Uma ufuna ukwazi ukuthi yiziphi ipulasitiki ezibolayo?, kanye nokwazi isikhathi sokuphila kwayo okuwusizo, kusuka kuyiphi impahla eluhlaza eyenziwe, kusukela nini ikhiqizwa futhi uma ingasetshenziswa kabusha, le mibuzo izophendulwa kulokhu. isihloko esithakazelisayo, ngakho ngikumema ukuba uqhubeke ufunda.
Yiziphi i-Biodegradable Plastics?
Ngaphambi kokuthi kusetshenziswe ipulasitiki esekwe kwizinsalela ngawo-1930s, kwasetshenziswa izinto ezivele ngokwemvelo ze-bioplastic. Ngaleso sikhathi, izinto eziningi zepulasitiki zazikhiqizwa kuma-polymers asuselwa ku-biologically. Ngaleyo minyaka, umthombo wemvelo wokukhiqiza ama-bioplastics noma amapulasitiki emvelaphi yezinto eziphilayo kwakuyinjoloba yemvelo, i-cellulose, yokwenza i-Parkesin ngawo-1850, okwathi kamuva, ngo-1868, yaveza izinto zepulasitiki ze-celluloid ngisho ne-cellophane ekupheleni kwekhulu leminyaka. XIX kanye nokuqala kwe-XX. Kanye neminye imikhiqizo yavela ezingxenyeni ezine-casein, okuyinhlanganisela yobisi okwakhiqizwa ngayo i-Galatita ngo-1897.
Ngeminyaka yo-1940 yekhulu lama-1990, i-bioplastic yokuqala yobuchwepheshe eqashelwa ngokuba nemishini emihle kakhulu kanye nokuzinza okuhle kwamakhemikhali yakhiqizwa. Kodwa-ke, kusukela ngeminyaka yawo-XNUMX kuya phambili kwaqhubeka nokuthola lokho okwamanje okwaziwa ngokuthi ama-bioplastics (i-PLA noma ama-PHAs nama-plasticized starches) akhiqizwa ngenxa yentuthuko ocwaningweni lwamakhemikhali aluhlaza kanye namakhemikhali endabuko okusetshenziswa kwe-biomass, okungukuthi. , ukusetshenziswa kwesitashi, ushukela, i-cellulose nabanye.
Ngokusekelwe kulokhu okutholakele, njengoba ucwaningo luqhubeka, kutholwe okusha kwama-polymers avela emithonjeni yebhayoloji noma ebolayo ehlala ivela, njenge-PEF, ehluka ngokuya ngezinsiza ezahlukahlukene ezihlaziywayo futhi ezisetshenziselwa ukusungula iPlastiki entsha ye-Biodegradable, ngenhloso yokuzuza ukusetshenziswa okungcono kakhulu kwemfucuza evela ezintweni ezingavuthiwe ezahlukahlukene ezivela emithonjeni yebhayoloji.
ukuvuselelwa kwamapulasitiki
Njengoba amanani kawoyela ehla, ucwaningo lwathuthukela ukukhiqiza ipulasitiki emafutheni, ukuthola ipulasitiki eshibhile yemvelaphi yezinto ezimbiwa phansi, okwavumela ukukhiqizwa kwenani elikhulu lemikhiqizo yepulasitiki eguquguqukayo futhi ehlala isikhathi eside. Lokhu kuholele ekwehleni kwentshisekelo yokuqhubeka nokukhiqiza i-Biodegradable Plastic. Nokho, njengoba ukungcoliswa kwemvelo okubangelwa ukulahlwa kwenani elikhulu lemikhiqizo yepulasitiki yemvelaphi yezinto ezimbiwa phansi sekwaziwa, intshisekelo yokwenza imikhiqizo nge-Biodegradable Plastic isiphinde yavela.
Le ntshisekelo entsha yokukhiqiza i-Biodegradable Plastic ibangelwa ukungcola okukhiqizwa upulasitiki wemvelaphi yezinto ezimbiwa phansi kanye nokwenyuka kwentengo kawoyela, kanye nokwehla okuphawulekayo kwemithombo kawoyela. Kuhambisana nentshisekelo yemiphakathi yesayensi neyezimboni yokwenza ucwaningo ukuze kukhiqizwe amaPlastiki angenwa yi-Biodegradable Plastic noma ama-EDP (ama-polymer namapulasitiki awonakaliswa imvelo).
