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Enzymatic depolymerisation of cellulose

Cellulose degree of polymerisation (DP) was determined in paper pulps and commercial powder celluloses before and after the enzymatic treatment with a blend of cellulases and hemicellulases. Three different methods were used: (i) chemical method, based on the measurement of the cellulose reducing power; (ii) viscosimetry; and (iii) gel permeation chromatography. Although based in very different principles, the ...

Laboratory paper pulp deinking : an evaluation based on image analysis, ISO Bri...

Image analysis, ERIC and ISO Brightness measurements were used to evaluate the effectiveness of laboratory deinking assays. The accurate measurement of the residual ink amount is difficult and the results depend on the methodology used. The three techniques correlate only when the same paper pulp sample is analysed and when the ink particle size distribution profile is similar. As the relative amount of each pa...

Factors influencing MOW deinking : laboratory scale studies

The deinking of MOW is examined at laboratorial scale. The effect of deinking aids, pre-washing and mixing are studied. The operating conditions during pulp treatment affect the pulp and paper properties, interfering with the mechanism of ink removal and modifying the ink particle characteristics. Pre-washing the pulp facilitates the deinking process. Cellulolytic enzymes and deinking chemicals are comparable i...

Enzymatic versus chemical deinking of non-impact ink printed paper

Enzymatic versus chemical deinking is examined for MOW and photocopy prints. Several enzymatic preparations and two fibre/ink particle separation methods are tested. Deinking was monitored by image analysis and standard pulp and paper characterisation procedures. The effectiveness of the fibre/ink particle separation method depends on the ink particle’s size: for smaller particles a washing step is recommended ...

Characterisation and application of glycanases secreted by aspergillus terreus ...

Two enzymatic extracts obtained from xylan-grown Aspergillus terreus CCMI 498 and cellulose-grown Trichoderma viride CCMI 84 were characterised for different glycanase activities. Both strains produce extracellular endoxylanase and endoglucanase enzymes. The enzymes optimal activity was found in the temperature range of 45-60 ºC. Endoglucanase systems show identical activity profiles towards temperature, regard...

Enzymatic modification of paper fibres

The enzymatic mode of action in paper fibre upgrading is still uncertain. In an attempt to clarify how enzymes modify pulp and paper properties, several parameters were analysed in the present work: (i) thermal analysis of the water–solid surface interactions; (ii) fibre cake permeability; (iii) particle size analysis. The results obtained suggest that enzymes modify the interfacial properties of fibres, increa...

Enzymatic upgrade of old paperboard containers

The use of enzymes in secondary fiber (old paperboard containers) upgrading was investigated. The following aspects were analyzed: (i) the effect of several enzymes and (non-hydrolytic) cellulose-binding domains on the pulp and paper properties; (ii) factors influencing enzymatic treatment of secondary fiber: enzyme dosage and reaction time; and (iii) enzyme action on fractions with different fiber-length. In g...

Effect of cellulase adsorption on the surface and interfacial properties of cel...

The surface properties of several purified cellulose (Sigmacell 101, Sigmacell 20, Avicel pH 101, andWhatman CF 11) were characterised, before and after cellulase adsorption. The following techniques were used: thin-layer wicking (except for the cellulose Whatman), thermogravimetry, and differential scanning calorimetry (for all of the above celluloses). The results obtained from the calorimetric assays were co...

Preliminary studies on enzymatic deinking

IV Iberian Congress on Biotechnology; I Ibero-American Meeting on Biotechnology

Induction of xylanolytic activity by Aureobasidium pullulans using xerographic ...