Determination of Ideal Cooking Conditions for Pulp Production from Avocado Wood (Persea americana Mill.) by Kraft Method

In this study, hand sheets were made from pulp produced by the Kraft method using avocado wood. The raw materials were supplied by a fruit orchard and consisted of avocado (Persea americana Mill.) trees that had completed their useful life and were cut during routine thinning maintenance. In order to determine the ideal cooking conditions in the production of pulp from avocado wood via the Kraft method, 16 cooks were carried out by varying the cooking time (T), active alkali (AA), and sulfidity (S) ratios. The general pulp properties, especially the screened pulp yield, pulp viscosity, and Kappa number, were evaluated. The pulp yield was taken as the primary basis in determining the cooking conditions. The ideal cooking conditions were also determined by considering some physical, mechanical, and optical properties of the paper. According to this study, the conditions found to be ideal in pulp production from avocado (Persea americana Mill.) wood via the Kraft method were: 18 % AA, 22 % S, and 75 min T.

Bar forces in pulp refiners

Refiners develop pulp properties by applying forces on fibres during bar crossings. The size of these forces is critical in developing fibre properties while avoiding fibre shortening. This study has shown that bar force calculated from Specific Edge load (SEL) gives the same result as vector-based derivations of average bar force. Predicted forces agree reasonably well with ones measured by a novel piezo-electric sensor in refiner bars and forces estimated from measurements of fibre shortening.

Carboxylated bleached kraft pulp from maleic anhydride copolymers

Seven copolymers of maleic anhydride were hydrolyzed and impregnated into sheets of bleached softwood kraft pulps to enhance market pulp properties. Drying the impregnated pulps at 120 °C for 10 minutes, attached to the fiber surfaces up 0.16 meq of carboxyl groups per gram of dry pulp. Heating the impregnated pulps regenerates succinic anhydride moieties which can then form stable ester linkages with cellulosic hydroxyls. The pH of the impregnation solution is important. Impregnation with solutions at pH 8 gave polymer contents without repulping issues. By contrast, impregnation at pH 4 gave dried pulp sheets that were too strong to enable repulping in a paper mill. Although most of the seven copolymers were fixed to cellulose, poly(ethylene-alt-maleic anhydride) gave the highest density of carboxyl groups. The simplicity of waterborne polymers and mild drying temperatures suggests maleic anhydride copolymer treatment could be implemented in a conventional market pulp mill.

CHLORINE DIOXIDE BLEACHING OF PULP FROM CROP RESIDUES: BAGASSE, KASH AND CORN STALKS

"This investigation describes the effect of hot chlorine dioxide delignification (DHT) of bagasse, kash and corn stalk pulps on pulp properties and effluent quality. The pulps were subjected to DHT at 85 °C for 45 min and the results were compared with those of the D0 process carried out at 70 °C for 45 min. The kappa numbers after the alkaline extraction (Ep) stage in DHT bleaching were always lower and brightness was higher, compared to the corresponding parameters in D0 bleaching, without impacting pulp viscosity. The final brightness of the corn stalk pulp was 84.8% at a kappa factor of 0.25 in the D0 process, while in the DHT process, the same type of pulp reached the brightness of 87.2% at a kappa factor of 0.15, saving 40% ClO2 in the first stage. Similarly, kash pulp exhibited 90% brightness at a kappa factor of 0.15, which also saved 40% ClO2, compared to the conventional D0 process. The brightness of bagasse pulp in DHT and D0 processes was almost similar. Oxygen delignified pulp had a lower effluent discharge than unbleached pulps in subsequent ECF bleaching. The COD value in DHT was lower than that in D0."

On the modeling of pulp properties in CTMP processes

The goal of this paper is to model the pulp properties fiber length, shives width and freeness. This will be done utilizing specific energy, flat zone inlet consistency and the internal variables, consistencies and fiber residence times estimated from refining zone soft sensors. The models are designed using more than 3600 hours of data from a RGP82CD refiner. The pulp properties are sampled using a measurement device positioned after the latency chest. Such measurements are noisy and irregularly sampled which opens for a number of challenges to overcome in modeling procedures. In this paper it is shown that the models for shives width and fiber length are capable of predicting most of the major dynamics. However, for freeness no reliable linear models can be derived. When estimating fiber length, the specific energy together with flat zone inlet consistency, fiber residence times and the consistency in the conical zone were the dominant inputs. For shives width it was found that a similar set of inputs resulted in the best models, except that the consistencies during normal process conditions did not significantly influence shives width. Furthermore, fiber residence times were shown to have considerably more pronounced impact on fiber length compared with shives width estimates.

