scholarly journals Total Chlorine-Free Bleaching of Populus deltoides Kraft Pulp by Oxone

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Mohsen Miri ◽  
Ali Ghasemian ◽  
Hosein Resalati ◽  
Farhad Zeinaly
Keyword(s):  
Kraft Pulp ◽  
Populus Deltoides ◽  
Paper Industry ◽  
Accelerated Aging ◽  
Environmental Pollutant ◽  
Acid Pretreatment ◽  
Elemental Chlorine ◽  
Alkaline Conditions ◽  
Pulp Strength ◽  
Two Stages

Since the bleaching process is one of the most important environmental pollutant stages in the pulp and paper industry, here, the total chlorine-free (TCF) bleaching of poplar kraft pulp by applying Oxone and peroxide under alkaline conditions has been investigated. The pulp samples were bleached in two stages of Oxone (OX) treatment using an AOX1OX2 sequence (A: acid pretreatment), and then the treated pulps were bleached by peroxide (P) to achieve target brightness (about 80%). The influence of various reaction parameters such as alkali charge, temperature, reaction time, and bleaching agent dosage was optimized. The final achieved brightness was more than 78%. Accelerated aging experiments showed more stability in brightness for the Oxone treated pulp, because alkali Oxone bleaching stops thermal degradation. Similarly, the AOX1OX2P bleaching sequence was found to be effective in regaining some strength that had been lost during acidification of the pulp. Improvement in pulp strength made with acid treatment was achieved along with significant amount of lignin removal and it demonstrates the feasibility of Oxone in TCF bleaching. Furthermore, other results indicated the feasibility of Oxone bleaching as an environmentally favorable alternative TCF bleaching sequence, compared with elemental chlorine-free bleaching approaches and also other TCF bleaching sequences.

Prebleaching of eucalypt kraft pulp with OP stages: Effect of an acid pretreatment or chelation step

TAPPI Journal ◽  
2012 ◽  
Vol 11 (6) ◽  
pp. 31-38
Author(s):  
TATIANA M. PÓVOAS ◽  
DINA A.G. ANGÉLICO ◽  
ANA P.V. EGAS ◽  
PEDRO E.G. LOUREIRO ◽  
LICÍNIO M. GANDO-FERREIRA ◽  
...  
Keyword(s):  
Eucalyptus Globulus ◽  
Comparative Evaluation ◽  
Kraft Pulp ◽  
Kraft Pulps ◽  
Acid Pretreatment ◽  
High Brightness ◽  
Pulp Viscosity ◽  
Brightness Reversion

We conducted a comparative evaluation of different treatments for the bleaching of eucalypt kraft pulps beginning with OP stages. The treatments tested were (1) an acid chelation stage with DTPA (OQP sequence); (2) a hot acid stage (AOP sequence); and (3) a chelant addition into the alkaline oxygen stage ((OQ)P and A(OQ)P sequences). The latter strategy was also studied for environmental reasons, as it contributes to the closure of the filtrate cycle. The OQP sequence leads to the highest brightness gain and pulp viscosity and the lowest peroxide consumption caused by an efficient metals control. Considering that the low biodegradability of the chelant is a problem, the A(OQ)P sequence is an interesting option because it leads to reduced peroxide consumption (excluding OQP) while still reaching high brightness values and similar brightness reversion to OQP prebleaching, with only a viscosity loss of 160 dm3/kg. Therefore, a hot acid stage could be considered when a separate acid Q stage is absent in a prebleaching sequence of Eucalyptus globulus kraft pulps involving OP stages.

