(Luận văn) development of novel titanate nanotubes reduced graphene oxide composite for the removal of heavy metals from aqueous solution

THAI NGUYEN UNIVERSITY UNIVERSITY OF AGRICULTURAL AND FORESTRY lu an n va VU THI HOAI tn to gh TOPIC TITLE: DEVELOPMENT OF NOVEL TITANATE NANOTUBES/ REDUCED GRAPHENE OXIDE COMPOSITE FOR THE REMOVAL OF HEAVY METALS FROM AQUEOUS SOLUTION p ie oa nl w d oi lm ul nf va an lu BACHELOR THESIS Study Mode: Full-time nh Major: Environmental Science and Management at Faculty: International Training and Development Center z z Batch: 2010-2015 om l.c gm @ Lu an n va Thai Nguyen, 15/01/ 2015 ac th si DOCUMENTATION PAGE WITH ABSTRACT Thai Nguyen University of Agriculture and Forestry Degree Program Bachelor of environmental Science and Management Student name Vu Thi Hoai Student ID DTN1053110084 Development of Novel Titanate Nanotubes/ Reduced Graphene Oxide Composite for the Removal of Heavy Metals from Aqueous Solution Thesis Tiltle lu an n va Prof Dr Nguyen The Dang, Thai Nguyen University of Supervisor(s) Agriculture and Forestry, Vietnam to tn Prof Ruey-an Doong, National Tsing Hua University gh Abstract p ie Graphene oxide (GO), is a two dimensional carbon nano-material which exhibits a nl w great adsorption potential Graphene functionalized composites enhance its adsorption efficiency for toxic heavy-metals from contaminated waste water Titanium nanotubes oa d and GO were assembled in basic medium via microwave-assisted hydrothermal lu an method The strong anchoring of TNT on the surface of GO sheets can be easily nf va observed by TEM (Transmission Electron Microscopy), XRD (X-ray Diffraction) oi lm ul Diffraction on GO sheets confirmed through D-band and G-band ration by Raman Spectroscopy As-synthesized TNT/rGO composite shows high efficiency and high nh selectivity toward heavy metals in aqueous solution The results indicated that at TNT/rGO composite with high adsorption efficiency and fast adsorption equilibrium z z can be used as a practical adsorbent for heavy metals in aqueous solution gm @ Keywords Titanate nanotube, Graphene oxide, composite, hydrothermal, adsorption 15/01/2015 Lu Date of submission: om 44 pages l.c Number of papers an n va ac th si ACKNOWLEDGEMENTS I am deeply indebted to my research supervisor Prof Ruey-An Doong, whose stimulating motivations and valuable ideas helped me to complete my thesis and I would like to offer my sincere gratitude to prof Dr Nguyen The Dang for his support throughout my thesis with his patience and knowledge whilst allowing me the room to work in my own way I attribute the level of my Bachelor degree to his encouragement and effort lu an I am grateful to Rama Shanker Sahu (PhD) and Yen-Tung Yang (PhD) for n va their valuable help, advices and constructive comments during all my experiments and to tn writing thesis gh p ie I would like to thank Duncan, Sammy, Joyce (MS) for their great support in nl w characterizing my samples, YC Ken Tsai (PhD) and Rudy (PhD) for their impressive oa help in adsorption studies d va an lu I would also like to thank Khanh, Linh and all FATECOL members, Biomedical Engineering and Environmental Sciences, National Tsing-Hua University, oi lm ul nf Taiwan, who provided their ongoing support, questions and suggestions z their support & endless love at nh Finally, I would like to express my love and gratitude to my beloved parents for z gm @ VU THI HOAI om l.c Lu an n va ac th si TABLE OF CONTENTS LIST OF FIGURES LIST OF TABLES LIST OF ABBREVIATIONS PART I INTRODUCTION 1.1 Research rationale lu 1.2 Research's Objectives an PART II LITERATURE REVIEW n va tn to 2.1 Overview of heavy metals 2.1.1 Definitions and sources of heavy metals gh p ie 2.1.2 Characteristics of heavy metals .7 2.2 Heavy metal pollution in the world and Vietnam nl w 2.2.1 In estuary, coastal and marine areas oa 2.2.2 In acid sulfate soil areas d an lu 2.3 Characteristics and hazards of some heavy metals 10 va 2.3.1 Arsenic (As) 10 oi lm ul nf 2.3.2 Cadmium (Cd) 11 2.3.3 Lead (Pb) 12 2.3.4 Copper (Cu) 13 nh at 2.4 Effects of heavy metal to environmental and human health 14 z 2.5 Some of treatment methods for the removal of heavy metals from aqueous solution 15 z gm @ 2.5.1 Carbon materials 15 l.c 2.5.2 Phytoremediation 18 om 2.5.3 Nanomaterials 19 Lu 2.5.4 Titanate nanotubes 19 an n va ac th si 37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.C.33.44.55.54.78.655.43.22.2.4.55.2237.