Total Bleaching Research Articles

Effectiveness, longevity, and color stability of in-office bleaching (6% H2O2 gel/Violet LED) and diastema closure with direct composite: 3-year follow-up

To reduce bleaching side effects, the use of low concentrations of Hydrogen Peroxide (HP) agents associated with hybrid light (violet LED/Diode Laser) has gained interest. Case report: The aim of this report is to describe a case of a 16-year-old patient that presented a complaint related to the color of his teeth and a maxillary midline diastema. In-office bleaching with 6% HP associated with hybrid light (violet LED/Diode Laser) was performed. The bleaching gel was applied once on the teeth and light-activated for 1 minute (15 times) followed by 1min intervals (15 times) with a total bleaching time of 30 minutes. After the bleaching procedure, the teeth were polished and the desensitizer was applied for 4 minutes. Two bleaching sessions were performed at a 1-week interval. The diastema was closed with direct resin composite restorations without any tooth preparation. The conventional 3-step bonding agent was used and A1 dentin shade and B1 enamel shade were used followed by polishing discs. At 3-year recall, discoloration and fractures were not found on the the teeth or restorations and patient was completely satisfied. Conclusion: the conservative and safe option of bleaching with a low-concentrated HP gel associated with violet LED light is an interesting option for young patients and presents longevity over time.

Single Vesicle Fluorescence-Bleaching Assay for Multi-Parameter Analysis of Proteoliposomes by Total Internal Reflection Fluorescence Microscopy.

Reconstitution of membrane proteins into model membranes is an essential approach for their functional analysis under chemically defined conditions. Established model-membrane systems used in ensemble average measurements are limited by sample heterogeneity and insufficient knowledge of lipid and protein content at the single vesicle level, which limits quantitative analysis of vesicle properties and prevents their correlation with protein activity. Here, we describe a versatile total internal reflection fluorescence microscopy-based bleaching protocol that permits parallel analysis of multiple parameters (physical size, tightness, unilamellarity, membrane protein content, and orientation) of individual proteoliposomes prepared with fluorescently tagged membrane proteins and lipid markers. The approach makes use of commercially available fluorophores including the commonly used nitrobenzoxadiazole dye and may be applied to deduce functional molecular characteristics of many types of reconstituted fluorescently tagged membrane proteins.

Formic Acid Pulping and TCF Bleaching of Cassava Stalks

The formic acid (FA) pulping process is well-known for its advantage to overcome the problems caused by the presence of high silica and fines content of agriculture residues during pulping. In this context a new and unconventional raw material, cassava stalk was pulped using formic acid followed by treatment withperoxyformic acid (PFA) treatment was applied to the formic acid treated pulps at 800C for two hours.It was found that the FA/PFA process lowered pulp yield of cassava stalks when FA concentration was increased. The PFA pulping decreased the kappa number of the pulps. After the FA/PFA treatment of cassava stalks, the pulp yield reached 37- 42% with kappa number of 21-34 at different formic acid concentrations. FA/PFA pulp from cassava stalks did not show promising result in total chlorine free bleaching and final brightness reached only up to 54%. DUJASE Vol. 6 (2) 1-6, 2021 (July)

Spectral analysis and kinetic studies of enzymatic delignification of kraft wood pulp by xylanase

The traditional bleaching methods used chlorine as bleaching agent which produced large amount of chlorinated organic compounds including dioxins which are persistent environmental pollutants. The alternate methods using peroxides and enzymes were developed to achieve total chlorine free bleaching. The xylanase enzyme was used as bleaching agent in this study. The delignification study was performed to evaluate the optimum conditions required for obtaining minimum kappa number of the pulp to remove maximum lignin from the wood fibres. The interactions of various factors such as pulp consistency, enzyme dosage and temperature were studied. The best conditions for enzymatic bleaching obtained were 10% consistency, 50 IU of enzyme dosage and 52oC in the range studied. The predicative mathematical models were developed for enzymatic bleaching. The activation energy for xylanase delignification of paper pulp was 13.989kJ/mol. The significant functional groups in bleached pulp samples were analysed using Fourier transform infrared spectroscopy and the surface morphology of pulp fibres was studied using Scanning electron microscopy images.

