental results it was foundthat CNS:hexane ratio of 1:8 provided maximum oilduring the beginning of extraction.The percentage yield of CNSL varies with the

extraction process. Indian native method of roastingnuts and collecting the expelled liquid is reported toyield about 50% of total oil content. Extraction withhot CNSL without charring the kernels gives about85–90% of total CNSL in India. Superheated steamtreatment and collection of condensate method im-proves the yield by further 2%.The actual composition of CNSL may vary with

the origin of the shells, their climatic conditions andmostly with the process of extraction, and in facta wide variation is reported in the composition ofCNSL. Cold solvent extracted CNSL indicate 90%of anacardic acid and nearly 10% cardol (a dihydricphenol). In addition to anacardic acid and cardol,natural CNSL contains small amount of other ma-terials, mostly 2-methyl cardol. It has been foundthat the substituent chain present in anacardic acid,cardanol and cardol is not homogeneous but consistsof mono-ole1nic, di-ole1nic and tri-ole1nic unsatura-tion. CNSL with a composition of 71.7% anacardicacid, cardol (18.7%), cardanol (4.7%), novel phenol(2.7%) and two uncommon ingredients (2.2%) hasalso been reported [8].Notes on various grades (natural grade and tech-

nical grade) and respective composition of CNSL [2]have been reported. Natural, i.e. cold, solvent ex-tracted CNSL, contains approximately 70% anacardicacid, 18% cardol, and 5% cardanol with the remainderbeing made of other phenols and less polar substances.In Technical, i.e. heat-extracted CNSL, the heatingprocess leads to decarboxylation of the anacardic acidto form cardanol. Typically, the composition of Tech-nical CNSL is approximately 52% cardanol, 10% car-dol, and 30% polymeric material, with the reminderbeing made up of other substances. The Technical

P. Das et al. / Biomass and Bioenergy 27 (2004) 265–275 267

CNSL is often further processed by distillation at re-duced pressure to remove the polymeric material. Thecomposition of the distilled Technical CNSL is about78% cardanol, 8% cardol, and 2% polymeric materialand the remaining other substances.Thus it is seen that commercial extraction process,

which gives higher oil yield is dominated by anacardicacid, which is highly corrosive and poisonous. Hence,decarboxylation of CNSL is carried out by boiling orheating CNSL upto 180◦C for several hours to getcardanol-rich oil.In the present study, CNS having a moisture con-

tent of about 10% was taken for the study. On simpleheating, at 100–175◦C the CNS produced dark brownoil. After collection of this oil the CNS was furtherpyrolysed at 500◦C under vacuum (720 mmHg). Thedetail of pyrolysis process and the physico-chemicalproperties of CNS oils has been discussed elsewhere[1]. The pyrolysis oil (oil CO2) has been found tohave a very high calori1c value (40 MJ=kg) almostcomparable to diesel fuel. Both the oils CO1 and oilCO2 have complete miscibility with diesel fuel. Un-derstanding of the physico-chemical nature of the oils,need proper chemical characterisation of the oils. Withthis perspective, a detailed chemical characterisationhas been carried out in the present study. The stabilitycharacteristics along with the miscibility characteris-tics of the oils with diesel oil have been reported inthe present paper. The corrosivity of both the oils hasalso been studied.

2. Characterisation of CNS oils and pyrolysisaqueous fraction (PAF)-techniques and methods

The detailed physicochemical characterisation ofCNS oils (oil CO1 and oil CO2) and PAF have beenmade, the process of which, has been detailed in thefollowing subsections.

2.1. Chemical characterisation of CNS oil andpyrolysis aqueous fraction

The stepwise procedure used for chemical charac-terisation of CNS oils and PAF has been presentedin the following schematic diagram (Fig. 1) and theprocess in detail is discussed in the later section.

