Preparation And Application Performance Of Organic-Inorganic Hybrid Membrane Based On Chitosan

Chitosan (CS), N-deacetylated form of chitin, is the second abundant renewable biopolymer. It has many unique properties such as soft molecular long chain, excellent forming film characteristics, ease of molecular design (synthesis, blending modification, grafting etc.). However, pure chitosan membrane is highly swollen in water, and has low mechanical strength and poor acid resistance property, in addition, membrane structure is difficult to control during the membrane process, the adsorption and separation mechanism of membranes need to be explored further. In this dissertation, chitosan was used as raw materials to prepare hybrid materials. Firstly, chitosan were premodificated by carboxylation, acylation reaction and shiff base reaction. After that, chitosan/silica hybrid membrane and chitosan/natural polymer/silica hybrid membrane material were prepared respectively with silicon coupling agent as crosslinking agent. The structure and performance of the obtained hybrid membranes were studied. In addition to, chitosan oxidation hybrid material, chitosan quaternary derivatives/silica, chitosan acylated derivatives/MWCNT hybrid systems were prepared respectively on the cotton fiber by dip-pad-cure propcesses and ultrasonic deposition method. The effect of these types of hybrid systems on structure, and performance of cotton fabrics were studied. These results are shown as follows:Chitosan/silica hybrid membrane was prepared by using chitosan and nano-SiO2modified in presence of coupling agent triethoxyvinylsilane. The distribution of SiO2on the surface of chitosan/silica hybrid membrane was investigated by SEM. The adsorption behaviors of direct dyes from aqueous solution onto chitosan/silica hybrid membrane were studied under various experimental conditions such as time, temperature, pH etc. The results showed that the nano-SiO2particles distributed enenly in the chitosan phase and there were interspaces between inorganic and organic phase in the hybrid membrane. Experimental results indicated that the adsorption capacity of hybrid membranes for the both direct dyes was higher when the concentration of Direct Pink12B and Direct blue B2RL were60mg/L, and adsorbed at55℃, pH8for4.5h. Adsorption equilibrium studies showed that adsorption of Direct Pink12B on hybrid membranes more followed Langmuir isotherm model while adsorption of Direct blue B2RL on hybrid membranes more followed Freundlich isotherm model.Novel chitosan/carboxylmethyl cellulose/silica hybrid membranes (CS/CMC/Silica) were prepared by combining chitosan with carboxyl methyl cellulose as the functional reagent and using3-glycidoxypropyltrimethoxysilane (GPTMS) as crosslinking agent. The hybrid membrane materials were characterized by FT-IR spectroscopy, scanning electron microscopy (SEM) and thermolgravimetry (TG) analysis and used to adsorb Blue RAW, Black ATT and Cr2O72-iron in textile wastewater. The influence of dyes and metal ion concentration, solution temperature, pH and adsorption time on adsorption performance of hybrid membrane was investigated. Compared with chitosan itself, the hybrid membranes showed significant changes in the molecular constitutions and thermal properties, which were more stable in acid solution and had the lower swelling properties. Adsorption capacity increased with the increase of initial dyes, Cr2O72-concentration and absorbing time, and decreased with the increase of biosorbent dosage and temperature. Adsorption equilibriums of Cr2O72-ion, Black ATT and Blue RAW were reached in about60min,90min and160min, respectively, and the kinetic data conformed better to the pseudo-second order equation.Oxidized starch crosslinked chitosan membrane (CS/OSR) and chitosan/Oxidized starch/silica hybrid membrane (CS/OSR/Silica) were prepared respectively by combination chitosan and oxidized starch as the functional reagent and using3-aminopropyltriethoxysilane as crosslinking agent. Both of the hybrid membrane materials were characterized by FT-IR spectroscopy, scanning electron microscopy and TG thermal analysis methods, which were used to adsorb direct blue B2RL and pink12B in textile dyes from aqueous solutions. The influences of types of membrane, temperature, and pH and adsorption time on adsorption performance of hybrid membranes were studied. Compared with chitosan itself, hybrid membranes showed significant changes in the molecular constitutions and thermal properties. It was more stable in acid solutions. Adsorption capacity was found to increase with pH value and time. When pH was9.82, at60℃, adsorption equilibrium of blue B2RL and Pink12B was achieved in about90min and60min, respectively. The kinetic data conformed better to the pseudo-second order equation.Modified cotton fabrics were prepared by pad-dry-cure technique from the aldehyde chitosan solution containing3-aminopropyltriethoxysilane (KH550) and1,2-Ethanediamine (EDA) respectively. The structural characterization of the modified cotton fabrics was performed by attenuated total reflection ATR, scanning electron microscopy (SEM) and thermogravimetry (TG) analysis and physical mechanical properties were measured. The adsorption kinetics of modified cotton fabrics were also investigated by using the pseudo first-order and pseudo second-order kinetic model. The dyeing rate constant k1, k2and half adsorption time t1/2were calculated, respectively. The results showed that the mechanical properties of different modified cotton fabrics have been improved, and the surface color depth values of K/S, UV index UPF and anti-wrinkle properties were better than those of untreated cotton. Dyeing kinetics data at different temperatures indicated that Direct Pink12B up-take on the modified cotton fabrics fitted to pseudo second-order kinetic model.Using2,3-epoxy-propyl dodecyl dimethyl ammonium chloride as cationic chitosan reagent, by deposition, chitosan quaternary ammonium salt/silica hybrid sol hybrid film were constructed on cotton fiber. SEM and EDS anylysis results confirmed the quaternary ammonium salt/silica hybrid film was deposited on the surface of cotton fiber. After deposition modification, surface properties of modified cotton such as wetting ablity, adsorption properties produced significant changes. With the assembly of deposition time increased and anti-UV properties increased.MWCNT were evenly dispersed in N-phthaloyl-O-succinyl chitosan DMF solvent under ultrasound condition. Cotton fabrics were impregnated in N-phthaloyl-O-succinyl chitosan/MWCNT DMF solution. Structure of modified cotton fabric was characterized by using infrared spectroscopy (FT-IR), scanning electron microscopy (SEM). The effect of PHCSSA concentration, MWCNT dosage, temperature and time on the surface properties (such as UV, hydrophobic properties and adsorption on methylene blue etc.) of modified cotton fabric was studied. The results showed that:N-phthaloyl-O-succinylated chitosan/MWCNT hybrid materials can be uniformly dispersed on the surface of cotton fabrics, UV performance, and adsorption performance on methylene blue dye of modified cotton fabrics have been significantly improved. When PHCSSA concentration of2g/L, MWCNT amount of7.5mg/L, bath ratio of1:100, the temperature is50℃, ultrasonic treatment30min, modified cotton fabrics had the higher UPF values and better adsorption on methylene blue.