Application of pure, thermostable, alkali-tolerant xylanase in bleaching of oxygen-delignified pine kraft pulp

TAPPI Journal ◽  
2015 ◽  
Vol 14 (11) ◽  
pp. 689-694
Author(s):  
QINGZHI MA ◽  
QI WANG ◽  
CHU WANG ◽  
NIANJIE FENG ◽  
HUAMIN ZHAI
Keyword(s):  
Intrinsic Viscosity ◽  
Chlorine Dioxide ◽  
High Purity ◽  
Kraft Pulp ◽  
Alkaline Media ◽  
Industrial Scale ◽  
Elemental Chlorine ◽  
Effect Of Oxygen ◽  
Alkaline Tolerant ◽  
Ecf Bleaching

The effect of oxygen (O2)-delignified pine kraft pulp pretreatment by high-purity, thermostable, and alkaline-tolerant xylanases on elemental chlorine free (ECF) bleaching of O2-delignification kraft pulp was studied. The study found that xylanase pretreatment preserved the intrinsic viscosity and yield of O2-delignified pulp while causing about 7% of delignification with high delignification selectivity. The xylanases with high purity, higher thermostability (75°C~80°C) in highly alkaline media (pH 8.0~9.5) could be applied on an industrial scale. Pulp pretreatment by the high-purity, thermostable, and alkaline tolerant xylanases could improve pulp brightness or reduce the chlorine dioxide (ClO2) consumption. In a D0ED1D2 bleaching sequence using the same amount of ClO2, the xylanase-pretreated pulp obtained a higher brightness (88.2% vs. 89.7% ISO) at the enzyme dose of 2 U/g pulp; or for the same brightness as control (88.2% ISO), the ClO2 dosage in the D0 stage was reduced by 27%, which represents a 16% savings in total ClO2 used for bleaching.

Optimization of elemental chlorine-free bleaching for a softwood kraft pulp • part 2: economic analysis of chemical and steam consumption

TAPPI Journal ◽  
2010 ◽  
Vol 9 (9) ◽  
pp. 47-53 ◽  
Author(s):  
BRIAN N. BROGDON
Keyword(s):  
Chlorine Dioxide ◽  
Previous Investigation ◽  
Kraft Pulp ◽  
Energy Costs ◽  
Alkaline Extraction ◽  
Stage Versus ◽  
Kraft Pulps ◽  
Steam Consumption ◽  
Elemental Chlorine ◽  
Softwood Kraft Pulp

Our previous investigation [1] re-analyzed the data from Basta and co-workers (1992 TAPPI Pulping Conference) to demonstrate how oxidative alkaline extraction can be augmented and how these changes affect chlorine dioxide consumption with elemental chlorine-free (ECF) sequences. The current study manipulates extraction delignification variables to curtail bleaching costs with a conventional U.S. Southern softwood kraft pulp. The economic advantages of ~0.35% to 0.65% H2O2 peroxide reinforcement in a 70°C (EOP)-stage versus 90°C (EO)-stage are predisposed to the brightness targets, to short or long bleach sequences, and to mill energy costs. Minimized bleaching costs are generally realized when a 90°C (EO) is employed in D0(EO)D1 bleaching, whereas a 70°C (EOP) is economically advantageous for D0(EOP)D1E2D2 bleaching. The findings we disclose here help to clarify previous ECF optimization studies of conventional softwood kraft pulps.

scholarly journals Abscisic Acid Priming Creates Alkaline Tolerance in Alfalfa Seedlings (Medicago sativa L.)

Agriculture ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 608
Author(s):  
Tian-Jiao Wei ◽  
Ming-Ming Wang ◽  
Yang-Yang Jin ◽  
Guo-Hui Zhang ◽  
Miao Liu ◽  
...  
Keyword(s):  
Abscisic Acid ◽  
Molecular Mechanisms ◽  
Leaf Damage ◽  
Alkaline Stress ◽  
Acid Pretreatment ◽  
Solution Ph ◽  
Expression Of Genes ◽  
Alkaline Tolerance ◽  
Alkaline Conditions ◽  
Medicago Sativa L

Soil alkalization triggers ion toxicity and osmotic and alkaline (high pH) stresses in plants, damaging their growth and productivity. Therefore, we investigated whether priming with abscisic acid (ABA) increases the tolerance of alfalfa seedlings to alkaline stress, and then examined the underlying molecular mechanisms. Alfalfa seedlings were pretreated with ABA (10 μM) for 16 h and then subjected to alkaline stress using a 15 mM Na2CO3 solution (pH 10.87). Compared with the control, ABA pretreatment significantly alleviated leaf damage and improved the fresh weight, water content, and survival rate of alfalfa seedlings under alkaline conditions. Abscisic acid pretreatment reduced accumulation of reactive oxygen species (ROS), increased activities of the antioxidant enzymes superoxide dismutase (SOD) and peroxidase (POD), maintained higher ratios of K+/Na+, Ca2+/Na+, and Mg2+/Na+, and increased accumulation of proline. In addition, ABA upregulated the expression of genes involved in proline biosynthesis (P5CS) and the sequestration of Na+ in vacuoles (NHX1 and AVP) under alkaline conditions. Abscisic acid priming increased tolerance to alkaline stress by maintaining homeostasis of ROS and metal ions and upregulating osmoprotection and the expression of stress tolerance-related genes.

