Al-Qadisiyah Journal For Engineering Sciences, Vol. 8……No. 2 ….2015 821 Degradation of Organic Dyes using Photo-Catalytic Technique M.Sc. Ayad Dari Jaafar Department of Chemical Engineering University of Technology E-mail: ayad.dari@yahoo.com Received 15 December 2014 Accepted 3 February 2015 ABSTRCT The present investigation is concerned to study the prepared of nano composite catalyst of titanium dioxide and carbon nanotube (TiO2/CNT) based on photo-catalysts process. The synthesized composite catalyst was characterized by Brunauer, Emmett and Teller (BET), Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), XRF and Raman Spectroscopy. Moreover, the nano composite catalyst was used as a dye to degradation of contaminated water that containing organic pollutants. The photo-catalytic degradation process was carried out at different operational parameters, (Initial concentration of hydrogen peroxide H2O2 of the medium, mixing speed, and flow rate for methylene blue (MB, C16H18N3SCl.3H2O) dye). The nano titanium dioxide / carbon nanotubes (TiO2/CNT) composite showed greater photo-degradation activity under solar and ultraviolet (UV) lamp. Keywords: photo-catalytic, carbon nanotubes, Titanium dioxide, Dyes degradation, nano technique. المحفز بالضوءاغ العضويه بتقنية االصب تكسر راياد داري جعفم.م قسم الهندسة الكيمياويه الجامعة التكنولوجية الخال صة ز تحفيلعملية ال (TiO2/CNT)تحضير العامل المساعد النانوي المركب من اوكسيد التتانيوم وانابيب الكاربون دراسةالبحث يتناول (, و تقنيات BETخصائص العامل المساعد بقياس المساحة السطحية للمركب المحضر باستخدام طريقة ) دراسةتم , حيثبالضوء العامل المساعد النانوي المركب عالوة على ذلك استخدم. ومقياس رامان XRD,XRF( , SEMالمجهر االلكتروني الماسح) عملية المحفز في كسرعملية الت دراسة عدة عوامل مؤثرة على تمت بعد ذلك . ملوثات المياه العضويه مثل االصباغكسير لت والعامل (, والجريان الحجمي للصبغةrpm) (, وسرعة الخلطmg/L) H2O2 لبروكسيد الهيدروجين ) التركيز االبتدائي للضوء .واالشعة الفوق البنفسجية اشعة الشمسالعامل المساعد النانوي كفاءة عالية تحت تاثير اظهر . ( (L/min) المساعد الصبغة, تقنية النانو. كسر, كاربون نانوتيوب, اوكسيد التيتانيوم , تالمحفز بالضوءمفاتيح الكلمات: mailto:ayad.dari@yahoo.com Al-Qadisiyah Journal For Engineering Sciences, Vol. 8……No. 2 ….2015 821 INTRODUCTION Degradation of organic pollutants and dyes such as methylene blue, bromo phenol blue, and Chicago sky blue from industrial waste water remains as a challenge because of low visible light photo catalytic activity of metal oxides and sulphides [1] . The possibility of combining heterogeneous catalysis with solar technology to achieve complete mineralization of toxic organic pollutants has received much attention [2] . Multi-walled carbon nanotubes (MWCNTs) could be considered as a good support for materials with field emission displays and photo-catalytic properties. On the other hand, a combination of Titanium dioxide (TiO2) and MWCNT could create many active sites for the photo-catalytic degradation [3] . Advanced chemical treatment processes are used many times to achieve better treated water quality for use and also when the necessary standards are not being met with the conventional means of treatment [4] .An advantage of photo-catalytic method includes low temperature, low expenses and also radically low level of energy consumption in this method [5] . Won C. O. and Ming L. C. were used the activated carbon materials and TiO2 composites by mechanical and hydrothermal treatment while demonstrated very good performance in the photo- catalytic degradation of methylene blue [6] . The Ferrous ion and TiO2 units were covered on the activated carbon surface and were developed through a deposition process of a sol-gel method. The Ferrous–AC/TiO2 samples show a strong degradation and can efficiently decompose the methylene blue (MB) solution under visible light (Za-Da Meng, Kan Zhang) [7] . Sonal S., Rimi Sh., Els., a comparative photo-catalytic study of