Research Articles

This paper presents the results of trials to evaluate the color-stripping behaviour of offset printing colors and the effect of coating on deinking performance. Oil-based four-color inks were separately printed as base printing on coated and uncoated white poster paper, and then extensive pulping and deinking processes were carried out. Standard offset printings were conducted on paper samples using cyan, magenta, yellow, and black colors (CMYK), and the effects of deinking efficiency on the removal of each color were analysed. The pulps were made at Micro-Maelstrom Laboratory Pulper at specified conditions with and without bleaching agents. Formamidin sulfinic acid and hydrogen peroxide formulation were used as reductive and oxidative bleaching agents, respectively. Flotation deinking and thickening of pulp were practiced using Degussa flotation and thickening cell. The changes in the optical properties, such as brightness, whiteness, and color value (CIE L⃰, a⃰ b⃰) of deinked pulp were determined. It was found that optical properties of color-stripped pulps from coated papers were better than that of uncoated office papers. However, yield was quite low in coated papers since fillers were lost during flotation process. Cyan color was found to be the most difficult one in four main color printing inks stripping out in deinking process.

Dried Distillers Grain with Solubles (DDGS) was evaluated as a bio-based fiber reinforcement. Composites of high density polyethylene (HDPE) composed of 25% by weight DDGS and either 0% or 5% by weight of maleated polyethylene (MAPE) were produced by twin screw compounding and injection molding. An improved DDGS bio-filler was produced by solvent treating DDGS (STDDGS). Injection-molded test specimens were evaluated for their tensile, flexural, impact, and thermal properties. Composite blends composed of STDDGS were superior to their DDSG counterparts. Composites made with STDDGS and MAPE had significantly improved tensile and flexural properties compared to neat HDPE. Impact strength of all composites was similar and lower than neat HDPE. Soaking of tensile bars of the various PE-DDGS blends in distilled water for 28 days altered their physical, color, and mechanical properties. Differential scanning calorimetery and thermogravimetric analysis were conducted on neat HDPE and DDGS composites to evaluate their thermal properties.

An attempt was made to reclaim and recover palm oil mill effluent (POME) for water reuse using tubular ultrafiltration (UF) and reverse osmosis (RO) membranes. The reclaimed water was compared with the final discharged water of the local mill. The raw POME was first subjected to a physical pre-treatment process to remove the content of organic matter and suspended solids. The pre-treatment process was coupled with membrane technology (UF and RO) to reclaim the clean water from POME. From the combined techniques of UF (5 bar) and RO (30 bar) the results showed that the turbidity and BOD5 were reduced by 99% and 98.9%, respectively. Compared to the final discharged POME, this suggested method gives a significant difference in BOD5 and turbidity. The final permeate of RO was found to comply with the standards for water reuse. Therefore, the combined UF and RO method is a viable alternative and has a great potential for use in the palm oil industry.

This research was based on three species: Citrus sinensis (orange), Olea europaea (olive), and Prunus amygdalus (almond). The biomass was determined for a complete tree without roots, but including stem, branches, and canopy or crown. The obtained results demonstrate that the stem volume is slightly higher for almond trees (0.035 m3/tree) than for olive trees (0.027 m3/tree). In comparison, the average stem volume of orange trees is lower (0.006 m3/tree). On the other hand, the total biomass volume including canopy branches is similar in all three species: 0.043 m3/tree for orange tree, 0.066 m3/tree for olive tree, and 0.040 m3/tree for almond tree. The new practical quantification model for these Mediterranean agricultural crops is based on total biomass calculations normally used in forestry stands. So, the obtained values were used to develop models for biomass of the stem, branches, and canopy, relating them with the diameter and volume stem. The regression analysis shows a significant correlation with minimized estimation errors. This allows a practical use of this model in biomass calculation in standing trees, both for total tree biomass and also for pruning material.

Combined decay and mold resistance of zinc borate-(ZB) and calcium borate-(CB) treated oriented strand board (OSB) from southern mixed hardwood (MHW) and southern yellow pine (SYP) was investigated. Tests were done with a brown-rot fungus, Gloeophyllum trabeum, and a white-rot fungus, Trametes versicolor, for 8 and 12 weeks, respectively. Wood species and fungus type had significant influence on the decay resistance. Decay caused by the brown-rot fungus was evident for all untreated SYP and mixed MHW controls. White-rot fungus did not cause significant sample weight loss for either species group. In the SYP OSB control inoculated with G. trabeum, the hyphae were abundant in wood rays and cell walls where they primarily penetrated through bordered and simple pits. The incorporation of ZB and CB into OSB provided significant protection against the fungi with no significant weight loss observed in the treated OSB. Microscopic analysis showed distinct evidence of fungal colonization and a thinning pattern of cell wall material. Untreated OSB samples from MHW and commercial OSBs were most susceptible to mold growth after 6 weeks. The borate-modified OSB from MHW and SYP effectively prevented the mold growth.

