Papers by Keyword: Citric Acid (CA)

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Authors: Noorizzah Ibrahim, Mohamad Kahar Ab Wahab
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.
Authors: Shariff Ibrahim, Megat Ahmad Kamal Megat Hanafiah, Faisal Fadzil
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";}
Authors: Gui Xin Wang, Chun Jing Liu, Yu Meng Zhang, Hui Fen Peng, Xin Wang
Abstract: The citric-acid coated Mn-Zn ferrite nanocrystalline was prepared by an improved co-precipitation method. X-ray diffraction (XRD) and TEM measurements indicated that the coated samples were pure spinel Mn-Zn ferrite nanocrystalline and the particles coated after boiling circumfluence were more homogeneous than that before boiling circumfluence. Vibrating sample magnetometer (VSM) indicated that the Ms of the coated samples was higher than that without coating. Specially when the content of citric acid is 4.76wt% after boiling circumfluence, the Ms of the coated sample is 54.15 emu•g-1 which is 28.7% higher than that without coating.
Authors: Yun Hui Xu, Sa Yin Lv, Yong Jin Deng
Abstract: The bamboo pulp fiber fabric was treated by chitosan with low molecular weight in aqueous citric acid. The effect of citric acid concentration, chitosan concentration, treatment time and reaction temperature on anti-creasing and mechanical properties of the fabric were studied, respectively. Meanwhile, the optimal finishing condition was obtained. The anti-wrinkle and hygroscopic properties of all processed fabrics improved markedly at the optimal technology. However, the breaking strength of the fabric decreased slightly after the optimal treatment. FT-IR characterization of the treated fabric showed that the chitosan was crosslinked on the bamboo pulp fiber fabric and the ester linkage was formed between the citric acid and bamboo pulp cellulose. The antibacterial property of the chitosan treated fabric increased dramatically. The resulting bamboo pulp fiber fabric treated by chitosan is a natural ecological textile product, having the various application and more potential chemical modification.
Authors: Bao Guo Ma, Jun Xiao, Hong Bo Tan
Abstract: This article reports on the study to evaluate the hydration process of cement by the addition of citric acid. Through the test of citric acid of cement paste, hydration heat performance, resistivity, chemical shrinkage, and combined with XRD, SEM, DSC-TG discusses the influence of citric acid on cement hydration process. The results thus obtained were compared to the hydration process of cement with the blank sample and vary of dosage of citric acid. The results show that: The early hydration about 1~2 h resistivity increases, dissolve balance stage was extended; The chemical shrinkage increased significantly, and increases with dosage; With the increase in citric acid dosage, AFt diffraction peaks increases, while the CH peak decreases, indicating that the citric acid accelerated the initial hydration of C3A, while inhibiting C3S hydration and promoting AFt generation. Key words: citric acid, mechanism ,hydration heat, resistivity
Authors: Cheng Feng Li, Xiao Lu Ge, Jia Hai Bai, Guo Chang Li
Abstract: The influence of citric acid on phase evolution of calcium phosphate is studied by the electrical conductivity of reaction solutions. The conductance curves are divided into three distinct regions and assigned to the formation of amorphous calcium phosphate (ACP), hydroxyapatite (HA) and the solubility of HA, respectively. When more citric acid is added, the width of region I decreases because more Ca2+ ions would prefer to foster the nucleation of HA from ACP. Decreasing rate of conductivity in region II becomes smaller with more addition of citric acid because the supersaturation of HA decreases in solutions. And thus, HA powders with larger grain size are synthesized with more citric acid addition.
Authors: Yu Shuang Li, Xiao Jun Hu, Xue Ying Song
Abstract: Cadmium contamination of soil has become a major environmental problem in the whole world. Soil washing is a possible remediation method for extracting contaminants from the contaminated soil. Natural organic acids seem to be promising environmentally friendly for removing toxic metals from soils. Batch soil-washing experiments were conducted to investigate the behavior of cadmium desorption from soils by citric acid. Results showed that cadmium removal by citric acid was highly dependent on the initial pH and the concentration of citric acid. The removal of cadmium declined sharply with the rise of pH. Contrarily, cadmium desorption increased with increasing citric acid concentration. More than 90% cadmium was extracted from soil by 80 mmol L-1 citric acid.
Authors: Tetsushi Taguchi, H. Saito, Masashi Iwasashi, Masataka Sakane, S. Kakinoki, Naoyuki Ochiai, Tetsuya Tateishi
Abstract: A biocompatible glue consisting of human serum albumin (HSA) and citric acid derivative (CAD), named CAD-A glue was developed. CAD was successfully synthesized by the reaction between citric acid and N-hydroxysuccinimide in the presence of 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide hydrochloride. When the CAD-A glue was applied to the collagenbased casings, it took 7 min to obtain half of maximum bonding strength (760 g/cm2). The bonding strength of this glue to collagen-based casings increased with increasing of HSA concentration.The bonding strength of CAD-A glue increased with increasing CAD concentration up to 200 mM, and then decreased with increasing CAD concentration under the fixed HSA concentration (50 w/w%). The CAD-A glue showed excellent wound closure ability rather than fibrin glue when applied to the mouse skin. These results suggested that this developed glue had both tissue compatibility and bonding strength for use in clinical field.
Authors: Wen Zheng Zhang, Zheng Liu, Ping Li Mao
Abstract: Magnesia (MgO) is a fundamental component of many minerals found in nature and is used widely in our life, especially in refractory industry. However, the antihydration of MgO is a key concern in refractory suspension processing, MgO additions only in form of coarse particles(≥ 50 μm) or its contents of up to 10 wt.% are as a result of their high possibility to take place hydration reaction in water and the reaction can lead to volumetric expansion obviously. In the present work, citric acid (CA) can complex with Mg2+ in the MgO suspension under the condition of 4h and 25°C, and the deposit of magnesium ion-CA complexes become protective coating to inhibit magnesia react with water to form Mg(OH)2.The test results of RSV of different additives shows CA is the best antihydration compound to inhibit MgO hydration comparing with EDTA-2Na,sodium pyrophosphate(SP),trimeric sodium phosphate(TSP), which RSV is only 5.3ml when its dosage is 0.3%wt.
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