ZnFe2O4 and (ZnFe2O4/multi wall carbon nano tubes) nano composite clearly indicated the enhancement of photo-catalytic activity in (ZnFe2O4/ multi wall carbon nano tubes) nano hybrid. MB was almost 84% degraded in the presence of ZnFe2O4 photo-catalyst, while 99% degradation was observed in case of ZnFe2O4/MWCNT composite after irradiation for 5 hours in the visible light [8] . In this work, the nano composite catalyst of titanium dioxide and carbon nano tube (TiO2/CNT) was prepared based on photo-catalysts process. The synthesized catalyst was characterized using a different analytical technique. The effect of nano photo-catalytic TiO2/CNT composite was also evaluated by methylene blue (MB) degradation in aqueous solution under an UV lamp and solar. EXPERIMENTAL WORK Catalysts Preparation Nano-TiO2 (5 gm) was added to the aqueous Fe (NO3) and stirred for 3 hrs. Resultant suspension was filtered and solids were washed with D.I. water until its pH reaches 7. A washed solid was dried in vacuum at 60 0 C for 2 hrs to obtain yellowish TiO2 powder loaded with Fe 3+ ions. It was coated on substrate and used in thermal furnace as a catalytic substrate. The above prepared catalytic substrate was placed at center of quartz tube in furnace at temperature 300 0 C – 800 0 C. It was then catalytically (Fe +3 ) deposited over TiO2 surface as CNTs, (Fig.1). Catalysts Characterization The Scanning Electron Microscopy (SEM) of carbon nanotubes and carbon nanotubes-TiO2 composite explain the different Morphology between the two prepared samples. The SEM images of 10,000 magnifications of the prepared catalysts are shown in (Fig.2) than indicates that the pure carbon nanotubes and composite materials present a homogeneous distribution of TiO2 on the CNTs. So it was considered that nano CNT-TiO2 composites could have much more activity and show an excellent photo-catalytic activity. Al-Qadisiyah Journal For Engineering Sciences, Vol. 8……No. 2 ….2015 831 The XRD (model PANalytical X'Pert pro MPD) patterns of the nano TiO2/CNT composites were displayed in (Fig.3). The patterns demonstrate the highly crystalline nature of the composites. The characteristic peaks for CNT at position of 2Ɵ= 26.5°. And you could see peak TiO2 at 2Ɵ= 43.5°. BET surface area was measured using a Surface Area analyzer (Q-surf 9600, USA) were used to observe the surface of the TiO2/CNT composites is 33 m 2 /gm. From (Fig.4) could be observed that the XRF for pure carbon nanotubes prepared until to 98% graphite. (Fig.5) shows Raman spectroscopy vs Wave number (cm -1 ) revealed invaluable insights into the purification of nanotubes. G-band (1568 cm −1 ) corresponded to the confirmation of MWCNTs. Defect induced D-band (1350 cm −1 ) was minimized after purifying CNTs. Photo-catalytic degradation of dye The photo-catalytic effect of nano TiO2/CNT composite was evaluated by methylene blue (MB) degradation in aqueous solution under solar and UV lamp (365 nm, 1.2 Mw/cm 2 ). Before turning on photo-catalytic unit, the solution mixed with composite and H2O2 for 30 min. Then, the solution was radiated with photo-catalytic unit, (Fig. 6). Sample of methylene blue (MB) solution were withdrawn at the rate of (0.5, 1, 1.5 and 2 L/ min) and concentration hydrogen peroxide H2O2 (200,300,400 and 500 mg/L).The agitation mixing (100, 250, 750 and 1400 rpm) with 50 mg/L from composite catalyst and pH=7 for mixture to degradation the dye. RESULTS AND DISCUSSION (Fig.7) shows, the Degradation of the methylene blue MB (ppm) versus UV illumination time (min) at different mixing agitation (rpm). From these figure, the prepared catalysts show the high photo-catalytic activity and degradation of methylene blue (MB). The increment of nano (TiO2/CNT) mixing in the composite (100, 250, 500, 750 and 1400 rpm) leads to increased photo catalytic activity and degradation ability. During initial 105 minutes the high