FENG Qingge

SHOYA Masami

SUGITA Shuichi

YAMAMICHI Hirohito

English

FENG, Qingge

1503

馮, 慶革

杉田, 修一

2627

スギタ, シュウイチ

SUGITA, Shuichi

SHOYA, masami

庄谷, 征美

ショウヤ, マサミ

YAMAMICHI, Hirohito

1505

山道, 浩仁

ヤマミチ, ヒロヒト

Hachinohe Institute of Technology Repository / 八戸工業大学学術リポジトリ

Study of Thermal Decomposition Process of Raw andHydrochloric Acid Treated Rice HuskQingge FENG*,Shuichi SuGITA**,ふ/1asanli SHoYA**and Hirohito YAMAMICHI*AbstractThe thermal decomposition process and product of raw and hydrochioric acid treated ricehusk were investigated by TG,DTA,XRD and XRF The results show that thermal decomposi―tion process of rice husk revealed three distinct stages of massioss,namely,removal of moisture,release of volatile matter and burning of combustible material  An exother■lic reaction andendotherHlic peak 、アas exhibit during the course of thermal decomposition and during theremoval of rnoisture,respectively  The properties of rice husk ash depend on the combustioncondition and the pretreated condition  Acid leaching of rice husk in dilute HCl and theappropriately combustion temperature helps in producing ash with high pure amorphous silicaand completely Ⅵrhite in color【9υ LυOr'S: Rice husk,Thernial decomposition,Process,PropertyRice husk is a Fibrous material with high silica content The major constituents of ricehusk are cellulose,lignin,and ash.  Though the actual composition is variation ttrith the varietyclimate and geographic location of grOwth,the following values rnay be considered typicali ash20%,lignin 22%,cellu10se 38%,pentOSans 18%,and Other organics 2% The ngnin,cellulose,and pentosans present in rice husk can be remOved by colltr01led combustion and rice husk ashwas obtainedl)'2).  The partially burnt rice husk ash contains carbon,and is therefore black incolor.  The fully burnt ash may be gray,purple,or、vhite,depending on the impurities presentand the burning conditions3) Earher work4)-6)indicates the nature of the thermal decomposi‐tion of acid―treated ground husk by using thermograviinetry.  But the thermal processes andthe property of rice husk ash 、ver not reported  ln view of this, the present 郡〆ork wasundertaken with the fonowing obiectiVes:(1)to study the thermal decomposition process ofraw and hydrochioric acid treated rice husk by thermogravirnetry(TG)and differential thermalanalysis(DTA),(2)the prOperty of thermal decomposition product by X―ray diffraction(XRD)and X―ray nuorescence(XRF)Received December 19, 2003・ Graduate School of Civil Engineeringホホ Department of Environmental and Civil Engineering,Hachinohe lnstitute of Technology, 88-1,ヽ/1yo,Hachinohe 031-8501一- 67 -―The Bulletin Of H I T VO1 231.  Experil■ntal sectiOnsl.l  lllaterials preparationRice husk was supphed by the Hachinohe city,Japan  The hydrochloric acid pretreatedrice husk, which is prepared by immersing rice husks in IICl aqueous solutions of differentconcentrations  The last husks ttrere washed repeatedly with water until the acid was un―detected in the filtrate and then air dried at rooin temperature1,2 Experil■ntal lnethods(1) thermal decomposition analysis was also performed On the DTA―TG experimentApproxirllately 50 1ng of sample were placed in a platinum cup for the analysisPlatinum crucibles and heat―treate 2-A1203 Were used as sample holders andreference sample,respectively  The curves、vere recorded simultaneously along、ハ/ithtemperature rise under oxygen―free conditions.  