Tgp chi Khoa hgc Trudng Dgi hgc Can Tha Phdn A: Khoa hgc Tv nhiin. Cdng nghi vd Mdi trudng: 35 (2014): 40-45
Tap chi Khoa hoc Tru'dng Dai hoc Can ThcJ website: sj.ctu.edu.vn
ANH H i r d N G CUA THCH GIAN PHAN U'NG VA NONG DO DUNG DICH KIEM TRONG QUA TRINH TAI CHE N H I T A PET BANG PHU'CRNG PHAP HOA HOC Van Pham Dan Thuy', Nguyin Thanh Viet', Truomg Ha Phuang An' va Doan Thi Ngoc Dung' ' Khoa Cong nghe, TrudngDgi hgc Cdn Tho
Thdng lin chung:
Ngdy nhgn: 02/10/2014 Ngay chdp nhgn: 29/12/2014 Title:
Effects of reaction lime and concentration of alkaline solution on recycling process of PET waste by chemical treatment
Tit khda:
Polyethylene terephthalate (PET), qud trinh ldi che, xir ly hoa hgc
Keywords:
Chemical treatment, polyethylene terephthalate (PET), recycling process
ABSTRACT
This study presents the preliminary lab scale results of chemical treatment process of waste polyethylene terephthalate (PET) bottles by using sodium hydroxide. Some important parameters such as operating temperature and immersing time and concentration of sodium hydroxide solution were studied. Operating temperature and immersing time were achieved at 75°C and in 30 minutes, respectively. The ash content of the sample was determined at SOO^C. The remaining of inorganic impurities after treating in alkali solution was very low and acceptable. The inorganic content separated from the PET waste increased with increasing amount of alkaline concentration. This investigation showed that an environmentally friendly method to recycle PET could be simply established.
TOM TAT
Nghien cuu ndy Irinh bay kit qud sa bg ciia qud trinh XU ly hod hgc polyethylene terephthalate (PET) bdi kiim trong phgm vi phong thi nghiim. Cdc thong so quan trgng nhu nhiet do, thai gian vd nong dg kiim ldn lugt dugc khdo sdt. Nhiet do vd thai gian toi uu cua phdn iing dgt dugc a 75°C vd 30 phiit. Hdm lugng tro cOa mdu dugc xdc dinh khi nung a nhiit do 800°C. Kit qud cho thdy, tgp chdt vo ca con lgi trong mdu sau qud trinh xir ly Id rdt thdp vd co the chdp nhgn. Hdm lugng tgp chdt vo ca logi ra li li thudn vol ndng do Idim. Quado, co thi Ih^ phuong phdp tdi chi PET CO thi thuc hiin dugc mgt cdch dan gidn vd khong dnh hudng din moi truong.
1 GlOn THIEU
Tfl khi dugc tdng hgp vd dua vdo sin xuit quy md cdng nghiep vdo nim 1940, san lugng nhua polyethylene terephthalate (PET) duge Min xudt vd tilu tiiu mdi ndm diu ting, ddng tiidi chit tiiii PET cung ting len ddng kl (Li et al, 2010). Theo thdng ke cua Euromonitor Intemational, nam 2011 cd khoang 446 ti chai PET dugc sd dyng fren toan thi gidi, tdng 30% so vdi nim 2006. Ba phin tu frong sd dd dugc su dyng ttong nginh cdng nghifp nude giii kb^t. E)en nim 2015, Euromonitor International dy tinh thi ttudng ddng gdi dd udng
toan ciu se tilu thu khoing 1,31 nghin ti chai, do dd tii chl chai PET li vin de cdp thilt khdng chi vi ylu td kinh ti ma edn vi ylu td mdi trudng. CJ Viet Nara, moi nam khoang 2 ti chai PET dugc san xuit va tieu thy, neu tdi che chiing si tilt kifm dugc khoang 36 ty ddng/ndm cho vin dl xfl ly rac thai nhua.
