Chemical conversion
Zahra Razmpour; ghasem asadpour; kermanian hossein; omid ramezani; Seyed Majid Zabihzadeh
Abstract
Sticky contaminants represent one of the biggest technical challenges in the paper recycling process. These contaminants reduce paper strength, cause plugging of wires and felts, and stick to or deposit on machine parts affecting the runnability of the paper machine In this study, firstly, the sticky ...
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Sticky contaminants represent one of the biggest technical challenges in the paper recycling process. These contaminants reduce paper strength, cause plugging of wires and felts, and stick to or deposit on machine parts affecting the runnability of the paper machine In this study, firstly, the sticky deposit of Docter blade dryer blades was subjected to multi-stage extraction with alcohol, aceton, toluene, and tetrahydrofuran solvents respectively. Then the nature of the resulting material and its physicochemical properties was investigated with FTIR analysis, GC-MS, TGA, XRF, SEM.. The results showed that the deposite originates from fiber, polymers such as polyvinyl acetate and styrene butadiene, which are components of hot melt adhesives, and fatty acid/resin esters. Fatty acids and resins are the most common organic compounds in stickies deposite. the possible origin of these compounds are chemical substances (saponified fatty acids), deinking steps and some resins and fatty acids used in the formulation of adhesives or more resistant resins and extractive materials related to Cellulose fibers. The observed minerals are mainly calcium, iron, silica and aluminum, which are present in the formulation of fillers and coating pigments during the papermaking process
Negin Ghahrani; Noradin Nazarnezhad; Omid Ramezani; Ghasem Asadpour
Abstract
Regeneration of cellulose by direct solvent dissolution essentially involves the pretreatment of cellulose with a solvent for swelling the cellulose chains and weakening the cellulose molecules bonds. Aqueous solutions based on sodium hydroxide (NaOH) are low cost, non-volatile, non-toxic, environmentally ...
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Regeneration of cellulose by direct solvent dissolution essentially involves the pretreatment of cellulose with a solvent for swelling the cellulose chains and weakening the cellulose molecules bonds. Aqueous solutions based on sodium hydroxide (NaOH) are low cost, non-volatile, non-toxic, environmentally friendly cellulosic solvent with fast dissolution power at low temperatures. The mechanism of cellulose dissolution in this solvent is not yet fully understood because there are parameters such as temperature, crystallization and degree of cellulose polymerization that affect the solubility of cellulose in the NaOH / urea system. Therefore, this study investigated the effect of kappa factor changes in chlorine dioxide bleaching on the dissolution of OCC recycled pulp on chemical compounds (lignin and hemicellulose) and the degree of polymerization. The results showed that with further reduction of lignin, the dissolution of pulp decreases and this reduction in dissolution is more severe in lignin levels below 3% (reduction from 44% to about 37% dissolution). It seems that during the bleaching process and part of lignin and hemicellulose removal, a part of cellulose with low degree of polymerization is also removed and the average polymerization of the remaining cellulose increases which is more resistant to the phenomenon of pulp dissolution. With increasing kappa factor (to 0.2 and 0.3), there was no significant change in dissolution and hemicellulose. In general, it seems that lignin and the degree of polymerization are not only the effective factors in OCC pulp dissolving and hemicellulose content also can be effective.
Pulp and paper
Jafar Azizi; Omid ramezani; Esmaeel Rasooly; Hamidreza Rudi
Abstract
Cellulosic fines are essential parts of paper making system which impart remarkable effects on the production process parameters and the quality of final product. In this study, properties of fiberfines prepared from three kinds of pulps including Kraft, chemical mechanical (CMP), and recycled (OCC) ...
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Cellulosic fines are essential parts of paper making system which impart remarkable effects on the production process parameters and the quality of final product. In this study, properties of fiberfines prepared from three kinds of pulps including Kraft, chemical mechanical (CMP), and recycled (OCC) were investigated. Required amounts of fines were prepared using Valley Beater apparatus. Then the fines were classified into three categories using dynamic drainage Jar (DDJ): fines passing a 100 mesh remained on 200 mesh (P100/R200), fines passing a 200 mesh remained on a 325 mesh (P200/R325), and fines passing a 325 mesh (P325). Fines properties including dimensional size, special hydrodynamic volume, colloidal charge, alkalinity, turbidity, viscosity, and specific area were examined. The results revealed that PH of fiber suspensions tended alkaline concurrently to the decreasing in dimensional size of fines. Additionally, the colloidal charge of the three types of fines, especially the charge associated with the fines passed through 200 mesh screen and remained on 325 mesh one, showed a different behaviour compared to those in the same classes with the adverse trend to the viscosity variation. Special hydrodynamic volume is consistent with the dimensional size and dimensional ratio with the lowest amount of it observed in the recycled pulp fines. Turbidity has a direct relationship with particles size, homogenous distribution and the specific area of the finesThe results of turbidity related to the fines passed through 200 mesh size showed different behaviour compared to other categories.
Pulp and paper
Noraldin Nazarnezhad; Naser Rasol pour hedayati; Omid Ramazani
Abstract
Chitosan is known as a natural polymer which improves strengths of papers. So, in this study investigated improvement of chitosan absorption on modified craft fibers and increase its efficiency. The effects of chitosan were experimented in three levels of 0%, 0.75% and 1.25% on modified kraft fibers ...
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Chitosan is known as a natural polymer which improves strengths of papers. So, in this study investigated improvement of chitosan absorption on modified craft fibers and increase its efficiency. The effects of chitosan were experimented in three levels of 0%, 0.75% and 1.25% on modified kraft fibers surfaces with 3% hydrogen peroxide in different pH levels (5.5, 7 and 8.5). The results showed that chitosan had better performance at low dosages and alkaline conditions. Also surface fibers modification by hydrogen peroxide caused increase of carboxyl groups and fibers anionic charge. Fibers anionic charge with participant of chitosan formed a dual system. The apparent density increased from acidic pH to alkaline. As, the highest apparent density were reached in alkaline pH and 0.75 % of chitosan. Also, tensile index and burst index of paper were reached in alkaline pH and 0.75 % of chitosan. Whereas, chitosan and the surface modified fibers of kraft pulp did not have a significant level on the tear index
