Adsorption of copper (II), chromium (III), nickel (II) and lead (II) ions from aqueous solutions by meranti sawdust.

Review on recent developments on pulp and paper mill wastewater treatment

The complexity of lignin and hemicellulose segmentation has been known since the middle of the ninetieth century. Studies confirmed that all lignin units in coniferous species and 47–66% of lignin moieties in deciduous species are bound to hemicelluloses or cellulose molecules in lignin–carbohydrate complexes (LCC). Different types and proportions of lignin and polysaccharides present in biomass lead to the formation of LCC with a great variety of compositions and structures. The nature and amount of LCC linkages and lignin substructures affect the efficiency of pulping, hydrolysis, and digestibility of biomass. This review paper discusses the structures, compositions, and properties of LCC present in biomass and in the products obtained via pretreating biomass. Methods for extracting, fractionating, and analyzing LCC of biomass, pulp, and spent pulping liquors are critically reviewed. The main perspectives and challenges associated with these technologies are extensively discussed. LCC could be extracted from biomass following varied methods, among which dimethyl sulfoxide or dioxane (Bjorkman’s) and acetic acid (LCC-AcOH) processes are the most widely applied. The oxidation and methylation treatments of LCC materials elucidate the locations and frequency of binding sites of hemicelluloses to lignin. The two-dimensional nuclear magnetic resonance analysis allows the identification of the structure and the quantity of lignin–carbohydrate bonds involved in LCC. LCC application seems promising in medicine due to its high anti-HIV, anti-herpes, and anti-microbial activity. In addition, LCC was successfully employed as a precursor for the preparation of spherical biocarriers.

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Lignin–carbohydrate complexes: properties, applications, analyses, and methods of extraction: a review

Use of rice straw as biosorbent for removal of Cu(II), Zn(II), Cd(II) and Hg(II) ions in industrial effluents.

This review article introduces recent scientific and technical reports due to near infrared spectroscopy (NIRS) at wood science and technology, most of which was published between 2006 and 2013. Many researchers reported that NIR technique was useful to detect multi traits of chemical, physical, mechanical and anatomical properties of wood materials although it was widely used in a state where characteristic cellular structure was retained. However, we should be sensitive and careful for application of NIRS, when spectra coupled with chemometrics presents unexpected good results (especially, for mechanical physical and anatomical properties). The real application for on-line or at-line monitoring in wood industry is desired as next step. Basic spectroscopic research for wooden material is also progressed. It should be a powerful and meaningful analytical spectroscopic tool.

/pdf/a-review-of-recent-application-of-near-infrared-spectroscopy-29bswjbu4c.pdf

A review of recent application of near infrared spectroscopy to wood science and technology

Foram analisados clones de Eucalyptus de ultima geracao, pertencentes as principais empresas brasileiras de celulose. Os estudos consistiram numa caracterizacao tecnologica detalhada da qualidade das madeiras utilizadas no processamento fabril das empresas. Foram realizadas analise quimicas detalhadas das madeiras e cozimentos kraft, simulando-se uma das modernas tecnica de digestor continuo. Os resultados indicaram a alta qualidade dos clones de Eucalyptus atualmente plantados no Brasil para producao de celulose.

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Caracterização tecnológica, para produção de celulose, da nova geração de clones de Eucalyptus do Brasil

Commercial bamboo chips were evaluated as raw material for dissolving pulp production. The chips were auto-hydrolyzed (AH) and subsequently cooked by the NaOH/AQ process and bleached to full brightness with the O-CCE-D-(EP)-D-P sequence. The term CCE designates a cold caustic extraction stage. The bamboo chip chemistry (22.4% lignin, 19.5% xylans, 49.3% cellulose, 16.8% total extractives, and 1.5% ash) was apparently unfavorable; however high quality dissolving pulp was produced using the aforementioned technologies, even when compared to results obtained with traditional eucalypt commercial wood chips. The pulp showed high brightness (92.4 % ISO) and α-cellulose content (94.9%). Its contents of hemicelluloses, extractives and ash were within acceptable levels for a dissolving pulp aimed at viscose rayon production. Thus, the bamboo chip furnish investigated can be regarded as a viable raw material for dissolving pulp production.

https://ojs.cnr.ncsu.edu/index.php/BioRes/article/download/BioRes_07_1_0640_RibasBatalha_CGBMB_Dissolving_Pulp_from_Bagasse/1334

