جستجوی مقالات مرتبط با کلیدواژه « کاغذ روزنامه باطله » در نشریات گروه « جنگلداری »

In this research, the effect of different concentrations of Pectinase has been investigated on deinking of old newspaper (ONP). ONP re-pulped at 5% consistency for 10 min in disintegrator (with 2650 rpm). Enzymatic treatment of recycled ONP pulp was done under constant conditions (10% consistency, duration time of 20 min, pH range of 4.5-5) at different Pectinase concentrations (0.05, 0.1, 0.2, 0.3 and 0.5% based on oven-dry weight of waste paper). The optical and physical properties of the standard paper (60 g/m2) made from treated pulps with different concentrations of Pectinase were evaluated in comparison with paper produced from control pulp (untreated ONP pulp by Pectinase). The results showed that using Pectinase in deinking of ONP led to a slight increase in the brightness and the yellowness and decrease the opacity. The brightness was improved to 43.83 ISO% (about one percent increase), but the yellowness decreased to 18.61 ISO% (about 3.5 percent) with increase in Pectinase dosage from 0.05% to 0.2%. The brightness reduced and the yellowness increased at higher concentrations than 0.3% Pectinase. The highest opacity (99.49 ISO%) was achieved using 0.5% Pectinase. The results of physical properties showed that, paper air resistance and density improved with increase in Pectinase dosage. Also treatment of pulp with 0.3% Pectinase has been resulted in the papers with higher burst and tear indices compared to control pulp.

This study was aimed to investigate the possibility of using magnesium hydroxide as an alternative for sodium hydroxide in deinking of newsprint and magazine mixture. The old newsprint and magazine mixture (ONP/OMG -70/30) was treated by magnesium hydroxide at three levels: 1, 1.5 and 2 percent (based on oven dried pulp weight), for 20 min. Optical and mechanical properties and effluent COD load were compared to those of control and NaOH treated samples. Results showed that effluent COD load of Mg(OH)2 chemical treatments was less than that of NaOH treatment. Also, results indicated that 1.5% Mg(OH)2 treatment, which was done in pulp deinking, had better results compared to other treatments and also NaOH treatment. In the other words, it is the best treatment for both optical and mechanical properties. Thus, substitution of sodium hydroxide by magnesium hydroxide for deinking of newsprint and magazine wastepaper suggested.

This study was aimed to investigate the effect of different charges of sodium silicate on chemical deinking of old newspaper. Chemical deinking process was accomplished with 1% hydrogen peroxide, 1% sodium hydroxide, 0.3% DTPA and 0.15% surface active agent at different charges of 0, 1, 2 and 3% sodium silicate on the basis of oven dry waste paper. The results of the optical properties of produced paper showed that the brightness of paper improved (50.9%) and the yellowness decreased (11.33%) with increasing of sodium silicate charge to 2%. Increasing of sodium silicate use from 0.3% did not indicate significant effect on opacity values. The highest opacity (98.8%) was achieved by 1% sodium silicate. The results of the physical properties indicated that increasing of sodium silicate use up to 2% resulted the paper with the highest bulk (2.75 cm3/g). Totally, the consequences of this research in relation to chemical deinking of old newspaper at different charges of sodium silicate showed that use of 2% sodium silicate would lead to produce the paper with higher brightness, caliper and bulk along with desirable opacity.

Due to the problems of deposition of sodium silicate on the equipment and decrease of the service age of implements, deinking of old newspaper was accomplished using organic complex of Sulvy-x in place of sodium silicate. Sulvy-x was used at four levels of 0.3, 0.5, 0.7 and 1% on the basis of oven dry waste paper and chemical deinking was done. The effect of various charges of Sulvy-x was investigated and on optical and physical properties of deinked pulp compared with those of control sample (ONP recycled using 2% sodium silicate) and its optimum usage was determined. The results of optical properties showed that the brightness of paper increased to 50.8 %ISO and the yellowness decreased to 11.96 %ISO by increasing of Sulvy-x charge up to 0.9%. Also, lower charge of Sulvy-x (0.3%) resulted the highest opacity of 98.63 %ISO. The results of physical properties indicated that the caliper of paper reduced to a minimum value of 109.8 µm. Higher charges of Sulvy-x in deinking process resulted the paper with the higher density. The highest density of 0.546 g/cm3 was observed using 0.9% Sulvy-x. Also, deinking of old newspaper with 0.3% and 0.7% Sulvy-x resulted the pulps with the highest freeness as 435 ml, CSF. In general, using different amount of Sulvy-x in place of sodium silicate resulted the papers with similar brightness, higher opacity and lower caliper compared to those of control sample. However, the paper with higher brightness and density, lower yellowness and desirable opacity could be produced using 0.9% Sulvy-x in chemical deinking of old newspaper.

