جستجوی مقالات مرتبط با کلیدواژه « refining » در نشریات گروه « کشاورزی »

Paper recycling currently is considered one of the most important solutions for the environmental and sustainable production of paper products. In addition to reducing the consumption of various resources such as water, energy, and virgin fibers using this process, the paper recycling rate is continuously increasing in different countries due to less pollution. Most of the recycled paper is usually used to produce packaging paper and board. Paper and paperboard should not only possess dry-strength, but also must be able to provide the required strength at wet condition for the packaging of products that need to be kept in the cold and freezer condition. For this purpose, different procedures such as refining and additives can be used. This research investigates the independent effect of each factor as well their interaction effect in order to improve the characteristics of office deinked pulp (DIP) for producing packaging paperboard.

DIP was obtained from Latif Paper Company. After refining the pulp to SR = 30, additives including cationic corn starch (at the levels of 1, 1.4, 2, and 3w%), wet strength resin (at the levels of 1, 2, and 3w%), and AKD (at the levels of 1, 2, and 3w%) were separately added to the pulp suspension based on the dry weight of pulp in order to manufacture handsheets with the basic weight of 120 g/m2. In order to compare and determine the effect of optimum treatment of the additives on the treated pulp, tests i.e. water absorption, tensile strength, burst and tear strength of the handsheets, as well as wet strength retention and absolute wet strength retention were measured. The relative retention strength was measured after determining the independent effect of each treatment on the tensile strength, burst, and tear strength of handsheets in both wet and dry conditions. The effect of optimal combination treatment on the characteristics of handsheets was investigated and compared, when the optimal values of each independent treatment were determined.

The independent effect of refining on the strength of handsheets made from DIP is statistically significant in the dry conditions. The results indicated that using 2w% cationic corn starch in the refined pulp could induce better performance in the term of increasing the strength of handsheets in dry conditions, specifically the tear strength, compared to the independent refining factor. Using wet strength resin and AKD also represented a significant increase in the strength of handsheets in the wet conditions and also a significant decrease in the water absorption compared to the control sample, respectively. Using of refining and optimal combination treatment of additives including 2w% cationic corn starch, 3w% wet strength resin, and 1w% AKD simultaneously caused a significant improvement in the wet and dry strength, and water absorption of handsheets.

All the properties of the handsheets were improved with the applying of optimal combination treatment including the refining of DIP and adding additives at the same time compared to the control sample, so it could be used for the packaging of products that should be stored in the refrigerator and freezer. The strengths of handsheets in the dry conditions are superior compared to the standard strength of bleached kraft paper according to the Iran national standard no. 2875 except for tear strength. The measurement of absolute relative retention wet strength demonstrated that the performance of the combination treatment is very suitable compared to other previous research reports. The combination treatment significantly has reduced the paper water absorption by 22 g/m2, which is suitable for paper storage in the freezer.

In the present study, the effect of chemical refining process on the oxidative stability of Bene kernel oil during 32 hours of thermal process at 170 ° C was investigated. Examination of fatty acid structure showed that the amount of trans fatty acid was very small after the thermal process. The trend of changes in tocopherol and polyphenolic compounds during the heating process was different from other studies. The rate of tocopherol changes increased at the end of the thermal process in crude, degummed and neutralized oils and decreased in bleached and deodorized oils. The reason for the increase in tocopherols was related to their regeneration process. Also, the amount of polyphenolic compounds after the thermal process compared to the zero moment was largely in line with tocopherol changes. The reason for the increase in phenolic compounds was related to the breakdown of these compounds and their becoming simpler compounds. Examination of oxidation stability tests (conjugated diene vlue and p-anisidine value) also showed that crude kernel oil was the most stable sample, followed by degummed, neutralized, deodorized and bleached oils, respectively. The reason that the decolorization step caused the lowest oxidative stability in Bene kernel oil can be attributed to the greatest reduction in the amount of tocopherol compounds in this oil sample compared to the zero moment. Also, the trend of changes in antioxidant activity was largely consistent with changes in antioxidant compounds.