Using Oxone and TAED activator in non-chlorine bleaching of soda bagasse pulp

2019 ◽  
Vol 34 (4) ◽  
pp. 422-432
Author(s):  
Farhad Zeinaly ◽  
Konstantin Gabov ◽  
Hadi Kanåni Sula ◽  
Arash Babavand ◽  
Pedro Fardim
Keyword(s):  
Paper Industry ◽  
Environmental Pollutant ◽  
Pulp Bleaching ◽  
Chemical Pulp ◽  
Chlorine Bleaching ◽  
Pulp Viscosity ◽  
Paper Company ◽  
High Level ◽  
Bagasse Fiber ◽  
Bagasse Pulp

Abstract Bagasse fiber has been used in the production of bleached chemical pulp by the Pars Paper Company. In this company, a conventional three-stage sequence of hypochlorite, alkaline extraction and second hypochlorite (HEH) is applied in pulp bleaching. Pulp bleaching is one of the most important environmental pollutant stages in the pulp and paper industry. In this research, the bleaching of soda bagasse pulp by applying Oxone and TAED-activator in non-chlorine bleaching sequences has been investigated. The unbleached pulp, with kappa number of 20, 955 ml/g viscosity and 37 % brightness, was prepared from Pars Paper Company. Results indicated that, the TAED at the first and second stages were more effective than in the Oxone stages. Moreover, the sequences, which contained TAED- and Oxone-second-stage, could reach the minimum level of kappa (1.7), but the highest brightness (80 %) was attained by using only TAED with a comparatively high level of pulp viscosity (752).

scholarly journals Acute ecotoxicity on Daphnia magna to evaluate effluent samples of Kraft pulp mill treated by UV/H2O2 process

2019 ◽  
Vol 14 (2) ◽  
pp. 1 ◽  
Author(s):  
Joicy Micheletto ◽  
Naiara Mariana Fiori Monteiro Sampaio ◽  
Henrique Zavattieri Ruiz ◽  
Lucia Regina Rocha Martins ◽  
Marcus Vinicius de Liz ◽  
...  
Keyword(s):  
Acute Toxicity ◽  
Daphnia Magna ◽  
Kraft Pulp ◽  
Paper Industry ◽  
Pulp Mill ◽  
Ph Variation ◽  
Kraft Pulp Mill ◽  
Kraft Process ◽  
Oxidant Concentration ◽  
Apparent Color

The pulp and paper industry is one of world’s largest water consumers, generating high volumes of effluents. The Kraft process produces effluents with high BOD, COD, suspended solids, lignin and a myriad of potentially toxic compounds, which require treatment before discharge into the aquatic environment. Advanced oxidation processes, such as UV/H2O2, have been applied as treatment alternatives because they can destroy many compounds before they mineralize. However, when the oxidation process is incomplete, occurs could be produced by products with high toxicity. This study evaluated the acute toxicity on Daphnia magna of two effluent samples of Kraft pulp mill (KE1 and KE2) treated by UV/H2O2 process. The effects of the pH variation and oxidant concentration on the removal of DOC, total UV-vis spectral area and apparent color were considered to adjust the experiments’ conditions with diluted effluent KE1. Both samples were treated at pH 4.0 and 70 mg L-1 of H2O2 for 40 min, achieving removals of up to 69.4% in apparent color, 73.7% of phenolic compounds and 68.9% of lignin compounds. When the reaction was applied in undiluted effluent samples, the acute toxicity for Daphnia magna decreased for KE1 after 780 min of treatment, whereas KE2 became four times more toxic. The data showed that although the treatment had been efficient considering physics and chemicals parameters, it is necessary follow the oxidative processes with ecotoxicological bioassays to guarantee their safety, since different effluents of the Kraft pulp mill could present different levels of organic compound mineralization.