Phytochemical composition, antioxidant and wound healing activities of Teucrium polium subsp. capitatum (L.) Briq. essential oil

ABSTRACT Teucrium poliumis widely used in Algerian folk medicine as to treat wounds. The aim of this study was to evaluate the chemical composition, antioxidant and wound healing properties of Teucrium polium essential oil. The composition was obtained by a combination of GC-FID and GC-MS analyses. The antioxidant activity was evaluated by in vitro assays (total antioxidant capacity, DPPH and bleaching of β-carotene). The in vivo wound healing potential of an ointment containing 10% of T. polium essential oil was investigated. The main components were in this order: β-pinene, germacrene, α-pinene, myrcene, limonene, bicyclogermacrene, trans-β-guaiene, spathulenol and β-bourbonene. Teucrium polium essential oil displayed a moderate antioxidant activity. The in vivo experiments showed that 10% OEO accelerated the wound healing process in comparison with controls. This study provides a scientific rationale for the use of Teucrium polium essential oil in the treatments of wounds.

Enzyme cocktail: An opportunity for greener agro-pulp biobleaching in paper industry

An enzyme cocktail (xylanase-15U, pectinase-2U, α-amylase-2.5U, protease-2U and lipase- 1.8U) from Bacillus halodurans was applied for the biobleaching of unbleached and ODL (oxygen delignification) agro based pulp in the R&D set up of Shreyans Paper Mills Ludhiana, India, upscaling from 5 g (at lab scale) to 100 g odp (oven dried pulp). Enzyme pre-treatment was carried out at temperature and pH optima of 65 °C and 9–9.5 for 90 min followed by reduced chemical treatment. In case of unbleached agro pulp, as compared to the total chemical bleaching in mill, enzyme cocktail pre-treatment reduced the chemical usage by 50% without compromising brightness and rather with increased tensile strength (23.55%), burst factor (20.3%) and tear factor (3.17%) and reduced kappa number (19.5%). In case of ODL pulp, enzyme cocktail pre-treatment reduced the chemical usage by 40%, yet increasing brightness (2.24%), tensile strength (20.96%), burst factor (5.1%) and tear factor (8.2%) with reduction in kappa number (4.54%). The enzyme cocktail thus can make the paper manufacturing process greener, safer, economical and eco-friendly and may replace big budget ODL technologies.

Utilization of sarkanda for making pulp and paper using elemental chlorine free and total chlorine free bleaching processes

A lignocellulosic non-wood material sarkanda available in abundance as waste, was evaluated for chemical constituents, pulping behavior, morphological properties, bleaching behavior and paper handsheet strength properties. Present study reveals that sarkanda contains cellulose 36.2 ± 0.5 %, hemicelluloses 35.2 ± 0.41 %, lignin 21.2 ± 0.22 % and ash 8.2 ± 0.3 %. Soda-anthraquinone pulping of sarkanda using 15 % active alkali resulted in unbleached pulp with 14.7 kappa number, 16.0 cP viscosity and 54.6 % pulp yield. With use of elemental chlorine free bleaching sequence, OD0EOPD, final bleached pulp achieved 85.7 % ISO brightness, whereas, using total chlorine free bleaching sequence, OZEOPPOPO, the brightness obtained was 81.9 % ISO. Elemental chlorine free bleached sarkanda pulp had tensile index of 39.4 N m/g, burst index of 3.4 kN/g and tear index of 5.7 mN m2/g. The study exhibits that sarkanda has potential to be utilized for papermaking. Such approach of using non-wood raw material with elemental chlorine free bleaching and total chlorine free bleaching sequences for papermaking can be a valuable approach for reducing pollutants generation, utilization of waste biomass and fulfillment of fibrous raw material requirement for paper industry.

Habilitación y obsolescencia de marcadores discursivos

The starting hypothesis of the article is that the discursive operators of Spanish have not been enabled by grammaticalization processes identical to those of other grammatical components (such as verbal or nominal morphemes or prepositions and conjunctions), since there has been no reduction in the functional scope nor a total bleaching, so that its link with the original lexical items has not disappeared. The consequence is that markers are not integrated into paradigms as closed as grammatical paradigms and both their obsolescence and their renewal, therefore, follow similar patterns to what happens in the evolution of the lexicon. This hypothesis is tried to verify in the article by means of the examination of some discursive markers that, having been used diachronically in Spanish, have been abandoned ina relatively short time.

