Papers by Keyword: Citric Acid (CA)

Abstract: In this research, the Thermoplastic Starch (TPS) is blended with Polylactic Acid (PLA). By treating TPS with CA, the interfacial adhesion of PLA/TPS blend was also being improved. The ratio between PLA/TPS was chosen at 60/40 and 40/60 and CA contents were varied from 0%, 3%, and 6%. After acidolysis of TPS by CA, the tensile strength (60/40) and (40/60) of the PLA/TPS blend were found to increase. However, the elongation at break of PLA/TPS (60/40) blend was lower compared to PLA/TPS (40/60) blend. Higher loadings of TPS in the blend tend to make the blend elongate due to the flexibility of TPS after CA modification. On the other hand, by modifying the TPS with CA, the surface tension at the PLS/TPS interface had been reduced. This can be seen through micrograph that obtained from scanning electron microscopy. Different CA content in PLA/TPS blend showed the dispersed or co-continuous structure, which were related with the mechanical properties.

Abstract: In this paper, nanosized La_0.85Na_0.15MnO₃ (LNMO) has been synthesized via sol-gel method by involving two major steps, first the complexation of citric acid (CA) with metal ions (MI) and second the polyesterification between CA and ethylene glycol (EG). The effect of molar ratio CA:MI varying from 2-4 on structure, microstructure and electrical transport properties of LNMO have been investigated by constant the amount of EG. All samples show single perovskite phase with hexagonal structure and space group R3c after sintering at 800°C for 10h. Sample of molar ratio 2.5 is observed to possess smallest grain sizes which yield high resistivity value compared with others, is suggested to originate from the increase of tunneling barriers (grain boundaries). The large low field magnetoresistance (LFMR) of about ~ -16% at 0.1T and low temperature confirmed the important role of grain boundaries in the nanosized LNMO.

Abstract: Carboxyl methylcellulose (CMC) doped with oleic acid (OA) and plasticized with glycerol was able to be produced into solid biopolymer electrolytes using the solution cast technique. The CMC-OA-glycerol solid polymer electrolyte obtained the highest conductivity of 1.64 x 10^-4 S cm^-1 at room temperature for sample Gly 40 wt. %. Within the temperature range investigated, the conductivity– temperature relationship of the biopolymer electrolytes is characteristically Arrhenius behaviour, suggesting that the conductivity is thermally assisted. Fourier Transform Infrared studies was carried out to determine the dissociation of free protons (H⁺) from the carboxyl group (–COOH) of glycerol.

Abstract: This research focused on physical and mechanical properties of biocomposite made from bamboo and citric acid as natural binder. Bamboo particles was mixed with citric acid at 0 – 40 wt% resin content based on air-dried particles and each mixture was hot pressed at 180 °C for 10 min. The result showed that addition of citric acid could improve significantly the physical and mechanical properties of particleboard. The thickness swelling was 50 % for bamboo binderless particleboard (0 wt%), whereas it decreased to 7 % under a resin content of 10 wt%. The optimum resin content in this study was 30 wt%, while the modulus of rupture dan the modulus of elasticity were 14 MPa and 4.5 GPa, respectively. The ester linkages were detected by Fourier transform infrared spectroscopy, indicating that carboxyl groups from citric acid reacted with hydroxyl groups from bamboo to produce better properties of particleboard, especially its dimensional stability. Based on these results, it was concluded that citric acid could be as a potential natural binder for bamboo particleboard.

Abstract: The removal of Pb(II) from aqueous solutions by citric acid modified rubber leaf powder (CARL) was investigated. The higher adsorptive removal of Pb(II) from aqueous solutions by CARL compared to untreated rubber leaf powder was due to the presence of more carboxylic functional groups in the former system. Batch adsorption experiments were conducted to study the effect of pH, contact time for the removal of Pb(II) from Pb(II) aqueous systems and the mechanism of adsorption process was studied by kinetic models, pseudo-first and pseudo-second order kinetic models. The functional groups on CARL played an important role in the adsorption of Pb(II). The kinetic and equilibrium adsorption data were well modeled using pseudo-first-order kinetics. Normal 0 21 false false false MS X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Calibri","sans-serif"; mso-fareast-font-family:Calibri; mso-bidi-font-family:"Times New Roman";}

Abstract: Novel solid polymer electrolytes containing carboxy methylcellulose (CMC) are prepared based on the vary concentration (0 - 45 wt. %) of citric acid (CA) via solution casting technique. The ion conductivity is studied by electrical impedance spectroscopy and the ionic mobility, μ and the diffusion coefficient, D is investigated by transference number measurement. The highest ionic conductivity at room temperature (303K) is 4.38 x 10^-7 S cm^-1 for 40 wt. % CA. The values of μ₊ and D₊ were higher than μ_- and D_- respectively, implying that the CMC-CA solid polymer electrolytes are proton conductor.

Abstract: To overcome the problem of volume change of SiO anode material, SiO/C composites are synthesized with different proportion of SiO and citric acid by ball milling and pyrolysis. The electrochemical performance and microstructure of the composites are investigated by XRDSEM and Land. The composite anode material shows a discharge capacity of 1768 mAh/g in the first cycle with the coulombic efficiency of 62%. After 50 cycles, the discharge capacity is about 540 mAh/g. The improved stability of the materials can be attributed to the carbon-coating formed during pyrolysis progress, which effectively buffer the volume expansion of SiO and improve the conductivity of the composites.

Abstract: Copper-substituted cobalt ferrite nanoparticles were prepared via a sol-gel route using citric acid as a chelating agent. The influence of copper concentration on the microstructure, crystal structure and antibacterial property of copper-substituted cobalt ferrite nanoparticles against E. coli and S. aureus has been systematically investigated. The results indicate that the substitution of copper influences strongly the microstructure, crystal structure, particle diameter and antibacterial property of cobalt ferrite nanoparticles.

Abstract: Extraction of citric acid from aqueous solutions with tertiary amine, dissolved in mixtures of kerosene and phase modifier have been studied as a function of exaction yield at different phase modifier volume fraction, temperatures, stirring speed and exaction time. The optimal experimental conditions of extraction were obtained: reaction temperature 303K, reaction time 3 min, the kerosene volume fraction 20%, and 45% 1−octanol as phase modifier, stirring speed 450rpm/min. Under these conditions, the extraction yield could reach 75%. The complex of citric acid and tertiary amine was a surfactant that makes surface tension decrease. The composition of the citric acid complex is (R₃N) · (H₃A). The formation of complex was exothermic reaction that the standard enthalpy change and standard entropy change are obtained: ΔH^θ=-10.17kJ/mol, ΔS^θ=-11.86J/(mol·K).

Abstract: Extraction behaviour of copper from Yunnan red soil by EDTA and citric acid were investigated. The influencing factors of EDTA and citric acid extraction were obtained. The EDTA and citric acid composite extraction for copper was also tested. The result showed that the extraction of copper for the system of low concentration citric acid (0.003 mol/L EDTA+0.05 mol/L) can reach to 64.8%, which is very close to that for thesystem of high concentration citric acid (0.003 mol/L EDTA+0.1 mol/L citric acid) (64.9%), and is high than that for 0.01 mol/L EDTA (61.1% )and 0.1 mol/L citric acid (61.2%).