Formaldehyde vs Paraformaldehyde
Formaldehyde yog ib qho yooj yim organic chemical compound uas tuaj yeem ua rau ntau hom. Paraformaldehyde yog ib hom zoo li no, qhov uas nws tso siab rau lub tsev tsim cov qauv ntawm formaldehyde tab sis txawv hauv cov qauv. Cov kev sib txawv ntawm formaldehyde formulations yog kev lag luam paub nyob rau hauv ntau yam lus thiab yog siv rau txawv hom phiaj nyob ntawm seb lawv cov khoom.
Formaldehyde
Formaldehyde yog ib qho yooj yim, organic, tshuaj lom neeg sib xyaw uas yog nyob rau hauv pab pawg ua haujlwm hu ua 'aldehydes', yog li lub ntsiab lus. Nws tseem yog daim ntawv yooj yim tshaj plaws ntawm aldehyde tam sim no nrog cov tshuaj formula CH2O lossis HCHO thiab nyob rau hauv lub xeev gaseous ntawm chav tsev kub. Formaldehyde gas tsis muaj xim thiab muaj cov yam ntxwv tsw nrog pungent xwm.
Formaldehyde yog kev lag luam tsim los ntawm catalytic oxidation ntawm methanol (CH 3 OH). Silver catalysts feem ntau yog siv rau hauv cov txheej txheem no. Ua ib qho yooj yim organic compound, formaldehyde ua txoj hauv kev raws li cov khoom pib hauv cov tshuaj tiv thaiv organic ntau heev. Nws kuj yog siv nyob rau hauv ntau industrially tseem ceeb polymerization cov tshuaj tiv thaiv xws li urea-formaldehyde resin, phenol-formaldehyde resin thiab lwm yam. Formaldehyde kuj yog siv nyob rau hauv zus tau tej cov ntau yam ntawm plastics, ntaub crease-resistants nyob rau hauv lub textile kev lag luam, cov khoom siv rau lub cav cav. thiab lwm yam. Dilute cov kev daws teeb meem ntawm formaldehyde kuj yog siv los ua cov tshuaj tua kab mob thiab khaws cia cov kab mob lom. Raws li tau hais los saum toj no, formaldehyde qhia tau hais tias muaj xwm txheej nyuaj vim nws siv ntau hom ntawv los ntawm cyclization, polymerization lossis dissolution; Txawm li cas los xij, nws tseem qhia cov yam ntxwv ntawm tib yam li formaldehyde. Muab tag nrho cov txiaj ntsig txawm li cas los xij, formaldehyde paub tias yog tib neeg carcinogen thiab, qhov tseeb, yog tshuaj lom rau txhua tus tsiaj raws li raug rau formaldehyde tuaj yeem ua rau mob hnyav. Tsis tas li ntawd, cov kev daws teeb meem ntawm formaldehyde qhia tau hais tias muaj kev cuam tshuam zoo heev thiab formaldehyde tuaj yeem tsim cov tshuaj tsis muaj zog / tawg heev.
Paraformaldehyde
Paraformaldehyde yog cov khoom polymerization ntawm formaldehyde. Polymers yog bulky molecules ua los ntawm ntau dua chav tsev molecules uas yog hu ua monomers. Qhov zoo tshaj plaws, polymerization yog txheej txheem ntawm reacting monomers uas yog lub tsev thaiv ntawm cov polymer, los ntawm cov tshuaj tiv thaiv uas khi cov monomers ua ke. Yog li ntawd, zoo ib yam li ntawm 8-10 units ntawm formaldehyde (ntawm no formaldehyde ua raws li cov monomer) polymerizes rau hauv paraformaldehyde, uas ua tau yog qhov tsawg tshaj plaws chav nyob ntawm lwm yam ua tau thib ob polymerizations. Formaldehyde tseem hu ua oxymethylene; Yog li paraformaldehyde yog tshuaj hu ua 'polyoxymethylene'. Lo lus 'poly' feem ntau txhais tau tias 'ntau'.
Paraformaldehyde cov ntaub ntawv maj mam thaum formaldehyde nyob rau hauv aqueous daws thiab cais tawm raws li ib tug dawb precipitate. Thaum lub sij hawm kev npaj ntawm saturated aqueous formaldehyde daws kuj hu ua formalin, methanol thiab lwm yam stabilizers feem ntau siv los tiv thaiv cov txheej txheem polymerization. Paraformaldehyde yooj yim de-polymerizes tso cov pa roj formaldehyde thaum cua sov qhuav, ua rau paraformaldehyde ua cov tshuaj lom neeg. Thaum de-polymerized, nws tuaj yeem siv ua tshuaj tua kab mob, fungicides thiab fixatives. Thaum nyob rau hauv daim ntawv polymer nws yog siv los ua cov thermoplastic hu ua 'polyoxymethylene yas'.
Qhov txawv ntawm Formaldehyde thiab Paraformaldehyde yog dab tsi?
• Formaldehyde yog ib qho yooj yim organic tshuaj compound whereas paraformaldehyde yog ib tug polymer molecule.
• Formaldehyde muaj qhov muaj zog thiab pungent tsw, qhov paraformaldehyde tsuas yog muaj ntxhiab tsw me ntsis tshwm sim vim yog tsim cov formaldehyde thaum decomposing.
• Paraformaldehyde yog dawb precipitate ntawm chav tsev kub tab sis formaldehyde yog roj.
• Paraformaldehyde tsuas yog ib hom kev npaj formaldehyde li no muaj kev txwv tsis pub siv thaum piv rau ntau daim ntawv thov ntawm formaldehyde.
• Paraformaldehyde tsawg dua tshuaj lom thaum piv rau formaldehyde.
