Volume 7 Issue 3

In this study, powdered activated carbon (PAC) was produced from agricultural waste biomass of kenaf (Hibiscus cannabinus L.) core or stalk, and the process variables were optimized by applying central composite design (CCD). The influences of carbonization temperature, duration of activation, and impregnation ratio on removal percentage of copper Cu(II) ions from aqueous solution and carbon yield were investigated. A quadratic model for adsorption percentage and a 2FI model for carbon yield were developed. The models were used to determine optimum process variables for production of activated carbon from the woody core of kenaf. From the analysis of variance (ANOVA), the most significant factor on each response of adsorption capacity and yield were identified. An activation temperature of (568±1)°C, activation time of 2.02 hours, and impregnation ratio of 1.75 were found as optimum production conditions. The experimental results showed excellent agreement with the predicted results obtained from a designed experiment that included the variables and responses of sorption capacity and yield. Textural properties of the prepared activated carbons were determined. The performance of the prepared activated carbon was further evaluated by fitting the equilibrium data with regression equations of Langmuir, Freundlich, and Temkin models at different temperatures. The research concluded that the prepared sorbent has good potential to remove Cu (II) ions from waste water.

The effects on both cellulose conversion rate and lactic acid yield were studied by adding inhibitors, including formic acid, acetic acid, furfural, and vanillin into the hydrolysate of steam-pretreated Lespedeza stalks. The results suggest that formic acid has a significant influence on the enzyme activity and poisoned bacterial cells, resulting in the reduction of cellulose conversion rate and lactic acid yield by 21% and 16.4%, respectively. Acetic acid showed a strong inhibition on simultaneous saccharification fermentation (SSF) process, but little effect on enzymatic hydrolysis. Hydrolysis and SSF were less affected by furfural and vanillin compared with weak acids. The lactic acid yield of Lespedeza stalks rinsed with water increased from 64.0% to 89.4%, and the time to reach the maximum concentration was shortened from 96 hours to 48 hours when compared with the unwashed materials.

This paper studies the influence of ammonia gas on wood color changes in response to an increasing demand for dark colored wood specimens. The darker wood color in ammonia fuming is accomplished through chemical reactions between ammonia gas and wood compounds. We exposed oak, maple, spruce, and larch wood samples to ammonia gas for 16 days. During fuming, the color changes were studied using CIE L*a*b* parameters. After fuming, the changes in extractives content, tannin, and nitrogen content were analyzed. The chemical changes of wood and residues of wood extractives after fuming were analyzed by FTIR spectroscopy. Oak wood reacted intensively with ammonia gas in a very short time, and the darkening was prominent for all the investigated wood species. It was established that tannin had no major influence on color changes of maple and larch wood in the ammonia-fuming process. The FTIR spectra of fumed wood indicated involvement of carbonyl groups, and the FTIR spectra of wood extractives indicated involvement of carbonyl, aromatic, and alcohol groups in reaction with ammonia gas.

The anatomical properties of seven hybrid poplar clones grown in three sites in southern Quebec, Canada were investigated. Radial and longitudinal variations in selected anatomical properties of wood were measured by image analysis of transverse sections and by fiber quality analysis. Results indicate that all measured anatomical properties varied significantly across sites. Clonal variation was highly significant for all anatomical properties studied, and broad-sense heritability ranged from 0.10 (average vessel lumen area) to 0.76 (cell wall area percentage). Genetic gain was positive for all anatomical properties. The variation in radial pattern was characterized by a rapid increase in the first few years in fiber length, width, and proportion, wall thickness, and percent cell wall area. Ray proportion remained constant, whereas the vessel lumen area and proportion decreased with cambial age.

Chemical modifications of hemp fibers were performed with acetic anhydride (AA) and vinyl acetate (VA) in the presence of pyridine or potassium carbonate as catalysts. Hemp fibers (Cannabis sativa) were successfully acetylated by VA in the presence of potassium carbonate (15% WPG), but no weight gain was obtained when pyridine was used as catalyst. Hemp fibers were also modified with acetic anhydride (AA) in the presence of potassium carbonate and pyridine as catalyst (14% and 16% WPG, respectively) under identical conditions, and the results were compared with those obtained using the VA technique. AA-modified, VA-modified, and control hemp fibers were characterized by Infrared (FTIR), 13C CP MAS NMR and thermo gravimetric analysis (TGA).