Each of the oils CO1 and CO2 was separated by liq-uid column chromatographic technique and tested byTLC plates (thin layer chromatographic plates) spot-ting and the resulting fractions were analysed by dif-ferent analytical techniques discussed in Section 2.1.2.The aqueous fraction was extracted with diethyl

ether (1:1 v/v) [9]. The ether soluble fraction, termedas COEt1, was evaporated and was analysed by FTIRand GC/MS techniques. The diethyl ether insolublefraction, COEt2, was also evaporated to dryness andthe residue was analysed by FTIR as well as byGC/MS.

2.1.1. Fractionation of oilFor oil CO1: One gram of oil was adsorbed on 2 g

of silica gel and then transferred to a glass columnof 450 mm long × 25 mm ID packed with 60-120mesh size silica gel in hexane. The column was elutedsequentially with solvent hexane–ethyl acetate mix-ture in diJerent proportions as well as chloroform–methanol mixtures as follows. The fractions 27-95,(volume 15 ml each) eluted sequentially with 85%hexane, 15% ethyl acetate to 50% hexane and 50%ethyl acetate was combined, evaporated to dryness,and weighed to get 807:7 mg of pure compound (aschecked by spotting on TLC plates) by CO1-I. Thefractions 109-155, eluted with 10% hexane and 90%ethyl acetate, and 1nally eluted with 90% chloroformand 10% methanol was combined, dried and weighedto give 91:8 mg of pure compound CO1-II.For oil CO2: Similarly, 1 g of oil CO2 were ad-

sorbed on 2 g of silica gel and transferred onto theprewashed and activated silica gel (60-120 mesh)packed in 450 mm long × 25 mm ID glass column.The column was eluted sequentially with varioussolvents as follows. The fractions 20-36 eluted with95% hexane and 5% ethyl acetate were combined andyielded 320 mg of pure compound COPyr1. The frac-tions 99-112 eluted with 80% hexane and 20% ethylacetate yielded 220 mg of pure compound COPyr2.The fractions 113-129 eluted with 75% hexane and25% ethyl acetate yielded 127:5 mg of compoundCOPyr3. The polar fractions of pyrolysis oil, whichcould not be separated by column chromatographyusing hexane–ethyl acetate mixture, were rechro-matographed, the column being packed by silica gelof 70-325 mesh size and eluted with chloroform–methanol mixtures. Here the subfractions 33-37 eluted

268 P. Das et al. / Biomass and Bioenergy 27 (2004) 265–275

pyrolysis

Liquid columnchromatographic separation

CNS for pyrolysis

100 –1750C Oil CO1

Combustible oil fraction Oil CO2

Non-combustible aqueous fraction

Liquid columnchromatographic separation

CO1-I CO1-II

COPyr4 COPyr5

CNS

Ether solubles Ether insolubles

COEt1 COEt2

Ether extraction Diethyl ether (1:1)

COPyr1 COPyr2 COPyr3

Fig. 1. Schematic diagram of chemical characterisation of CNS oils and PAF.

with 95% chloroform and 5% methanol were com-bined and yielded 80 mg of pure compound COPyr4.The subfractions 41-43 eluted with 90% chloroformand 10% methanol were combined to get 95 mg ofcompound COPyr5. The most polar fraction of theoil could not be separated by liquid chromatography,and requires to be separated by HPLC, which has notbeen done in the present study.All the fractions separated was distilled, weighed

and sent for further analysis.

2.1.2. Chemical analysesThe CNS oils, PAF and fractions separated, were

analysed by Fourier Transform Infra-Red spectro-scopic (FTIR) technique. Figs. 2 and 3 show the FTIRspectra representing the functional group composi-tional analysis of oil CO1 and oil CO2, respectively.FTIR spectra was recorded using a Nicolet Magna550 series FTIR with an online plotter to produce theIR spectra of the derived oil. The compounds sepa-rated as above were analysed by FTIR and GC/MS

Fig. 2. FTIR spectrum of oil CO1.

and their structures were elucidated by 1HNMR,13CNMR. The 1HNMR and 13CNMR spectra wereobtained at frequency of 300 MHz using a Varian

P. Das et al. / Biomass and Bioenergy 27 (2004) 265–275 269

Fig. 3. FTIR spectrum of oil CO2.

