II. Lub khob ntawv khov nab kuab uas lwj tau yog dab tsi?
Cov khoom lwj taukhob ntawv ice creammuaj peev xwm lwj tau. Nws txo qhov hnyav rau ib puag ncig. Nws tuaj yeem txo cov khoom pov tseg los ntawm kev rhuav tshem cov kab mob me me thiab rov ua dua tshiab. Lub khob ntawv no yog qhov kev xaiv ruaj khov thiab zoo rau ib puag ncig. Nws muab kev daws teeb meem ruaj khov dua rau kev lag luam noj mov.
A. Lub ntsiab lus thiab cov yam ntxwv
Cov khob ntawv ice cream uas lwj tau yog cov thawv ntawv ua los ntawm cov khoom siv lwj tau. Nws dhau los ntawm cov txheej txheem lwj hauv ib puag ncig tsim nyog. Piv rau cov khob yas ib txwm muaj, cov khob ntawv lwj tau muaj cov yam ntxwv hauv qab no:
1. Kev tiv thaiv ib puag ncig. PLA lwj taukhob dej khov nab kuabyog ua los ntawm cov hmoov txhuv nplej siab. Yog li, nws tuaj yeem lwj hauv qhov chaw ib puag ncig. Qhov no tuaj yeem txo qhov ua rau muaj kuab paug rau ib puag ncig. Nws muaj txiaj ntsig zoo rau kev tiv thaiv lub ntiaj teb ib puag ncig.
2. Siv tau dua tshiab. PLA yog ua los ntawm cov khoom siv rov ua dua tshiab, xws li cov hmoov nplej cog. Piv rau cov yas petrochemical, cov txheej txheem tsim khoom ntawm PLA muaj kev siv hluav taws xob tsawg dua thiab cov pa roj av uas ua rau lub ntiaj teb sov. Nws muaj kev ruaj khov zoo dua.
3. Pob tshab. Cov khob ntawv PLA muaj pob tshab zoo. Qhov no tuaj yeem pom tseeb xim thiab tsos ntawm cov dej khov nab kuab. Nws tuaj yeem txhim kho kev lom zem ntawm cov neeg siv khoom. Tsis tas li ntawd, cov khob ntawv tuaj yeem hloov kho thiab kho kom haum rau tus kheej. Qhov no muab rau cov tub luam ntau lub sijhawm ua lag luam.
4. Tiv taus cua sov. Cov khob ntawv PLA muaj kev ua tau zoo. Nws tuaj yeem tiv taus zaub mov ntawm qee qhov kub. Lub khob ntawv no zoo heev rau kev tuav cov zaub mov txias thiab kub xws li ice cream.
5. Lub teeb yuag thiab ruaj khov. Cov khob ntawv PLA yog qhov sib dua thiab yooj yim nqa thiab siv. Lub caij no, cov khob ntawv PLA yog tsim los ntawm cov txheej txheem tsim khob ntawv tshwj xeeb. Qhov no ua rau nws cov qauv ruaj khov dua thiab tsis yooj yim rau kev hloov pauv thiab tawg.
6. Daim ntawv pov thawj thoob ntiaj teb. Cov khob ntawv PLA ua raws li cov qauv ntawv pov thawj ib puag ncig thoob ntiaj teb. Piv txwv li, tus qauv European EN13432 biodegradation thiab tus qauv American ASTM D6400 biodegradation. Nws muaj kev lees paub zoo.
B. Cov txheej txheem biodegradation ntawm cov khob ntawv uas lwj tau
Thaum PLA cov khob dej khov nab kuab uas lwj tau raug pov tseg, cov hauv qab no yog cov ntsiab lus ntxaws ntawm lawv cov txheej txheem lwj:
Cov yam tseem ceeb uas ua rau cov khob ntawv PLA lwj hauv cov chaw ib puag ncig yog cov av noo thiab kub. Thaum muaj av noo thiab kub nruab nrab, cov khob ntawv yuav pib cov txheej txheem lwj.
Hom thawj yog hydrolysis.khob ntawvpib cov txheej txheem hydrolysis nyob rau hauv kev cuam tshuam ntawm cov av noo. Cov av noo thiab cov kab mob me me nkag mus rau hauv cov qhov me me thiab cov kab nrib pleb hauv lub khob ntawv thiab cuam tshuam nrog PLA molecules, ua rau muaj kev sib xyaw ua ke.
Hom thib ob yog enzymatic hydrolysis. Enzymes yog cov biochemical catalysts uas tuaj yeem ua kom cov tshuaj decomposition sai dua. Cov enzymes uas muaj nyob hauv ib puag ncig tuaj yeem ua rau cov khob ntawv PLA hydrolysis. Nws rhuav cov PLA polymers ua cov molecules me me. Cov molecules me me no yuav maj mam yaj hauv ib puag ncig thiab lwj ntxiv.
Hom thib peb yog kev lwj ntawm cov khoom me me. Cov khob ntawv PLA yog cov khoom uas lwj tau vim muaj ntau yam kab mob me me uas tuaj yeem lwj PLA. Cov kab mob me me no yuav siv PLA ua lub zog thiab rhuav tshem nws mus ua carbon dioxide, dej, thiab biomass los ntawm kev lwj thiab kev lwj.
Qhov kev puas tsuaj ntawm PLA khob ntawv nyob ntawm ntau yam. Xws li av noo, kub, av noo, thiab qhov loj thiab tuab ntawm khob ntawv.
Feem ntau hais lus, PLA khob ntawv yuav tsum siv sijhawm ntev dua los ua kom puas tsuaj tag nrho. Cov txheej txheem ua kom puas tsuaj ntawm PLA khob ntawv feem ntau tshwm sim hauv cov chaw ua composting lossis cov chaw ib puag ncig zoo. Ntawm lawv, cov xwm txheej uas ua rau muaj av noo, kub, thiab kev ua haujlwm ntawm cov kab mob me me. Hauv cov chaw pov tseg hauv tsev lossis cov chaw tsis zoo, nws qhov kev puas tsuaj yuav qeeb dua. Yog li, thaum tuav PLA khob ntawv, nws yuav tsum tau ua kom ntseeg tau tias lawv tau muab tso rau hauv lub kaw lus kho pov tseg tsim nyog. Qhov no tuaj yeem muab cov xwm txheej zoo rau kev puas tsuaj.