Synthesis Of Chemically Modified Starches And Their Properties For The Removal Of Phenol

Starch is stored as food material in plant,which is composed of glucose units and connected to each other by glycosidic linkages.The starch is constituted of amylose and amylopectin.Amyloses structure is linear and comprised of glucose units connected by ? 1-4 linkage while the structure of amylopectin is branched containing 95%? 1-4 and 5%? 1-6 linkage.Starch is renowned for its biodegradability,low cost,easy availability and has many applications in food and other industries.Nevertheless,aboriginal starch has limited applications due to poor solubility in water,retrogradation,loss of viscosity and lack of functional groups.In order to foreclose these weaknesses,starch should be modified to enhance its applications in various aspects.There are different ways to modify the starch including chemical,physical,enzymatic modification and so on.The most commonly used method is chemical modification.The well-known methods used for the chemical modification of starch are acid hydrolysis,cross-linking,acetylation/esterification,oxidation,grafting and so on.Phenol and phenolic compounds are generated environmental problems and affect the humane life.Phenol makes an easy approach to the human body through inhaling the smoke of cigarette,cigar and pipe.The most common problems caused by the phenol are irritation in eyes and skin and damages to kidneys and liver.Various methods were used for the removal of phenol,especially by chemical precipitation,electrochemical deposition,ion exchange,flotation,adsorption and so on.Among these methods,adsorption is supposed to be one of the most beneficial methods.Activated carbon and synthetic polymeric adsorbents are considered as good adsorbents.But these adsorbents also have limitations for they are non-biodegradable,non-renewable and may act as secondary pollutants.Starch is a good choice to replace these adsorbents because it is biodegradable,environmental friendly,easily available and low in price.Native starch is not an effective adsorbent to remove phenol.The modified starches were used to remove phenol.However,their adsorption capability,novel preparation methods and mechanism still open for further exploration.This thesis focuses on the synthesis of chemically modified starches and their properties for the removal of phenol.Carboxymethyl starch grafted polymethacrylic acids(CMS-g-PMAAs)were synthesized by the reaction of carboxymethyl starch with methacrylic acid in the presence of initiator potassium persulfate(KPS).The successful synthesis of the modified starches was investigated by proton nuclear magnetic resonance(1H NMR)and Fourier-transform infrared(FT-IR)spectroscopy.The crystalline nature of the modified starches was analyzed by X-ray diffraction(XRD).The thermogravimetric analysis(TGA)and differential thermal analysis(DTG)were performed to check the thermal properties of the modified starches.The morphology of the modified starches was examined by SEM.The modified starches were tested as adsorbents for the removal of phenol from the gaseous mixture.The adsorption efficiencies of phenol were 0.244 g/g,0.247 g/g and 0.250 g/g for CMS-g-PMAA1,CMS-g-PMAA2 and CMS-g-PMAA3,respectively.Different normal and porous succinylated starches were synthesized by reacting normal starch and porous starch with succinic anhydride in the presence of DMF solvent and pyridine.The successful synthesis of the different succinylated starches was confirmed by 1H NMR and FT-IR.The crystalline nature of normal starch,porous starch,and succinylated starches was tested by using XPert PRO(Cu K?,?=1.54 A).The thermal stability of the succinylated starches was studied by TGA and DTG.The surface morphology of the normal and porous succinylated starches was examined by SEM.Afterwards,these succinylated starches were used as adsorbents for the removal of phenol.The adsorption efficiences of phenol were 0.165 g/g,0.173 g/g,0.183 g/g and 0.189 g/g for SS1,SS2,SS3 and SS4,respectively.For the removal of phenol,different succinylated carboxymethyl starches were synthesized.In this synthesis,carboxymethyl starch was reacted with succinic anhydride in the presence of pyridine and DMF solvent.During synthesis,double carboxylic groups were introduced on the starch backbones.The structure of the different succinylated carboxymehtyl starches were investigated by 1H NMR and FT-IR.The TGA and DTG analysis were performed to check the thermal properties of the succinylated carboxymethyl starches.The crystalline and amorphous nature of the succinylated carboxymethyl starches were analyzed by XRD.The different succinylated carboxymethyl starches were used as adsorbents for the removal of phenol.The adsorption efficiencies of phenol were 0.321 g/g,0.322 g/g and 0.324 g/g for S-CMS1,S-CMS2 and S-CMS3,respectively.Different carboxymethyl starch grafted poly vinyl imidazoles were synthesized by the reaction of carboxymethyl starch with vinyl imidazole in the presence of initiator potassium per sulfate and solvent water.The variant proton environment and functional groups present in the synthesized carboxymethyl starch grafted poly vinyl imidazole were checked by 1H NMR and FT-IR.The XRD analysis showed that after modification the crystallinity was lost.The thermal properties were determined by the TGA and DTG analysis.The surface morphology of the carboxymethyl starch and carboxymethyl starch grafted poly vinyl imidazole was examined by SEM.The carboxymethyl starch grafted poly vinyl imidazole was found to be a good adsorbent for the removal of phenol from the gaseous stream.The adsorption efficiencies of phenol were found to be 0.190 g/g,0.192 g/g and 0.199 g/g for CMS-g-PVI1,CMS-g-PVI2 and CMS-g-PVI3,respectively.Dually modified starch-phosphate grafted polymethacrylic acids were synthesized via phosphorylation and free radical polymerization.The successful synthesis of the dually modified starches was confirmed by 1H NMR and FT-IR.The thermal stability and crystallinity of the modified starches were investigated by TGA and XRD.The surface morphology of the modified starches was checked by SEM.The modified starches were tested as adsorbents for the removal of phenol from the gaseous mixture.The starch-phosphate grafted polymethacrylic acids showed an excellent affinity toward phenol.The adsorption efficiencies of phenol were 0.100 g/g,0.148 g/g and 0.151 g/g for SP-g-PMAA1,SP-g-PMAA2 and SP-g-PMAA3,respectively.The results showed that the obtained chemically modified starches can be used as adsorbents for the removal of phenol from the gaseous mixture.They have promising applications in cigarette industries.