This study has been conducted in order to investigate the effect of using ONP recycled fibers on the mechanical and optical properties of local mixed hardwoods kraft pulp at Iran Wood and Paper Industry (Chooka). ONP and virgin kraft pulp have been prepared from Chooka’s waste paper storage and pulping digester, respectively. ONP has been repulped in the common method as used by paper recycling industry. After determination of the initial freeness of each pulp, they have been separately refined to reach the appropriate freeness value required to produce kraft paper. The pulps, then, have been mixed at 90.10, 80.20, 70.30, 50.50 and 30.70 percentage rates of recycled fibers and virgin kraft pulp, respectively. According to the related standard test method, handsheets were made from each treatment and their mechanical and optical properties have been measured. The results were compared with those of control sample (100% virgin kraft) using ANOVA technique and classification of the means was done by Duncan test. Finally, to determine the best treatment, normalization equation was calculated. The results show that the values of tensile, tear, and burst indices, folding endurance and density of the combined papers have been increased compared with those of control sample, but the values of bulk, thickness, brightness and opacity of the combined samples have been decreased. The scores of the treatments indicate that 50 percent of recycled fibers can be used in the furnish to produce paper with suitable mechanical and optical properties.

Deinkability of old newspaper was investigated using cellulase at different concentrations and treatment times. The results of optical properties of the made papers indicated that by increasing the enzyme concentration to 0.05 percent the brightness was increased to 47.5% ISO and yellowness decreased to 11.03% ISO. While at higher charges than 0.05 percent, brightness value the was decreased and yellowness increased. Opacity of paper was improved to 99.3% ISO by increasing the enzyme charge to 0.1% but it was reduced at higher levels than 0.1%. It was observed that enhancing of treatment time to 15 minutes and also using one-stage washing resulted in the highest brightness of 47.5% ISO, the lowest yellowness of 11.03% ISO and the opacity of 97.4% ISO. Maximum opacity was observed at treatment time of 10 minutes. With regard to the results from paper provided with enzymatic deinking of old newspaper, we could produce the papers with desirable brightness and low yellowness using optimum charge of 0.05% cellulase and treatment time of 15 minutes along with one-stage washing. We could also obtain higher opacity values using 0.1 percent enzyme or 10 minutes treatment time.

In this study, deinkability of old newspaper by conventional method and the effect of washing, flotation and combined washing/flotation processes were investigated on optical and superficial properties of the produced papers. The results from measuring of the optical and superficial properties indicated that using chemical treatment time of 20 minute and one stage washing resulted the papers with the highest brightness degree of 50.9% ISO and the lowest yellowness degree of 14.8% ISO, opacity degree of 97.8% ISO, dirt count of 507 and dirt area of 2205.5 mm2/m2. When the flotation process applied solely to deinking, opacity degree was improved to 99% ISO while the papers produced had lower brightness and higher yellowness, dirt count and dirt area. Also, the results obtained from distribution and the area of ink particles on both wire and felt sides of the papers showed that wire side of papers contained the higher ink count and ink area. With regard to the results obtained from optical and superficial properties of the made papers from deinking of old newspaper, application of washing process has more efficiency for removing of ink particles compared to flotation or combined washing and flotation processes, and the made papers have more desirable optical and superficial properties.

In this research، deinking of waste newspaper was investigated by chemical and enzymatic methods. Chemical deinking of waste newspaper was accomplished under the following conditions: treatment time of 10،20 and 30 minutes، chemicals usage as hydrogen peroxide 1%، sodium hydroxide 1%، DTPA 0. 3% and surface active agent 0. 15% (based on oven-dried waste paper)، consistency of 10% by washing، flotation and combined washing and flotation processes، separately. Enzymatic deinking was carried out using cellulase enzyme at different concentrations of 0. 025، 0. 05، 0. 1 and 0. 2 percent (based on oven-dried waste paper)، treatment time of 10،15 and 20 minutes، consistency of 10% at a pH range of 5-5. 5 by washing process. The results obtained showed that increase of cellulase concentration from 0. 025 to 0. 1% along with improving the deinking efficiency decreased dirt count and dirt area at both wire and felt sides. Deinking efficiency was decreased as cellulase concentration increased to 0. 2%. In general، the results from comparison of the appearance properties of the waste newspaper deinked by chemical and enzymatic methods showed that papers with the same appearance properties as chemical method can be produced using cellulase. However، chemical deinking of waste newspaper resulted in papers with lower dirt count، lower dirt area and improved deinking efficiency. In all chemical and enzymatic treatments performed، wire side had higher dirt count and the lower dirt area compared to felt side.