Volume 5 Issue 1

The waste originated in temples is presently piled up at one place and then disposed off in water bodies or dumped on land to decay, leading to water and soil pollution. The present work aims to determine the biogas yield and nutrient reduction potential of Ocimum sanctum (basil) leaf waste obtained from temples. Laboratory scale digesters of 2.5 L capacity were used and fed with basil leaf waste, which was digested in a batch reactor for a retention period of 30 days at room temperature. Preliminary results indicate that the process is effective in reducing the pollution potential of the basil waste. The process removed up to 73% and 42% of total solids and BOD, respectively, along with biogas production.

The isolation of cellulose from different lignocellulosic biomass sources such as corn cob, banana plant, cotton stalk, and cotton gin waste, was studied using a steam explosion technology as a pre-treatment process for different times followed by alkaline peroxide bleaching. The agricultural residues were steam-exploded at 220 ºC for 1-4 min for the corn cob, 2 and 4 min for the banana plant, 3-5 min for the cotton gin waste, and for 5 min for the cotton stalk. The steamed fibers were water extracted followed by alkali extraction and finally peroxide bleaching to yield cellulose with different degrees of crystallinity. The degree of polymerization of the cellulose fraction ranged from 167.4 to 1615.7. Longer residence time of the steam explosion led to an increase in cellulose crystallinity. The ten isolated cellulose samples were further characterized by SEM, FT-IR, and thermal analysis. Four lignin preparations were also obtained from steam-exploded corn cob, banana plant, cotton stalk, and cotton gin waste after alkali treatment. The SEM micrographs of the lignin showed different morphological structure for the different agricultural residues. The FT-IR and TGA analyses showed that the steam pre-treatment led to an extensive cleavage of ether bonds, condensation reactions, and some demethylation of aromatic methoxyl groups in the lignin structure. The thermal stabilities of the isolated lignins were different for different agricultural residues.

The use of low-cost, locally available, highly efficient, and eco-friendly adsorbents has been investigated as an ideal alternative to the current expensive methods of removing dyes from wastewater. This study investigates the potential use of activated carbon prepared from the peel of Cucumis sativa fruit for the removal of methylene blue (MB) dye from simulated wastewater. The effects of different system variables, adsorbent dosage, initial dye concentration, pH, and contact time were investigated, and optimal experimental conditions were ascertained. The results showed that as the amount of the adsorbent increased, the percentage of dye removal increased accordingly. The optimum pH for dye adsorption was 6.0. Maximum dye was sequestered within 50 min of the start of each experiment. The adsorption of methylene blue followed the pseudo-second-order rate equation and fit the Langmuir, Freundlich, Dubinin-Radushekevich (D-R), and Tempkin equations well. Maximum removal of MB was obtained at pH 6 as 99.79% for adsorbent doses of 0.6 g/ 50 mL and 25 mg/L initial dye concentrations at room temperature. The maximum adsorption capacity obtained from the Langmuir equation was 46.73 mg g-1. The rate of adsorption was found to conform to pseudo-second-order kinetics with a good correlation (R2 > 0.9677) with intraparticle diffusion as one of the rate-determining steps. Activated carbon developed from the peel of Cucumis sativa fruit can be an attractive option for dye removal from wastewater.

Batch adsorption studies were undertaken with the abundantly available waste biosorbent Tectona grandis L.f. leaf powder for removal of cadmium(II) from aqueous solutions. The adsorption experiments were performed under various conditions such as time, temperature, different initial Cd(II) concentrations, pH, adsorbent dosage, and adsorbent particle size. The data showed that in 30 minutes, 1 g of Tectona grandis L.f. could remove 86.73% of cadmium(II) from 50 mL aqueous solution containing 100 mg L-1 of Cd. The isothermal data fitted well to both Langmuir and Freundlich models for Cd(II) adsorption on Tectona grandis L.f. Using the Langmuir model equation, the monolayer sorption capacity of Tectona grandis L.f. was evaluated to be 29.94 mg g-1. The optimum pH value was found to be 5.5. The pseudo-first-order and pseudo-second-order kinetic models were used to describe the kinetic data. The dynamic data fitted well to the pseudo-second-order kinetic model. Cd(II) adsorption was only marginally affected in the temperature range of 30 to 50oC. An SEM of Cd(II) loaded powder showed formation of agglomerates. The FTIR of Cd(II) loaded powder showed negative shift in the wave numbers.