A new cantilever beam apparatus has been developed to measure static and vibrational properties of small and thin samples of wood or composite panels. The apparatus applies a known displacement to a cantilever beam, measures its static load, then releases it into its natural first mode of transverse vibration. Free vibrational tip displacements as a function of time were recorded. This paper compares the test results from the cantilever beam static bending and vibration with standard mid-point simply supported bending samples. Medium density fiberboard panels were obtained from four different commercial sources. Comparisons were made using a set of fiberboard panels with thicknesses of 8.1, 4.5, 3.7, and 2.6 mm and nominal densities of 700, 770, 780, and 830 kg/m3, respectively. Cantilever beam static modulus and dynamic modulus of elasticity linearly correlated well but were consistently higher than standard mid-point bending modulus of elasticity having linear correlations of 1.12:1 and 1.26:1, respectively. The higher strain rates of both the static and vibrating cantilever beam could be the primary reason for the slightly higher dynamic modulus values. The log decrement of the displacement was also used to calculate the damping ratio for the cantilever beam. As expected, damping ratio had a slightly decreasing slope as density increased. This paper discusses the new apparatus and initial results.

Mulberry branch, consisting of bark and stalk, was used as raw skeleton material without any chemical pre-treatment to synthesize an eco-friendly mulberry branch-g-poly(acrylic acid-co-acrylamide) (PMB/P(AA-co-AM)) superabsorbent composite. The synthesis conditions and properties of the PMB/P(AA-co-AM) superabsorbent composite were investigated. The results showed that under the optimal synthesis conditions, the water absorbency of the prepared PMB/P(AA-co-AM) reached 570.5 g/g in deionized water, 288.0 g/g in tap water, and 70.0 g/g in 0.9 wt% aqueous NaCl solution. The PMB/P(AA-co-AM) composite also exhibited excellent water retention capacity as well as a rapid water absorbency rate. The urea loading percentage of the PMB/P(AA-co-AM) composite was controlled by the concentration of aqueous urea solution. The release of urea from the loaded PMB/P(AA-co-AM) composite in deionized water initially exhibited a high rate of release for 60 min, followed by a rapid decline. Meanwhile, the PMB/P(AA-co-AM) superabsorbent composite with larger particle size achieved a better sustanined release of urea.

An indigenous strain of Trichoderma viride produced high titers of cellulase complex in solid-state bio-processing of agro-industrial orange peel waste, which was used as the growth-supporting substrate. When the conditions of the SSF medium containing 15 g orange peel (50% w/w moisture) inoculated with 5 mL of inoculum were optimal, the maximum productions of endoglucanase (655 ± 5.5 U/mL), exoglucanase (412 ± 4.3 U/mL), and β-glucosidase (515 ± 3.7 U/mL) were recorded after 4 days of incubation at pH 5 and 35 °C. The enzyme with maximum activity (endoglucanase) was purified by ammonium sulfate fractionation and Sephadex G-100 column gel filtration chromatographic technique. Endoglucanase was 5.5-fold purified with specific activity of 498 U/mg in comparison to the crude enzyme. The enzyme was shown to have a molecular weight of 58 kDa by sodium dodecyl sulphate poly-acrylamide gel electrophoresis (SDS-PAGE). The shelf life profile revealed that the enzyme could be stored at room temperature (30 °C) for up to 45 days without losing much of its activity.

Most studies aimed at determining rates of hardwood delignification and carbohydrate degradation have focused on understanding the behavior of a single wood species. Such studies tend to determine either the delignification rate or the rate of carbohydrate degradation without examining the potential interactions resulting from related variables. The current study provides a comprehensive evaluation on both lignin and carbohydrate degradation during kraft pulping of multiple hardwood species. The kraft delignification rates of E. urograndis, E. nitens, E. globulus, sweet gum, maple, red oak, red alder, cottonwood, and acacia were obtained. Furthermore, the kinetics of glucan, xylan, and total carbohydrate dissolution during the bulk phase of the kraft pulping process for the above species were also investigated. The wide ranges of delignification and carbohydrate degradation rates were correlated to wood chemical characteristics. It appears that the S/G ratio and lignin-carbohydrate-complexes (LCCs) are the main characteristics responsible for the differences in kraft pulping performance among the hardwoods studied.

A simple and rapid dual-wavelength spectroscopic method is used for simultaneous determination of pentoses and hexoses in the prehydrolyzate from lignocellulosic biomass. The method is based on the following reaction mechanism: in the solution of hydrochloric acid, phloroglucinol gives color reaction with sugars or their degradation products, showing maximum absorbance at 553 nm and 410 nm. Based on dual-wavelength spectrophotometric measurement, the pentoses and hexoses can separately be quantified. It was found that the derivatives from these two different sugars have an isosbestic point at 425 nm. According to the validation results, high accuracy and reasonable recovery rate is shown with the present method (pentoses recovery 97.1 to 100.0%, hexoses recovery 97.2 to 102.0%). Additionally, the interferences from substances including lignin, furfural, 5-hydroxymethyl furfural (HMF), glucuronic acid, and galacturonic acid are insignificant. All of the above results illustrate the suitability of this method for analyzing sugars in the lignocelluloses prehydrolyzate, especially hardwoods or herbaceous plants, based on forest-related biorefinery research.