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Wang L.,Zhejiang University of Science and Technology | Wang L.,Zhejiang Yongtai Paper Group Industry Co. | Zhang Y.,Lakehead University | Fatehi P.,Lakehead University
Palpu Chongi Gisul/Journal of Korea Technical Association of the Pulp and Paper Industry | Year: 2016

Dissolved substances (DS) in papermaking suspension contribute a large portion of negativity to the total dissolved and colloidal substances (DCS). Compared to colloidal substances (CS), dissolved substances are clearly more difficult to be removed by fixing agents (FA). Formation of polyelectrolyte complexes (PECs) between fixing agents and dissolved substances plays a very important role in clarifying the mechanism of a fixing agent acting on DCS. This study, therefore, focused on the characteristics of PECs formed between fixing agents and dissolved substances. Three polyamines (PA) with different molecular weight and slight different charge density were synthesized and used as fixing agents, in four different kinds of water including, two kinds of DCS water separated from a same deinked pulp (DIP) but with different size and distribution of CS particles, and two kinds of DS water modeled by oxidized starch (OS) and hemicelluloses (HC). The formation of PEC in these systems and their corresponding characteristics were characterized using focused beam reflectance meter (FBRM), laser particle size analyzer (LPSA), turbidity meter, and charge detection. From the results, it is concluded that for a given DS component and a certain kind of fixing agent, the formation of DS-fixing agent PECs highly depended on the molecular weight of the fixing agent and its dosage. A fixing agent with enough low molecular weight could form big but loose and dispersible DS-FA PECs, increasing its dosage would produce denser and smaller PECs; and a fixing agent with enough high molecular weight could directly form dense PECs, increasing its dosage increased the size of PECs. Depositing DS-FA PECs onto small CS particles also played an important role in forming new CS particles with larger sizes, and in this case, a fixing agent with higher molecular weight tended to produce more large particles.


Wang L.,Zhejiang University of Science and Technology | Di T.,Tianjin University of Science and Technology | Luo L.,Zhejiang Yongtai Paper Group Industry Co. | Hu Z.,Zhejiang University of Science and Technology
Appita Journal | Year: 2014

In improving the application convenience of the first generation of starch based fixing agents (SBFs) which are made by cationization followed by acid hydrolysis, three new SBFs were made respectively by degrading the molecular weight of raw starch with acid hydrolysis, enzymatic hydrolysis and hypochlorite oxidation, followed by etherification. The degree of substitution and molecular weight of the three SBFs were controlled to be similar. The performance of these experimental SBFs in controlling the dissolved and colloidal substances and paper strengthening was measured and compared to that of a traditional polyamine fixative. The results show that the polyamine fixative is better in neutralizing the dissolved substances, while the SBFs are better in fixing the colloidal substances and better in enhancing paper strengths. Among the SBFs, the effectiveness of controlling dissolved and colloidal substances and paper strengthening, from best to worst, is in the order of enzymatic, acid and finally hypochlorite degradation.


Wang L.,Tianjin University of Science and Technology | Wang L.,Zhejiang University of Science and Technology | Wang L.,Zhejiang Yongtai Paper Group Industry Co. | Zhang Y.,Tianjin University of Science and Technology | Li G.,Tianjin University of Science and Technology
BioResources | Year: 2014

Five polyamine fixing agents with different molecular weights but slightly different charge densities were used to treat a deinked pulp. Their efficacy in controlling colloidal substances (CS) in the pulp was measured using focused beam reflectance measurements (FBRM). The objective was to determine if the colloidal substances were affected by the fixing agents by a "colloidal fixation" mechanism, i.e., colloidal particles being fixed onto pulp fiber in an un-agglomerated, single-particle state, or a "colloidal agglomeration" one, i.e., colloidal particles being coagulated by fixing agents into bigger agglomerates. The results showed that colloidal fixation does take place, especially for the polyamine with the smallest molecular weight. Among the five polyamines, it was found that higher molecular weights tended to result in more extensive colloidal agglomeration, but the effect of charge density was almost insignificant. Because it is efficient in differentiating between these two fixation mechanisms, FBRM is a powerful tool in screening different fixing agents.


