DEVELOPMENT OF CELLULOSIC PAPER-BASED TEST STRIPS FOR Cr(VI) DETERMINATION

Paper-based test strips specific for the Cr(VI) determination in aqueous solutions were developed by impregnating a color-forming reagent, diphenylcarbazide, and a quaternary ammonium salt (Aliquat 336) into paper sheets. The results showed that the quaternary ammonium salt could effectively retain the colored complex in the paper substrate. This paper-based test strip showed a high selectivity for Cr(VI) in the samples to be tested. The method was applied to synthetic samples, and the results were compared to these from a reference method. The current work demonstrated that with a color chart, this portable paper-based test strip has the potential to be used for field screening or on-site semi-quantitative analysis

THERMAL STABILITY OF METAL-PITCH DEPOSITS FROM A SPRUCE THERMOMECHANICAL PULP BY USE OF A DIFFERENTIAL SCANNING CALORIMETER

Pitch-related deposition has been a significant issue in paper mills that produce wood-containing paper grades. A component analysis showed that a mill deposit sample was a mixture of wood resin, fiber, metal cations, and other inorganics. Based on the differential scanning calorimeter (DSC) method, some critical parameters, including pH, metal cations, and their interactions, on the thermal stability of pitch-related deposits were studied. The valency of metal cations determined the ability of capturing pitch the formation of deposits. Trivalent Al3+ or Fe3+ ions had much stronger effects than divalent Ca2+, Mg2+, or Mn2+. It was also found that a higher pH and trivalent Al3+ or Fe3+ increased the thermal stability of deposits formed in colloidal pitch solutions

Pretreatment by Ceriporiopsis subvesmispora and Phlebia subserialis of wheat straw and its impact on subsequent soda-AQ and kraft-AQ pulping

Pretreatments of wheat straw with two dif erent lignin­degrading fungal cultures ­ Ceriporiopsis subvesmispora and Phlebia subserialis­ were carried out and their ef ects on soda­AQ and kraft­AQ pulping were studied. After two weeks of bio­treatment of the wheat straw, both fungus were found to be suitable for bio­chemical pulping. The fungal pretreatment decreased the kappa number by as much as 24% and the unbleached pulp brightness increased by about 7% at a constant yield. Furthermore, the bio­pretreatment increased the brightness of the fully bleached pulp by about 1 ISO% point. This can apparently reduce the amount of the chemicals used in the bleaching process. The results on the sugar analysis of the pulps showed that in terms of carbohydrate composition, there were no significant dif erences between the bio­treated and control pulps. However, the strength properties of the un­bleached and bleached chemical straw pulps decreased slightly after the fungal pretreatment. This is dif erent from reported results that the strength properties of mechanical pulps were improved after the fungal pre­treatment. There was no dif erence of the two white­rot fungal species, Ceriporiopsis subvesmispora and Phlebia subserialis in term of their ef ect on the strength properties

IMPACT OF FURFURAL ON THE SUGAR ANALYSIS OF PRE-HYDROLYSIS LIQUOR OF KRAFT-BASED DISSOLVING PULP PRODUCTION PROCESS USING THE HPAEC TECHNIQUE

High performance anion-exchange chromatography with pulse ampero-metric detector (HPAEC-PAD) is a reliable method to systematically determine the sugar contents in pulp and paper waste streams, including bleaching and extraction liquors. We used the same method to determine the sugar content of industrially produced pre-hydrolysis liquor (PHL) from a kraft-based dissolving pulp production process. The analysis showed that the traditional method cannot be applied for sugar analysis, and an improvement on the method was required. In fact, the presence of furfural in the PHL sample was the reason for the required modification. It was noted that the removal of furfural via evaporation could improve the reliability of the HPAEC technique for sugar assessments. If the concentration of furfural was higher than 0.045% (wt.) in the PHL, the error introduced in the sugar analysis was profound. Also, the industrially produced PHL contained more furfural than the laboratory produced PHL under the same hydrolysis conditions. Consequently, the concentration of furfural in the PHL should be taken into account for sugar analysis using the HPAEC technique