VXR 300S instrument. The samples were dissolvedin chloroform-d. The most probable structure of eachof the compounds was interpreted with the help ofchemical shift (�) value with respect to intensity.The sample procedure for spectrometric elucidationof one of the compounds (COPyr4) has been shownin detail in Fig. 4. The GC/MS analysis was doneusing a Hewlett Packard 5890A GC/MS system witha 30 m × 0:25 mm ID-capillary column coated withpolysiloxane. The initial oven temperature of GC was40◦C for 2 min and then programmed to increaseat a rate of 5◦C=min to 270◦C. Helium was usedas the carrier gas with a Gow rate of 0:7 ml=min.The m=z (ratio of mass to charge) values, whichrepresent the most probable fragments of the com-pounds elucidated, have been presented for eachcompound.

2.2. Stability, miscibility and corrosioncharacteristics of oil fractions

The stability characteristics of oil CO1 and oilCO2 were studied in terms of variation of viscos-ity over time. They have been compared with thatof sugarcane bagasse oil obtained under identicalpyrolysis conditions. Viscosity measurements weredone over a period of time under two diJerent stor-age conditions, one stored at room temperature andthe other stored at 60◦C, for each of the oil sam-ples. The kinematic viscosity was measured with

Fig. 4. 1H NMR and 13C NMR spectra of compound COPyr4.

Cannon-Fenske viscometers according to the standardprocedure (ASTM D-445-88).In order to identify how the CNS oils can be used

within petroleum-based infrastructure, the miscibilityof CNS oils were investigated with diesel. Oil CO1and CO2 were mixed with diesel in diJerent ratioand the physical properties viz. pH and viscosity weremeasured for each of the mixtures.Corrosion test on copper (Cu) and stainless steel

(S.S.) was performed with CNS oils. Polished Cu andS.S. (grade 316) strip were immersed in a given quan-tity of oil sample kept at 50◦C and the weight losscharateristics of the strips were tested with time. Eachof the strips was removed at 24-h interval, washed andweighed. The corrosiveness was expressed in termsof mil per year (mpy) verses time. Corrosion test wasalso performed with oil stored at room temperatureover a year and the weight loss of the material im-mersed was measured in mpy.

270 P. Das et al. / Biomass and Bioenergy 27 (2004) 265–275

3. Results and discussion

3.1. Oil functional group composition

Table 1 represents the comparative details of func-tional group compositional analysis for the CNSoils, obtained from the Fourier Transform Infra-Red(FTIR) spectra. The presence of water impurities andother polymeric O–H in the oil are indicated by thebroad absorbance peak of O–H stretching vibrationbetween 3600 and 3050 cm−1. The presence of alka-nes is indicated by the strong absorbance peak ofC–H vibrations between 3000 and 2800 cm−1 andthe C–H and deformation vibrations between 1475and 1350 cm−1. The absorbance peak at 1714 cm−1

represent the CKO stretching vibration indicatingthe presence of ketones, aldehydes. The presenceof both O–H and CKO stretching vibrations alsoindicate the presence of carboxylic acids and theirderivatives esters. The possible presence of alkenesis indicated by the absorbance peaks between 1650and 1580 cm−1. The peaks between 1300 and 950 aredue to the presence of primary, secondary and tertiaryalcohols, phenols, ethers and esters showing the C–O stretching and O–H deformation vibration. Ab-sorbance peaks between 900 and 650 cm−1 indicatethe possible presence of single, polycyclic and substi-tuted aromatic groups. The presence of aromatic ring(900 and 650 cm−1) and CKO stretching as well asC–O stretch indicate the presence of aromatic esters.It is interesting to note that oil on comparison to oilCO2, oil CO1 is not having absorbance peaks between1780 and 1640 cm−1 of CKO stretching vibrations,indicating the absence of acid or esters group.

