Papers by Keyword: Organic Acid

Abstract: Rice husk and bamboo leaves are types of agricultural wastes that can easily be found around the world. Rice husk contains over 60 % of organic silica while silica bamboo leaves extract consist of more than 70 % silica content. Parameters such as concentration of acid and weight percentage of rice husk and bamboo leaves used during acid leaching method were also compared. In this paper, citric acid (C₆H₈O₇) was used for production of silica from rice husk and bamboo leaves. Samples were characterized using X-Ray Fluorescence (XRF) and Field Emission Scanning Electron Microscope Energy Dispersive X-Ray spectroscopy (FESEM / EDX). The performance of glaze on ceramic will be analyzed by undergoes hardness testing. The result indicates that highest percentage silica of rice husk and bamboo leaves after leaching was on 1.0M.

Abstract: In this study, high molecular weight (HMW) poly (l-lactic acid)s (PLLAs) were synthesized by direct polycondensation using organic acid catalysts alone in a nitrogen-controlled environment. The melting point and enthalpy of the pre-polymer produced by melt polycondensation increased as molecular weight grew during solid-state polycondensation. It was observed that the nitrogen-controlled external environment had lower molecular weight than air, but the low molecular weight tail was significantly reduced, as indicated by gel permeation chromatography. This is because it inhibited the reverse reaction by preventing the penetration of water inside the reactor. Also, the control of moisture improved the color of PLLA. The amount of organic acid catalyst used was 1 wt%, which was favorable for achieving HMW. Both p-toluenesulfonic acid and 4-ethylbenzenesulfonic acid are examples of organic acids that were able to produce HMW PLLA.

Abstract: The effect of metal salt coating process on the bond strength of the bonded interface of 5052 aluminum alloy and 316L stainless steel was investigated by SEM observations of interfacial microstructures and fractured surfaces. Aluminum alloy surfaces were coated by boiling in 5% aqueous solution of NaOH for 5 s and 98% formic acid and 99.7% acetic acid for 20 s and 20 s respectively. Bonding process was performed at bonding temperature of 733 ~ 773 K under a pressure of 20 MPa (bonding time of 900 s). From this study, it is found out that the bonded strength of the joint increased with the rise in bonding temperature with or without metal salt coating process. However, it is understood that with metal salt coating process, high strength joint can be achieved with lesser deformation and lower bonding temperature. From the experimental results, it is found out that metal salt generation processing is effective at removing oxide film and substitution to a metal salt on the aluminum surface.

Abstract: An organic acid antifreeze coolant was developed in this paper which consisted mainly of deionized water, organic acid, pyrrole compound, alkali and dye. Glycol, nitrite, chromate, inorganic phosphate and other harmful additives were not contained in this formulation. The coolant overcomes the disadvantages in environmental protection, heat transfer and cost of the current technology which uses the ethylene glycol as antifreeze. The coolant has good low temperature protection, thermal conductivity and corrosion protection performance. Further more, the coolant has the advantages of simple preparation, good storage stability and a promising prospects.

Abstract: Effect of organic matter and organic acid on the heavy metals, especially, chromium (Cr) release in the sediment was researched. Glucose and soluble organic starch was used as organic matter, as well, citric acid and ethylene diamine tetraacetic acid (EDTA) were simulated as organic acid. The results showed that best adsorption time of glucose on Cr was 5h, the optimal dosage was 0.1g g^-1; best adsorption time of organic soluble starch was 4h, and the optimum adding amount of 0.08g/g; best adsorption time of citric acid was 5h, the best concentration 0.005mol g^-1; optimal adsorption time of organic acid EDTA was 3h, the optimum adding amount of 0.12g g^-1. Glucose, soluble starch and citric acid significantly effected on the release of Cr in the sediment, however, influence of EDTA on the release of Cr was not so evident.

Abstract: Phosphate-solubilizing bacteria were extensively studied in many environment. However, little is known about them in drill cuttings, as wastes from drilling process. A phosphate-solubilizing bacterium strain PSB13 was isolated from petroleum-contaminated drill cuttings. This strain was identified as Pseudochrobactrum sp. based on its 16S rDNA sequence and phenotypic characteristics. This strain could solubilize 97.6 μg/ml phosphates in 6 days when grown in NBRIP liquid medium. The increase in solubilization of phosphate coincided with the drop in pH, which indicates organic acid was responsible for the phosphate-solubilization. Phosphate-solubilizing bacterium was reported in drill cuttings for the first time, which suggests its potential in the bioremediation of petroleum-contaminated drill cuttings.

Abstract: In the assembly of electronic products, developing good organic acid fluxes plays an important role in improving the solderability of lead-free solders. In this paper, a variety of fluxes containing 5% (mass fraction) organic acid activators were prepared. Effects of different activators on the spreading rates of Sn-0.3Ag0.7Cu solder were studied. The results show that: activity of monobasic acids are weak except for benzoic acid; dibasic acids and polybasic acids have relatively strong activity but serious corrosion and slightly less activity persistence. Compounding palmitic acid and adipic acid in the mass ratio of 1:2 as the activator, the average spreading rate of Sn-0.3Ag0.7Cu solder is 71.11% in maximum. Compounding succinic acid and adipic acid in the mass ratio of 3:7 as the activator, the average spreading rate is up to 72.49% in maximum. And solder spots are in-erratic, bright and plump, meeting the quality requirements of electronic micro-connection.

Abstract: Agricultural wastes such as palm ash and rice husk have a possibility to be used as a usefully renewable source for production of energy and silica (SiO₂). Extensive researches have been carried out to extract silica from agricultural wastes such as rice husk, due to silica as a useful raw material for industrial application. In the previous studies, the strong acid leaching treatment was carried out to remove metallic impurities and organics contained in rice husk. A strong acid leaching treatment, however, is significantly hazardous to the environment and people [. In this study, the environmentally benign and economically effective process to produce SiO₂ materials from palm ash has been established by using citric acid leaching, not the conventional strong acids. Results showed that silica can be extracted from palm ash using citric acid leaching treatment under the optimum extracting conditions with 70°C of solution temperature, 60 minutes of reaction time and concentration of citric acid of more than 2%. The purity of silica extracted is more than 90%.

Abstract: Density functional theory and the hard and soft acid-base theory are widely used in quantum mechanics and computational chemistry. This article combined them to describe the iron oxide adsorption of humic acid free energy relationship, and predict the free energy relationship equation, which plays an important role for the study of the formation mechanism of organo-mineral complexes in soil carbon sequestration.

Abstract: The pre-treatment of sulfuric acid methyl ester with gas chromatography-mass spectrometry (GC/MS) analysis techniques was utilized to study the difference of the organic acid content in different flue-cured tobacco leaf (L8-L12): from the bottom of the eighth leave up to the twelfth leave) and its influence on flu-cured tobacco quality. The results show that malic acid, γ-e ketone acid, citric acid, malonic acid, linolenic acid and palmitic acid had a higher content relatively in different flue-cured tobacco leaves and they are the main acidic components.The difference of total organic acids content from the eighth to the twelfth leave was L8>L9>L12 >L10>L11; The content proportion ranges of non-volatile acid, senior saturated fatty acid and senior unsaturated fatty acid in total organic acids were 88.49%~94.38%,3.01%~5.10% and 2.61%~6.40%, respectively. The difference analysis of organic acids content in different leaf position indicated that the organic acids content in the eighth and twelfth leaves was moderate and they could be considered as the superior and slap-up tobacco raw materials.