İki ışıkla aktive olan ofis tipi beyazlatma ajanlarının farklı estetik restoratif materyallerin mikrosertliği üzerine etkisi

Background: Irradiation sources have been used to reduce the total in-office bleaching time. However, little is known about the effects of the light irradiation bleaching systems on the restorative materials. This in vitro study evaluated the microhardness of 6 different restorative materials during office bleaching procedures with blue light emitted diode and diode laser photoactivation.Materials and Methods: FiltekTM supreme (nanofilled), Tetric EvoCeram (nanohybrid), Tescera ATL (ormocer), Clearfill Majesty Esthetic (nanofilled), Durafill VS (microfilled) and IPS Empress II (ceramic) restorative materials were selected in this study. Twenty specimens, 10 mm in diameter and 2 mm thick, were fabricated from each material using a Teflon mold. All specimens were randomly assigned to two groups (n=10). Group 1 received two topical applications of 35% hydrogen peroxide and was photoactivated using blue light emitted diode (800 mW/cm2) for 20s. Group 2 received topical application of 46% hydrogen peroxide using diode laser (wavelength 980 nm, average power 7 watt, energy setting 200 J, continuous mode) for 30s. Baseline and after bleaching microhardness measurements were taken with a Vickers hardness tester that was used with a 300 g for the porcelain and 100 g for the composite and ormocer specimens, the dwell time was 30 s for all groups. Data were analyzed statistically, with one-way-analysis of variance (ANOVA), post-hoc Tamhane's T2 and independent t tests.Results: After application of both office bleaching agents, microhardness of all restorative materials tested were significantly decreased (p<.05). However, Tetric EvoCeram composite resin material showed the least microhardness value (p<.05). Conclusion: Blue light emitted diode and diode laser activation hydrogen peroxide office bleaching agents have similar effects on the reduction of microhardness of restorative materials. The data of this study revealed that after bleaching, nanofilled (FS, CME), microfilled (Df) specimens demonstrated lower changes in microhardness values than nanohybrid (TEC) composite material.

Antagonistic, synergistic and interaction effects of process parameters during oxygen delignification of Melia dubia kraft pulp

Melia dubia is a recently identified hardwood for papermaking. This study reports oxygen delignification of its kraft pulp. Modeling of O2 delignification was done implementing central composite design taking temperature, time and NaOH charge as process parameters while pulp yield, kappa number, intrinsic viscosity and brightness were the process outputs. The high precision quadratic models developed for O2 delignification revealed antagonistic, synergistic and significant interaction effects between temperature, time and NaOH charge. The optimum values of process parameters estimated were 90 °C, 90 min and 1.39% respectively which gave pulp yield 96.64%, total kappa number 10.52, intrinsic viscosity 628.54 cm3/g and brightness 42.52% which were very much comparable to other papermaking raw materials. On the whole, the optimization desirability obtained for O2 delignification was 0.621. The overall O2 delignification efficiency based on the total kappa number and the true lignin kappa number was found to be 30.33% and 38.23% respectively. The O2 delignification practiced in this investigation led to 10.42% increase in brightness and 19.93% reduction in viscosity which would prove advantageous for subsequent elemental and total chlorine free bleaching.

A new era of straw-based pulping? Evidence from a carbon metabolism perspective

Abstract Straw pulping plays a vital role in virgin pulp supply and regional agricultural residue utilization. However, a significant decrease in its production has been observed. From an environmental perspective, why has there been a sharp decrease in straw pulping? Are there any innovations in straw pulp production that alleviate the heavy environmental burdens of straw pulping? In this study, factors contributing to the decrease in straw pulp are examined. An innovative technique to produce straw pulp is introduced and its environmental performance is analyzed and compared with conventional pulping. The results show that the main reasons contributing to the environmental burdens of straw pulping lie in the difficulties in black liquor extraction and alkaline recovery for the black liquor. Technical processes are changed in the innovative technique of straw pulping through using a rapid displacement cooking process, converting black liquor into fertilizers, utilizing total chlorine-free bleaching, etc. The new technique (Case B) achieves superior environmental performance than that of the conventional technique (Case A) from a carbon metabolism perspective. Specifically, 1022.90 kg and 857.80 kg of biogenic-carbon (bio-carbon), and 594.32 kg and 628.13 kg of fossil-carbon are needed to make 1 ton of bleached straw pulp for Case A and Case B, respectively. The carbon efficiencies for Case A, Case B (when pulp is the only desired product) and Case B (when including other products) are 39.10%, 46.63% and 92.21%, respectively. The carbon factors for Case A, Case B (when pulp is the only desired product) and Case B (when including other products) are 3.66, 3.60 and 1.86 kg CO2-eq, respectively. In addition, the corresponding E factors, which reflect the waste generation level, are 3.20, 2.69, and 1.39 kg, respectively. The new technique for straw pulping, which follows the principle of a circular economy by fully utilizing resources and reducing the generation of waste, achieves both economic and environmental benefits. It is a promising technique for straw pulping.