3.2. Chemical composition of oil CO1 and oil CO2

The analytical details along with the most probablestructures of the compounds separated from oil CO1and oil CO2 have been presented in Tables 2 and 3, re-spectively. The oils are composed of long chain com-pounds (C6–C15). Each of the compounds has a uniquehead and tail like structure with the phenolic groupbeing at the head and long linear chain forming thetail. The long chain diesel like structure attributes tohigh C/H ratio as reGected by very high heating value,comparable to fuel oil and diesel, as well as indicatesthe high miscibility with diesel fuel as per like dis-

solves like principle (con1rmed and reported in Sec-tion 3.5). It is also interesting to note that unlike com-mercial cold processed CNSL, which is dominated bypoisonous and corrosive anacardic acid, the CNS oilsin the present study are free of anacardic acid. Thisis attributed to decarboxylation of anacardic acid un-der the present reaction conditions. On the other hand,presence of strongly polar phenol group induces an-tioxidant characteristics thereby contributing to highstability.

3.3. Composition of pyrolysis aqueous fraction

The compositional analysis of the aqueous fractionas shown in Table 4 is seen to be mainly composedof phenols, ketones and acids.

3.4. Stability characteristics of bio oil (viscosityvariation)

The change of viscosity of CNS oils at diJerentstorage conditions are presented in Figs. 5 and 6. Thechange in the viscosity of sugarcane bagasse pyrolysisoil, produced under same pyrolysis conditions as forCNS, has also been presented (Fig. 5) for comparisonof nature of viscosity variation between the two kinds.It will be appropriate to mention here that the higherinitial viscosity of CNS oils compared to bagasse oilis attributed to CNS oils having less moisture content(3–4 wt%) compared to bagasse oil (11–12%). It isvery interesting to note that oil CO1 and oil CO2 whenstored at room temperature show almost no change inviscosity with time hence proving that both the oilsare very stable at room temperature (unlike bagassepyrolysis oil). However, storing the CNS oils at 60◦Cresults in an increase of viscosity, the rate being higherin case of oil CO2 than oil CO1. In the presence ofinhibitor hydroquinone, added in a concentration of0:1 wt% of oil, the rate of increase of viscosity of oilCO2 has been found to reduce as shown in Fig. 5. Thisis due to the suppression of thermal polymerisation ofunsaturation present in the CNS oils, by the inhibitor.

3.5. Miscibility study of bio oil with diesel

The oils CO1 and CO2 have been found completelymiscible in diesel as reported earlier [1]. This be-haviour is unlike any other pyrolysis oil. The oils have

P. Das et al. / Biomass and Bioenergy 27 (2004) 265–275 271

Table 1FTIR functional group composition of CNS pyrolysis oil

Frequency Frequency (cm−1) Group Class of compoundrange (cm−1)

Oil CO1 Oil CO2

3300–3600 3352 3379 O–H stretching Polymeric O–H, water impurities3050–2800 3022,2936,2857 3015,2936,2857 C–H stretching Alkanes1750–1650 — 1714 CKO stretching Ketones, aldehydes, Carboxylic acids1650–1580 1602 1608 CKC stretching Alkenes1550–1490 — — –NO2 stretching Nitrogenous compound1470–1350 1463, 1372 1463,1371 C–H bending Alkanes1300–950 1278,1153,1015 1172,1102,1020 C–O stretching Primary, secondary and tertiary alcohol915–650 915, 785,697 915,783,703 O–H bending Phenol, esters, ethers Aromatic compounds

Table 2Composition of oil CO1

Fraction Analytical technique used Analysis details Name and most probable structure

CO1-I FTIR, 1HNMR, 13CNMR IR (KBr) �(cm−1): 3363, 2930,2849, 1601, 1454, 1265, 1153,695; 1HNMR(CDCL3; 300 MHz)�:0.9(t, 3.2H, CH3), 1.35 (16.2 H,CH2), 1.55(11H, Ar–C–CH2), 2.0(2.3 H, CH2–CK), 2.55(t, 2 H,CH2–Ar), 2.8 (2.4 H, KC–C–CH2–CK), 5(4.3H, CHK), 5.4(1H, Ar–OH), 6.7–7.2 (4 H, HAr);13CNMR(CDCL3; 300 MHz)�:11.036, 14.126, 29.1,11–35, 38,112.573, 115.400, 120.958, 128.246,129.430, 130.045, 131.028, 144.98,155.599