Ukushintsha amapulasitiki anezinsalela ezimbiwa phansi asetshenziselwa ukukhiqizwa kwezinto ezihlukahlukene ezihlukahlukene zePlastiki ye-Biodegradable kuyisinyathelo esingazuzisa imvelo ngokunciphisa umphumela ongcolisayo okhiqizwa amapulasitiki asekelwe ezinsalela. Lokhu kubangele umfutho omusha ocwaningweni lokuthola amapulasitiki emithonjeni ehlukene yemvelaphi yemvelo, futhi ama-polyhydroxyalkanoates ayindlela esebenza kahle. Ikakhulukazi njengoba imfucuza evela ku-Biodegradable Plastics ingaphathwa njengaleyo yemvelaphi ephilayo futhi ukuwohloka kwayo kwenzeka ngezikhathi ezifushane.
Ukugcizelela
Ukwakhiwa kokukhiqizwa kwe-Biodegradable Plastic kunenjongo yokuthi ngesenzo sezinto eziphilayo zingayihlanganisa ukuze zithole ikhabhoni, ekudleni izinto zepulasitiki. Kukhona amapulasitiki athile emakethe akhiqizwe ngezinto eziphilayo noma ezisekelwe ku-biobased, okuyizinto ezivuselelekayo ezifana nobhanana noma ubhanana, umdumbula, i-cellulose, imidumba ehlinzeka ngenani elikhulu le-lactic acid, uwoyela wesoya kanye nesitashi samazambane. Lolu hlobo lwepulasitiki uma lufinyelela impilo yalo ewusizo luyi-Biodegraded by aerobic microorganisms.
I-Biodegradable Plastics i-biodegraded by amagciwane adinga ukuba khona komoyampilo noma i-aerobic, kuma-composters amakhulu, ezinye zezimboni ezinokushisa okuphezulu kanye nomoya-mpilo owanele. Kodwa-ke, amanye amaPlastiki e-Biodegradable noma ama-biobased Plastics awakwazi ukubola ngesikhathi esifushane, lokhu kungenxa yokuthi obunye ubuchwepheshe buye bathuthukiswa ukuthi, ukuba nensalela yemifino njengomthombo, kubangela i-polymer enezici ezifanayo njengepulasitiki. yemvelaphi yezinsalela zensalela ngenjongo yokugcina izici zayo zemishini kanye nokululaza kancane kancane. I-Biodegradable Plastics, ngenxa yokuthi inezinto ezimbalwa zomshini, ayikwazi ukugaywa kabusha.
Sekukhiqizwe izithasiselo zesizukulwane esisha, ezinobuchwepheshe be-anaerobic enzymatic obukhiqiza ipulasitiki esekelwe ezintweni eziphilayo lapho ijikijelwa endaweni yokulahla imfucumfucu noma endaweni yokulahla imfucumfucu futhi ngenxa yokunqwabelana kwemfucuza kanye nokuba khona okuncane komoyampilo, amagciwane anaerobic andayo, aqala ukuwohloka kwe-biodegradation ngokushesha kwalezi zinto zepulasitiki.
Lezi zithako ezintsha zivumela ipulasitiki ukuthi igaywe kabusha, njengoba ingathinti izici zayo zangempela futhi, ngokungafani nobuchwepheshe obufana nezithasiselo eziwonakaliswa yi-oxidation, izinga lokushisa eliphezulu noma ukuchayeka kokukhanya okuphezulu, okuthi, ngaphansi kwezimo zemvelo, ziqale ukudilika, ukushintsha izakhiwo zabo, ukukhiqiza amapulasitiki amancane futhi kuvimbele ukugaywa kabusha kwawo, lokhu ngoba amayunithi e-biodegradation ahamba ezindleleni zebhayoloji hhayi ezingokwenyama.