We have developed a semi-empirical model to relate the tensile energy absorption (TEA) of paper sheets formed from high-consistency refined pulp to pulp properties, including water retention value (WRV), fibre length, and fibre curl. TEA is shown to be related to the normalized stretch (ratio of stretch to tensile strength) and the tensile strength of the pulp. Normalized stretch appears to be a function of fibre curl, whereas tensile strength for a given pulp is a function of the fibre length, fibre curl, and WRV. The manner in which these three pulp properties develop in a given refining operation determines the development of TEA.

Structural and chemical changes were investigated in Hornbeam (Carpinus betulus) chips that had been exposed to Phanerochaete chrysosporium BKM-1767 fungus. Samples subjected to fungal treatments for durations of 1, 2, and 4 weeks were investigated and compared with a control sample not subjected to fungal treatment. Results of scanning electron microscopy indicated that fungal hyphae were present on the surfaces of all chips exposed to the fungus. In the samples treated for a 2 or 4-week period, these hyphae additionally penetrated into vessels and lumens through ray cells, softening and destroying the cell walls. FT-IR spectra indicated that fungal treatment modified the chemical structure of the wood. Furthermore, there was a remarkable decrease in the amount of lignin in woods exposed to fungus. Lignin decreases after 1, 2, and 4 weeks of treatment were 2.83%, 11.4%, and 18.56%, respectively. Measurement of fiber dimensions indicated that cell wall thicknesses decreased after treatment, but that the lumen width increased compared with the control sample.

The effect of corn stover lignin structure alteration caused by white-rot fungi pretreatment on the pyrolysis kinetics was studied by FTIR and TG/DTA. Results showed that biopretreatment had a remarkable effect on lignin pyrolysis. Biopretreatment can decrease the activation energy and increase the pre-exponential factor in the initial stage of pyrolysis, which makes it possible to start the lignin pyrolysis at a relatively gentle condition and improve the availability of biomass pyrolysis as a renewable energy. Analysis by FTIR showed that white-rot fungi destroyed the aromatic skeletal carbons, which are the main ether and carbon linkages of lignin, converting lignin into compounds having relatively simple structures. The relationship between the pyrolysis characteristics and the structure alteration pretreated by white rot fungi showed that the deconstruction and depolymerization of recalcitrant linkages of lignin could accelerate the reaction and lignin pyrolysis with lower energy consumption.

This paper reviews recent results in the field of chemical modification of wood with linear chain anhydrides. Though the main focus is on work performed by the author, this is described in the context of related progress in the field. The combined research has demonstrated the effectiveness of chemical modification applied to solid wood and wood raw material for composites production in overcoming the main disadvantages of wood. Wood samples and wood chips/strands have been chemically modified with a series of anhydrides at equivalent levels of modification, under identical conditions, and the question was to determine which is the primary factor controlling the biological durability, the degree of cell wall bulking by the bonded adduct, or the extent of hydroxyl substitution. The results have clearly indicated that the degree of cell wall bulking caused by the adduct, rather than the extent of hydroxyl substitution, is the primary factor controlling the biological durability and water vapour sorption. Despite the large difference in OH substitution level, reaction with different anhydrides results in the same level of protection against decay, marine borers and termites, and in the same level of water vapour sorption. These observations suggest that the mechanism of protection is not chemical/biochemical in origin, but relates to the bulking of the cell wall by the reacted adduct.