Cardanol:

OH

CO1-II FTIR, 1HNMR, 13CNMR IR (KBr) �(cm−1): 3345, 2931,2850, 1610, 1452, 1261, 1022,807; 1HNMR(CDCL3; 300 MHz)�:0.9 (2.5H, CH3), 1.3 (20.5H, –CH2), 2.0 (3.5 H, CH2–CK), 2.5(2.3H, CH2–Ar), 5.35 (1.9H, Ar–OH), 5 (1.8H HCKCH), 6.2(2.3H, Ar–H), 6.6–6.7 (1.3H, HAr);13CNMR(CDCL3; 300 MHz)�:14.183, 22.767, 24.554, 25.650,27.295, 29.782, 31.332, 32.013,35.899, 114.775, 126.905–130.469,144.915, 155.664.

Cardol:

OH

HO

been mixed with diesel in diJerent ratio and the phys-ical properties like pH and viscosity of each mixturehas been reported in Table 5. From the results it isseen that the oils can be upgraded in terms of increaseof pH and decrease of viscosity on mixing with dieselas required.

3.6. Corrosivity of oil CO1 and oil CO2

Oil CO2 stored at room temperature over 1 yearperiod shows a weight loss for Cu and S.S. strip ofabout 0.73% (0:232 mpy) and 0.046% (0:021 mpy),respectively. Fig. 7 shows the weight loss of Cu strip in

272P.Dasetal./B

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Table 3Composition of oil CO2

Fraction Analytical technique used Analysis details Name and most probable structure

COPyr1 FTIR, 1HNMR, 13CNMR IR (KBr) �(cm−1): 3363, 2930, 2849, 1601, 1454, 1265,1153, 695; 1HNMR(CDCL3; 300 MHz)�: 0.9 (3.2H, CH3),1.35 (16.2H, CH2), 1.55 (11H, Ar–C–CH2), 2.0(2.3 H, CH2–CK), 2.55(2 H, CH2–Ar), 2.8 (2.4 H,KC–C–CH2–CK),5 (4.3H, CHK), 5.4 (1H, Ar–OH), 6.7–7.2 (4 H, HAr);13CNMR(CDCL3; 300 MHz)�: 11.036, 14.126, 29.1, 11–35,38, 112.573, 115.400, 120.958, 128.246, 129.430, 130.045,131.028, 144.98, 155.599

Cardanol:

OH

COPyr2 FTIR, 1HNMR, 13CNMR IR (KBr) �(cm−1): 3363, 2930, 2849, 1601, 1454, 1265,1153, 695; 1HNMR(CDCL3; 300 MHz)�: 0.9 (5.8H, CH3), 1.3(11.8H, CH2), 4.2 (3.47H, CH2–O–CKO), 7.4–7.8 (3.64 H,HAr); 13CNMR(CDCL3; 300 MHz)�: 11.045, 14.203, 19.819,22.7, 23.071, 23.837, 24.565, 27.983, 29.793, 32.04, 32.846,37.488, 38.82, 68.243, 128.891, 130.979

Di-n-octyl phthalate:

C

O

O (CH2) 7

(CH2) 7O

O

C

CH3

CH3

COPyr3 FTIR, GC-MS IR (KBr) �(cm−1): 2956, 2930, 2859, 1729, 1459,1265, 1067,802

Bis (2-ethylhexyl) phthalate:

The strong characteristic peak of phthalic ester of mass 149is present (base peak). Further cleavage of the molecular ionleads to lower fragments, the m=z of each of which, has beenpresented along with their probable fragments.