Kwenziwe ngesitashi
Umkhiqizo oyinhloko wokukhiqiza i-Biodegradable Plastics isitashi, lena i-polymer yemvelo esekelwe kummbila, ukolweni noma amazambane. Kule mithombo emithathu yezinto ezingavuthiwe okukhiqizwa ngayo isitashi, engcono kakhulu yileyo ekhiqizwa isitashi samazambane. Lokhu kungenxa yokuthi ngaphandle kokuba insiza evuselelekayo, umjikelezo wayo wokukhiqiza mfushane futhi inesivuno esikhulu ngehektha ngalinye ekhiqizwayo, idla amanzi amancane futhi ikhiqiza umthelela omuhle emkhakheni wezolimo ngokubuyisela ukunwetshwa komhlaba ongasasebenzi.
I-Biodegradable Plastic ikhiqizwa ngokusekelwe kwisitashi esikhishwa emmbila, siguqulwa ama-microorganisms abe ama-molecule amancane e-lactic acid lapho kwenziwa khona amaketanga e-polymeric e-polylactic acid (PLA). Iziphambano zamaketango e-PLA zisungula ishidi lepulasitiki elibolayo lapho kungenziwa khona imikhiqizo ehlukahlukene yepulasitiki engangcolisi.
Lawa ma-Biodegradable Plastics abangelwa ukucutshungulwa kwesitashi, angajovwa, akhelwe futhi afakwe ku-thermoform noma angabunjwa ukuze kwandiswe izinga lokushisa, okufana nalokho okwenzeka kumapulasitiki endabuko akhiqizwa ku-petroleum futhi ngokufanayo, imikhiqizo ewumphumela inezindawo ezifanayo zamakhemikhali angokwenyama.
Izakhiwo
Ubudlelwano phakathi kwesitashi namanzi kuwumkhiqizo wokuba khona kwenani elikhulu lamaqembu e-hydroxyl avimbela ukumuncwa kwamanzi futhi abe nomthelela omubi ebusweni bemikhiqizo yePlastiki ye-Biodegradable. Lesi simo siye saholela ophenyweni oluhlukahlukene ekuguquleni isitashi semvelo ngokusebenzisa ukusabela kwamakhemikhali okushintsha amaqembu e-hydroxyl kanye nokusebenzisana namanye ama-polymers angaphansi kwe-hydrophilic noma ukuguqula imikhiqizo ngezindlela ezibonakalayo ngokusebenzisa izindlela zokuvinjelwa ezifana nokumbozwa kwendawo. Lokhu kwehliswa kwe-hydrophilicity kwehlisa izindleko.
Uhlobo lwe-Biodegradable Plastics
Ngokukhula, izimboni zisebenzisa iziqukathi ezikhiqizwe nge-Biodegradable Plastics njengendlela yokufaka isandla ekwehliseni ukungcoliswa kwemvelo. Ngokunjalo, njengokweseka lonke uphenyo olwenziwayo ukuze kwandiswe ukukhiqizwa kwe-Biodegradable Plastics okungaholela kumthelela omuhle ekukhiqizweni kwezolimo ngaphandle komthelela omncane kwezemvelo. Amapulasitiki okwenziwa ngawo amapulasitiki angaboli ahlukaniswa kanje:
Ama-polymers akhishwe ngokuqondile ku-biomass
Lolu hlobo lwe-polymer lusesigabeni socwaningo futhi kuhloswe ngalo ukukhiqiza amashidi adliwayo kanye nezendlalelo, okuhloswe ngawo ukulondoloza ukudla. Ukuze wenze lokhu, kuhlolwa ama-polysaccharides ahlukene kanye nama-hydrocolloids emvelaphi yamaprotheni, njengesitashi se-cassava enziwe nge-glycerol, i-polyethylene glycol, isitashi sommbila esijwayelekile kanye ne-pre-gelatinized, i-carboxymethylcellulose, i-pectin exutshwe ne-sodium alginate, i-pectin, i-gum tragacanth, i-gum guar, i-ethylcellulose, i-gelatin yengezwe ne-glycerol, i-gelatin-casein cross-linked ne-transglutaminase, i-sorbitol ne-sucrose, i-casein, i-whey, i-soy kanye ne-wheat gluten.
Ngenxa yokuthi i-wheat gluten isetshenziswa kulawa ma-polymer asuswe ku-biomass, inobuthi kulabo abangazwani ne-gluten kanye nabaphethwe yisifo se-celiac, esithinta u-15% wabantu bomhlaba futhi siyakhula. Ukusetshenziswa kwe-gluten kulolu hlobo lwe-Biodegradable Plastics kuholela emthelela omubi empilweni yabantu, ngenxa yalokhu, kuyisizathu sokufuna isisombululo nokulawula ukusetshenziswa noma cha kwe-gluten ekwenzeni lolu hlobo lwepulasitiki.