Assessment of physical properties of self-bonded composites made of cellulose nanofibrils and poly(lactic acid) microfibrils

Cellulose nanofibrils and poly(lactic acid) microfibrils, two bio-based polymers were used to elaborate composite films, and their properties were evaluated. Cellulose nanofibrils were obtained from organic pulping with total chlorine-free bleaching and were manufactured using high-pressure homogenization; while poly(lactic acid) microfibrils were obtained from a commercial partner. Morphological aspects of cellulose nanofibrils were assessed by atomic force microscopy showing traditional morphology for the elaborated nanofibrils, as well as the effects of sonication on the poly(lactic acid) microfibrils. Self-bonded composite films with different compositions were fabricated by hot pressing following methodologies previously reported. Uniaxial tensile stress was measured with a universal testing machine showing a decrease in most mechanical properties because of the low interactions between cellulose nanofibrils and polylactide microfibrils. Water vapor permeability was evaluated with a thermohygrometer and surface energy with the sessile-drop contact angle method these results showed good values for printing and gluing, with surface free energies ranging between 27 and 60 m Nm−1. Furthermore, industrial standards for paper-like materials and thermal properties of the composites were also analyzed of which it is to highlight the good bending strength as well as the concurrence of the results of Parker Print Surface tests with those of water contact angle.

Environmental Aspect of Using Chlorine Dioxide to Improve Effluent and Pulp Quality During Wheat Straw Bleaching

This paper illustrates the need of using the agro waste (wheat straw) as a substitute for forest products in paper industry. It aims on using the soda-AQ pulping process for converting waste to fibrous pulp. Further, it emphasizes on use of chlorine dioxide in place of elemental chlorine and hypochlorite during bleaching with aim of reducing the wastewater load and improving the pulp quality. Complete chemical characterization of wheat straw was performed. The soda-AQ (anthraquinone) method was opted for cooking and to make a pulp of kappa number 13. The pulp was bleached with elemental chlorine and calcium hypochlorite based sequences. To study the impact of adding chlorine dioxide on paper properties and effluent quality, elemental chlorine and hypochlorite were replaced with dioxide. The total elemental chlorine free bleaching sequence was also studied. The hand sheets were prepared to analyze the bleached and unbleached pulp properties using standard methodology. The effluent quality was studied by measuring the properties COD, BOD, TDS, TSS, TS, colour, lignin and adsorbable organic halides. Proximate chemical analysis of wheat straw showed that it contains holocellulose 67.3 ± 0.16%, hemicelluloses 39.2 ± 0.7%, cellulose 34.2 ± 0.9%, lignin content 14.9 ± 0.09% and ash 9.2% that mainly composed of silica (7.7%). With soda-AQ process a pulp with 53% yield and good strength properties was obtained. The bleached pulp of chlorine dioxide based sequences was having better strength properties in comparison to chlorine based sequences. Total replacement of elemental chlorine with chlorine dioxide reduced the BOD (52%), COD (49%), colour (43%), lignin (57%) and AOX (63%). Research concluded that wheat straw can be utilized by paper mills to combat the problem of waste management, air pollution due to its burning and issues of raw material for papermaking. Soda-AQ pulping method was found to be effective for preparing the wheat straw pulp. Use of elemental chlorine free bleaching may prove to be a reliable approach for better environmental management with high pulp characteristics.

Production of cellulose nanoparticles from blue agave waste treated with environmentally friendly processes

Tequila elaboration leaves two main byproducts that are undervalued (bagasse and leaves). Organosolv pulping and Total Chlorine Free bleaching were integrated to obtain cellulose fibers from agricultural waste which consisted of blue agave bagasse and leaf fibers; together they represent a green process which valorizes biomass waste. The obtained celluloses were characterized by FT-IR, colorimetry, and SEM and their extraction yields were evaluated. These celluloses were used to produce cellulose nanocrystals and cellulose nanofibers. First, an acid hydrolysis was performed in a sonication bath to induce cavitation during the reaction to produce cellulose nanocrystals. Then a high-pressure homogenization was selected to produce cellulose nanofibers. These nanocelluloses were characterized by powder XRD, Nanosizer, zeta potential, NMR, and electronic microscopy. Results showed that cellulose from organosolv pulps bleached with TCF bleaching is suitable for nanocellulose production. Moreover, the use of a new step to separate cellulose nanocrystals resulted in yields almost doubling traditional yields, while the rest of the properties remained within the expected.