OO

O

O

m=z: 390[M+:], 57[CH3–CH2–CH2–CH+2 ],

113:

C2H5

|CH3 – (CH2)3 – CH – CH2+

;

P.Dasetal./B

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273

132: (C8H6O2+ , loss of two –OR groups),

149:

O

C

OH

O

C

+

::

,

167:

C

O

OH

O

C

..

OH

+

,261: (M+:-29, loss of C2H5 group),

279:

C

O

OH

O

C

..

OR

:

+

COPyr4 FTIR, 1HNMR, 13CNMR IR (KBr) �(cm−1): 2963, 2921, 2862, 1740, 1463, 1270,1073, 805; 1HNMR(CDCl3; 300 MHz)�: 0.9–.96 and 1.22–1.46 (38.7H, CH3, –CH2), 4.3 (4.2 H, Ar–C–CO–O–CH2), 7.5–7.7 (4.6 H, Ar–H); 13CNMR(CDCL3; 300 MHz)�:11.034, 14.126, 23.060, 23.816, 28.997, 29.772, 30.434,38.801, 68.270, 76.675, 77.100, 77.516, 128.890, 130.979,132.511, 167.898

Di-n-decyl phthalate:

OO

O

O

COPyr5 FTIR, 1HNMR, 13CNMR IR (KBr) �(cm−1): 3348, 2931, 2851, 1612, 1452, 1260,1024, 811; 1HNMR(CDCL3; 300 MHz)�: 0.9 (3.3H, CH3),1.3 (20.2H, –CH2), 2.0 (3.5 H, CH2–CK), 2.5 (2.23H, CH2–Ar), 5.35 (1.5H, Ar–OH), 5 (1.5H HCKCH), 6.2 (2.23H,Ar–H), 6.6–6.7 (1.08H, HAr); 13CNMR(CDCL3; 300 MHz)�:14.212, 22.768, 24.943, 25.671, 27.316, 29.793, 31.822,31.164, 32.024, 35.947, 100.292, 114.8, 126.925–130.498,46.107, 155.599

Cardol:

OH

HO

274 P. Das et al. / Biomass and Bioenergy 27 (2004) 265–275

Table 4Composition of pyrolysis aqueous fractions

Fraction Analytical technique used Compounds present Remarks

COEt1 FTIR, GC-MS 2-cyclopentane-1-one, 1, 2-cyclopentanedione,3-ethyl-2-hyd- 1,2,4-cyclopentanetrione, 3 methyl-cyclohexanone, butanoic acid, 1, 4:3, 6-dihydro-alpha-d-glucopyranose

Mainly composed of ketones and acids

COEt2 ,, 3-methyl phenol and 2-methyl phenol Mainly composed of phenols

0

10

20

30

40

50

60

70

0 2 5 14 30 42 365

time (in days)

visc

osi

ty (

cSt)

at

60°C

Oil CO1

Oil CO2

Bagasse pyrolysis oil

Fig. 5. Viscosity variation of CNS oil and bagasse pyrolysis oilwith time (stored at room temperature).

0

10

20

30

40

50

60

70

0 1 1 2 3 5 7 14 21time (days)

visc

osi

ty(c

St)

at

60 °

C

Oil CO2 without inhibitor

Oil CO2 with inhibitor

Oil CO1 without inhibitor

Fig. 6. Viscosity variation of CNS oil with time (stored at 60◦C).

Table 5Miscibility study of oil CO1 and oil CO2 with diesel

Oil:diesel pH Viscosity in cSt (at 60◦C)

Oil CO19:1 6.3 164:1 6.7 121:1 6.9 5

Oil CO29:1 3.9 214:1 4.2 12.41:1 4.5 3.5

0

0.5

1

1.5

2

2.5

3

3.5

4

24 48 72 96 120 144 168time (hour)

mil

per

yea

r

Oil CO2Oil CO1

Fig. 7. Cu strip corrosion test results of CNS oils.

mpy versus time for oil CO1 and CO2 stored at 50◦C.The weight loss characteristics of S.S. strip kept in oilCO2 at 50◦C is shown in Fig. 8. It can be seen that therate of corrosion over period of heating time decreaseswith a maximum at the beginning for each. Though,on a comparative basis the corrosivity is higher for Cuthan the S.S. as expected, yet corrosivity for both the

P. Das et al. / Biomass and Bioenergy 27 (2004) 265–275 275

0

0.05

0.1

0.15

0.2

0.25

0.3

24 48 72 96 120 144 168

time (hour)

mil

per

yea

r

.