As the consumption of OCC pulp is increasing globally, practical studies are needed to reduce energy consumption and improve the quality of this pulp using enzymatic treatments. In this study, the effect of refining on cellulase enzyme performance on OCC pulp properties was investigated. OCC pulp with 4% consistency, 50 ° C constant temperature, 1 hour duration and 4-5.5: pH with cellulase enzyme at three levels of 0.1, 0.3, 0.5 percentages (based on dry weight of pulp) were pretreated. Pulp freeness and hand sheet strength properties were measured according to TAPPI standard codes. The results showed that the enzymatic treatment of cellulase increased pulp freeness and improved paper strength properties and this effect was more in unrefined OCC pulps than refined OCC pulps. Overall, enzymatic cellulase treatment can reduce pulp refining and reduce energy consumption and improve OCC pulp quality.

The effect of applying the sequence of enzymatic treatment and refining was investigated on the properties of deinked pulp from mixed office waste paper (MOW). Refining was applied for 700 and 1500 revolutions. Enzymatic treatment was applied for 60 minutes with temperature of 60°C and 13% of consistency. Applying enzymatic treatment led to decrease in strength properties of paper and also decrease in freeness of the pulp. The refining process resulted in increase of paper properties and decrease in freeness of the pulp. By applying enzymatic treatment before refining, the freeness of pulp changed significantly so that, the freeness of the pulp was 496 and 390 for 700 and 1500 refining revolution respectively just for refining but these numbers changed to 397 and 544 for same revolutions for “enzymatic treatment + refining” sequence. In a normal condition increase of refining revolution lead to decrease in pulp freeness but that was interestingly the freeness increased for 1500 refining revolution. This means that the enzymatic treatment was effective. Generally, refining itself improved the quality parameters of pulp and paper, but applying this process after enzymatic treatment changed everything.

Nowadays, the problem of water and soil resources pollution is major and influential issue for the healthy living of humans and living things. Nitrate is one of the decentralized sources of environmental pollution in wastewater or agricultural drainage that caused by excessive use of fertilizer. The infiltration and leakage of these waters into surface water and groundwater sources cause to contaminating these waters with nitrate. Nitrate moves easily into the soil profile due to its negative charge and lack of adsorption on the soil surface that cause to contamination on surface and groundwater. Different physical and chemical methods are commonly used to nitrate adsorption from various municipal, industrial and agricultural wastewaters, which are complex and costly on industrial scales. In this research, various methods of nitrate adsorption have been studied and the main focus of the study is on the process of surface adsorption by cheap biochar as an effective process and a suitable method in the final refining of nitrate-contaminated waters.

The negative effects of air pollution impress plants to develop different morphological and anatomical changes. On the other hand in large cities plants (especially trees) help to increase the quality of air. Therefore the plants which balance internal structure and polluted environment, can deeply affect the quality of air in the cities. This study determine the suitable indexes to select tolerance of species which are widely planted in Tehran. In order to carry out this research, seven study areas was selected. Seven morphological (Leaf area, Dry and wet weight, thickness, specific leaf area, water content percentage) and 20 anatomical parameters was measured and calculated on Robinia pseudoacacia, Fraxinus rotundifolia, and Platanus orientalis. Sorkhe-Hesar and Azadi was introduced as areas that affect air pollution and climate and soil parameters was similar in both areas. Significant decrease and increase in some vegetation characteristics was observed in all study species. Leaf thickness (Sorkhehesar= 0.12, Azadi= 0.14 and P<0.01), Upper cuticul thickness (Sorkhehesar= 1.9, Azadi= 3.5 and P<0.05), Rp/Rs (sorkhehesar= 1.2, Azadi= 1.9 and P<0.05) and abaxial stomata density (Sorkhehesar= 347, Azadi= 444 and P< 0.05) shows significant increase in Black locust. Significant relations with air pollution tolerance indicator is the most in Black locust and the least in plane. The results of this study introduce R. pseudoacacia as suitable species than the other plants (plane and ash) to air pollution condition.