Effluent effects on the nutrient concentrations and growth of reed canarygrass (Phalaris arundinacea L.) and hybrid poplar (Populus deltoides × P. Petrowskyana L.)

2009 ◽  
Vol 89 (2) ◽  
pp. 223-234 ◽  
Author(s):  
S J Patterson ◽  
D S Chanasyk ◽  
M A Naeth ◽  
E. Mapfumo
Keyword(s):  
Kraft Pulp ◽  
Populus Deltoides ◽  
Hybrid Poplar ◽  
Pulp Mill ◽  
Phalaris Arundinacea ◽  
Nutrient Concentrations ◽  
Leaf Biomass ◽  
Reed Canarygrass ◽  
Kraft Pulp Mill ◽  
Pulp Mill Effluents

Using effluent as a source of irrigation water and to provide nutrients for plant growth is gaining favour as an environmentally positive practice instead of discharging effluent into surface water bodies. A growth chamber study was conducted to evaluate pulp mill wastewater as an irrigation source. This study evaluated the effects of water (TPW), municipal effluent (ME), and Kraft pulp mill effluent (KPME) and waste activated sludge (WAS) at rates of 1.5, 3, and 6 mm d-1 on available soil nutrients, nutrient uptake, and growth of reed canarygrass (Phalaris arundinacea L.) and hybrid poplar (Populus deltoides × P. petrowskyana L.). Increasing the application rate significantly increased biomass for both crops, but the KPME treatment significantly decreased leaf biomass of the hybrid poplar. Effluent applications did not result in toxic accumulations of nutrients within the analyzed tissues for either reed canarygrass or hybrid poplar. Only the WAS treatment significantly increased soil available concentrations of P, K, S, B, Mn, and Zn. Results of the study found lower irrigation rates of Kraft pulp mill effluents could be used as supplementary source and provide nutrients for reed canarygrass and hybrid poplar. Key words: Biomass, effluent irrigation, hybrid poplar, nutrient concentration, reed canarygrass

Lignin modification in the initial phase of softwood kraft pulp delignification with polyoxometalates (POMs)

Holzforschung ◽  
2007 ◽  
Vol 61 (5) ◽  
pp. 492-498 ◽  
Author(s):  
Biljana Bujanovic ◽  
Sally A. Ralph ◽  
Richard S. Reiner ◽  
Rajai H. Atalla
Keyword(s):  
Kraft Pulp ◽  
Lignin Content ◽  
Kappa Number ◽  
Ring Cleavage ◽  
Residual Lignin ◽  
Glucose Content ◽  
Lower Glucose ◽  
Softwood Kraft Pulp ◽  
Alkaline Conditions ◽  
Extraneous Material

Abstract Commercial softwood kraft pulp with kappa number 30.5 (KP30.5) was delignified with polyoxometalates (POM, Na5(+2)[SiV1(-0.1)MoW10(+0.1)O40]), and POM-treated kraft pulp of kappa number 23.6 was obtained (KPPOM,23.6). Residual lignin from pulps was isolated by mild acid hydrolysis and characterized by analytical and spectral methods to gain insight into lignin reactions taking place during the initial delignification phase. Lignin from POM-delignified pulp was isolated in lower yield. Comparative analysis of residual lignins (RL-KP30.5, RL-KPPOM,23.6) showed that POM leads to products enriched in carbonyl/carboxyl groups and carbohydrates. POM lignins have a lower molecular mass and a lower content of phenolic hydroxyl and methoxyl groups. Based on these results and FTIR spectra, we suggest that aromatic ring cleavage and quinone formation occur during POM delignification. The degree of lignin-cellulose association increases after POM delignification. Lignin-cellulose association was found to be partially unstable under mild alkaline conditions, as residual lignin isolated after alkaline extraction of KPPOM,23.6 pulp (RL-KPPOM/NaOH) exhibited lower glucose content, higher Klason lignin content, and less extraneous material.

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