Application of self–cleaning treatment on cotton and pes/co fabric using tio2 and sio2 coating synthesized by sol–gel method - Bui Mai Huong

Journal of Science and Technology 55 (1B) (2017) 77–84 APPLICATION OF SELF–CLEANING TREATMENT ON COTTON AND PES/CO FABRIC USING TiO2 AND SiO2 COATING SYNTHESIZED BY SOL–GEL METHOD Bui Mai Huong*, Trinh Thi Kim Hue Department of Textile–Garment Engineering, Faculty of Mechanical Engineering, HCMUT–VNUHCM, 268 Ly Thuong Kiet Street, District 10, Ho Chi Minh City, Vietnam *Email: bmhuong@gmail.com Received: 30 December 2017; Accepted for publication: 3 March 2017 ABSTRACT The photocatalytic activity of TiO2–SiO2 coated and TiO2 coated on 100% cotton and PES/Co fabrics was investigated through the self–cleaning of red wine stains and coffee stains. It was shown that a TiO2 species could be produced at temperatures of 25 °C, 40 °C and 60 °C with acceptable photo–activity and TiO2–SiO2 nanocomposites were prepared by a sol–gel process at a low temperature. The discoloration of red wine and coffee led to CO2 evolution that was more efficient for TiO2–SiO2 coated cotton for samples than of TiO2 coated ones. The textile surface did not show any change after several consecutive light–induced discoloration cycles of a red wine stain and coffee stain. The structural properties of these nanocomposites were characterized with scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT–IR). The scanning electron microscope (SEM) photo showed that the TiO2– SiO2 layer is thicker than TiO2 layer on the cotton fabric and PES/Co fabric and the Ti–particles were always surrounded by amorphous SiO2 and never alone by themselves. The TiO2–SiO2 nanocomposites were coated onto cotton and PES/Co fabrics by a simple dip–pad–dry–cure process. Keywords: self–cleaning, fabric, TiO2–SiO2, coating, sol–gel method. 1. INTRODUCTION The term of “making clothes wash themselves” has become more popular in recent years, when fabric only need a spot of sunshine to get rid of those spills and stains during usage. The method developed is a saving efficient way to grow special nanostructures, which can degrade organic matter when exposed to light, directly onto textiles. In the research field of self–cleaning in recent years, crystalline TiO2 has received much attention due to their interesting properties as photocatalyst. Nano–sized particles show high photoactivity due to their large surface area per unit mass and diffusion of the electron/holes before recombination [1]. The commercial use of TiO2 as photocatalyst is becoming widespread in the areas of: (a) for water purification; (b) air purification; (c) sterilization/disinfection; and (d) systems involving applications of the recently Application of self–cleaning treatment on cotton and PES/Co fabric using TiO2 and SiO2 78 reported superhydrophilic effect [1]. A several studies also report the nucleation of anatase at relatively low temperatures: (a) from sol–gel coated substrates exposed to boiling water; (b) at 100 °C from sol–gel exposed to water vapor; (c) at temperatures 60–180 °C from TiO2–SiO2 films exposed to water vapor [1–3]. In the last case, the treatment with water vapor reduced the temperature necessary to produce anatase crystallites in the sol–gel films to temperatures below 100 °C by phase separation of the TiO2 from the SiO2; (d) anatase nano–crystals were produced more recently on cotton fabrics from the TTIP alkoxide solution at low temperature by sol–gel process with grain sizes of ∼20 nm. The anatase phase was attained on the cotton textile surface by boiling the textiles in water for 3 h [1, 4, 5]. It was concluded that self–cleaning fabrics have been successfully prepared by depositing and grafting TiO2 nanoparticles via an aqueous sol process at low temperature. Anatase TiO2 nanoparticles were well developed in size of 3–5 nm. These TiO2–coated cotton fabrics possessed distinct self–cleaning properties, such as bactericidal activity and photocatalytic decomposition of dyes. The photocatalytic activity of the treated fabrics was fully maintained upon several numbers of photodegradation cycles [2]. In addition, the photocatalytic activity of TiO2–SiO2–coated cotton textiles were investigated