Ama-polymers avela ku-classical chemical synthesis
Lolu hlobo lwama-polymers akhiqizwa yi-classical chemical synthesis zisebenzisa ama-biological monomers avela emithonjeni evuselelekayo. Ama-monomers ayinhlanganisela yesisindo samangqamuzana aphansi ahlanganiswe ukusabela kwamakhemikhali phakathi kwawo, angakhiqiza i-molecule enesisindo esikhulu, esibizwa ngokuthi ama-polymers noma i-molecule enkulu ne-three-dimensional.
ama-polymers avela kuma-microorganisms
Lezi zikhiqizwa ngenxa yezinqubo zokuvutshelwa, okuthi, kuye ngokuthi imvelaphi yekhabhoni esetshenzisiwe, isebenzisa imizila ehlukahlukene ye-biosynthetic. Lawa ma-polymers akhiqizwa ama-microorganisms ahlukahlukene futhi isibalo sabakhiqizi siyanda futhi umthombo owodwa yizitshalo ze-transgenic. Amapulasitiki angaboli asuka kubhaktheriya ahlukaniswa kuleli qembu, lapho kutholakala khona ama-polyhydroxyalkanoates (PHA) kanye ne-polylactic acid (PLA). ama-polyhydroxyalkanoates (PHA) ngenxa yokuthi atholakala ezinsizeni ezivuselelekayo futhi ngenxa yekhono lawo lokuwohloka kwemvelo, abizwa ngokuthi “amapholima aphindwe kabili aluhlaza”.
I-Polylactic acid (PLA)
Phakathi nenqubo ye-photosynthesis yezitshalo, ama-carbohydrate ahlanganiswa ukuze akhiqize ushukela nesitashi (i-polymer yemvelo), ngenhloso yokugcina amandla. Umthombo okuvela kuwo i-polylactic acid ummbila nokolweni okusanhlamvu okunenani elikhulu lesitashi kuzinhlamvu zazo. I-Biodegradable Plastics lapho akhiwa khona kusukela kule polymer anendawo yokuba ne-resin engakwazi ukujova, ebunjwe ngokukhipha futhi i-thermoformed.
Lolu hlobo lwe-polymer lungenye ye-Biodegradable Plastics efundwa kakhulu futhi ibilokhu itholakala emakethe kusukela ngawo-1990. Ukukhiqizwa kwayo kusuka ekukhipheni isitashi esitshalweni sombila, esiguqulwa sibe i-molecule encane ngamagciwane, i-lactic acid noma i-2-hydroxypropionic monomer, eyenza amaketanga anezakhiwo zamangqamuzana afana namapulasitiki emvelaphi yezinsalela. I-PLA iwuhlobo lwePlastiki ye-Biodegradable esetshenziselwa ukwenza iziqukathi zokudla namabhodlela epulasitiki eziphuzo ezibandayo.
I-Polyhydroxyalkanoate (PHAs)
Lolu hlobo lwe-Biodegradable Plastics olubizwa nge-Polyhydroxyalkanoate (PHAs), lukhiqizwa kakhulu amagciwane e-Gram negative, futhi kancane kakhulu amagciwane e-Gram positive. I-PHA yatholwa okokuqala kwakuyi-PHB, ngonyaka we-1925 e-Pasteur Institute, lapho u-Lemoigne efunda i-PhB. I-Bacillus megaterium futhi yabona ukukhiqizwa kwe-PHB. Ngo-1958, ososayensi uMacrae noWildinson banquma lokho I-Bacillus megaterium igcine i-polymer lapho ubudlelwano phakathi kwe-glucose ne-nitrogen bungalingani kanye nokuwohloka kwayo lapho ikhabhoni noma umthombo wamandla uhluleka. Cishe ama-polyhydroxyalkanoate ahlukene ayi-150 aziwa njengamanje.