Vdi nhiing uu diem vl tinh chit hod ly nhu dp bin cao, khdi Iugng nhe, ngogi quan dep, chdng thim khi tdt, fro, gii thdnh thip, PET ngdy cang dugc sfl dung rpng rii ttong cdng nghifp. Cy the, hau hit cic chai nude gi^ kbit diu dugc lira tu
Tgp chi Khoa hgc Trudng Dgi hgc Cdn Tho Phdn A: Khoa hgc Tv nhien. Cdng nghf vd Moi Irudng. 35 (2014): 40-4 f nhya PET. Tuy nhiin, bl mat cd nhilu Id rong, xdp
tao diiu kifn eho vi khudn vi mui tich tu rat khd riia sgch la nhugc dilm cua PET, do dd cic nhi khoa hgc khuyin cao khdng nln dung chai nhya PET di qua su dung. Thay vdo dd, viec tai chl cin dugc quan tim.
Nhim tan dung ngudn PET tiiai thay tiie cho ngudn tii nguyen hoi thach dang ngdy cang cgn kift va gdp phdn bio vf mdi tnrdng, nhieu cdng ttinh nghiin eflu vl tdi chl PET da v i dang dugc thyc bifn {Vijgykumar et ai 2010; Semiha, Ciineyt, 2014; Fonseca et ai, 2010; Vo Thi Hai. Hodng Nggc Cudng, 2008). Tren thi gidi, PET tai ehi dugc ling dung ttong sdn xuit xo sgi, mang mdng,
Bang 1: Cdc iing dung ciia R-PET (don vi trifu pounds) {NAPCOR, 2013)
diy, nhya 1^ tiiugt va mgt sd ITnh vuc khac. Cac ling dung cda sin lugng PET tdi ehi (R-PET) dugc trinh biy ttong Bing 1. Tuy nbiln, d nude ta vin de xu 1;^ PET thdi hiu nhu chua dugc quan tdm trong khi nguy co tu rac th^ niy di v i dang tdng rit nhanh. Hifn nay, vifc thu gom, phin logi, xfl I;^
PET thii d nude ta dien ra mft cdch ti^ phdt, vi lgi ich kinh t l la cbinh. Ben cgnh dd, tgi cic co sd tai ehl da ed ddu bifu ve sy d nhilm dat, nude vd khdng khi dnh hudng den radi trudng song cfla cdng ddng. Trudc thyc trgng dd, nlu khdng chii dgng tim ra bifn phip xfl ly, tdi chl PET thii phii hgp thi ehflng thyc sy ttd thdnh mft mdi lo ngai ldn ddi vdi nude ta.
Cic loai san pham l.Spi
2. Tara ho$c m ^ g m6ng 3. Day
4. Nhva ky thu§t
5. Chai chiia thirc pham va nude giai khat 6. Chai khong ti^p xiic thgc ph^ra 7. LTng dung khac
Tong cOng
2006 422 74 132 9 139 49 30 855
2007 383 128 144 11 136 60 38 900
2008 391 153 137 7 141 55 31 915
2009 344 159 114 10 203 65 42 937
2010 381 195 127 9 216 58 16 1002
2011 398 202 120 242 57 21 1040
2012 512 307 136 276 50 31 1312 Hifn nay, cd nhilu phuong phdp khdc nhau dl
xu I;^ PET thdi nhu chdn lip, tii su dung lai hoic tdi che. Do hdu hit nhya PET khdng the tu phan buy sinh hgc, khi xfl ly bing eich ddt hoac chdn tip s€ gdy d nhiem mdi trudng, thoai hod dat, phdt sinh cdc khi ddc hai giy inh hudng den sue khoi con ngudi. Do dd, tai che PET Id phuang phdp kha thi nhit cho vifc xfl ly PET thii. Dae bilt, diy cdn la nguon nguyen Ufu ddu vdo gid re cho mdt s6 nganh sin xuat khic. Hinh 1.1 trinb bdy cac phuong phdp xu ly PET thai phd biin nhit hifn nay.