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.66 2.6 Overview of handling heavy metals in aqueous solution using Titanate nanotube / reduced graphene oxide composite 20 2.6.1 Scientific Basis of handling heavy metals in aqueous solution by rGO-TNT composite 20 2.6.2 Some research results of absorption of heavy metals in water by rGO-TNT composite 20 2.6.3 Prospects of technological rGO-TNT composite in removal of heavy metals in aqueous solution .21 PART III METHODS 22 3.1 Materal 22 3.1.1 Chemicals .22 lu an 3.1.2 Instruments .22 n va 3.2 Methods 23 tn to 3.2.1 Synthesis of TNT 23 3.2.2 Synthesis of Graphene oxide 24 gh p ie 3.2.3 Synthesis of rGO-TNT Composite 25 3.2.4 Adsorption Experiment 25 nl w 3.2.5 The method of determining the characteristics of the material 27 oa PART IV RESULTS 32 d lu an 4.1 Characterization of GO and titanate nanotubes/rGO composite 32 nf va 4.2 Morphology of TNT, GO and rGO-TNT composite 35 oi lm ul 4.3 Application into removal of heavy metal ions 36 PART V DISCUSSION AND CONCLUSION 39 at nh 5.1 Discussion 39 z 5.2 Conclusion 40 z om l.c gm @ REFERENCES 42 Lu an n va ac th 37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.99 si 37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.C.33.44.55.54.78.655.43.22.2.4.55.2237.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.66 LIST OF FIGURES Figure 3.1 Schematic of TNT synthesis.………………………… .…24 Figure 3.2 Schematic of GO synthesis…… ……………………… …… …… 25 Figure 3.3 Adsorption experiment of Copper by TNT and rGO-TNT ………………27 Figure 3.4 Atomic adsorption spectroscopy (AAS)…………………… … …… 28 Figure 3.5 Raman spectroscopy…………………………………………………… 30 lu an Figure 3.6 Schematic of TEM …………………………….…………… .…… 31 n va Figure .7 The process TEM characterization…… ………………………… ….32 to tn Figure 4.1 Raman spectra of GO, rGO-TNT materials…………….…………… …33 gh p ie Figure 4.2 XRD patterns of GO……………………………………………… 34 nl w Figure 4.3 XRD patterns of TNT and rGO-TNT composite…………… …… .35 oa Figure 4.5 TEM images of the synthesis TNT and rGO-TNT composite………… 36 d lu va an Figure 4.6 The adsorption of Cu(II) by TNT at pH=5 in aqueous solution at room oi lm ul nf temperature.……………………………………………………………….… … 37 Figure 4.7 The adsorption of Cu(II) by rGO /TNT composite in aqueous solution at at nh room temperature.………………………… ……….… 38 z z om l.c gm @ Lu an n va ac th 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37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.C.33.44.55.54.78.655.43.22.2.4.55.2237.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.66 LIST OF TABLES Table 4.1 The results of Cu (II) adsorption experiment by TNT, was observed by Atomic adsorption spectroscopy (AAS) ……………………………………………37 Table 4.2 The results of Cu (II) adsorption experiment by rGO-TNT, was observed by Atomic adsorption spectroscopy (AAS)…………………………………………… 38 lu an n va tn to gh p ie oa nl w d oi lm ul nf va an lu at nh z z om l.c gm @ Lu an n va ac th 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37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.C.33.44.55.54.78.655.43.22.2.4.55.2237.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.66 LIST OF ABBREVIATIONS Abbreviations Full text content lu an TNT Titanate nanotube GO Graphene oxide TNT-rGO Titanate nanotube and reduced graphene oxide XRD X-Ray Diffraction TEM Transmission Electron Microscopy AAS Atomic adsorption spectroscopy n va tn to gh p ie oa nl w d oi lm ul nf va an lu at nh z z om l.c gm @ Lu an n va ac th 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37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.C.33.44.55.54.78.655.43.22.2.4.55.2237.