Research Articles

Biosorption was carried out in a batch process to test the suitability of corncob for the removal of manganese ion (Mn(II)) from aqueous solution. The amount of metal ions removed from solution depended on the metal ion-substrate contact time, ion concentration, temperature, and pH. The adsorption capacity of the biosorbent from corncob was also enhanced by treatment with acid. Kinetic modeling of the data obtained from the study showed that the biosorption of Mn(II) ions by the untreated and acid-treated corncob followed the Largergren pseudo-first order model. The adsorption capacity of the raw biomass was found to be 6.54 mg/g, while acid-treated biomass showed an adsorption capacity of 7.87 mg/g. The data obtained from this study fitted well with the Freundlich and Langmuir adsorption isotherms.

The Raffia textilis fiber has interesting specific mechanical properties among other vegetables fibers. But its production remains entirely based on empirical knowledge. The fibers are dried in the open air and in the shade for about 48 hours. This study explores the effect of the drying temperature, from 30° to 70°C, on its drying kinetics. It was found that the drying duration passes from 55 min at 30 °C to 20 min at 70 °C. Among the three models used to simulate the drying kinetics, the Page model yields the best results. The values of the parameters of this model agree with the hypothesis that the water diffusion is one-dimensional. The activation energy of water in the fiber varies from 49 to 71 KJ/mol, depending on the model used. The effective diffusion coefficient is about 3x10-14 m2.s-1 at 30 °C. This low value justifies the traditional use of the raffia leaves for house roofs.

the effect of organic bound Na groups on pyrolysis and gasification behaviors of alkali lignin, an experimental study was carried out by Thermogravimetric Analyzer coupled with Fourier Transform Infrared Spectrometry (TG-FTIR). Acid precipitated lignin (APL) and Alkali soluble lignin (ASL) were selected as the testing samples, and physiochemical properties were studied by FTIR, 1H NMR, and SEM analyses. The research results showed that the pyrolysis and gasification characteristics of alkali lignin depended on phenolic sodium (-CONa) and carboxylate sodium (-COONa) groups (PCSG). In pyrolysis stage, PCSG improved the yields of alcohols and hydrocarbons but inhibited benzenes. During gasification stage, in the present of PCSG, the peak value of gasification rate increased, yet the initial gasification temperature decreased. Meanwhile, CO releasing was relatively concentrated and intensively increased from 37 min (740 oC) to 42 min (840 oC).

With the rapid development of the packaging industry, the requirements for physical properties of corrugated paperboard tend to become higher and higher, especially for the strength properties. A water glass-starch compound system was employed as a surface sizing agent to improve the strength of linerboard in this work. The viscosity of water glass-starch compound system, and its impacts on ring-crush strength and bursting strength of linerboard were evaluated. Cobb value and contact angle were used to characterize the waterproof performance of paper after surface sizing. Compared with conventional surface sizing agents, water glass-starch compound system overcame the defects of low coating weight and inadequate stiffness of the sizing layer, allowing ring-crush strength and bursting strength of linerboard to increase by 91% and 50%, respectively. Additionally, the compound system had higher solids content, low viscosity, and good film-forming ability, which will bring a lot of convenience to production.

The synthesis and characterization of a novel fixative, guar gum-graft-poly(acrylamide-co-diallyldimethylammonium chloride) (GG-g-p(AM-co-DADMAC)) polymer is described. The grafted polymerproved to be effective at adsorbing hydrophobic wood resin particles onto papermaking fibre surfaces, thus removing wood resins from the water phase where they have a tendency to aggregate and form troublesome deposits. The new polymer combines the colloidal stabilising features of a natural product, guar gum, and the wood resin fixative properties of a synthetic polymer p(AM-co-DADMAC). GG-g-p(AM-co-DADMAC was effective over the entire pH range as compared to other commercially available polymeric fixatives that were evaluated.