The use of old corrugated container (OCC) is considered an effective solution by the paper industries in paper and paperboard productions bearing environmental and economic reasons. The strength properties of pulp made from recycled paper is weaker than the original pulp for various reasons, such as hornification. Therefore, various methods as adding strength enhancing materials and mechanical treatments are used to improve the quality of them. Because of little amount of production, many of the paper recyclers have limitation in investment of using mechanical treatments (refiners) in their production line. In this research, using cationic starch and cellulose nanofibers(CNF) was investigated as strengthen additives and as an alternative for mechanical refining in the paper and paperboard production from OCC. In this study, cationic starch in one level (2%) and cellulose nanofibers in 3 levels (2, 4, 6%) were used and compared to control (refined and non-refined) samples. Results showed that 2% CS and 4% CNF improved the tensile and burst indices same as or more than refining of pulp, while the pulp dewatering time and paper density were equal. Therefore, the aforementioned conditions are recommended as a substitute for refining in small units of waste paper recycling for paper and paperboard production.

In this study the beatability of soda and monoethanolamine pulps was compared. The refining of pulps was done in pilot scale Voith refiner Model LR 40. The results show that the maximum tensile and burst indices of monothanolamine pulp are reached with consumption of 70 kWh energy in pilot scale Voith refiner and the increasing of energy more than this level has the adverse effect on these indices. In the case of soda pulp increasing the energy up to 500 kWh has the linear relationship with tensile and burst indices. In comparison to monoethanolamine pulp, the refining of soda pulp is more difficult and needs more energy. Using monoethanolamine pulp resulted in saving of energy by 70-80 % to reach the optimum strength indices.

The objective of this study was determination of the best method of bleaching including refining and bleaching (RB) or bleaching and then refining (BR) on chemical mechanical pulp (CMP) for the production of newsprint. Wood raw material consists of mixed wood forest species was chipped and air dried to calculate the moisture content. Wood composition percentages for CMP pulping was 40% poplar, 30% maple, 7.5% oak, 7.5% alder, 7.5% willow, and 7.5% Persimmon. In order to remove heavy metal ions of pulp, the chelating was carried out with DTPA. TCF Bleaching carried out by 3% H2O2 and 2.5% NaOH based on dry weight of pulp with initial brightness of 44.6% ISO. Pulp bleaching was done in two stages, before and after the refining by laboratory PFI mill beater. Finally, handsheets were made from the RB and BR treated pulps and the sheet properties were evaluated according to TAPPI test methods. The results showed that BR treatment increased tensile, burst, tear indices, brightness, scattering coefficient, and density, but reduced yellowing, opacity, and light absorption coefficient. The results confirmed the conventional method of CMP pulp treatment (BR) in MWPI.

In order to investigation the use of bio-refining of silicon on cadmium and lead in spinach, in the pot experiment Qaemshahr Agriculture University in 2012 as a completely randomized design with four replications. Treatment include silicon (150mg/kg of Potassium silicon), Pb (100 mg/kg of chloride) ,Cd (100 mg/kg of chloride),silicon, silicon and control as used soil. The results showed that the use of silicon,Pb accumulation in shoot and roots decreased (34/4 ,65/2 percents) and also Cd accumulation in shoot and roots decreased (25/7 , 37/0 percents) respectively. The lowest shoot and root lengh was with Cd and Pb application, that less than in comparison with control(42/4 , 27/8 percents) respectively. At least bush fresh weight obtained with Pb and Cd separate application and silicon and Cd joint application . results this experiment can reception that silicon application caused the decrease Cd and Pb accumulation in shoot and root spinach plant.