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.66 PART I INTRODUCTION 1.1 Research rationale Pollution of air, water and soil is a worldwide issue for the eco-environment and human society Most of the earth's surface is covered by water, and most of the human body is composed of water These are the two facts illustrating the critical linkages between water, health and ecosystems It can be seen that, water is the most essential compound on the earth for the human activities Providing clean water is the prime lu an requirement of the human being for their better health Since the fast growing sector of n va industries, expansion of population, and urbanization have largely contributed to the tn to severe contamination of water, air and soil Chemical and fertilizers use in domestic gh p ie and agricultural activities leads to the lifetime threatening diseases Intense use of nl w heavy metals in industries for dyeing, paint etc is becoming one of the most serious oa environment problems globally Its presence in low concentration of heavy metals in d lu va an various water resources could be harmful to human health The treatment of heavy oi lm ul nf metals is so important due to their persistence in the environment In order to remove the heavy metals, various techniques have been developed The at nh traditional treatment processes for heavy metals include chemical precipitation, z electrolysis, adsorption, and ion exchange Among these methods, adsorption is an z gm @ efficient technology, which has been widely used for the removal of metal ions in aqueous solutions A wide variety of adsorbents including activated carbon, water om l.c treatment sludge, zeolite, fly ash, and biomass have been reported to effectively adsorb Lu an metal ions, showing varying extent of effectiveness in removing the toxic pollutants n va from air, water and soil ac th 37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.99 si 37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.C.33.44.55.54.78.655.43.22.2.4.55.2237.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.66 More recently, one-dimensional (1-D) titanate nanotube (TNT) have been reported to be an attractive adsorbent to effectively adsorb a wide variety of metal ions including Cu, Pb, Cd, and Zn because of their large specific surface areas and layered structures TNT is considered as a modified structure in photo catalysis owing to its special electronic and mechanical properties, high photo catalytic activity, large specific surface area and high pore volume, a potential material for removal of metal ions in the aqueous solution Besides, in the past few years, Graphene oxide (GO) have attracted tremendous lu an interest in the world Graphene is a two-dimensional carbon nanomaterial with single n va layer of sp2 hybridized carbon atoms arranged in six membered rings Graphene has tn to strong mechanical, thermal, and electrical properties with a theoretical value of gh p ie specific surface area at 2630 m2/g GO is a functionalized graphene with varying nl w oxygen containing groups Several views have been reported on applications of GO in oa different areas such as physics, chemistry, biology, and material science In particular, d lu va an graphene based materials are used as adsorbents for pollutants removal since graphene oi lm ul nf oxide possesses several functional groups and has strong acidity, exhibiting high adsorption for basic compounds and cations Graphene also has a hydrophobic surface at nh and presents high adsorption to chemicals due to strong π–π interaction z Among several physical, chemical and biological treatment techniques, the adsorption z gm @ is one of the simplest, fastest and most efficient processes or the removal of heavy metals Considering all aspects and issues mentioned above, I have paid attention to om l.c the preparation of titanate nanotube/reduced graphene oxide composite and Lu an subsequently used them as adsorbents n va ac th 37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.99 si 37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.C.33.44.55.54.78.655.43.22.2.4.55.2237.