Umkhiqizo wokuqala ovela kule polymer wayaziwa ngokuthi "i-Biopol" umthombo wawo uvela ku-Ralstonia eutropha, kusuka ku-glucose ne-propionic acid. Njengamanje, i-Biopol ihlanganiswa nekhabhoni isuka kubhaktheriya eyodwa, enamandla amakhulu okubola kanye nezakhiwo ezingcono ze-thermomechanical kune-PHB emsulwa.
I-Polyhydroxyalkanoate (PHAs) iyakwazi ukubola, ayinabuthi futhi iyavumelana nemvelo. Ukukhiqizwa kwe-Biodegradable Plastic kuholela ekwehleni kokuncika ekukhiqizeni ipulasitiki njengento ephuma embonini kawoyela, ngakho-ke kuncishiswe udoti oqinile namagesi adala umphumela we-greenhouse.
I-Biodegradable Plastics kanye Nemboni
Ngokolwazi olubikwe yi-International Association and Working Group of Biodegradable Polymers (IBAW), indawo lapho kukhiqizwa khona i-Biodegradable Plastics iqondiswe emikhakheni yokugcinwa, imithi, ezolimo neminye imikhiqizo elahlwa. Zibuye zisetshenziswe ekwenzeni omakhalekhukhwini, amakhompyutha, izinsiza zevidiyo nokunye. Kufanele kuqashelwe ukuthi ngokusho kuka-10% wepulasitiki esetshenziswa ekwenzeni imikhiqizo embonini ye-elekthronikhi ine-Biodegradable Plastics.
I-Fossil-based Plastics kanye nemvelo
Kusukela ipulasitiki yaqala ukusetshenziswa ukwenza izinto, le mboni isiphenduke into eyenzeka. Okuholela ekwenziweni kwezinhlobonhlobo zezinto ezikhathini ezedlule ebezingabalulekile empilweni yansuku zonke yabantu. Lezi zenziwa ukuze ziphendule imboni enkulu ekhiqize izinto ezihlukahlukene ezisetshenziswayo futhi ngenxa yezazi zemvelo ziye zasebenzisa igama elithi "Plastic Civilization", ngenxa yokubaluleka kwalolu lwazi ekuthuthukiseni nasekuthuthukiseni izinga lempilo. womphakathi endaweni yesayensi nobuchwepheshe.
Cishe yonke imikhiqizo ipakishwa noma yenziwe ngepulasitiki, ingilazi egudluzayo, amaphepha namakhadibhodi okugoqa kanye neziqukathi. Ipulasitiki isetshenziswa njengamasonga okudla, imithi, imishini, izinto zikagesi, nezinye izinhlobo zemikhiqizo elahlwa ngaphandle kwanoma ikuphi ukubaluleka lapho isifinyelele ukuphila kwayo okuwusizo noma lapho kuthengwa omusha. Lokhu kuholele emqaleni wokulahlwa kwezindawo ezinkulu zasolwandle, ezinikeza igama elithi "isobho lepulasitiki", okudala indawo yokulahla enkulu kunazo zonke emhlabeni.
Lokhu kwanda okukhulu kukadoti wepulasitiki kuye kwadala inkinga enkulu yokungcoliswa kwemvelo, ngamapulasitiki aphezulu naphansi. Izici zepulasitiki evela ku-petroleum zivuna ukumelana kwayo okukhulu nokucekelwa phansi yizimo zemvelo futhi ngisho nangaphezulu ngoba ayiboli. Imisebe yelanga ye-UV kuphela engabangela ukuwohloka kwesikhathi esimaphakathi epulasitiki, kancane kancane ibhidliza izibopho ze-polymeric futhi iguqule ibe umkhiqizo ophukayo futhi ongenasici.
Ukunqwabelana okuphezulu kwamapulasitiki aphonswa endaweni ezungezile kuthinta imizimba yamanzi ngokuhudulwa emifuleni futhi ahanjiswe aze ageleze olwandle; kungcolisa amanzi ngemikhiqizo equkethwe; Babangela izifo ezinjengodenga, ngenxa yokuma kwamanzi angcolile nasezitsheni zepulasitiki okuyizindawo zokuzalanisa omiyane. Kuthinta imisebenzi yezokungcebeleka kanye nezokuvakasha, ngokuthinta indawo yemvelo kanye nezindawo ezinjengamapaki, imigudu, imigwaqo, izikhungo nezakhiwo.