in this study, the effect of refining on the optical and mechanical properties of pulp and paper made from recycled banknote paper was investigated. For this purpose, fifty Rials waste banknote papers were cut into strips with a width of 15 mm. First, retail banknote papers were pretreated with acid under conditions pH=3 and 4 hours treatment time in ambient conditions. After acidic pretreatment, a acidic treatment was done under conditions pH=3 and 1.5 to 2 hours treatment time in 95° C, and the amount of consumed acid was 0.3% for banknote papers weight. To separate ink particles from fiber surfaces, a alkaline treatment was performed after acidic treatment under conditions 2 hours treatment time in 95° C, and 3% NaOH for dry pulp weight. After alkaline treatment, obtained pulp was poured into a laboratory mixer and by mixer was stirred in 2 minutes until the fibers are so far apart. Then, the freeness of pulp was measured. Obtained pulp was refined by PFI refiner in refining intensities of 50, 100 and 150 and then, the freeness of obtained pulps were measured. After refining, for each of the pulps, hand sheet papers were made and the properties of them were determined. The results indicated significant differences between pulp and paper properties made of waste currency papers with 4 different refining intensities in 1% confident level. As increasing of refining intensity and refining revolutions, burst strength, tensile strength, folding strength and brightness of papers increased but tear strength of papers and freeness of pulps decreased.

This study was conducted with the aim of fabricating lab-scale samples of transparent papers with overbeating method. Hence, bleached soda pulp from bagasse fibers was subjected to post-bleaching with sequence of DED to remove any residual chromophores. Then this pulp was refined with PFI mill to achieve different levels of 55, 130, 200, and 260 mL,CSF (Canadian standard freeness). Results indicated that refining has significant effect on optical properties especially transparency so that the maximum value was observed in handsheets made of pulp according to TAPPI standard T 205 om - 8 with least freeness, i.e 55 mL. The variations of transparency due to refining were also further explained by measuring scattering coefficient, opacity and brightness of the specimens. In addition, mercury porosimetry and analyzing the pictures of scanning electron microscopy (SEM) demonstrated the severe variations of pore structure in paper during refining which have great influence on developing transparency.

In this research، the effect of different steps of enzymatic treatment including enzymatic pre-refining and post-refining by Endoglucanase was investigated on the quality of OCC pulp. Three pulps including a: control sample (without enzyme addition)، b: enzymatic pre-refining (enzyme treatment + refining) and c: pre and post enzymatic refining (enzyme + refining + enzyme) were made from OCC pulps. Enzymatic treatment was done at optimum conditions before determined (concentration of 1u and time duration of 0. 5 hour) under constant process conditions and refining accomplished at given revolution of 2000. Obtained results from this research indicated that applying enzymatic pre-treatment had efficient in improving the physical and mechanical of paper and showed the highest strength than to the other treatments. Using Endoglucanase at two stages (before and after refining) caused to improve pulp drainability and decrease the paper strength properties. In general، the maximum tear index was observed in enzymatic pre-refining step.

In this study the effects of separate and combined refining of Hornbeam (Carpinus betulus) CMP and imported long fiber (LF) pulps on the prepared handsheets properties is evaluated in two states. In the first state, Hornbeam CMP and long fiber pulps were separately PFI-milled to reach to 250-400 ml, CSF (261, 309, 362 and 410) and 400-600 ml, CSF (410, 474, 530 and 590), respectively. Then, they were mixed at the ratio of 80/20 and laboratory handsheets were made and their physical, mechanical and optical properties were determined. In the second state, the average freeness value for each mixture of the pulps from the first state (261 Hornbeam + 410 LF, 309 Hornbeam + 474 LF, 362 Hornbeam + 530 LF, 410 Hornbeam + 590 LF) was calculated and the real freeness value for each mixture was reached to the calculated one using combined PFI-milling. Handsheets were then made from each mixture of the pulps and their physical, mechanical and optical properties were determined. The comparison of the results showed no significant difference at 1% experimental error level between properties of the papers prepared from both states. However, higher PFI revolutions improved the properties of papers. On the other hand, it was observed that combined refining of the pulps led to saving in refining energy use and, thus, is recommended.