The heatiェlg rate、、アas 10°C O nlin~1,(2) the properties of thermal decomposition product were conducted by XRD and XRF,2. Results and discussiOn2.l Thermal decomposition process of raw and hydrochloric acid treated ricc huskThe sirnultaneous「rG and DTA curves for untreated and various hydrochloric acid leachedrice husk samples were shown in Figs.1-5,  The nature of the TCl curves indicated that theloss of mass occurred in three mttOr stages.One intermediate stage of inappreciable mass losswas also observed after the arst stage.  This result is in good agreement with previous、vork2)TGlmgl TG―DTA???0?????????????0010(1000 0―- 68 -―Temp(℃)Fig l TG and DTA curves for rice huskAtmosphere:oxygen freoCruciblei ptat num312跡ⅡⅣ3921%Reference:α―A1203Sttle weighti 30 44mgHcating rate:10 deg/min478ヽ 176X3060℃972℃4220℃3689℃∞Study of Thermal Decomposition Process of Raw and HydrOchloric Acid Treated Rice Husk(FENG・SUGITA・S■OYA・YA卜lmllcII)TG―DTA0,000000???????「??????????????6000Temp(℃)Fig 2 TG and DTA curves for rice husk treated wvith 0 5N HCl at 20°C fo  4 hours0??TC―DTADTA(μり010000000Temp(℃)Fig 3 TG and DTA curves for rice husk treated、vith lN HCl at 20°C for 4 hoursThe various stages of decomposition and the temperature range for each stage ttrere identinedfroln the trend of the rrc}and DTA curves  The four direrent stages are rnarked in the nguresas I,II,III,IV.  The temperature ranges were given in Table l.  The percentage and the massloss in each stage as calculated froni the T(3 curves are indicated in Table 2  Table 3 showsvarious peak temperatures in the DAT curvesThe TG curves sho、キアthat the mass loss in the nrst stage took place in the range 39-140°CThe DTA curves indicated an endother■lic peak ar und which corresponds to the maxirnum???????????????―- 69 -―Sa『,le Heint:30引聴‖eating rate:10 deg/田inAtaosttere:oxygen f「ee4061℃Ⅱ 4137ヽ Cruciblet plati「HΠReferance:`Y―A1203V 336跡3341℃069℃324X  133常3731℃Salplo woighti 30 01田gHeating ratol 10deg/hinAtnospherei oxygen free4238℃Crucible:platintmReferenco: α―A12113V  33叫3353℃90,9℃266X091X4255ヽ3768℃???The Bulletin Of H I T V01 23TG―DTADTA(μV)100,00000Temp(℃)Fig 4 TG and DTA curves for rice husk treated with lN HCl at 20°C for 24 hoursTG―DTADTA(μV)0000(l∞00000000Oll「????????????000 0????????【??，?????000Temp(℃)Fig 5 TG and DTA curves for rice husk treated with 3N HCl at 20°C for 4 hoursrate of mass loss  The mass loss ranging from 2 66 to 4.78% assoCiated in this stage may beattributed to the removal of moisture frorn the material  lt was also reported earlier that thethermal decoinposition of over dried husk、vas neghgible belo、v200°CThe second stage、,、アa  identined as a plateau in the TG curves in the range 123-228°C、vithan inappreciable mass of 0 54-1760/。,while the DTA curves do not show any peak in this stageThis may be considered as a transition stage.In the nrst and second stage the mass loss for the untreated husk was higher than that for―- 70 -一Sattle weight:30 51mg‖eating rate1 10deg/minAtm(sphere:oxygen f「9oCrucible:platinmReference:α―A12034025常4284℃V 3342ヽ3353℃879℃377 ヽ 11齢3717℃Sa,,le weight:30 59mg‖eating rate: 10deg/minAtrosphere:oxygen f「eeCruc blet pIBtinlHlReference: α―A12034076X4327℃肛336叫Ⅳ3 0BX3351℃866℃03716℃Study of Thermal Decomposidon PrOcess of Raw and HydrOchioric Acid Treated Rice Husk(FENG°SUGITA・S■OYA・Yハ』江州川ICHI)Table l  Temperature range for different stage of mass loss in the TG curvesTreatmentTreatment time         Temperature range(°C)(hOur)        stage l    stage II    Stage III   Stage Iヽ/untreated sample0 5 N HCi treatedl N HCitreatedl N HCi treated3 N HCltreated41-12741-12341-12440-14039-136224-369228-373211-377219-372208-37244244127-224123-228124-211140-219136-208369-91873-885377-929372-920372-919Table 