Effect of bleaching using sodium hydroxide on pulp derived from Sesbania grandiflora

World demand for paper is increasing. Short rotation pulpwood is needed. Sesbania grandiflora also known as Turi, is a fast growing and straight log species. The scholarly information of Turi as pulpwood are still limited. This paper aims to provide information of sodium hydroxide effect on the paper made from pulp derived from Turi. Sodium hydroxide is a common chemical using as part of full stage chemical bleaching in pulp industrial. Kraft pulp that produced using Turi, was bleached with sodium hydroxide at 3%, 6% and 9% based on pulp weight, respectively. Unbleached pulp was served as blank test. The optical and mechanical properties of handsheet paper made from bleached kraft pulp were evaluated according to TAPPI standard. The brightness and opacity of handsheet made from bleached pulp were improved with increasing the concentration of sodium hydroxide. The mechanical properties of handsheet were improved with using 3% sodium hydroxide and gradually decreased after 3% sodium hydroxide. In conclusion, sodium hydroxide is potential to improve optical properties of Turi pulp and improve the mechanical properties of paper made from Turi pulp at certain level. Excessive usage of sodium hydroxide brings adverse effect to mechanical properties of paper made from Turi pulp.

Dynamic-head space GC-MS analysis of volatile odorous compounds generated from unbleached and bleached pulps and effects on strength properties during ageing

Mixed hardwood unbleached (UB) and final bleached (FB) pulp along with the pulp of intermediate bleaching stages from an integrated paper mill have been undertaken for this study. Headspace GC-MS analysis of these pulps was made to identify the odorous compounds which are volatile organic compounds (VOCs), generated during ageing for 60 days. The result showed that a number of pre-generated VOCs such as aliphatic hydrocarbons and aldehydes are observed in the pulp sample which might be came from the process and it has been observed that upon ageing at ambient conditions, some acid functionalized VOC were generated in the pulp. The generation of these VOCs were established by ATR-FTIR analysis and the results showed that intensity of peak absorbance near 3340 cm − 1 {\text{cm}^{-1}} and 1641 cm − 1 {\text{cm}^{-1}} which represents the –OH stretching of acidic functional group and C=O stretch of aldehyde and acidic functional groups increased after ageing. Generation of acid functionalized volatile compounds were observed more in bleached pulp than in unbleached pulp. Degree of polymerization (DP) is pretty much related to the strength of paper. DP of both unbleached and bleached pulp gets reduced upon ageing while more reduction were observed in bleached pulp. Bleached pulps are more prone to degrade as compared to the unbleached pulp in terms of strength properties such as tensile index, breaking length, burst and double fold were observed. 12.3 % and 21.8 % reduction in tensile index was observed for UB and final bleached FB pulp respectively. Burst index of UB and FB pulp were found reduced to 23.8 % and 41.9 % respectively due to ageing. Reduction in the mechanical and optical properties was also observed in intermediate bleaching stages. There is much evidence for the contribution of VOCs to the degradation of paper. The results are strongly suggested that acid functionalized volatile compounds can have strong effects on degradation of cellulosic paper.

Delignification of unbleached pulp by ternary deep eutectic solvents

The processing of lignocellulosic materials is very limited because of their low solubility in water and some organic solvents. Fifteen ternary deep eutectic solvents (DESs) were prepared and tested as solvents suitable for delignification of unbleached pulp. The selected ternary DESs are composed of quaternary ammonium salts and amino acids as hydrogen-bond acceptors, and organic acids and polyvalent alcohols as hydrogen bond donors, with molar ratios varying for the individual components. The delignification efficiency is significantly influenced by the degree of penetration of the solvent into the pulp fibre structure. Therefore, the density and viscosity analysis of individual solvents was performed. Unbleached beech pulp with initial kappa number 13.9 was treated with the prepared DESs. The kappa number indicates the residual lignin content or the bleachability of pulp. The efficiency of the solvents ranged from 1.4% to 28.1%. The most suitable for the pretreatment of fibres, based on lignin removal efficiency, were found to be three DESs, in the following order: malonic acid/choline chloride/1,3-propanediol (1:1:3) > choline chloride/acetamide/lactic acid (1:2:3) > choline chloride/urea/lactic acid (1:2:3).

Characterization of Porous Structures of Cellulose Nanofibrils Loaded with Salicylic Acid

Bleached and unbleached pulp fibers were treated with 2,2,6,6-tetramethylpyperidine-1-oxyl (TEMPO) mediated oxidation to obtain cellulose nanofibrils (CNFs). The resulting bleached and unbleached CNFs were mixed with salicylic acid (0, 5, 10, 20 wt%) before casting and freeze-drying or 3D-printing. A series of methods were tested and implemented to characterize the CNF materials and the porous structures loaded with salicylic acid. The CNFs were characterized with atomic force microscopy and laser profilometry, and release of salicylic acid was quantified with UV-visible absorbance spectroscopy, conductivity measurements, and inductive coupled plasma mass spectrometry (ICP-MS). Fourier-transform infrared spectroscopy (FTIR) complemented the analyses. Herein, we show that aerogels of bleached CNFs yield a greater release of salicylic acid, compared to CNF obtained from unbleached pulp. The results suggest that biodegradable constructs of CNFs can be loaded with a plant hormone that is released slowly over time, which may find uses in small scale agricultural applications and for the private home market.