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.66 electrons and therefore have a smaller electron mean free path than lighter atoms) (Roson Ct Ste Ksan Diego) Successful imaging of materials using TEM depends on the contrast of the sample relative to the background Samples are prepared for imaging by drying on a copper grid that is coated with a thin layer of carbon Materials with electron densities that are significantly higher than amorphous carbon are easily imaged lu an n va tn to gh p ie oa nl w Figure The process TEM characterization d oi lm ul nf va an lu at nh z z om l.c gm @ Lu an n va th 37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.99 ac 31 si 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and z 865 cm-1 modes for the composites match with titanate structure (Habashi 2009 and z gm @ Liu et al, 2005) In addition, the peaks of the composite are broader and significantly om l.c shifted 98 cm-1 to 228 cm-1 The peak blue shift and broadening of the Raman spectra were analyzed using the most intense in this stage (228 cm-1 peak) The peak position Lu an and broadening of Raman spectrum is mainly affected by the size of the nanomaterial n th 37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.99 va as well as defects and temperature ac 32 si 37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.C.33.44.55.54.78.655.43.22.2.4.55.2237.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.66 Raman spectroscopy is also widely used for the characterization of the electronic structure of carbon products A change in Raman band intensity and blue shifts provide information on the nature of carbon- carbon bonds and defects The Raman spectra in Figure 4.1 show the characteristic D and G bands at 1346 cm-1 and 1589 cm1 found in GO and the composite The D band is common feature for sp defects in carbon, and the G band provides information on plane vibrations of sp bonded carbons The intensity ratio of the D band to the G band usually reflects the order of defects in GO or graphene Compared to GO, rGO-TNT composites show two lu an differences in the Raman spectra First, the calculated ID/IG of the rGO-TNT samples n va were lower than that of GO, indicating a lower density of defects present in rGO to tn Second, the G band shifts by ~ 5cm−1 in the rGO-TNT Therefore, both the change in gh ie p Raman band intensity and the blue shift of the G band provide clear evidence for the oa nl w presence of graphene in the composite) d an lu oi lm ul Intensity (a.u.) nf va GO at nh z z 30 40 60 om theta 50 l.c 20 gm @ 10 Lu an n va Figure 4.2 XRD patterns of GO th 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37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.C.33.44.55.54.78.655.43.22.2.4.55.2237.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.66 X-ray diffraction can also provide information on the crystal structure of the GO, TNTs and rGO-TNT Figure 4.2 shows a XRD pattern of GO with a sharp peak at about 2θ = 10.5o corresponding to (002) reflection was observed, giving an interlayer spacing of 0.9 nm lu an n va tn to Intensity (a.u.) rGO-TNT TNT gh p ie 20 30 40 50 60 70 80 theta oa nl w 10 d an lu Figure 4.3 XRD patterns of TNT and rGO-TNT composite nf va oi lm ul The crystal structures of as-prepared TNT and RGO–TNT electrodes were analyzed by XRD, as shown in Figure 4.3 The peaks present clearly represent the formation of nh at titanate nanostructures, derived from microwave-assisted hydrothermal conditions, can z z be assigned as NaxH2-xTi3O7 in our TNT nanostructures However, no apparent peaks gm @ for graphene were observed in the rGO–TNT sample Similar results were also om l.c reported by others However, the existence of graphene in our rGO–TNT electrode can be clearly elucidated by the above Raman analysis and following TEM, SEM images Lu an n va th 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37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.C.33.44.55.54.78.655.43.22.2.4.55.2237.