Pathogenicity of isolates ofMagnaporthespp. from wheat and grasses infecting seedlings and mature wheat plants in Argentina

Wheat blast of wheat (Triticum aestivum), caused byMagnaporthe oryzaepathotypetriticum(MoT; anamorphPyricularia oryzae) is a destructive disease in the South American countries of Brazil, Paraguay and Bolivia. In Argentina, the fungus was recently recorded on wheat and barley plants in the northeast part of the country, Buenos Aires and Corrientes Provinces, with a potential for spreading. This work aimed to study, for the first time, the morphocultural and pathogenic characteristics ofMagnaportheisolates collected from wheat and other herbaceous species in Argentina and three neighbouring countries (Paraguay, Brazil and Bolivia) and determine their aggressiveness on wheat varieties. Statistical differences among isolates, culture media, and development conditions were found for conidia colour, growth rate, size and sporulation rate. Pathogenicity tests performed on seedlings with 19 isolates ofMagnaporthespp. under greenhouse conditions showed a maximum disease severity of 55.3% and 66.7% for varietiesBIOINTA3004 and Baguette 18, respectively. Weed and grass isolates were infectious on wheat, demonstrating their potential epidemiological role on the disease. Spike disease severity was 34.6% for the host × pathogen interaction ofBIOINTA3004 × PY22. Observed symptoms included partial or total spike bleaching, and glume and rachis discolouration. The 1000‐grain weight was significantly reduced to 38.5% and 63.1% for cultivarsBIOINTA3004 and Baguette 18, respectively. The disease affected grain germination, which fell to 65.9% for seeds infected with thePYAR22 isolate. Symptoms observed in infected grains were partial spotting, grain softening, and rot symptoms with the presence of a greyish mould.

Lignin valorization from side-streams produced during agricultural waste pulping and total chlorine free bleaching

Blue agave biomass (bagasse and leave fibers) was subjected to an organosolv pulping process along with a total chlorine free bleaching sequence to obtain cellulose for nanocellulose production. In this work, black liquors were collected after each pulping and bleaching stages, isolating lignin by selective precipitation. Physico-chemical characterization of the different samples was accomplished. Higher yields in lignin extraction are achieved from bagasse than from leaves. High recovery lignin yields could be achieved (∼90% for bagasse and ∼75% for leaves. As it was expected, the lignin extraction yields were reduced as bleaching sequence went on. An exhaustive physico-chemical characterization of all the samples was accomplished. The purity of the lignins, referred to the acid insoluble and soluble lignins, were lower for the bleaching stages, but remained with a purity level higher than 75% for every sample, which is a good purity level compared to lignin from other feedstock, and higher than 85% for the lignin from organsolv stage regardless of its source and being always higher for organsolv lignin than leaves ones. The molecular sizes of lignin samples were also measured. Chemical analysis was effected through Fourier transform infrared spectroscopy, nuclear magnetic resonance and pyrolysis, establishing in this way the chemical structure of the different lignins. Thermal properties were evaluated demonstrating by this the potential of valorization of lignin as part of an integrated biorefinery process. Bagasse lignins presented higher yield, purity and even better conditions in some case to be use in an integrated biorefinery.

Preparation and Fundamental Characterization of Cellulose Nanocrystal from Oil Palm Fronds Biomass

The objective of this work was to isolate cellulose nanocrystal (CNC) from oil palm fronds (Elaeis guineensis) and its subsequent characterization. Isolation involves sodium hydroxide/anthraquinone pulping with mechanical refining followed by total chlorine free bleaching (includes oxygen delignification, hydrogen peroxide oxidation and peracetic acid treatment) before acid hydrolysis. Bleaching significantly decreased kappa number and increased α-cellulose percentage of fibers as confirmed by Technical Association of the Pulp and Paper Industry standards. Transmission electron microscopy (TEM), X-ray diffraction, Fourier transform infrared spectroscopy and thermogravimetric analysis revealed that acid hydrolysis along with bleaching improved crystallinity index and thermal stability of the extracted nanocrystals. It was observed that CNC maintained its cellulose 1 polymorph despite hydrolysis treatment. Mean diameter as observed by TEM and average fiber aspect ratio of obtained CNC was 7.44 ± 0.17 nm and 16.53 ± 3.52, respectively making it suitable as a reinforcing material for nanocomposite.