Cd hai phuang phip tii ehl PET chinh la phuong phip eo hgc v i phuang phip hoi hgc. Vdi phuang phdp co hgc, ehi don thuin li thu gom, riii;
sach, bim nhd, say khd, tdi gia cdng. Tuy nhiin, nhugc diim cfla phucmg phdp nay Id hgt nhya tdi chl cd chat lugng thip, khdng xdc djnb dugc thdnh phin va him lugng tgp chat nln PET sau tdi che c6 do nhdt rit thip. Do dd, tdi chl hoi hpc dang ngiy cing ttd nen hieu qui dk xd Iy PET thai. Han nOa, diy edn l i phuang p h ^ md ra hudng mdi ban eho viec sfl dung ric thai tu nhya PET.
1 PET tiiii 1
^
1 Chdn ldp
f
Tdi cbe Tai che ca hpc
i
Phuong phip tach
i
Phuang phip tuyen ndi phuang phdp boa tan
^
1
Su dyng lgi
^
Tii che khac 1 Tdi chi hoi hoc j Thuy phin (axit, kilm)
i
Methanol phdn Glycol phdn Hinh I: Sato VhM qui trinh thu h6i va tai chl niiira PET thii (Dutta, Soni, 2013)
Top chi Khoa hgc TrudngDgi hgc Cdn Tha Phdn A: Khoa hgc Tv nhiin. Cdng nghi vd Mdi trudng: 35 (2014): 40-45 2 PHlTONG PHAP NGHIEN ClJtJ
2.1 Nguyen lifu v4 boa chit
V|t lifu sfl dung frong n ^ l n eflu nay la nhua PET tii chai nude giai kbit Sau dd, PET dugc phin tdch ndp, nhan vd cdt nhd vdi kich tiiudc khoing 8-10 mm.
Sodium hydroxide (NaOH) (Xilong Chemical Co., Ltd, made in china 96%), vdi mft lugng nhit djnh dugc pha loang frong nude cit dl su dung frong nghien cuu niy. Dung dich AgNOa 0,1 N ciing dugc su dyng trong nghiin eflu niy.
2.2 Phmmg phap nghilo cuu xa ly vol dung dfch kiim nong
Ban diu, PET thdi dugc xfl ly vdi dung dich kiim d nhift dd 15°C vdi ndng do kilm. vd thdi gian khdo sat tuang dng. Tilp theo, PET dugc rua nhiiu lin bdng nude di logi toan bd kilm edn bim trin bl m?t cua manh nhya. Qua trinh nia kit thflc khi dung djch nude rfla cd pH = 7. Miu dugc lam khd d nhift df phdng. Cudi ciing, can dk xic djnb ham lugng tgp chit hi loai ra sau qud ttinh xfl ly.
Mdi thf nghifm diu thyc hiln 3 Ian dl liy gid tti trung binh.
Xdc djnh hdm lugng tro cua mdu PET trudc vd sau qud trinh xu ly kiim
Cdn 1 g mau PET thii cho vio cie nung da bJIt
trudc khdi lugng. Chuyin cdc vdo d6t ttong Id nung d nhift do 800°C frong 2 gid, din khi mdu hi tto hda hoin toan, cd miu tring xdm. Ldm ngudi cdc ttong binh hut im khoing 1 gid vd dem can.
Lap lgi tiii nghiem eho cdc mlu PET dugc xd Iy d eic ndng dp kilm khdc nhau. M6i thi nghifm diu dugc tiiyc hifn 3 lin dl kilm tta dd l$p igi cda phan flng. Khi dd, ham lugng tto (% tto) ciia miu duge xdc djnh theo cdng thflc:
^tro- = =aiExi&0(%) (1) Trong dd; mo (g): khdi lugng cdc
rai (g): khdi lugi^ cdc va mau ra2 (g): khdi lugng c6c vi miu sau khi nung 3 KET QUA VA THAO LU^N 3.1 Xii 1^ PET vdi dung dich kiem ndng Kit qua Hlnb 2 eho thiy lugng tgp chit bi loai tang din khi ndng dd kilm vi thdi gian ngdm tang.
Trong 30 phut diu tiln, lugng tap chit bi loai ting nhanh; tfl 30 din 60 phdt, lugng tap chit logi ra giam vi ddn on dinh. Phin flng tach, logi tgp chit ehi xay ra ttong 30 phut diu tiln. Sau qua trinh xfl ly kilm, ngodi keo dan thi mot lugng ddng kl tgp chit vd ca cung bi logi. Kit qud tdch logi tgp chit vd CO dugc ttinh biy d phin tilp theo. Ci hai ylu td ndng dd kilra va that gian deu inh hudng din qua trinh loai tap cliit td PET thii.