Dissolved and colloidal substances (DCS) and the charge demand of papermaking process waters and suspensions: A Review

Dissolved and colloidal substances (DCS) in the process waters of paper machine systems can interfere with the retention of fine particles, retard the drainage of water from the wet web, and generally hurt the intended functions of various polyelectrolytes that are added to the process. This review considers publications that have attempted to characterize the nature and effects of different DCS fractions, in addition to some of the ways that paper technologists have attempted to overcome related problems. The consequences of DCS in a paper machine system can be traced to their ability to form complexes with various polyelectrolytes. Such tendencies can be understood based on a relatively strong complexing ability of multivalent materials, depending on the macromolecular size and charge density. Continuing research is needed to more fully understand the different contributions to cationic demand in various paper machine systems and to find more efficient means of dealing with DCS

Application of Polyaniline/Clay Combination to Cellulosic Paper as an Approach to Conductivity Development

A polyaniline/clay combination was prepared via: 1) mixing polyaniline dispersion with clay; or 2) in situ polymerization of aniline in the presence of clay. To deliver electrical conductivity to cellulosic paper, the polyaniline/clay composition was applied to the paper surface by Meyer rod coating. The conductive paper was analyzed by Scanning Electron microscopy (SEM) and Fourier Transmission Infrared spectroscopy (FT-IR). For comparison purposes, conductive paper was also prepared by in situ polymerization of aniline in the presence of cellulosic fibers. The in-situ formed polyaniline was deposited on the fiber surface, and the polyaniline-deposited cellulosic fibers were made into paper sheets. It was found that at the same aniline content, paper surface coating with polyaniline/clay composition gave a much higher conductivity in comparison with the use of polyaniline-deposited cellulosic fibers for paper sheet formation

SUBSTITUTION OF HIGH-YIELD-PULP FOR HARDWOOD BLEACHED KRAFT PULP IN PAPER PRODUCTION AND ITS EFFECT ON ALKENYL SUCCINIC ANHYDRIDE SIZING

In recent years there has been an increasing interest in using high-yield pulp (HYP) as a partial replacement for hardwood bleached kraft pulp (HWBKP) in the production of high-quality fine papers as a cost-effective way of improving the product performance. This study investigated the substitution of HYP for HWBKP and its effect on the Alkenyl Succinic Anhydride (ASA) sizing performance. The results showed that the substitution of an aspen HYP for HWBKP can increase the ASA sizing performance at a HYP substitution as high as 15 to 20%. The ASA addition sequence has an influence on the ASA sizing performance and first adding ASA to the HYP followed by mixing with kraft pulps was the preferred method. Using precipitated calcium carbonate (PCC) as a paper filler at a dosage of less than 20% can increase the ASA sizing performance due to the contribution of the calcium soap of the hydrolysed ASA. A PCC dosage greater than 20% resulted in a negative impact on the sizing performance. It was also found that different PCC loading sequences can also affect the ASA sizing performance

EFFECTS OF THE ENDOXYLANASE TREATMENT ON FIBER CHARACTERISTICS, BRIGHTNESS STABILITY AND STRENGTH PROPERTIES OF BLEACHED WHEAT STRAW PULP

The pretreatment of soda-anthraquinone (AQ) wheat straw Pulp with Purified endo-(1,4)-beta-xylanase was studied. Different xylanase dosages (0, 2, 20 and 100 IUg(-1)) were applied to the Pull) before ail ECF (Elemental Chlorine Free) bleaching sequence. The fiber characteristics, brightness stability and strength properties of the obtained pulps were determined. The results showed that the fiber characteristics were not significantly affected by the enzyme pretreatment. Oil the other hand, the xylanase pretreatment lowered the strength properties of the pulp. A slight improvement in lignin removal was observed, thus improving pulp bleachability, the results agreeing with those obtained oil wood pulps. Furthermore, higher paper brightness stability was obtained by the xylanase pretreatment, explained by the removal of the metal ions from the Pulp samples