Oil CO2

Fig. 8. S.S. corrosion test results for oil CO2.

metals decreases with time. The above behaviour ofsuch low corrosivity despite of low pH is attributed tothe fact that the moisture contents are as low as 3–4%in CNS oils and in addition the water is completelymiscible and even over a period of 1 year there is nostrati1cation observed.

4. Conclusion

The CNS oil is comprised of oil oozed upon heat-ing CNS upto 175◦C and the oil obtained thereafteras condensates from the pyrolysis of CNS. Both theoils together amount to about 40% by weight of theshell, which is otherwise obtained by solvent extrac-tion process. Unlike the cold solvent extraction pro-cess, both the oils show the signi1cant absence ofanacardic acid. Cardanol and cardol are the major con-stituents of CNS oil at 175◦C, whereas, the CNS py-rolysis oil is a mixture of cardanol, di-n-octyl phtha-late, bis (2-ethyl hexyl) phthalate, cardol, di-n-decylphthalate. The absence of anacardic acid in cashew nutshell oil is attributed to decarboxylation of anacardicacid at pyrolysis reaction conditions.The unique characteristics of the CNS oil are the

presence of long (C-6–C-15) linear chain in the com-pounds, which is giving the excellent solubility indiesel oils [1] and light lubricating oils. The high C/H

ratio contributes to the high heating value (36 MJ=kgfor oil CO1 and 40 MJ=kg for oil CO2) equivalent tothat of fuel oil. The strongly polar phenol group, onthe other hand, induces the antioxidant characteristicsas reGected by the very little change of viscosity overtime when stored in room temperature. The oils aregetting polymerised due to the unsaturation present inthe side chains as reGected by the change in viscosityunder high-temperature storage conditions. The cor-rosivity of the oils is very mild towards copper andstainless steel. The aqueous fraction of the pyrolysisprocess can also be a good source of diJerent ketonesand acidic compounds as well as of alkyl phenols if aproper extraction process can be adopted for recoveryof these chemicals.The long linear chain indicates the higher cetane

number unlike other pyrolysis oils from diJerent agroresidues. This could qualify the CNS oils as a com-pression ignition fuels with probably slight modi1ca-tion in the injection system and ignition timing overconventional diesel engine.

References

[1] Das P, Ganesh A. Bio-oil from pyrolysis of cashew nut shell—a near fuel. Biomass and Bioenergy 2003;25(1):113–7.

[2] http://www.epa.gov/chemrtk/casntliq/c13793tp.pdf.[3] Mahanwar AP. Characterisation and Processing of CNSL,

Master of Science (Technology) Thesis, 1994, Department ofChemical Technology, University of Bombay, Bombay.

[4] Acland JD. East African crops. FAO and Longman; 1977.p. 29–32.

[5] Woodroof JG. Tree nuts, production, processing and products,vol. I. AVI Publications Co; 1967. p. 221–5.

[6] Gedam PH, Sampathkumaran PS. Cashew nut shell liquid:extraction, chemistry and applications. Progress in OrganicCoatings 1986;14:115–57.

[7] Rajapakse RA, Gunatilaake PA, Wijekoon KB. Journal ofNational Science Council Sri Lanka 1977;5:117.

[8] Hartley L. Secondary compounds within the Anacardiaceae,1998. The paper is also available electronicallyat http://www.colostate.edu/Depts/Entomology/courses/en570/papers 1998/hartley.htm.

[9] Sipila K, Kuoppala E, Fagernas L, Oasmaa A. Characterisationof biomass based Gash pyrolysis oil. Biomass and Bioenergy1998;14(2):103–13.