2 0 - 1 8 - ' ? 1 6 -
^ 1 4 -
[
8^
^ S f t y s l
Ifm
1 //
1 •
6 , 10
- = * S 5
^ —S. T T
^ — *
• N a O H l %
• NaOH 2%
T NaOH 3 % H NaOH 4%
• NaOH 5%
1 1 1 1 1 20 30 40 50 60
Time (minDte)
Hinh 2: Anh hudng cua thoi gian vi nong d$ kilm len kh^i iu-grng tap chat lo^i ra ttr PET _ I--- A~ u' - u i I . chat loai ra ty le thuan vdi nong do kiem, ket qua Thyc ngh,fm da Chung mmh rang, lugmg tap 4„„,rtrfi biy 6Hinh3.
42
Tap chi Khoa hgc Trudng Dgi hftc Can Tha Phdn A: Khoa hoc Tv nhiin, Cong nghi vd Mdi trudng: 35 (2014):
:40S
3 0 -
2 5 -
SI 2 0 -
s
1 5 -
1 1 1 1 2 4 6 8
Alkali concentration (%)
I I
1 10
Hinb 3: Anh hurdng cua ndng df kilm den liryng tap chat loai ra Tap chat hi loai sau qui trinb xu ly kilra bao
gdm keo din nhan, PVC vd chat ddn vd ca. Phan ldn keo dan nhin chai PET thudng chfla axit abietie, cie axit ndy tan vd hgn ttong mdi trudng
N a O H + C19H29COOH — Kit qui kilm tra tgp chat cfla dung dich kiem sau qua frinh xu ly PET thai ttong Hinh 4. Kit tfla tting thu duge chung rainh sy hien diln cfla PVC
kilra, vi vdy khi ngdm frong dung dich kilm keo niy de phin r i v i tieh ra khdi bl mat PET {Trdn Vinh Diiu vd Tran Trung Li, 2006).
- ^ CigHjgCOONa + H j O
frong tgp chat b; loai. 6 nhift df 60 - VO^C PVC tdc dyng vdi NaOH theo phuang ttinh phin ung:
f—CH2 —CH —Cl—) nNaOH (—CH2—CH — O H — ) nNaCI
CH3COOH + NaOH *- CHaCOONa + H2O NaCI + AgN03 ^ AgCl + NaNOj
\^<lpA|MO.ife«dJa
Hinh 4: Kit tua tring ciia AgCl
r<ip chi Khoa hgc Trudng Dgi hgc Cdn Tho Phdn A: Khoa hgc Tu nhien, Cong nghi va Moi trudng: 35 (2014). 40-45 3.2 Ket qua xdc djnh him lirgng tro ciia
PET tbai vi PET sau khi xur ly
Bang phuang phdp nung mau khdo sat d 800 °C ttong 2 gid, ham lugng tto dugc xac dinh.
=
0 . 2 5 -
^ 0 . 2 0 -
•g 0 . 1 5 -
Ashco 1 1
0 -
1
* t
A l k a l i cODcentration (^o)
Hinb 5: Ndng dg kiem anh hirdng den qua trinh loai tap chit vd ca tur PET thai Kit qud thi i ^ i f m Hinh 5 cho tiiiy, sau khi
nung PET d nhiet do 800 "C tiii khdi lugng tro cdn lgi it, cu till khi xfl \</ PET thai vdi 10 % kilm thi lugng tgp chat cdn lgi ttung binh khoing 0.06 % ttgng lugng cfla PET.