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.66 4.2 Morphology of TNT, GO and rGO-TNT composite The morphological evolution of titanate in rGO-TNT composite was observed by TEM (transmission electron microscopy) images lu an n va tn to gh p ie oa nl w d lu va an Figure 4.5 TEM images of the synthesis TNT and rGO-TNT composite oi lm ul nf Figure 4.5a show the TEM image of TNT before the attachment of rGO The titanate nanotube showed tubular structures with lengths around 200-250 nm And, the TEM at nh observation in Figure 4.5b reveals numerous overlapped layers with high transparency, z implying very thin sheet- like structure No trace of spherical titanate nanotubes z gm @ precursors was found in hybrid materials, implying the successful interaction of Ti species in between carbonaceous layers and subsequent transform to sheet-like om l.c structure In addition, Raman spectra detected on large area showed the presence of Lu an dominant Ti and O species together with small amount of C It can be obviously three va components were well distributed in the hybrid material as shown in the mapping in n th 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37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.C.33.44.55.54.78.655.43.22.2.4.55.2237.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.66 Figure 4.5c Such characteristics demonstrate that the rGO sheets were assembled on the titanate nanotubes 4.3 Application into removal of heavy metal ions The absorption capacity of Copper ion by the TNT and rGO/TNT composite were examined Table 4.1 The results of Cu (II) adsorption experiment by TNT, was observed by Atomic adsorption spectroscopy (AAS) Cont.(mg/L) lu 10 20 0.317 0.332 0.383 0.447 0.591 10 0.303 0.303 0.304 0.306 0.31 30 0.303 0.304 0.305 0.31 0.306 0.303 0.303 0.306 0.306 0.306 0.301 0.301 0.302 0.305 0.303 an Time(min) n va tn to gh ie p 60 oa nl w 180 d nf 0.8 oi lm ul 0.6 at nh 0.4 C/C0 ppm ppm ppm 10 ppm 20 ppm va TNT an lu 1.0 0.2 z z 0.0 -0.4 30 60 90 120 Time (min) 150 om l.c gm @ -0.2 180 Lu an n va Figure 4.6 The adsorption of Cu(II) by TNT at pH=5 in aqueous solutionat room temperature th 37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.99 ac 36 si 37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.C.33.44.55.54.78.655.43.22.2.4.55.2237.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.66 Figure 4.6 shows the absorbed amounts of Cu(II) ion by different concentration of TNT including 1ppm, 2ppm, 5ppm, 10 and 20ppm, and different absorption time (10, 30 or 180 minutes) The adsorption of copper ion by titanate nanotubes increased rapidly with the increase in the equilibrium Cu (II) concentration The higher is the concentration, more stronger is the adsorption capacity The amount of heavy metal has reduced from 0.591 mg/L to 0.31 mg/L at the concentration is 20 ppm and mitigation under the next period Table 4.2 The results of Cu (II) adsorption experiment by rGO-TNT, was observed by an n va 10 20 0.317 0.332 0.383 0.447 0.591 gh Cont.(mg/L) 0.303 0.303 0.302 0.306 0.305 0.303 0.303 0.303 0.304 0.304 0.304 0.303 0.303 0.304 0.303 0.301 0.301 0.301 0.302 Time(min) tn to 10 p ie nl w 30 60 oa 0.301 d 180 an lu rGO-TNT 1.0 ppm ppm ppm 10 ppm 20 ppm nf va 0.8 oi lm ul 0.6 0.4 at nh 0.2 z C/C0 lu Atomic adsorption spectroscopy (AAS) z gm @ 0.0 -0.2 30 60 150 180 Lu 90 120 Time (min) om l.c -0.4 an Figure 4.7 The adsorption of Cu(II) by rGO /TNT composite in aqueous solution at n va room temperature th 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0.015 mg /L and was slightly increased from 0.001 to 0.003 mg/L at 180 minutes When increasing the concentration to 20 ppm, the lu an beginning adsorption with no adsorbent was 0.591 mg/L and with 10 mg of TNT/rGO n va composite in 10 minutes, the adsorption capacity was 0.305 mg/L and it was 0.302 tn to mg/L, 180 minutes When compared with TNT, the adsorption capacities of the gh p ie rGO/TNT composite reached higher than TNT It is well known that adsorption oa of rGO/TNT nl w strongly depend on the pore structure and surface area as well as surface functionality d oi lm ul nf va an lu at nh z z om l.c gm @ Lu an n va th 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titanate lu an nanotubes/reduced graphene oxide composite by hydrothermal method, and their n va adsorption capacity was evaluated XRD, TEM, and Raman spectroscopy studies tn to revealed the structural morphology of the synthesized material and confirmed the gh p ie formation of titanate nanotube of lengths 200-250 nm The presence of rGO nl w component in the rGO-TNT composite and the structural properties were confirmed by oa Raman spectroscopy and X-Ray diffraction d lu va an Experimental