Dissolving pulp production from bamboo

This study evaluated the effect of cooking temperature and residual alkali on kraft pulp yield, bleachability, and quality. We cooked Eucalyptus grandis wood chips to kappa number 16-17 using high and low residual alkali (14-18 g/L and 3-4 g/L) and high and low temperatures (170°C and 160°C). We then quantified process yield and evaluated pulp quality through measurement of strength properties, carbohy- drate composition, hexenuronic acid content, alkali-leachable lignin content, and residual lignin nature. After oxygen delignifying the pulps and bleaching them to full brightness with the sequences D(EOP)DD and D(EOP)(ZE)D, we determined their bleachability and brightness stability. Low temperature and low residual alkali during pulping resulted in the highest screened yield (54.2%) and viscosity (64.6 mPas). Pulps cooked at low residual alkali showed about 1.7%-2.1% higher yield, 20%-30% higher viscosity, and higher strength properties (except for tear index) than those cooked at high residual alkali both at 160°C and 170°C. Lower temperature and/or residual alkali during pulping favored pulp refining. Pulps produced at high residual alka- li showed slightly lower oxygen delignification efficiency (2%-3%), but significantly higher (10%-15%) bleach- ability, as measured by active chlorine consumption, regardless of cooking temperature. Pulps cooked at high residual alkali showed higher initial brightness (6-8% ISO) for a fixed kappa, which carried on across oxygen delignification and ECF bleaching processes. Oxygen delignification filtrates of pulps cooked at low residual alkali contain substantially more COD and color than those cooked at high residual alkali because the former pulps are richer in alkali-leachable lignin. Pulping conditions did not affect pulp brightness stabil- ity. Pulps produced at high residual alkali showed lower contents of xylans and of hexenuronic acids and higher quantities of lignin containing carboxyl and aliphatic hydroxyl groups. Pulps cooked at 160°C pre- sented higher xylan and hexenuronic acid content in relation to those cooked at 170°C.

/pdf/influence-of-pulping-conditions-on-eucalyptus-kraft-pulp-1s5yjpbm5t.pdf

Influence of pulping conditions on eucalyptus kraft pulp yield, quality, and bleachability

Seventy five Eucalyptus wood clones obtained from different geographic regions in Brazil were used for this study. Based on statistical analysis it was demonstrated that an active alkali charge and also wood lignin and extractive contents presented a significant effect on pulping yield. Wood specific gravity did not present a significant effect on pulping yield but affected wood consumption for pulp production (m3wood/ ton pulp). Wood specific gravity, lignin content and extractive content were recommended as criteria to establish wood quality prior to pulping characteristics determination.

/pdf/analise-de-criterios-de-qualidade-da-madeira-de-eucalipto-2c17ble0qk.pdf

Análise de critérios de qualidade da madeira de eucalipto para produção de celulose kraft

Foram estudados dois clones de Eucalyptus com densidades basicas de 447 e 552 kg/m³. O processo kraft foi utilizado para a producao de celulose, tendo sido aplicadas diferentes cargas de alcali para se obterem polpas com numero kappa 18 ± 0,5. As polpas foram branqueadas pela sequencia ODEopDD, a alvuras de 90 ± 1% ISO, e refinadas, sendo suas propriedades fisico-mecânicas e opticas analisadas. A madeira de baixa densidade mostrou-se mais recomendavel para a producao de celulose, por ter apresentado maior rendimento depurado, viscosidade da polpa mais elevada, ter requerido menor carga de alcali no cozimento, ter proporcionado menor teor de solidos no licor residual e menor consumo de reagentes quimicos no branqueamento. As propriedades mecânicas e estruturais das polpas nao foram afetadas significativamente pela densidade basica das madeiras.

/pdf/influencia-da-densidade-basica-da-madeira-na-qualidade-da-41u25wuayp.pdf

Influência da densidade básica da madeira na qualidade da polpa kraft de clones hibrídos de Eucalyptus grandis W. Hill ex Maiden X Eucalyptus urophylla S. T. Blake

José Lívio Gomide

Papers

Caracterização tecnológica, para produção de celulose, da nova geração de clones de Eucalyptus do Brasil

Dissolving pulp production from bamboo

Influence of pulping conditions on eucalyptus kraft pulp yield, quality, and bleachability

Análise de critérios de qualidade da madeira de eucalipto para produção de celulose kraft

Influência da densidade básica da madeira na qualidade da polpa kraft de clones hibrídos de Eucalyptus grandis W. Hill ex Maiden X Eucalyptus urophylla S. T. Blake