Volume 8 Issue 3

In order to improve the molecular weight and application of a lignin byproduct, the trimethyl quaternary ammonium salt of lignin-sodium alginate polyampholyte (QL-SA) was prepared with trimethyl quaternary ammonium salt of lignin (QL) and sodium alginate (SA), using the cross-linker glutaraldehyde. Its structure was analyzed by FTIR, SEM, and analysis of nitrogen and carboxylic contents. Results showed that QL and SA were grafted successfully. The nitrogen content was diminished from 4.21% to 3.69% and its carboxyl content increased from 2.66 mmol/g to 6.47 mmol/g. The product behaved as flocculant by electrostatic interactions and bridging actions. The effects of QL-SA on the flocculation performance of dyes were investigated with methylene blue and acid black ATT water as the representative dyes. The maximum decolorization rate of acid black ATT was 94.91% and methylene blue was 97.11% under the corresponding optimal conditions (5 g/L of the flocculant at pH 3, 30 °C, and 8 g/L at pH 8, 30 °C). The effect of QL-SA was found to be markedly superior to SA and QL on the whole. The QL-SA showed promise for practical applications.

The potential to remove Cu2+ ions from aqueous solutions through biosorption using roasted barley powder and alkalized barley was investigated in batch experiments and in fixed-bed columns. The influences of initial concentrations (40 to 600 mg/L) of the metal ion, the amount of adsorbent (0.01 to 0.25 g), the contact time (2 to 240 min), and the pH (1.0 to 5.5) were all studied. An isotherm model was applied to describe the equilibrium. The percentage of adsorption increased with increasing pH-values up to 5.5 and with dosage of adsorbent up to 0.1 g. The equilibrium adsorption capacities of Cu2+ after 3hours were 43.8 and 51.3 mg.g-1 for barley and alkalized barley, respectively. These values are higher when compared with the adsorption capacity of various adsorbents reported in literature. The adsorption data fit well to the Langmuir isotherm model, and the experimental results indicate that chemisorption onto the surface of the barley and alkalized barley is the major adsorption mechanism for binding Cu2+ ions for both sorbents.

A new starch-based adhesive with high solid content, high binding force, and low viscosity was prepared via hydrolysis of cassava starch with α-amylase using glycerol as a plasticizer and Ammonium Zirconium Carbonate (AZC) as a crosslinker. The adhesive was applied to coated paper as a partial substitute for SBR latex. The effects of α-amylase, glycerol, AZC, and temperature on the starch adhesive and its performance in application were investigated. The prepared crosslinking cassava starch adhesive showed a significant effect when the starch slurry concentration was 50% (w/w), the dosages of glycerol and α-amylase were 15% and 0.075%, respectively, and the enzymolysis starch was crosslinked with 12% AZC at 50 oC. The modified starch improved the paper in terms of surface strength, gloss, whiteness, and smoothness when 20% SBR latex was substituted into the coating formulation. Statistical analysis indicated that the crosslinking temperature and AZC had significant effects on the performance of the paper, while glycerin and α-amylase had little effect on it. Spectral analysis of the product showed that the crosslinking reaction took place between AZC and cassava starch. The average particle size was 528.6 nm. Scanning Electron Microscope (SEM) images of the paper surface were consistent with the other measured surface properties.

Nanoscience and nanotechnology provide numerous opportunities for enhancing the properties of wood composites. Formaldehyde emissions from wood composites are of great importance because of their negative impact on human health. Developing low formaldehyde-emitting particleboard and plywood panels as environmentally friendly composites by nanotechnology was the object of this study. The urea formaldehyde and melamine urea formaldehyde resins that were used to produce particleboard and plywood panels, respectively, were reinforced with various nanomaterials at different loading levels. Formaldehyde emission tests were carried out according to standard TS 4894 EN 120. The results acquired in this work indicated that nanomaterial reinforcement significantly affected the formaldehyde emission properties of the particleboard and plywood panels. Formaldehyde emissions of the composite panels decreased after reinforcement with nanoSiO2, nanoAl2O3, and nanoZnO materials at proper loading levels. Therefore, using nanotechnology, it is possible to produce environmentally friendly wood composite panels with low formaldehyde emissions.

In the papermaking process, the removal and control of dissolved and colloidal substances (DCS) is a key issue for reducing the usage of fresh water. The use of nano TiO2 for removal of dissolved substances (DS) and colloidal substances (CS) was investigated through monitoring the titration process of nano TiO2 colloids to sodium laurate (C11H23COONa, DS simulacra) and stearic acid (C17H35COOH, CS simulacra) solution with COD (chemical oxygen demand), DLS (dynamic light scattering), SEM (scanning electron microscope), and zeta potential, respectively. The results indicated that most of the simulacra molecules could be removed from the aqueous solution by the flocculation with nano TiO2 colloids. The removal of CS by nano TiO2 colloid arose from heterocoagulation rather than from charge neutralization, in which nano TiO2 was adsorbed onto the surface of CS particles and bridged CS to form flocs. While in the removal process of DS by nano TiO2, the negative-charged portion of the DS molecule was adsorbed onto the surface of nano TiO2 particles with a mono- or multilayer, eliminating the repulsive force between nano TiO2 particles and resulting in their flocculation.