through the self–cleaning of red wine stains. The discoloration of red wine led to CO2 evolution that was more efficient for TiO2–SiO2–coated cotton for samples than of TiO2–coated ones. The textile surface did not show any change after several consecutive light–induced discoloration cycles of a red wine stain. By high–resolution transmission electron microscopy (HRTEM), the TiO2–SiO2 layer thickness on the cotton fibers was detected to 20–30 nm. The TiO2 and SiO2 were both observed to have particle sizes between 4 and 8 nm. Further electron microscopy work coupled with energy dispersive spectroscopy (EDS) showed that the Ti–particles were always surrounded by amorphous SiO2 and never alone by themselves [4]. Infrared spectroscopy revealed that no modification of the cotton could be detected after photo–discoloration processes with TiO2–SiO2, taking a wine stain as model compound. The mixed TiO2 and SiO2 colloids lead during the dip–coating and subsequent thermal treatment on cotton to an organized structure of highly dispersed TiO2 particles always surrounded by amorphous silica [4, 6, 7, 8]. Therefore, this study demonstrates that the photocatalytic activity of TiO2–SiO2 coated and TiO2 coated on 100% cotton and PES/Co fabrics can be successful by the self–cleaning of red wine stains and coffee stains. It was shown that a TiO2 species could be produced at low temperatures with acceptable photo–activity on non–heat resistant materials and TiO2–SiO2 nanocomposites could be prepared by a sol–gel process at a low temperature. 2. MATERIALS AND METHODS 2.1. Materials Titanium tetra isopropoxide (TTIP, 97 % purity), methyltrimethoxysilane (MTMS, 98 % purity), SiO2 nanoparticles (5–15 nm) were purchased from Sigma – Aldrich. The other chemicals used to include ammonia (28 % – 30 %), acetic acid (99.9 %), nitric acid (70 %) were purchased from Xilong Chem Co. Ltd. (China). The commercial 100 % cotton fabrics, woven weave, weight 135 g/cm2, warp density 90 threads cm–1, weft density 85 threads cm–1, scoured and bleached (supplied by X28 Co, Viet Nam) were used. PeCo 65/35 fabrics, warp density 51 threads cm–1, weft density 27 threads cm–1. Samples were prepared with the size of 4 cm × 12 cm. Bui Mai Huong, Trinh Thi Kim Hue 79 2.2. Preparation of TiO2 nanosols Titanium tetra–isopropoxide (TTIP, 5 ml) was added dropwise into 100 mL acidic water containing 1 mL nitric acid 70 % and 10 mL acetic acid 99.9 % under stirring. The mixtures were heated at different temperatures, namely 25, 40 and 60 °C, and kept vigorously stirred for 16 h, pH = 1–2. The prepared TiO2 nanosols were named as A25, A40 and A60. 2.3. Preparation of TiO2–SiO2 composite colloids The SiO2 powder (5–15 nm) was added to TiO2 nanosol (A60) and dispersed in an ultrasonic bath for 15 min. The TiO2/SiO2 mixture was kept for 12 h to form TiO2–SiO2 composite particles (pH = 3–5). The TiO2–SiO2 layers in a 1:1, 1:2, 2:1 volume mixture made up of the TiO2 colloid A60 and SiO2. The prepared TiO2/SiO2 nanocomposites were named as B1, B2 and B3, respectively. 2.4. Coating process The as–prepared TiO2 nanosols and TiO2–SiO2 composite colloids and were used to prepare thin coatings on substrates (cotton fabrics and PeCo fabrics) by a dip–pad–dry–cure process. The cleaned substrates were dipped in TiO2 sols and TiO2–SiO2 composite colloids for one minute, pressed with a padder at a nip pressure of 2.75 kg/cm2 to keep the same amount of TiO2 and TiO2–SiO2 composite on each of the fabric substrates. After 5 min, the padded fabrics were put in ammonia gas for neutralization to get pH = 7 of the fabric surface. The substrates were dried at 80 °C for 5 min in a preheated oven and finally cured at 120 °C for 3 min. 2.5. Characterization The structure and morphology of these coatings were investigated using scanning electron microscopy (SEM, Hitachi S4800). The chemical composition of the samples was identified by infrared spectrometer (IR, Tensor 27, Bruker). The characterization experiments were implemented at Ho Chi Minh city Academy of Science and Technology, Vietnam. 