The drying process of Norway spruce (Picea abies [L.] Karst) wood exposed to infrared heat radiation was studied by measuring the moisture profiles of the wood samples at controlled temperature during drying. The thermal treatment was executed in a purpose-made industrial pilot-plant containing the heat radiators covered by infrared (IR) transmition filters. The moisture content of the samples was detected at certain stages of the process. Based on the results of exposing the samples to IR radiation for 15, 25, 35, and 45 hours, the drying mechanism of wood is discussed. The moisture transport mechanism was explained by a semipermeable membrane process considering the moisture content as a dilute aqueous solution. If the semipermeable cell wall allows only the passage of water but not that of solute molecules, water diffusing from the region of higher (center) to lower (periphery) water content produces osmotic pressure difference between the two sides of the cell walls. The importance of this osmosis was considered in the approach of moisture migration.

In this study the effect of virgin and recycled plastics on water absorption of nanocomposites from newsprint fiber and organoclay was studied. Newsprint fiber was mixed with either virgin or recycled polypropylene (PP) at 30% by weight fiber loading. The samples were made by melt compounding and then injection molding. The concentration was varied as 0, 2.5, and 5% for nanoclay. The amount of coupling agent was fixed at 10% for all formulations. The long-term water absorptions of samples were evaluated by immersing them in water at room temperature for several weeks, and water diffusion coefficients were also calculated by evaluating the water absorption isotherms. The results indicated that whether or not virgin plastic is used has a significant effect on the water absorption of composites. The water absorption of the newsprint fiber/recycled plastic composites was higher than those of virgin plastics. Furthermore, with addition of nanoclay content in composites, water absorption decreased. Water absorption of all formulations was proved to follow the kinetics of a Fickian diffusion process. Morphological findings showed the formation of intercalated morphology and better dispersion with 2.5% of nanoclay.

The objective of this work was to compare the adsorption of different polysaccharides and cellulose derivatives on cellulose nanofibril films. Cellulose films having the native cellulose I structure were prepared from hardwood kraft pulp by extensive mechanical disintegration. Further fractionation enabled the preparation of reproducible, nanometer-scale thickness films. Systematic comparison by Quartz Crystal Microbalance with Dissipation (QCM-D) showed that various industrially available galactomannans have almost as good affinity to cellulose surface as xyloglucan and that most of the polysaccharides attach irreversibly to cellulose nanofibrils at low pH (4.5) and intermediate ionic strength (10 mM). SPR results support the QCM-D findings. Atomic Force Microscopy (AFM) imaging and Digital Pulsed Force Mode (DPFM) measurements further confirmed that a uniform non-aggregated layer of polysaccharides was formed that changed the properties of the NFC film.

100% natural tannin-based rigid foams were synthesized. Tannin-furfuryl alcohol networks were polymerized in an acid environment applying a temperature between 120° and 160°C. The process was developed in two ways: in a ventilated oven and in between the heated plates of a press. The foams produced showed a high homogeneity in both cases. By modifying the formulation in terms of type and amount of components it was possible to produce two kinds of foams: (1) light with density of approximately 50 Kg/m³, and (2) resistant having a density of approximately 180 Kg/m³. The compression resistance and the water absorption of these materials were evaluated. The results of these tests, in comparison with those of formaldehyde-reinforced tannin foams, indicated that these lightweight foams have lower mechanical strength but higher water affinity. The latter was also demonstrated with moisture uptake measurements. Particular attention was dedicated to the press-produced foams for their possible application as core-layer for lightweight composite panels.

Kinetic modeling of enzymolysis of pulp fiber waste pretreated by a wet oxidation process was studied. First, a wet oxidation pretreatment of fiber waste was carried out. It was found that hemicellulose were removed efficiently, yielding material with a pentosan content of 4% (based on the o.d. biomass). A statistical kinetic model was developed based on the experimental results of the enzymatic hydrolysis of wet oxidation pretreated material. The model can be described as follows: RSY (reducing sugar yield)=12.48×C0.4261×(1-e-0.2021t) ×100%, an equation that can be used to predict the reducing sugar yield in an enzymolysis process. The RSY by enzymatic loading of 35FPU/g achieved almost the highest yield after 48 h, and there was no significant improvement with further extension of the enzymolysis time. The modeling was validated within the enzymatic loading range of 15 to 35FPU/g and provided a satisfactory interpretation of the experimental data.