degradation at mixing speed 1400 rpm at constant (flow rate for mixture 1.5 L/min, CH2O2= 300 mg/L, CCNT/TiO2= 50 mg/L and pH=7) is 0.74, the dyes were rapidly degradation in all case due to the effect of the solid nano materials. (Fig. 8) shows, the photo-degradation ability of the samples also improved with the increment of flow meter recycles for mixture (0.5, 1, 1.5 and 2 L / min). This indicates that the increasing flow rate for mixture (MB dyes with nano (TiO2/CNT) composite) increase degradation of methylene blue (MB) until 1.5 (L/min) is 0.74. Then increasing flow rate to 2 (L/min) the degradation of dyes is 0.69 because at 1.5 (L/min) the better flow rate to distribution in photo-catalytic reactor and when this flow, the solar energy absorbed by nano composite is very sufficient to degradation the dye. Carbon nanotubes CNTs might accept the photo-induced electron (e-) into the conduction band of the TiO2 particles by (UV + solar) irradiation (Eq.1). It is considered that electrons in CNTs are transferred to the conduction band in the TiO2 particles. In this time, the electrons in conduction band might react with (O2 - .). Simultaneously, a positive charged hole (h+) might be formed with electron transfer from valence bond in TiO2 to CNTs (Eq.3). The positive charged hole (h + ) might react with OH - derived from H2O. with this understanding, the role played by CNTs can be illustrated by injecting electrons into TiO2 conduction band under (UV + Solar) irradiation and triggering the formation of very reactive superoxide radical ion (O2 - . ) ((Eq.2 and hydroxyl radical OH . ) (Eq.4)). consequently, both radical group (superoxide radical ion (O2 - . ) and hydroxyl radical (OH . )) are responsible for degradation of the organic compound as MB. ⃗⃗ ⃗⃗ ⃗⃗ ⃗⃗ ⃗⃗ ⃗⃗ ⃗⃗ ⃗⃗ ⃗ (1) Al-Qadisiyah Journal For Engineering Sciences, Vol. 8……No. 2 ….2015 838 ⃗⃗⃗⃗ ⃗⃗⃗⃗ ⃗⃗ ⃗ (2) ⃗⃗ ⃗⃗ ⃗⃗⃗⃗ ⃗⃗ ⃗⃗ (3) (4) Plots the variation in dye degradation against hydrogen peroxide concentration in solution keeping all other parameters unchanged. Different concentrations of (200,300,400 and 500 ) were added to study the effect of concentration on the degradation process. The rate of degradation goes on increasing with the increase in concentration of H2O2 and becomes maximum at 300 mg/L (Degradation of methylene blue is 0.74) and then starts decreasing with further increase in concentration of H2O2 (Degradation of methylene blue is 0.62, 0.45 at CH2O2 is 400 and 500 mg/L sequentially) .The addition of H2O2 may play an important role in the limitation rate of photogenerated hole-electron pairs that contribute to degradation rate MB dyes, (Fig. 9). As can be seen, the degradation increases with increasing initial concentration of , as the formation of hydroxyl radicals is insufficient, this may explain the ability of to trapping the electrons preventing the electron-hole recombination hence decrease the chance for formation of radicals on the surface of the catalyst. However, as the initial concentration of increases beyond a certain value (300 , the increase in decomposition rate becomes less. This is because at higher concentration, more is produced leading to a faster oxidation rate. However, the excess free radicals prefer to react with the excess of rather than with the dye. CONCLUSION The synthesis and characterization of nano TiO2/CNT composites thermally derived from CNTs by an improved oxidation method because the conductive structure of the CNT scaffolds might facilitate the separation of the photo-generated electron/ hole pairs at the CNT-TiO2 interface leading to the faster rates of photo-catalytic oxidation. In addition, the application of anodic potentials on irradiated TiO2/CNT composites films might result in a further enhancement. The structural variations, elemental analysis and surface morphology were investigated through preparation of TiO2/CNT