In this study, CMP pulp yield and refining energy consumption of treated pulp affected by the fungus Phanerochaete chrysosporium BKM - 1767 were evaluated and compared with control samples. After preparing fungal specimens, hornbeam chips were treated at three levels 1, 2 and 4 weeks under temperature 39oC with relative humidity 65%. For preparing CMP pulp from treated chips, Production conditions were as follows: cooking temperature 165oC, cooking time (80 and 90 minutes), the percentage of sodium sulfite chemicals: 14%, 18%, 22% in comparison to the cooking liquid to chips which was 7 to 1. The results showed that treated wood, rate of output has decreased. In comparison to the control group. The reduction for treatments for the weeks 1, 2 and 4 was about 1.64, 2.84, and 6.20 percent respectively. Furthermore, increasing the consumption of chemicals has increased the yield, which actually increased the severity of reactions compression yield after cooking. The results of refining showed increasing the fungal treatment period caused easier refining and less consumed energy so that the week 4 treatment caused 40% reduction in refining energy.

The possibility to improve the test liner board properties using mechanical treatments (refining) was studied. Old Corrugated Container (OCC) fibers used in a recycled paper manufacturing company were quantitatively and qualitatively analyzed and hardwood and softwood fibers content were estimated as 22.6% and 60%, respectively. The mechanical treatment of pulp fiber was performed in a Valley Beater until the target freeness of 400 ml CSF. Then hand sheets with the basis weight of 127 g/m2 were made and the apparent density, Gurley air resistance, burst strength, folding endurance, Elmendorf tear strength, tensile strength and RCT were measured according to TAPPI standards. The results showed that all the properties of the refined sample increased compared to the control sample. Comparing the strength properties of the paper produced from refined pulp with the relevant values in Iranian national standards indicated the 33%, 50%, 117% increase in burst index, tensile index, and tear index, respectively. The refined pulp RCT strength increased by 28% compared to that of control sample. As the results indicated, test liner boards with suitable strength can be manufactured locally and even exported.

Fiber external fibrillation is one of the refining effects in conventional refining which is accompanied with other effects such as internal fibrillation. Objective of the present study was to investigate the effect of fiber external fibrillation on paper properties. Softwood kraft pulp and poplar wood CMP pulp produced at Mazandaran Wood and Paper Industries was used. An ultra-fine friction grinder was used to generate the external fibrillation. Results showed that, increasing the fiber external fibrillation increased the density of paper sheets and lower refiner gaps decreased the light scattering coefficient. Increased fiber external fibrillation improved the tensile strength of the paper sheets by about 20% and internal bonding was increased from 33% to 46% compared with unrefined fibers.

The pulp strength properties of old corrugated containers (OCC) are reduced as a result of recycling process. So at present paper, improvement of OCC pulp properties was investigated through refining and also using cationic starch and imported unbleached softwood kraft pulp (USKP). In addition to studying the effects of each of above mentioned parameters, the effects of combined treatment of refining + cationic starch, refining + USKP, and cationic starch + USKP were also investigated. Cationic starch at 3 dosing levels (0.5, 1.0 and 1.5%) and USKP at 3 dosing levels (5, 10 and 15%) were used in admixture with refined and unrefined OCC pulps. The results have shown that treatments such as refining, cationic starch, USKP, and cationic starch + USKP significantly improved the OCC strength properties. The highest strengths were obtained from treatment of 1% cationic starch + 15% USKP, which in comparison with reference sample; about 40% increase in burst and tensile strength, and 30% increase in tear strength were occurred. Air resistant, in treatment where 1.5% cationic starch was used in refined pulp, was increased 45% as compared with the reference sample. The results showed that the optimum treatment, in terms of obtaining highest improvement in OCC pulp properties, was a combined treatment of refining + cationic starch + USKP. However, depending on the required end use quality, OCC pulp can be improved by using refining treatment with or without using different dosages of cationic starch and USKP.