Kraft pulping and bleaching of Eichhornia crassipes (Mart.) Solms (water hyacinth)

Eichhornia crassipes (water hyacinth) was pulped by means of a kraft pulping process with reagent loads of 10 and 20% on a dry matter basis to determine yield, rejects, kappa number, and ash. Fiber classification, brightness, opacity, and viscosity were measured in the brown pulp. Bleaching was performed by means of an O1O2D1(PO)D2HD3 sequence. Yield, kappa number, pH, ash, brightness, opacity, and viscosity were evaluated in the bleached pulp. Finally, a microanalysis of inorganic elements was carried out in both the bleached and unbleached pulp ash. The highest kraft pulp yield was 26.4%, with a 10% reagent load at 120 °C and 30 minutes cooking. It was determined that E. crassipes cellulosic pulp contains large amounts of fines. Results of the bleaching sequence indicate low brightness (58.0 %) and low viscosity (6.43 cP). The most abundant inorganic elements in the ash of both bleached and unbleached pulp were Ca, Mg, P, and Si. These results suggest that E. crassipes biomass might complement cellulosic fibers in pulping processes of low yield, such as the wood fibers used to produce handmade paper.

Effect of bark content in mixed hardwood chips on pulp and papermaking properties

Effect of different proportions of bark in mixed hardwood (about 70 % eucalyptus and 30 % poplar) chips on pulp and papermaking properties was studied. Increased proportion of bark in raw material chips resulted in increased active alkali consumption, increased reject content in pulp and reduced pulp yield after kraft pulping. The unbleached pulp obtained with higher proportion of bark in mixed hardwood chips also has higher kappa number, lower brightness and viscosity as compared to pulp obtained with bark free mixed hardwood chips. The soda loss and ash content in pulp were severely increased from 12.8 kg/t to 312 kg/t of pulp and 0.7 % to 21.1 %, respectively with the increase of bark portion from 0 to 100 % in raw material furnish. The physical strength properties like tensile, burst and tear indices in the pulp obtained from bark were reduced by 58.5 %, 60.7 % and 68.4 %, respectively as compared to that with bark free mixed hardwood.

Bioconversion of pine stumps to ethanol: pretreatment and simultaneous saccharification and fermentation

The technical viability was investigated for the conversion of Pinus pinaster stumps to value-added products via a chain of pretreatments and simultaneous saccharification and fermentation (SSF) steps to obtain bioethanol. Sequential steam explosion (SE), organosolv (OS) pretreatment and soda-anthraquinone pulping (Na/AQ) were performed resulting in an unbleached pulp (UBP), which was successfully converted via SSF to bioethanol with concentrations up to 79 g l−1, which corresponds to a conversion yield of 97% and productivity of 1.09 g l−1 h−1 at 15% total solids. Accordingly, delignification steps by oxygen bleaching are not necessary for bioethanol production. Different industrial softwood (SW) pulps were also tested as reference materials. Total lignin contents up to 4.5% in SW-based pulps had no adverse effects on SSF efficiency.

