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XIN-SHENG CHAI,JINGHONG ZHOU,HONGXIANG ZHU,XIANNAN HUANG 한국펄프·종이공학회 2006 한국펄프종이학회 기타 간행물 Vol.- No.-
This paper describes a technique combining chemometrics with UV spectroscopy for the determination of the concentrations of two tissue additives (i.e., wet strength and softening agents) in a cellulose fiber containing solution. In single agent solutions, the concentration of the additive can be measured by UV spectroscopy at the wavelength where the species having absorption. For a binary (i.e., containing two additives) solution system, the spectral characterization is very complicated. However, if aided by a chemometrical calibration technique, each additive in the binary solution can be qua ntified simultaneously. The present method is very rapid and simple, it can easily perform a continuous measurement in the changes in the additives’ concentration after fiber addition, and therefore this becomes a valuable tool for the adsorption kinetics study of chemical additives onto the cellulose fibers. The time-dependent adsorption behaviors of the wet-strength, softening agent, and their both on fiber were also presented.
Qingxi Hou,Xin-sheng Chai,Junyong Zhu 한국펄프·종이공학회 2006 한국펄프종이학회 기타 간행물 Vol.- No.-
This paper reports an improved headspace gas chromatographic method for the determination of carboxyl group content in wood fibers. Pretreatment of wood fibers was applied using dilute HCl to convert carboxyl groups to carboxylic acid groups and then using deionized water to wash fiber samples thoroughly. The samples were finally air dried. Sodium bicarbonate solution was used to react with carboxylic acid groups of the pretreated fibers in a closed testing vial to release carbon dioxide. The content of carboxyl groups in fibers was accurately quantified by determining the amount of carbon dioxide released by a headspace gas chromatograph equipped with a thermal conductivity detector. The modified process for fiber sample pretreatment increased the reliability and accuracy in measuring carboxylic acid groups. The present method is simple, accurate.
Hui-Chao Hu,Xin-Sheng Chai,Ying-Xin Tian,Wei-Feng Si,Gang Chen 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.3
This paper reports on a headspace gas chromatographic method (HS-GC) for the determination of residual formaldehyde in formaldehyde related polymer latexes. The method is based on the reaction between formaldehyde and borohydride in a sodium hydroxide solution (1 mol/L), in which formaldehyde is quantitatively converted to methanol within 30 min at 90 8C and then determined by HS-GC. The results showed that the repeatability of the method had a relative standard deviation of less than 5.0%; the limit of quantification (LOQ) was 17.3 mg, and the recovery ranged from 96.2–102%. The present method is simple, rapid, and accurate.
Yoon, Sung-Hoon,Chai, Xin-Sheng Korean Chemical Society 2006 Bulletin of the Korean Chemical Society Vol.27 No.11
The general objective of the present study was to investigate the potential application of the UV spectroscopic method for determination of the polymeric additives present in papermaking fibrous stock solutions. The study also intended to establish the surface-chemical retention model associated with the adsorption kinetics of additives on fiber surfaces. Polyamide epichlorohydrin (PAE) wet strength resin and imidazolinium quaternary (IZQ) softening agents were selected to evaluate the analytical method. Concentrations of PAE and IZQ in solution were proportional to the UV absorption at 314 and 400 nm, respectively. The time-dependent behavior of polymeric additives obeyed a mono-molecular layer adsorption as characterized in Langmuir-type expression. The kinetic modeling for polymeric adsorption on fiber surfaces was based on a concept that polymeric adsorption on fiber surfaces has two distinguishable stages including initial dynamic adsorption phase and the final near-equilibrium state. The simulation model predicted not only the real-time additive adsorption behavior for polymeric additives at high accuracy once the kinetic parameters were determined, but showed a good agreement with the experimental data. The spectroscopic method examined on the PAE and IZQ adsorption study could potentially be considered as an effective tool for the wet-end retention control as applied to the paper industry.
Sung-Hoon Yoon*,Xin-Sheng Chai 대한화학회 2006 Bulletin of the Korean Chemical Society Vol.27 No.11
The general objective of the present study was to investigate the potential application of the UV spectroscopic method for determination of the polymeric additives present in papermaking fibrous stock solutions. The study also intended to establish the surface-chemical retention model associated with the adsorption kinetics of additives on fiber surfaces. Polyamide epichlorohydrin (PAE) wet strength resin and imidazolinium quaternary (IZQ) softening agents were selected to evaluate the analytical method. Concentrations of PAE and IZQ in solution were proportional to the UV absorption at 314 and 400 nm, respectively. The time-dependent behavior of polymeric additives obeyed a mono-molecular layer adsorption as characterized in Langmuir-type expression. The kinetic modeling for polymeric adsorption on fiber surfaces was based on a concept that polymeric adsorption on fiber surfaces has two distinguishable stages including initial dynamic adsorption phase and the final near-equilibrium state. The simulation model predicted not only the real-time additive adsorption behavior for polymeric additives at high accuracy once the kinetic parameters were determined, but showed a good agreement with the experimental data. The spectroscopic method examined on the PAE and IZQ adsorption study could potentially be considered as an effective tool for the wet-end retention control as applied to the paper industry.
In-Digester Demethylation Kinetics for VOC/TRS Formation During the Kraft Pulping of Loblolly Pine
Yoon, Sung-Hoon,Chai, Xin-Sheng,Zhu, Junyong,Kim, Byong-Hyun,Song, Byoung-Kyu 한국공업화학회 2003 Journal of Industrial and Engineering Chemistry Vol.9 No.2
The objective of this study was to examine the reaction kinetics of demethylation and VOC/TRS formation during the kraft pulping process. The methyl mercaptan and dimethyl sulfide were taken into account as the major compounds for TRS, and methanol for the major VOC. On the basis of H-factor process variable, the kinetic analysis was conducted using the mechanistic assumptions of two parallel competing reaction and bimolecular-type second order reaction, Demethylation appeared to be proportional to the degree of delignification. The rate constants of the demethylation showed as high a value in the order of ten as the delignification rate constants. Sulfidity has a significant impact on both demethylation and delignification. Higher sulfidity-dependency was observed in demethylation rates. The VOC formation rate was highly proportional to the effective alkali charge in the kraft process, whereas TRS formation to sulfidity. VOC formation rate appeared to be about seven times higher than TRS formation at a lower level of sulfidity, but the difference between them increasingly decreased with increasing sulfidity. These results suggest that higher effective alkali charge at a given level of sulfidity should be instrumental to minimize the TRS formation during the kraft pulping.