composites under ultraviolet UV and solar light irradiation. The TiO2/CNT composite showed greater photo-degradation activity under UV and solar light irradiation. Changes of color disappearance for relative methylene blue (MB) degradation concentration under UV and solar light irradiation in the solution as a function of time was studies. The MB degradation with CNT/TiO2 composite was carried out to observe the UV photolysis effect. REFRENCES [1] Sonal S., Rimi Sh., Charanjit S., Bansal S., "Enhanced Photocatalytic Degradation of Methylene Blue Uing ZnFe2O4/ MWCNT Composite Synthesized by Hydrothermal Method", Indian Journal of Materials Science, Hindawi, http://www.hindawi.com, Volume 2013. [2] Noureddine B., Samir Q., Ali A., Yhya A.,"Solar Photocatalytic Degradation of Textile on Dynamic Pilot Plant using Supported TiO2" ,The Arabian Journal for Science and Engineering, vol35, No.2A, 2010. [3] Won-Chun O., Ming-Liang Ch.,"Synthesis and Characterization of CNT/TiO2 Al-Qadisiyah Journal For Engineering Sciences, Vol. 8……No. 2 ….2015 832 composites Thermally Derived from MWCNT and Titanium (IV) n-Butoxide", Department of Advanced Materials & Science Engineering,Vol.29 , 356-706. 2008. [4] Kumr R., Singh R.N., Municipal Water and Wastewater Treatment, Environmental Engineering Series, 93, 2014. [5] Ehrampoush M. H., Moussavi GH. R. , Ghaneian M. T. ,Rahimi S. , Ahmadian M.," Removal of methylene Blue Dye from Textile Simulated Sample using tubular Reactor and TiO2/ UV-C Photocatalytic Process",vol.8, No.1, 2011. [6] Won-Chen O., Ming-Liang Ch.,"Synthesis and Characterization of CNT/TiO2 Composites Thermally Derived from MWCNTs and Titanium (IV) n-Butoxide", vol.29, No. 1, 2008. [7] Za-Da M. , Kan Z. and Won-Chun O. ,"Preparation and characterization and Visible Light Photocatalytic Activity of Fe-Treated Ac/TiO2 Composites for Methylene Blue", vol.46, 2009. [8] Sonal S., Rimi Sh., Charanjit S. and Bansal,"Enhanced Photocatalytic Degredation of Methylene Blue Using ZnFe2O4/ MWCNT Composite Synthesized By Hydrothermal Method", Indian Journal of Materials Science, Hindawi, volume 2013 Figure (1): Carbon nanotubes deposit it TiO2 Particles Process. Furnace 100-1100 0 C Quartz tube Ceramic Basin TiO2 Particles (Hydrocarbon Source+ Nitrogen)gas Control Al-Qadisiyah Journal For Engineering Sciences, Vol. 8……No. 2 ….2015 833 Figure (2): SEM images of the (a) functionalization of carbon nanotubes (b) Nano (CNT/ TiO2) Figure (3): XRD of composite (TiO2/ CNT) TiO2 CNT b a 2 theta (') Intensity Al-Qadisiyah Journal For Engineering Sciences, Vol. 8……No. 2 ….2015 831 Figure (4): XRF of carbon nanotubes. Fig.(5) Raman spectra of nano composite Figure (5): Raman spectra of nano composite D= 1350 cm -1 G=1568 cm -1 Al-Qadisiyah Journal For Engineering Sciences, Vol. 8……No. 2 ….2015 831 Figure (6): Photo-catalytic unit. Figure (7): The Degradation of the methylene blue MB (ppm) with UV illumination time (min) at different mixing agitation (rpm) at constant CH2O2= 300 mg/L and flow rate = 1.5 L/min, ( pH= 7 and CCNT/TiO2 = 50 mg/L). 0 0.2 0.4 0.6 0.8 0 50 100 150 D e g ra d a ti o n o f M B UV illumination Time min Series1 Series2 Series3 Series4 Series5 1400rpm 250rpm 750rpm 100rpm 500rpm Al-Qadisiyah Journal For Engineering Sciences, Vol. 8……No. 2 ….2015 831 Figure (8): The Degradation of the methylene blue MB (ppm) with UV illumination time (min) at different flow rate (Liter/min) at constant CH2O2= 300 mg/L and mixing agitation = 1400 rpm ,(pH=7 and CCNT/TiO2 = 50 mg/L). Figure (9): The Degradation of methylene blue MB (ppm) with different concentration of Hydrogen Peroxide H2O2 (mg/L) at constant flow rate =1.5 L/min and mixing =1400 rpm, (PH=7 and CCNT/TiO2 = 50 mg/L). 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0 50 100 150 D e g ra d a ti o n o f M B UV illumination Time min Series1 Series2 Series3 Series4 0.5 L/min 1 L/min 1.5 L/min 2 L/min