The emission of formaldehyde vapors from adhesives such as urea formaldehyde (UF) and phenol formaldehyde (PF) is a main concern for the wood composite industry. The ability of laccase enzymes to modify the fiber in pulp industries has given hope to the wood composite industry to prepare composites without using external adhesives. In the present work, rubber wood fiber was treated with different amounts of laccase enzymes at varying time intervals. Although laccase is known to cause changes to lignin, FTIR analysis of treated fiber revealed no significant difference in the chemical composition of cellulosic fiber as compared to the untreated fiber. SEM analysis exhibited a thin uniform layer of lignin deposition on the fiber surface that may be precipitated back when the reaction reaches equilibrium. XRD showed a 10% increase (maximum) in the crystallinity index of treated fibers as compared to untreated fiber. The treated fibers were dried and pressed at different platen temperatures for various time intervals without any adhesive. Mechanical properties such as MOE, MOR, and IB were done to analyze the performance of binderless fiberboard as per ASTM D1037. Binderless fiberboard of density 750 (±10) MPa that was fabricated from the fiber treated at 6 U/g enzyme for 60 min and pressed at 200 °C for 6 min showed good performance.

The existence of tar compounds in producer gas is one of the major problems found in biomass gasification; these compounds need to be removed before the producer gas can be used. In order to predict the need for producer gas cleaning for catalytic conversion into traffic fuels and chemicals, the gas has to be accurately characterised and defined. In this study, tar compounds from producer gas of two small-scale downdraft gasifiers were collected, identified, and quantified. Based on the results, there were several tar compounds present in the gas flow. Toluene and naphthalene were the most abundant compounds, totalling more than 70% of the total volume of tars while tar concentration levels were in the range of 200 to 400 mg/Nm3. These concentrations were found to be consistent with values presented for similar-type gasifiers using wood chips.

Bacterial cellulose (BC) synthesized by Gluconacetobacter sucrofermentans has a high degree of crystallinity, durability, great resistance, and biocompatibility. This study evaluates the effect that carbon and nitrogen sources, present in HS (Hestrin–Schramm) culture medium, have on BC from G. sucrofermentans CECT 7291 used to restore damaged documents. The initial pH of the medium and the temperature were set for all assays, which were conducted in static conditions. The cellulose layers were obtained at four time points. The growth media were characterized at each time point (pH and carbon source consumption). Cellulose layers were washed, pressed, dried, and characterized by determining their pH, dry weight, and optical and mechanical properties. The best combination of carbon and nitrogen sources proved to be fructose plus yeast extract–corn steep liquor, with or without ethanol, which provided a good balance between BC production and carbon source consumption, and generated a resistant and homogeneous cellulose layer.

Acrylic styrene latex was used in combination with nanoclay at two different loading levels and calcium carbonate at four loading levels to improve printability characteristics of mechanical printing paper. SEM micrographs indicated filling of the voids and covering of the printing paper surface. Different rheological behavior of the coating that contained two coating pigments, in addition to their different viscosity, was clearly evident. Calcium carbonate was more advantageous due to the reduction in pumping costs. Paper coating improved roughness and air-permeability properties. Water absorption of the coated paper was decreased by at least 50% which significantly affects the dimensional stability of the paper during web offset printing. Specular gloss and print density were significantly increased at a 1% probability level by coating the surface of the paper. Contrary to the control sample, picking of the paper (which is of great importance after printing and for linting on the printing cylinder) did not occur.

In this study, β-1, 4-endoglucanase from Penicillium simplicissimum H-11 was purified to homogeneity using ammonium sulfate followed by Sephadex G-100 chromatography. The purity of the enzyme was confirmed by HPLC and 12% SDS-PAGE, indicating a single peak with a molecular mass of 33.2 kDa. This protein had mostly α-helix structures, as confirmed by FTIR spectrometry. The optimum pH and temperature were 3.2 and 60 °C with pH stability of 2.8~5.6 and temperature stability of 50 °C for 12 h and 4 h, respectively. A metal profile of the enzyme showed that Mg2+ and Sn2+ were strong activators, while Cu2+ was a strong inhibitor. An interesting feature of this enzyme is that it can effectively hydrolyze microcrystalline cellulose, filter paper, and CMC-Na, thus revealing both endo- and exo-glucanase features of the enzyme. The kinetic constants Km and Vmax were 14.881 mg/mL and 0.364 mg/mL/min, respectively, against CMC-Na as a substrate.