Wang L.,Zhejiang University of Science and Technology | Di T.,Tianjin University of Science and Technology | Zhang Y.,Tianjin University of Science and Technology | Luo L.,Zhejiang Yongtai Paper Group Industry Co. | Zhao H.,Zhejiang University of Science and Technology
Starch/Staerke | Year: 2014

Starch-based fixatives (SBF), specifically low molecular weight, highly-cationic starches (LHCS), have been reported to efficiently control dissolved and colloidal substances (DCS) in pulp suspensions, and to enhance paper strengths. However, as their degree of substitution (DS) was as high as 0.65, their preparation cost was very high. In this study, two products with lower DSs of just 0.08 (LHCS 0.08) and 0.22 (LHCS 0.22) were prepared and compared to a traditional polyamine (PA) fixative. It was found that the novel LHCSs interacted more readily with the anionic pulp fibers while the PA interacted more readily with the anionic DCS. Consequently, both LHCS 0.08 and LHCS 0.22 increased the paper strength more than the PA. Moreover, it was found that the LHCS 0.22 was most efficient in fixing the colloidal substances onto fibers, while the PA was most efficient in neutralizing the dissolved substances. We conclude that LHCS with DS as low as 0.22 can be used as a good fixative, however, starch with DS of only 0.08 is not efficient enough. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Wang L.,Zhejiang University of Science and Technology | Wang L.,Tianjin University of Science and Technology | Wang L.,Zhejiang Yongtai Paper Group Industry Co. | Wang L.,South China University of Technology | And 5 more authors.
Cellulose Chemistry and Technology | Year: 2015

For a good performance, most wet end agents used in paper industry must adsorb onto pulp fibers. In this work, we studied the effect of four fixing agents, namely polyamine (PA), polydiallyldimethyl ammonium chloride (PDADMAC), polyethyleneimine (PEI) and a low-molecular-weight and highly cationic starch (LHCS), in promoting the adsorption of some typical wet end chemicals, specifically fluorescence whitening agent (FWA), methyl violet (MV) tinting dye, cationic starch dry strengthening agent (DSA-CS), poly(amidoamine)epichlorohydrin wet strengthening agent (PAE), and cationic polyacrylamide (CPAM) retention agent, onto a bleached chemithermomechanical pulp (BCTMP). It was found that the adsorptions of the wet end chemicals could be improved by all the four fixing agents. When the dosages of the fixing agents were based on the same weight, the LHCS was almost as effective as PA, PDADMAC and PEI, in improving the adsorptions of the negatively charged FWA, and the positively but weakly charged MV and DSA-CS, while it was slightly less effective in enhancing the adsorptions of the highly cationic additives, such as PAE and CPAM. When the dosages of the fixing agents were based on equal charges, the LHCS improved the adsorptions much more than the other three fixing agents. The fact that the LHCS tends to interact more with colloidal substances, while the other three fixing agents interact more with dissolved substances can be used to explain the phenomena discovered.


Xia X.,Tianjin University of Science and Technology | Liu Z.-H.,Tianjin University of Science and Technology | Wang L.-J.,Tianjin University of Science and Technology | Wang L.-J.,Zhejiang University of Science and Technology | And 3 more authors.
Chung-kuo Tsao Chih/China Pulp and Paper | Year: 2016

A polyamine (PA) fixing agent, and a cationic polyacrylamide (CPAM) retention aid were used individually as well as in combination to treat deinked old newspaper pulp, and focused beam reflectance measurement (FBRM) were utilized to measure the quantity, size and size distribution of the colloidal particles remained in the pulp, with the objective to elucidate the combinative effect of fixing agent and retention aid on controlling dissolved and colloidal substances (DCS) in papermaking pulp raw material. The results indicated that when the PA was used individually to treat the pulp, some colloidal agglomerates were formed which were not fixed onto fiber or trapped in fiber mat, thus resided in pulp filtrate; when the CPAM is used individually, its charge was neutralized easily by the DCS, therefore, its ability to reduce the quantity of colloidal particles in the pulp was decreased greatly, and the bigger colloidal agglomerates were not formed; when PA and CPAM were used in combination, those agglomerates formed by PA but resided in the aqueous phase were further retained onto fiber by CPAM, therefore, better effect in reducing the quantity of the colloidal particles without forming bigger colloidal agglomerates was achieved. © 2016, China National Pulp and Paper Research Institute(CNPPRI). All right reserved.


Luo L.-Z.,South China University of Technology | Luo L.-Z.,Zhejiang Yongtai Paper Group Industry Co. | Wang J.-H.,Zhejiang Yongtai Paper Group Industry Co. | Qiu Z.-Q.,South China University of Technology | And 2 more authors.
Chung-kuo Tsao Chih/China Pulp and Paper | Year: 2013

The latest trend of the paper industry is greater consumption of secondary fibres and closure of the process water systems. Under these conditions the microbiological activity increases considerably and therefore, problems of runnability and production of paper machine occur. To control microorganisms and associated problems, microbiology, analytical chemistry and papermaking technology are the important theoretical basis. This paper presented a review of the knowledge about microorganism species, microbiological detection methods, discussed how to analyze the propagation of the microorganisms and what we should pay attention to in the prevention and control of microbiological pollution.

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