A batch study of boron removal from aqueous solutions by adsorption using rice husk was carried out. The effect of selected parameters such as particle size, pH, adsorbent dosage, and initial concentration of adsorbate on boron removal was investigated in the study. Results showed that the maximum boron removal was obtained with the rice husk particle size between 0.425 mm and 1.0 mm at pH 5. Boron removal was increased with an increasing amount of adsorbent dosage but decreased as the initial concentration of adsorbate increased. A Freundlich isotherm was used to describe the potential of boron adsorption using rice husk. The maximum adsorption capacity of rice husk was found to be 4.23 mg/g for boron removal.

Eucalyptus wood is among the most important biomass resource in the world. Wood mechanical defibration and fibrillation are energy-intensive processes utilized not only to produce pulp for papermaking, but also to produce reinforcement fibers for biocomposites, nanocellulose, or pretreat lignocellulosic material for biofuels production. The structural features of different Eucalyptus hybrids affecting the refining energy consumption and produced fiber furnish properties were evaluated. The defibration and fiber development were performed using an alkaline peroxide mechanical pulping (APMP) process, which included chelation followed by an alkaline peroxide treatment prior to wood chip defibration. Despite the similar wood densities and chemical compositions of different Eucalyptus hybrids, there was a clear difference in the extent of defibration and fibrillation among the hybrids. The high energy consumption was related to a high amount of guaiacyl lignin. This observation is of major importance when considering the optimal wood hybrids for mechanical wood defibration and for understanding the fundamental phenomena taking place in chemi-mechanical defibration of wood.

The effect of laboratory refining on de-inking potential of inkjet printed handsheets was investigated. Pulp samples containing 80% short fiber and 20% long fiber were beaten in a PFI mill to reach four predetermined freeness levels of 650 (unrefined), 550, 430, and 340 mL CSF, and then handsheets were made. Handsheets were identically inkjet printed and then de-inked. Results revealed that, at lower freeness value, the brightness of de-inked pulps was higher, but the opacity decreased. The surface roughness of handsheets produced using different refined pulp before de-inking was reduced. Our results showed that refining will impart a positive effect on handsheets’ de-inking potential, and de-inking printed papers produced from pulps refined to lower freeness generated the highest brightness. The results revealed that both tensile and tear strength indices of de-inked pulp were lower. However, the tear strength index of unrefined sample and the tensile strength index of pulp refined to 430 ml CSF were higher than for undeinked samples.

Henan is the main agricultural province in China and is the top producer of wheat, representing 25% of the national wheat output. Henan has been the top province in terms of total food crop production since 2000. So, agricultural residue resources, which could provide material for future social and economic development, are abundant in Henan. But the province is facing critical problems from burning agricultural residues. Both efficient use and environmental protection of the resources are beginning to receive more attention. This study assessed the agricultural residue resources available for utilization and examined recent development targets in Henan. Agricultural residues were estimated for the base year 2009. Approximately 59.12 million tonnes of agricultural residues were consumed in various ways, and the average percentage of agricultural residue utilization was 70.07%. Agricultural residue is mainly used as a fertilizer, an energy source, industrial material, forage, and as feedstock for edible fungi. Short-term targets were provided for the development of suitable uses for agricultural residues through several demonstration projects, which will help to increase the efficient use of agricultural residue in Henan, China.

The effect of compressive pretreatment before chemical pulping on the properties of poplar kraft and soda-AQ pulp was evaluated. Compressive pretreatment not only resulted in the dissolution of hemicellulose, but also leached extractives. Pulps made from compressive pretreated wood chips required lower beating energy than the untreated pulps to achieve the same beating degree of 45°SR, and the brightness of the handsheets was improved by 2% ISO. Compressive pretreatment allowed for efficient delignification and saved about 6% alkali consumption to achieve similar pulp screen yield. Furthermore, a higher content of fines and slightly lower mechanical properties were observed after the compressive treatment.