PET tiidi chua xfl \y kiem cd him Iugng tto eao vi ed su khic bift nhieu gifla cdc mdu dugc xu ly vdi cdc ndng do kilm khic nhau. Cd thi thay, bao bi nhya PET dugc sdn xuat chfla nhieu loai chit dgn, hda chit phy gia. Him lugng tto thu dugc chinh la him lugng cic hgp chit niy. Tfl bieu dd Hinh 5 cho thiy, him Iugng tto cdn lai ttong mdu gidm khi tang ndng df kilm, dieu dd cho thdy ndng dd kilm ed inh hudng din qua trinh tich loai tgp chit
Sau qui frinh xfl ly kilm vdi cdc ndng dp % khac nhau thi hieu suat cua qud ttinh tdch logi fro dugc tinh theo cdng thuc (2). Dd thj Hmh 6 cho
thay, khi tang ndng dg kiem tu 1-10 % thi hifu suit cfla qui trinh tich logi fro cung tang. Hifu sudt ciia qud trinh logi tgp chit vd ea ti If thuin vdi ndng dp kiem, khi tdng ndng dp kilm thi lugng tap chat vd CO edn lai ttong mau li khi thip. Dilu niy chdng td ngoai khd nang tdch logi keo ddn, PVC, qua ttinh xfl ly vdi dung dich kilm cdn cd khd nang tdch logi cdc chat ddn vd ea.
Hifu sudt (P) cua qud trinh tdch logi tto dugc xic dinh theo cdng thde:
niE^E)
P = • s x ie& (%) (2) Trong dd: mo (g): khdi lugng tto cfla mau khdng xfl ly --r^ ^
mi (g): khdi lugng tro cfla cac mau xfl ly vdi cdc ndng do kiem tuong ung
Tgp chi Khoa hgc Trudng Dgi hgc Cdn Tho Phdn A: Khoa hoc Tv nhiin. Cong nghi vd Mdi irudng: 35 (2014): 40-4 f
8 0 -
g 6 0 - o u
^ 5 0 - 4 0 -
• ^ *"~~'
y ^
I I I I
2 4 G 8
Alkali concentration (%)
10 1
Hinh 6: Hifu suit ciia qua trinh tach loai tro 4 KET LUAN
Ca hai ylu td thdi gian phin iing va ndng do kiem diu inh hudng din qud trinh loai tap chit tfl PET thai. Thuc nghifm cho thay, ham lugng tap chit dugc tdch ra tu PET thai tang khi tang thdi gian phdn flng va ndng do kiim. Kit qud khdo sit ham Iugng tto cfla mlu cho thiy mdt lugng ddng ki tgp chit vd ca bi logi sau qui frinh xu ly kiim.
TAI LIEU THAM KHAO
1. Ak9ad20g"lu Semiha, Uiu Cuneyt, 2014.
Recycling of waste PET granules as aggregate in alkali-activated bias fiimace slag/raetakaolin blends. Consfruction and Building Materials 58: 31-37.
2. Krishna Dutta, R. K. Soni, 2Q13.:^,Review^:
on Synthesis of Value-Added Products from Polyethylene Terephthalate (PET) Waste.
Polymer Science, Ser. B, Vol. 55, Nos. 7-8, pp. 430-452.
3. Napeor, 2013. Report on Postconsumer PET Container Recycling Activity in 2012.
http/www.napeor.eoni/PETi^t__reports.htin I, assessed on 30/7/2014.
4. R. Lopez Fonseca, I. Duque Ingunza, B.
deRivas, S. Amaiz, J.I. Gutienez Ortiz, 2010.
Chemical recycling of post-consumer PET wastes by glycolysis in the presence of metal salts. Polymer Degradation and Stability, Volume 95, Issue 6, Pages 1022-1028.
J. Shen Li, Ernst Worrell, K. Patel Martin, 2010. Open-loop recycling: A LCA case study of PET bottie-to-fibre recycling.
Resources, Conservation and Recycling, Volume 55, Issue I, Pages 34-52.
6. Sinha Vijaykumar, R. Patel Mayank, V.
Patel Jigar, 2010. Pet Waste Management by Chemical Recycling: A Review. J Polym Envuon 18:8-25.
7. Trin Viiih Dieu, Trin Trung Ll, 2006. Mdi trudng ttong gia cdng chat deo vd eompozit.
Nha xuat ban Bach khoa Hd Ndi.
8. Vd Thi Hai, Hoang Nggc Cudng, 2008.
Phan flng cit mach poly(etiiylen terephtiialat) (PET) hr vd chai bing dietylen glycol (DEC), Science & Technology Development, Vol 11, No.06.