2.6. Evaluation of the textile cleaning action The textile cleaning action was evaluated by the discoloration of a wine stain and coffee stain, which was added on to the bleached fabrics surface, after 0, 4, 8 and 24 h in a solar light irradiation. The test was implemented at Textile–Dyeing Laboratory of Thanh Cong Textile Garment Investment Trading Joint Stock Company (TCG), Vietnam. 3. EXPERIMENTAL RESULTS 3.1. Assessment of water absorbance of TiO2–SiO2 coated fabric Figure 1 describes the water absorption ability of the cotton fabric treated with sol TiO2 with at different of temperature of 25°, 40°, and 60° without the exposedness to UV. The three samples show the round shape water drops with the contact angle between the water drop and the fabric surface is greater than 90°. This demonstrated that fabric surface coated with sol TiO2 became hydrophobic. Ap 80 F co fab co Pe an exp rea the spr fab tha hig sam the plication of s Figure 1. Wa igure 2. Wate However, lloids (Figur ric coated w ated with on Co fabrics a gle smaller t lain this ph cts to the b PeCo fabric As shown ead out imm ric surface. t the absorp her than th ples is low re is the app elf–cleaning ter absorbanc r absorbance when dripp e 2), the wa ith TiO2–S ly sol TiO2 re also intro han 30 °C. enomena, w onding of Ti surface hav in Figure 2 ediately to The percent tion ability at of cotton er than that earance of treatment o e capacity of sol TiO capacity of co colloid ing the wat ter drops wi iO2 colloid h and untrea duced in Fig The FI–IR s here we fou –O–Ti and e the higher , the water d fabric surf age of trans of the PeCo fabric. The of the cotto the stretchin n cotton and cotton (upper 2 at different tton (above) s at different er drop on t ll spread ou ave higher ted fabric. T ure 1. The a pectra of co nd only dou Ti–O–Si, th water absor rops on fab ace. The dr mittance illu fabric coa percentage n samples. F g vibration C PES/Co fa line) and PeC temperature. and PeCo (un mixing ratio. he fabric su t the fabric capability o he differen ngle of thre ated PeCo f ble covalen e inverse ch bance than u ric coated w ops were al strated in F ted with sol of transmit igure 3 sho =O. These bric using Ti o (under line der) fabrics tr rface coated surface. This f water abso ces when co e water drop abrics in Fig t bond C=O emical react ntreated fab ith TiO2–SiO most compl igure 3 and TiO2 and T tance of the wed that, at peaks 1272 O2 and SiO2 ) fabrics treat eated with Ti with the T can be said rbance than ating on co possessed ure 3 can b . When this ion occurs t ric. 2 colloids t etely contac Figure 4 als iO2–SiO2 co ion bonds the peak 17 cm–1, 1407 ed with O2–SiO2 iO2–SiO2 that the the one tton and a contact e used to bonding hat make ended to ted with o proved lloids is of PeCo 13 cm–1, cm–1 and 28 app ox ph an the vib ob the app bo the 90 cm–1 are earance of idation of th otocatalytic d cotton fabr similar pro ration. The servation the appearance earance of nding of Si– photocataly Figure 3. F Figure 4. FT respected the bondin e sol TiO2 c activity. Fig ic treated w file. The va peaks 1000 lowest line of the Ti– Ti–O–Si bo Ti. This bon tic activity o T–IR spectra 2:1(m –IR spectra o (mid to the stretc g of carbox oating and T ure 4 presen ith sol TiO2 lues in the cm–1, 150 correspond O–Ti bonds nd in the co ding surface f the TiO2/S of untreated iddle line) and f untreated co dle line) and t hing vibrat ylic group iO2–SiO2 c ts the spec (60 °C) and range of 31 0 cm–1 and s to cotton f respect to ating TiO2/ acidity of th iO2 coating cotton fabric treated with tton fabric (u reated with s B ion C–H. T and Ti ato olloid coatin ific FT–IR s the TiO2–SiO 00–3600 cm 2997 cm–1 abric treated the wavele SiO2 at the e nano mix on the cotto (upper line), t sol TiO2 A60 pper line), tre ol TiO2 A60 ( ui Mai Huon he peak 15 ms. This bo g leading to pectra of un 2 2:1 colloi –1 correspon present the with sol Ti ngth ranges peak 897 cm ture TiO2/Si n fabric. reated with T (lower line). ated with TiO lower line). g, Trinh Thi 32 cm–1 sho nding impr the easier a treated cott d. Three spe d to O–H s C–H vibra O2 at 60 °C 450–700 c –1 notices t O2 and also iO2–SiO2 coll 2–SiO2 colloi Kim Hue 81 wed the oves the nd faster on fabric ctra have tretching tion. By , there is m–1. The he stable increases oids ds 2:1 Ap 82 fou den 3.2 8 h all dis int sol Dis Tim Un