results obtained in this study clearly demonstrate that TNT/rGO oi lm ul nf composite are an effective adsorbent for heavy metals The amount of heavy metal has reduced from 0.591 mg/L to 0.304 mg/L at the concentration was 20 ppm in 30 at nh minutes and mitigation under the next period The experiment also compared the z absorption capacity between rGP/TNT and TNT, the results shows that the absorption z gm @ capacitie of the rGO/TNT was higher than TNT; it depends on the pore structure and surface area as well as surface functionality of rGO/TNT Thus, it is suggested that om l.c TNT/rGO prepared here could be a promising candidate sorbent material for removing Lu an heavy metal ions from aqueous solutions beyond the ordinary use of adsorbents The n va th 37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.99 ac 39 si 37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.C.33.44.55.54.78.655.43.22.2.4.55.2237.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.66 outstanding physicochemical properties of the TNT/rGO materials will play a very important role in environmental pollution management in the future 5.2 Conclusion In conclusion, results shown in the thesis clearly indicate the morphology of TNT and rGO by SEM and TEM The adsorption of Cu ions by TNT/rGO composites was examined and analyzed The TNT/GO nanocomposites showed excellent adsorption capacity toward Cu (II) adsorption and the adsorption can be complete within 30 This finding is interest and can be extended to remove other toxic chemicals in waters lu an and soils n va * There still lies a necessity in continuing the research on the adsorption of titanate tn to nanotube/reduced graphene oxide on the other materials such as metals (Pb, As, gh p ie Hg, ) nl w * Researching the adsorption of heavy metal ions of TNT/rGO to large scale that oa may have high practical applicability d lu va an * Significant tests regarding the ability to remove other ions on TNT/rGO to be oi lm ul nf used for a variety of different contaminated water environment Although every attempt has been made to make the review work presented in Section- at nh as up-to-date as possible, unintentional omission of important references if any, is z regretted In this report, Graphene oxide (GO) was prepared from graphite powder z gm @ according to the modified Hummer method The present study may be extended to other methods for high quality Graphene oxide In the present experiment, Cu(II) was om l.c adsorbed by TNT and rGO-TNT, we have done only single metal (Cu) adsorbent Lu an However in future we can with different heavy metals removal experiment n va th 37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.99 ac 40 si 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37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.99 ac 41 si 37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.C.33.44.55.54.78.655.43.22.2.4.55.2237.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.66 REFERENCES Alkorta, I., Hernández-Allica, J., & Garbisu, C (2004) Plants against the global epidemic of arsenic poisoning Environment international, 30(7), 949-951 Åström, M., & Björklund, A (1995) Impact of acid sulfate soils on stream water geochemistry in western Finland Journal of Geochemical Exploration, 55(1), 163-170 Bissen, M., & Frimmel, F H (2003) Arsenic—a review Part I: occurrence, toxicity, lu an speciation, mobility Acta hydrochimica et hydrobiologica, 31(1), 9-18 n va Bryan, G W., & 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37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.99 ac 43 si 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Wang, H., Liu, G., Chen, S., Wang, Y., & Cao, A (2010) l.c Folding/aggregation of graphene oxide and its application in Cu< sup> om 2+ removal Journal of colloid and interface science, 351(1), 122-127 Lu n va treatment Journal of Environmental & Analytical Toxicology an Yifei, G (2012) Nanomaterials as sorbents to remove heavy metal ions in wastewater th 37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.55.77.77.99.44.45.67.22.55.77.C.37.99.44.45.67.22.99 ac 44 si 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