2 Percentage(%)of lnass loss in different stageTreatmentTreatment tilne   Stage I    Stage II   Stage III   Stage IV(hour)       Percent    Percent    Percent    Percentuntreated sample0 5 N HCi treatedl N HCi treatedl N HCl treated3 N HCi treated392141374255402540763122336233443342336044244478324266377308Table 3 Peak temperature(°C)in DTA curves corresponding to different stages ofmass iossTreatmentTreatment time(hou■1)Stage I    Stage II   Stage III   Stage IVuntreated sample0 5 N HCI treatedl N HCI treatedl N HCI treated3 N HCI treated4424497 2 endo96 9 endo99 9 endo87 9 endo86 6 endo306 0 exo334 1 exo335 3 exo335 3 exo335 1 exo422 0 endo406 1 endo423 9 endo428 4 endo432 7 endoendo l endother■lic, xo: exotherHュicthe HCI treated husk,、vhic  was attributed to the dry processing to the treated husk,The third stage of decolnposition took place in the range 208-377°C indi at g a steep fallin the TG curves.The mass loss associated with this stage(3921-4255%)may be due to theremoval of volatile rnatter.  The removal of volatile rnatter for untreated husk was lower thanthat for the treated husk, The I)TA curves exhibit exothernlic peaks in the rage 306 0-335.3°C.It、アas note that the temperature of exother■lic peaks or the treated husk、、アas higher than thatfor the untreated husk, For untreated husk it was 306.0°C and for]ICl treatinent it Ⅵ as、「ithinthe ralages 334.1-335.3°C,respectivelyThe fourth stage of lnass loss(3122-33.62解`)in the range 369-929°C corresponds to thecombustion process.  The TC}curves showed a gradual decrease in the rate of rnass loss andthe DTA curves indicated an exothernlic reactionAmong the four stages,the■la]or decomposition occurred in the third and fourth stages.一- 71 -一The Bulletin of H I T V01 23Table4 Ef[ect Of cOmbustion temperature and pretreatment onthe color Of rice husk ashColor of ashCombustiontemperature(°C) unpretreated ashsample Acid pretreatment ash sampleBlakGrayGrayGrayGrayGrayGrayGrayGrayBlakBlakBrownBrownLight brown(whitish)ヽヽ「hiteWhtieWhiteWhiteThe mass 10ss of the third stage、vas higher as compared to the fOurth stage2.2 Thermal decomposition productThe c010r of rice husk ash is shown in Table 4  The co10r of the acid pretreated ashsamples(ADR)varies frOm black,brOwn,Iight brown,and white The color of the untreatedash samples(RHA)shOws the black and gray,At the lower combustion temperature,forexample,below 450°C(RHA sample)and 500°C(ADR sample),the samples were black in cO10r,it is because that these samples cOntained partially decomposed organic matter or unoxidizedcarbon  Above 550°C,the ditterent cO10rs of the samples are due to the lnetallic impurities inrlce husk ashTable 5 shows the chemical compOsition of、ve■―burnt rice husk ash obtained from theanalysis by X―ra fluorescence.  It indicated Si02 WaS main compOsition and the lower Ofamount of rnetallic impurities in the ash samples  The rnain rnetanic impurities in the ash arepotassiunュ,calciunl,phOsphorOus,rnagnesiuin iron, and sodium  The concentration of potas―siuna is greater than those of the other metallic elements.  