fab Tre sol Tre TiO plication of s Those rem nd a thin b se film coat . Assessmen On the su then 20 h e three heatin coloration c ensively unt TiO2 A60 e T coloration e treated ric ated with TiO2 A60 ated with 2–SiO2 2:1 elf–cleaning arks are ill ut most hom ed on fabric Figur t of self–cle rface of untr xposure tim g mixture an be clearl il 8 h and a xhibited the able 1. Red w 0 h treatment o ustrated by ogenous co treated with e 4. SEM ima aning abilit eated fabric e as display of 25 °C, 4 y seen only lmost disapp best self–cle ine stain on tr n cotton and SEM image ating film TiO2–SiO2 ge of untreate y of TiO2–S , the coffee a ed in Table 0 °C and 60 after 4h sun eared until aning effect eated cotton 4 h PES/Co fa of coated f on fabric tre 2:1. d and treated iO2 coated nd wine sta 1 and Table °C, the se light exposu 20 h. Amon . fabric after di bric using Ti abric as sho ated with T PeCo fabric. fabric ins have rem 2. When coa lf–cleaning re. The disc g them, the fferent exposu 8 h O2 and SiO2 wn in Figu iO2 A60 an ained even ting with so effect occur olorations c samples trea re time. 20 h re 5. We d a very after 4 h, l TiO2 at red. The ontinued ted with is at Dis Un Tre A6 Tre 2:1 ab the exp an red mo is dis CO ion film tha ob co Pe Treated w greater than 8h exposure coloration Ti treated fabric ated with sol 0 ated with TiO This prov ility of coate stain from p osure to su d hole (h+) w wine and c ve up to the The self–c higher than appearing a OH bondin bonding m attached o n usual. The This stud tain when tr lloids synthe Co fabric fr ith different that treated time and the Table 2. Coff me TiO2 2–SiO2 ed the impa d fabric. Th enetrating i nlight, the p hich receive offee stains path of TiO leaning abil that of the c fter 8 hours. g, therefore ake a huge n the fiber s photocataly y demonstra eated with T sized by so om stains, e mixture rati with only so vanishing o ee stain on tre 0h ct of nano e nano SiO2 nto the fiber hotocatalytic the energy . The electr 2. ity of PeCo otton sampl The PeCo f during paddi of nano mol tructure of t tic activity h 4. ted that tha iO2 nano s l–gel metho ven with ha o of the TiO l TiO2. We f stain at 20 ated PeCo fa SiO2 in the created the structure. W activity oc from the un ons received samples coa es. Accordin abric mainl ng processe ecules conne he fabric. T appened fas CONCLU t self–cleani olution prep d. The coati rd stains su B 2–SiO2, the could see th h exposure bric after diff 4h mixture of thin film on hen the TiO curred and g stable cation energy to ted with the g to table 1 y consists of s of TiO2 an ct together his will form ter leading t SIONS ng capacity ared at 60 ° ng film on s ch as wine ui Mai Huon self–cleanin e intensive time. erent exposur SiO2–TiO2 the fabric s 2 coating fil enerated the from “pigm overcome th sol TiO2 an and 2, the s C=O, C–O d TiO2–SiO2 to form a th the bigger o the faster s of cotton a C and with urfaces prot or coffee st g, Trinh Thi g capability discoloration e time. 8h on the self– urface and p m in fabric s pair of elec ent” color i e restricted d SiO2–TiO2 tains are co , –O–C=O, on the fabr ick and hom anatase cry tain discolo nd PeCo fab nano TiO2– ected the co ains. The n Kim Hue 83 of fabric of stain cleaning revented urface is tron (e–) nside the area and colloids mpletely –COH, – ics, these ogenous stals size ration. rics can SiO2 2:1 tton and ano TiO2 Application of self–cleaning treatment on cotton and PES/Co fabric using TiO2 and SiO2 84 acted as semiconductor photocatalyst with the support of nano SiO2 forming a film on fabric that prevent stain from penetrating deeply in to the fiber structure and accelerate the faster discoloration. The preparation can be simply and effectively done at laboratory atmosphere. The fibers maintain their original shape and the coating made a homogenous film on fabric surface as illustrated by SEM images. The influence of treatment on tensile strength and other physical properties of fabric as well as the antibacterial properties of sol–gel TiO2–SiO2 can be investigated in future work of this study to confirm the effectiveness of this treatment on commercial fabric. Acknowledgements. 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