Dye photodegradation employing mesoporous organosilicas functionalized with 1,8-naphthalimides as heterogeneous catalysts

Abstract Mesoporous organosilicas containing covalently bound 1,8-naphthalimides (NI) were shown to be efficient heterogeneous catalysts for the photodegradation of methylene blue (MB), a typical textile pollutant. The NI-containing mesoporous silicas (SBANI materials) were prepared by a co-condensation reaction, in conditions similar to those used for inorganic SBA-15. For the photocatalytic tests, the SBANI materials were suspended in aqueous MB solutions, and the suspensions were irradiated with a 100 W Hg lamp (bandpass filter: 320–480 nm). The activity of the SBANI catalysts was proportional to the NI content in the sample. When MB was irradiated in the presence of a sample with high NI content, total bleaching of MB was observed after 300 min irradiation. In addition, blue shifts in the visible MB band were observed during irradiation. The results can be explained by concomitant mineralization and N -demethylation of MB. N -demethylation led to the formation of azure dyes, which were detected in the reaction mixtures after irradiation. The photocatalytic activity can be attributed to the formation of NI triplets, which can react with MB by both Type (II) (via oxygen reactive species) and Type I (via electron transfer) mechanisms.

Biochemical methane potential of kraft bleaching effluent and codigestion with other in-mill streams

A biochemical methane potential assay was conducted to investigate the anaerobic digestibility of bleaching effluent from hardwood kraft pulping and the potential of codigestion with other effluents from an integrated pulp and paper mill. Four in-mill streams were tested individually and in combination: total bleaching effluent, alkaline bleaching effluent, kraft evaporator condensate, and chemithermomechanical pulping effluent. The total bleaching effluent, consisting of the chlorine dioxide bleaching and alkaline bleaching effluents, exhibited the highest potential for organic matter degradation and methane generation. Chemical oxygen demand (COD) removal ranged from 57%–76%, and methane generation was 220–280 mL/g COD contained in the wastewater, depending on the degree of dilution. When codigestion was tested, the composite consisting of total bleaching effluent, chemithermomechanical pulping effluent, and kraft condensate was most efficient in terms of COD removal (51%) and methane generation (200 mL/g COD contained in the wastewater). The total bleaching effluent is the largest contributor to the overall amount of wastewater at this mill; it contains relatively low concentrations of anaerobic inhibitors such as adsorbable organic halogens (36 mg/L), total sulfur (170 mg/L), and resin and fatty acids (3.2 mg/L). Therefore, the total bleaching effluent from hardwood kraft pulping may be considered for full-scale anaerobic wastewater treatment, either as a singular stream or as part of a composite stream including other in-mill effluents.

Effect of Two-step Thermal Treatments on Peroxide Bleachability of Thermomechanical Pulp

In hydrogen peroxide bleaching of thermomechanical pulp (TMP), reaction temperature and time are the main factors that can improve the bleachability of pulp fibers. However, high temperatures can induce some problems such as cellulose degradation, yield loss, low fiber strength, and high environmental load. These negative effects of high temperature are mainly caused by radicals formed from the decomposition of hydrogen peroxide. To avoid the adverse effects of high temperature, we used two-step thermal treatments during hydrogen peroxide bleaching of TMP. The temperatures used in the two-step thermal treatments were 80 and 45 ˚C for a total bleaching time of 1 hour. In H2O2 bleaching of TMP, two-step thermal treatments were found to have had positive effects on the optical and physical properties of the pulp. The ISO brightness of the pulp bleached by two-step thermal treatments with hydrogen peroxide was identical to that of pulp bleached by conventional hydrogen peroxide bleaching. The post color number (PC number) of TMP was sharply increased after bleaching at 80 ˚C for 40 minutes. The post color number of TMP bleached by two-step thermal treatments is lower than that of TMP bleached by a one-step thermal treatment. The zero-span tensile index was also improved by two-step thermal treatments.