КРЕМНІЙОРГАНІЧНІ ПОКРИТТЯ ДЛЯ ЗАХИСТУ ПАПЕРУ, ОТРИМАНІ З ЕЛЕМЕНТАМИ ЗОЛЬ-ГЕЛЬ ТЕХНОЛОГІЇ

Мета. Розробка двошарових кремнійорганічних покриттів для захисту паперу звикористанням золь-гель технології та оцінка ефективності їх застосування приексплуатації в умовах підвищеної вологи.Методика. Дослідження проведені з використанням стандартнихзагальноприйнятих методик та методу кількісної ІЧ-спектроскопії.Результати. Розроблено захисні двошарові покриття для паперу з небіленоїцелюлози із використанням елементів золь-гель технології на основі силоксанів, щомістять групи →Si – OK та →Si – OЕt у функціональному підшарі таполіетилгідридсилоксан – в поверхневому. Дана кількісна оцінка застосування такихпокриттів для захисту паперу у вологих умовах. Визначено найбільш ефективні захиснікремнійорганічні покриття та оцінено їх ефективність при експлуатації.Наукова новизна. Вперше обґрунтовано доцільність застосування технології звикористанням золь-гель елементів на стадіях гідролізу та конденсації, що дозволяєефективно використовувати силоксани з групами →Si – OK та →Si – OC2H5 в якостібазових для формування функціональних підшарів на поверхні целюлозовмісних матеріалів.Практична значимість. Досліджено особливості формування системисилоксанових покриттів для захисту паперу з небіленої целюлози із елементами золь-гельтехнології. Показана ефективність застосування двошарової системи, що включаєможливість зв’язування гідроксильних груп поверхні паперу та додаткового формуваннягідрофобного захисного шару шляхом застосування силоксанів з різнимиреакційноздатними групами біля атома кремнію (→Si – OK, →Si – OEt, →Si – OH, →Si –H). Обґрунтовано доцільність застосування технологій з використанням золь-гельелементів на стадіях гідролізу та конденсації. Запропоновано схему формування захиснихдвошарових покриттів для паперу з небіленої целюлози, досліджено її механізм, данакількісна оцінка та визначено найбільш ефективні системи захисних кремнійорганічнихпокриттів. Purpose. Development of two-layer silicon-organic coatings for paper protection using solgel technology and evaluation of their application efficiency in conditions of high humidity.Methodology. The researches were carried out using standard common methods andquantitative IR spectroscopy.Findings. Protective two-layer coatings for paper made from unbleached cellulose with theuse of sol-gel elements based on siloxane-based materials containing → Si-OK and → Si-OEt inthe functional sublayer and polyethylhydrisiloxane-in the surface are developed. This is aquantitative assessment of the application of such coatings to protect paper in wet conditions. Themost effective protective silicon organic coatings are determined and their efficiency duringoperation is estimated.Originality. For the first time, the feasibility of using the technology using sol-gel elementsat the stages of hydrolysis and condensation has been substantiated, which allows the effectiveuse of siloxanes with Si-OK and → Si-OC2H5 groups as the base for the formation of functionalsublayers on the surface of cellulosic materials.The practical value. Silicone coatings to protect the paper, obtained with elements of solgel technology. The features of the formation of a system of siloxane coatings to protect paperfrom unbleached pulp with elements of sol-gel technology are investigated. The feasibility andefficiency of using a two-ball scheme, which includes the possibility of binding hydroxyl groups ofthe paper surface and the additional formation of a hydrophobic protective ball by usingsiloxanes with different reactive groups near the silicon atom (→ Si-OK, → Si-OEt, → Si-OH, →Si - H). In addition, the feasibility of applying technologies using sol-gel elements in the stages ofhydrolysis and condensation has been substantiated. The scheme of formation of protective twolayer coatings for paper made of unbleached cellulose was proposed, the mechanism of itsformation was investigated, a quantitative assessment was made and the most effective schemes ofprotective silicon-organic coatings were determined.

Characterization of Physical and Mechanical Properties of Bleaching Paper from Rice Straw

This paper aimed to determine the characteristics of physical and mechanical properties of rice straw hand sheet and investigated the optimal conditions for making rice straw paper. The chemical composition of rice straw determined with the TAPPI standards. The conditions of making paper hand sheet composed of pulping time: 2 hours, 4 hours, pulping temperature: 100°C, 130°C, pulping solvent: 2 wt% NaOH, 4 wt% NaOH and bleaching: unbleached pulp, bleached pulp with 2% H2O2. The paper hand sheet was tested based on TAPPI methods, basic weight TAPPI- T410-om-93, thickness TAPPI- T411-om-89, moisture content TAPPI- T412-om-93, brightness TAPPI T452 om-92, opacity TAPPI standard T 425 om-91, burst strength TAPPI T403 om-97, tensile strength TAPPI T494 om-01, and tear strength TAPPI-T414-om-88. The results showed that the optimal conditions of rice straw hand sheet including pulping time: 2 hours, pulping temperature: 100°C, pulping solvent: 2 wt% NaOH, and bleaching: unbleached pulp gave the highest the physical and mechanical properties form other conditions. This conditions showed as the basic weight 62.27 g/m2, thickness 259.30 µ, opacity 93.34 ISO%, burst strength 64.75 kPa.m2/g, tensile strength 95.33 N.m/g, and tear strength 473.55mN.m2/g. In this condition, the paper hand sheet used at the lowest concentration of pulping solvent and non-bleached, which reduces environmental pollution.

MORPHOLOGICAL, PHYSICAL AND THERMAL CHARACTERIZATION OF MICROFIBRILLATED CELLULOSE

ABSTRACT The aim of this study was to characterize microfibrillated cellulose (MFC) produced with a Masuko Sangyo Super Masscolloider using bleached and unbleached pulp of Eucalyptus spp. The MFC was characterized regarding morphology (TEM), crystallinity, viscosity, zeta potential and thermal properties (TGA). Regardless of the fiber type, the processing dramatically reduced the dimensions of the material, so as to obtain structures with nanometric dimensions. MFC produced with unbleached pulp preserved the original brown color of the pulp, which may be advantageous for some applications in the packaging sector, while films produced with bleached pulp were more translucent. The MFC showed lower values of viscosity and crystallinity index in relation to cellulosic pulp. The zeta potential was influenced by the type of fiber used. The main thermal transitions in MFC occurred after 200 ºC, demonstrating the potential of this material forhigh-temperature applications.