It can be seen that these metalsincluding potassium are substantially reduced by treating with HCl and high pure silica wasobtained.Table 5 Chemical compositions(%)OfRHA with X ray auorescence analysisSample   Si02  A1203  Fe203  CaO  MgO  Na20  K20   P205  ]｀′生nO   ClADR-4ADR-1-24ADR-3-4RHA55-49861991599139 58021<010<010031021021010072<010<010<010031003005004007018011008052001001001011Note:ADR-4(l NHCl,4h),ADR-124(l NHCl,24h),ADR-3-4(3 NHCl,4h),RHA55-4,heating temperature 700°C,maintaining tiine 4 h―- 72 -―Study of Thermal Decomposition Process of Raw and Hydrochioric Acid Treated Rice Husk(FENG・SUGITA・SHOYA・Yl【、lAIヽICHI)00K40KI(CPS)Fig 6 XRD of RHA at direrent temperatures(holding time:4 hours)AI I)istorted quartz structure  B: ιY一Cristobalit1 400°C,2 550°C,3 600°C,4 700°C,5 800°C,6 900°C,7 1,000°C12K0.OK30   35   40   45   50   55   6020(°)Fig 7 XRD of ADR at different temperatures(holding time:4 hours)A: 正)istorted quart3 structure1 600°C,2 700°C,3 800°C,4 900°C,5 1,000°C,6 1,100°CThe properties of rice husk ash were sho、、アn in Fig.6 and Fig。7  All the ash samples upto RHA-700 and ADR-900 show a broad peak centered around 22 2°(2θ)on the XRD.Itindicated the for■l of silica in rice husk ash is amorphous,  The RIIA sample at 800°C indicatesshght crystaHinity and all RHA sample after 900°C are crystalhne. The crystalhne phaseabove 800°C is identified as α―cristabahte,Ⅵrith a trace of tridymite  On the other hand,「Fhe(CPS)15    20    25   30   35    40   45    50   55   6020(°)―- 73 -―BBB BAAThe Bulletin Of H I T V01 23ADR sample at l,000°C and above indicate a shght crystallinity  The phase is identined as acrystalline phase of distorted quartz structure,caused by lattice disorder  The results showthat hydrochloric acid treatment of rice husks inhibits the gro、vth of the crystaHize phase fromamorphous silica in rice husk ash.  It also shows that widening the ashing temperature rangeis benericial to the industrial production  To our knowledge,this anding has not been reportedpreviously in the literature4。 ConclusionsWithin the lirnits of the present studies the follo、パ ing cOnclusions can be dra、vn.1) 「Γhermal decomposition process of rice husk revealed three distinct stages of massloss,namely,removal of rnoisture,release of volatile matter and burning of combus_tible material The mttor decOmposition occurred in the release of volatile matterand burning of combustible material2)The DTA records exhibit an exothermic reaction during the course of thermaldecomposition and endothermic peak during the removal of mOisture.3) 「Fhe properties of rice husk ash depend on the combustion condition and the pretreatedcondition  Acid leaching of rice husk in dilute HCl and the appropriately combustiontemperature help in prOducing ash with high pure amorphous sihca and completelywhite in colorReferences1)2)3)4)5)6)HoustOn,DF,“Rice hulls'',Rice chemistry and Technology(EditOr:D F Houston),American Association of cereal chemistry, St Paul,WIinnesOta, 1972,301-352C real, M D Alcala, J ⅣI Cri do, Preparation of silica fOrm rice husks, 」ourn l of the AmericanCeramic Society,79,(1996)2012-2016Qingge Feng,Shuichi Sugita,ect,「Γhermal decompOsition of hydrochiOric acid treated rice husk andproperties of its prOduct,Journal of the Society of lnOrganic WIaterials,9,(2002)505-510A Chakraverty,Pふ/1ishra,H D Bane巧ee,Inv stigation of combustiOn Of ra、、アand ac d―leached icehush fOr prOduction of pure amorphous white silica  Journal of rnaterials science,23,(1988)21-24A Chakraverty,Pふ/1ishra)and H D Banettee,InVestigation of thermal decomposition of rice huskThermochim Acta,94,(1985)267275」ose James and M Subba Rao,Silica frOm rice husk through thermal decomposition,ThermochimActa,97,(1985)329-336―- 74 -―

Study of Thermal Decomposition Process of Raw and Hydrochloric Acid Treated Rice Husk

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Study of Thermal Decomposition Process of Raw and Hydrochloric Acid Treated Rice Husk

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