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.
Pulp and paper
Iman Akbarpoor; Hossein Resalti; Ahmad reza Saraeyan
Abstract
In this study, Deinking of old newspaper was investigated by chemical and enzymatic methods. Chemical treatment was done using chemicals at different times of 10, 20 and 30 minutes, consistency of 10%, temperature of 50±1!C along with washing, flotation and combination of washing/flotation. While, ...
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In this study, Deinking of old newspaper was investigated by chemical and enzymatic methods. Chemical treatment was done using chemicals at different times of 10, 20 and 30 minutes, consistency of 10%, temperature of 50±1!C along with washing, flotation and combination of washing/flotation. While, Enzymatic treatment was accomplished at different concentrations of 0.025, 0.05, 0.1 and 0.2% of cellulase enzyme (on the basis of oven dried waste paper), pH range of 5-5.5, different times of 10,15 and 20 minutes, consistency of 10%, temperature of 50±1!C along with washing. The results comparison of optimum chemical and enzymatic treatments showed that, deinked pulp by chemical method had higher brightness and yellowness. Also, deinked pulp by chemical method resulted the papers with higher bulk, higher caliper and higher air resistance.
Hamid reza Mehri Iraie; Ali Ghasemian; Hossein Resalati; Ahmad reza Saraeyan; Iman Akbarpour
Abstract
This research was conducted to investigate the bleaching of combined old newspapers (ONP) and old magazines (OMG) deinked pulp using sodium dithionite. The pulp was bleached using 0.5, 0.75, and 1% sodium dithionite and different times of 30, 60 and 90 minutes. The pulps were then refined to 300 ml, ...
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This research was conducted to investigate the bleaching of combined old newspapers (ONP) and old magazines (OMG) deinked pulp using sodium dithionite. The pulp was bleached using 0.5, 0.75, and 1% sodium dithionite and different times of 30, 60 and 90 minutes. The pulps were then refined to 300 ml, CSF freeness and standard handsheets were made from the refined pulps. The optical and mechanical properties of handsheets and the COD of bleaching effluent were measured according to TAPPI standard test methods. The results showed that the brightness of paper was increased significantly with increase in time and sodium dithionite charge. When the charge of bleaching agent increased, the mechanical properties of handsheets and COD load of bleaching effluent were increased and paper bulk and opacity decreased but these changes were not statistically significant. Increasing the bleaching time from 30 to 90 minutes resulted in a significant improvement in tensile, burst and tear indices but the opacity of paper was reduced.
Ahmad reza Saraeian; Mozhdeh Mashkour
Abstract
Considering the problems initiated by sodium silicate on reducing the life expectancy of processing equipments and paper strength, recycling of old newspaper using Poly (acrylic acid), Sodium Salt Grafted to Poly (ethylene oxide) complex were investigated. The organic complex was used at 0.3, 0.5, 0.7, ...
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Considering the problems initiated by sodium silicate on reducing the life expectancy of processing equipments and paper strength, recycling of old newspaper using Poly (acrylic acid), Sodium Salt Grafted to Poly (ethylene oxide) complex were investigated. The organic complex was used at 0.3, 0.5, 0.7, 1, 2 and 3% levels (based on dry weight of waste paper) in deinking. The effect of various charges of the organic complex on the physical and optical properties of deinked pulp was studied and compared with the control (ONP deinked using 0.5% sodium silicate). The results of physical properties measurements showed that the lowest paper caliper (143.07 µm) and the highest density (0.43 g/cm3) were obtained by increasing the complex charge up to 2%. Also, the highest and lowest freeness was observed applying 3% (426.66 mL CFS) and 2% (350 mL CSF) organic complex respectively. These values were less than the freeness of the control sample. The results of optical properties analysis indicated that the brightness increased to 48.01% ISO and the yellowness was reduced to 6.23 % ISO by as the dosage of organic complex was increased up to 1%. The opacity of paper decreased as the organic complex charge increased. In general, the paper with higher density and brightness, lower yellowness and suitable opacity could be produced using 0.7- 2% Poly Acrylic Acid-Sodium Salt grafted to Polyethylene Oxide complex in deinking of old newspaper