Pulp properties and spent pretreatment solution resulting from reed pulping with a low alkali loading

Using reed (Phragmites australis (Cav.) Trin. ex Steud) as raw material, straw pulp was prepared by low alkali (less than 6%) pretreatment combined with mechanical grinding. The effects of pretreatment times and alkali dosages on pulp properties and pretreatment solution were investigated. The results demonstrated that alkali pretreatment affected FPI beating efficiency, and the beating energy consumption was lowest when pretreated with alkali dosage of 4%. With 5% NaOH pretreatment, the produced handsheets showed excellent properties that exceeded the requirements of food packaging paper and C-class corrugated paper. Moreover, low silicon content (≤1.12 g/L) in the pretreatment liquor had an almost negligible effect relative to alkali recovery. Therefore, this study is important for researchers and industrial representatives seeking to use reed straw as material for pulping.

Effect of introducing ozone in elemental chlorine free bleaching of pulp on generation of chlorophenolic compounds

Effect of using ozone before elemental chlorine free (ECF) bleaching of oxygen delignified wheat straw pulp produced following soda-anthraquinone pulping on bleaching effluent and pulp properties was studied. The effluent generated during bleaching of pulp contains high amount of adsorbable organic halogens (AOX), chemical oxygen demand (COD), biochemical oxygen demand (BOD) and highly toxic chlorophenolic compounds. This study is aimed to utilise green chemistry approach during bleaching of one of the abundantly used agro residue wheat straw for improving the quality of bleaching effluent and pulp properties. Introducing ozone stage before ECF bleaching resulted in significant reduction of chloriphenolic compounds like chlorocatechols by 48.9 %, chloroguaiacols by 33.3 %, chlorovanillins by 28.4 % and chlorophenols by 26.7 % in the effluent compared to those of control. Incorporation of ozone before ECF bleaching BOD, COD, AOX and colour were reduced by 40.0 %, 41.1 %, 46.7 % and 57.8 %, respectively, as compared to control. Optical properties like brightness and whiteness of the pulp bleached using ozone were also improved by 2.5 units and 4.0 units, respectively as compared to that with control.

The Effect of Soda Pulping Variables on Pulp Properties of Coir Fiber

The potential use of coir fiber for pulping and papermaking has been investigated. This research aimed to study effects of pulping processing variables (temperature, pulping time, and alkali charge/solvent pulping) on the properties of pulp (residual lignin, alpha cellulose, kappa number and pulp yield) from coir fiber. For this purpose, the coir fibers were cooked using alkali charge (10 to 20% oven dried, as NaOH), pulping time from 60 to 120 min and temperature from 65 to 180oC. Results indicated that alkali charge and pulping time gave more impact on the properties of pulp than temperature. Pulping at high temperature, long pulping time, and high alkali charge resulted in decreasing of lignin, pulp yield, and kappa number but instead on alpha cellulose content. Keywords: coir, soda pulping, lignin

Evaluation of Rhododendron Luteum and Rhododendron Ponticum in Pulp and Paper Production

In this study, Rhododendron luteum and Rhododendron ponticum were evaluated as raw material for pulp and paper production. 12 different sodium borohydride (NaBH4) added cooking trials were performed for each sample and kraft method was used for pulp production. Pulp properties, such as yield, kappa number and viscosity, and physical properties, such as breaking length and burst index, were determined for each trial. Besides, the effects of active alkali and NaBH4 on the pulp and paper properties were also examined. Optimum cooking conditions were obtained by using 18 % active alkali for NaBH4-free cooking experiments and 0.5 % NaBH4 and 18 % active alkali for NaBH4-added cooking experiments. In NaBH4-added pulping condition, the screened yield, kappa number and viscosity of R. luteum were found to be 43.4 %, 40.1 and 949 cm3/g1, respectively. The respective values for R. ponticum were 41.9 %, 44.5 and 885 cm3/g1. The screened yields of R. luteum and R. ponticum increased by about 2.8 % and 5.3 %, respectively, with 5 % addition of NaBH4 compared to NaBH4-free cooking experiments. Furthermore, with the addition of NaBH4, the kappa numbers decreased while the viscosity increased. The physical properties of the produced papers were also improved by using NaBH4 in cooking liquor. According to the obtained results, it was found that R. luteum and R. ponticum species can be evaluated for pulp and paper production.