Chemical conversion
Milad Poladi; Seyed Hassan Sharifi; Seyed Majid Zabihzadeh; Mostafa Nikkhah Dafchahi
Abstract
Cellulose is the most abundant bio-polymer and also has many potential and applications, Therefore, in order to convert it to solvable cellulose in many commercial solvents, it is necessary to modify the cellulose structure with a variety of methods of derivation. Cellulose derivatives have an increasing ...
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Cellulose is the most abundant bio-polymer and also has many potential and applications, Therefore, in order to convert it to solvable cellulose in many commercial solvents, it is necessary to modify the cellulose structure with a variety of methods of derivation. Cellulose derivatives have an increasing share in the cellulosic products marketing and it is used in various industries such as sanitary, pharmaceutical, food and industrial., Carboxymethyl cellulose is one of the most important commercial cellulose ether derivatives. The purpose of this study was to investigate the conversion of alpha-cellulose derived from the Deltoides pine species into a useful and more valuable product that called Carboxymethyl cellulose. In order to optimize and investigate the interaction of different process variables, response surface methodology (RSM) was used. For modeling the process, important operational parameters such as concentration of NaOH, ratio of Monochloroacetic acid to cellulose, temperature and the time of etherification as independent variables and the degree of substitution of the samples were considered as the desirable response. Analysis of variance and response level were used to create a function between variables and responses, and optimal conversion conditions were determined. The results showed that the best value presented in the optimal condition proposed by software for the degree of substitution was 31 percent for concentration of etherification, 1.09 for the ratio of Monochloroacetic acid to cellulose, 60 °C for the etherification temperature and 157 minutes for the etherification time.
Chemistry of wood
Seyed Hassan Sharifi; Saltanat Archin; Leila Aghanaghifar
Abstract
DOR:98.1000/1735-0913.1398.34.16.66.1.1575.1603 One of the most important sources of environmental pollution is dye from industrial wastewater which is harmful for human health and environment. Therefore, the aim of this study was to evaluate removal of Methylene Blue (MB) dye from aqueous solutions ...
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DOR:98.1000/1735-0913.1398.34.16.66.1.1575.1603 One of the most important sources of environmental pollution is dye from industrial wastewater which is harmful for human health and environment. Therefore, the aim of this study was to evaluate removal of Methylene Blue (MB) dye from aqueous solutions by straw using ultrasonic wave with response surface methodology. The batch experiment was conducted to evaluate the effect of dye concentration, contact time, adsorbent dosage and pH on dye removal from aqueous solution. Response surface methodology was applied to appraise the effect of these different variables. The dye concentration in the solutions was measured by spectrophotometer at the wavelength of 664 nm. The results showed that the optimum parameter values for maximum color removal efficiency were: dye concentration 20 mg/L, reaction time 8 min, dose of adsorbent 4 g/L and pH=9. The Maximum and minimum dye removal were obtained 92.29 and 47.5 percent, respectively. Analysis of variances test showed that the quadratic model was the best model to explain the interaction of variables. Based on analysis of variance (ANOVA), the coefficient of determination value (R2 =0.9116) was high, showing that the experimental values fitted well with the predicted values. In addition, the statistical analysis of the results indicated that in the range studied, dose of adsorbent and pH had a significant effect on color removal efficiency. The Gibbs free energy and enthalpy data verified its spontaneous and endothermic nature. In addition, survey of pseudo first and second order kinetics models presented that the adsorption process was compatible to pseudo-second order kinetics equation.
Pulp and paper
Seyed Hassan Sharifi; nouredin Nazarnezhad
Abstract
To reuse recycled cellulosic fibers in paper production, contaminated particles and other impurities of the fibers can be greatly removed using a de-inking stage which is considered as a supplementary step in waste paper recycling technology. The effect of using ultrasonic pretreatment on the deinking ...
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To reuse recycled cellulosic fibers in paper production, contaminated particles and other impurities of the fibers can be greatly removed using a de-inking stage which is considered as a supplementary step in waste paper recycling technology. The effect of using ultrasonic pretreatment on the deinking of old newspapers was investigated utilizing the common conventional chemical method across this research work. Experimental design method was served to optimize the amount of ultrasonic bath temperature and sonication time. Therefore, 13 tests were designed using Response Surface Methodology (RSM) and Central Composite Design with Design Expert 7.0.0 Trial software. Ultrasonic bath temperature and sonication time at three different levels (1, 0 and 1+) and two axial points (α + and α-) were used as independent variables, and the optical and mechanical properties of handsheets were used as dependent variables. Response surfaces and contour plots were served to show the interaction between the independent variables and the response variable. ANOVA test showed that the quadratic model is the best model to explain the interaction among the studied variables. The predicted values of the obtained model had much conformity with the experimental results (R2=0.98). According to ANOVA results, it can be concluded that the effect of each of the variables on the optimal properties is significant and the ultrasonic time is the most effective factor on the response. According to the results, the proposed optimum conditions to achieve the highest amount of mechanical and optical properties (43.43) are the ultrasonic bath temperature 47 oC and the ultrasonic time of 31 min.