Kubangela ukufa kwezilwane nezinyoni noma ngokusetshenziswa kwalawa mapulasitiki awonakele noma ngokuminyanisa, njengezilwane ezifaka amakhanda azo ezikhwameni futhi ezingakwazi ukuwukhipha kamuva. Ngokufanayo, izinyoni zilengiswa ngamasongo epulasitiki noma amageja ezikhwameni zepulasitiki. Ngokwesibonelo, ngo-1967, esifundeni saseLa Serena eChile, kwafa izimbuzi eziningana phakathi nesomiso eside esadla izinsalela zezikhwama ze-polyethylene ezaziphonswa ogwini ngabantu, futhi lapho zidla izinkomo, zafa. emahoreni ambalwa ukuyiqeda.
Iziqukathi zepulasitiki zomsuka wezinsalela zasendulo seziphenduke isiphazamiso esikhulu emadolobheni. Ngenxa yokuthi ukuphatha le mfucuza kubiza kakhulu kuziphathimandla zikamasipala eziphethe udoti ngenxa yobuningi bamakhonteyna nomthamo wawo. Ipulasitiki idala izinkinga ngesikhathi sokuqoqwa nokulahlwa kokugcina. Lokhu kungenxa yokuthi ukuqoqwa kwemfucuza, iloli eliqoqa udoti elikwazi ukuthutha amathani angaba ngu-12 kadoti ovamile, kuzothwala amathani amahlanu noma ayisithupha kuphela epulasitiki ehlanganisiwe kanye namathani amabili kuphela epulasitiki engahlanganisiwe.
Ipulasitiki etholakala kakhulu kudoti oqoqwe, ngaphezu kwanoma yini enye, iziqukathi zepulasitiki zePET ezivela emabhodleleni alahlwayo amanzi okuphuza, amafutha, iziphuzo ezibandayo, amajusi nokunye ukudla. Lokhu kungenxa yokuthi izinkampani ziyekile ukusebenzisa amabhodlela ezingilazi noma iziqukathi zase ziwashintsha ezitsheni zepulasitiki ezibuyiswayo nezingabuyiswa, okuholela enkingeni yokungcoliswa kwemvelo.
Ukuvikelwa Kwemvelo
Ukukhiqizwa kwe-Biodegradable Plastic kwafezwa ngenhloso yokuthi le nto yenziwa i-biodegraded ngesikhathi esincane ngesenzo sama-microorganisms futhi ngenxa yalokho yashabalala yonke. Le nhloso ifinyelelwe emikhiqizweni eyenziwe ngenayiloni: amagciwane amabili adla inayiloni, i-flavobacteria ne-Pseudomonas, ayangenelela ekuboleni kwawo. Ososayensi babheka umbono wokuthi ngokuzayo amanye ama-microorganisms azoshintsha izindlela zawo ze-metabolic futhi asebenzise ipulasitiki njenge-substrate.
Ukungcola kwamanje okubangelwa inani elikhulu lepulasitiki lemvelaphi yezinto eziphilayo kubangelwa ukuthi lolu hlobo lwepulasitiki lwakhiwe izakhiwo ezimelana nokubola, okuholela ekuthinteni izinga lempilo yezidalwa eziphilayo. Njengesixazululo sale nkinga yokungcoliswa kwemvelo, izimboni ziqondise izenzo zazo ekuthuthukisweni nasekusetshenzisweni kwezinto ezilula ezilulaza ngokwemvelo, ezinokusetshenziswa okuhlukahlukene kanye nezindleko eziphansi zokutshala izimali.
Le Plastic yeBiodegradable Plastic igaywa kabusha njengoba iyingxenye yenqubo evuselelekayo yokuthola izinhlanganisela zala mapulasitiki okuthi ekulungiseni kwawo kusetshenziswe izinhlanganisela zemvelo ukuze ziphinde zisetshenziswe, ngaphansi kwezimo zokuphepha nokuhlanzeka kwezimboni, ziyizinto ezinezici abazenzayo. ama-antioxidants, alawulekayo, amelana, angangeni manzi futhi aguquguqukayo, phakathi kokunye.
Uma ufuna ukwazi okwengeziwe ngezihloko ezihlobene nemvelo emangalisayo nokuthi ungayinakekela kanjani, ngikumema ukuthi ufunde lokhu okuthunyelwe okulandelayo: