Effect of acetylation on pretreated wood flour of four different wood species, Boabab (Adansonia digitata), Mahoganny (Daniella oliveri), African locust bean (Parkia biglobosa) and Beech wood (Gmelina arborea), had been investigated. The first batch of wood species were acetylated using acetic anhydride while the second batch were acetylated with commercial vinegar. Both experiments were conducted in the presence of varying amount of CaCl2 as catalyst and at temperature of 120°C for 3 h. The success of acetylation was determined based on Weight Percent Gain for each sample treated with either chemicals used. FT-IR, a veritable tool was used for the analysis of both treated and untreated samples to further investigate the success of acetylation. The results showed the presence of important band such as carbonyl absorptions at 1743, 1744, 1746, 1731, 1718 and 1696 cm−1 as appeared separately in the spectra of acetylated samples, confirming esterification occurred. The purpose of this work was to investigate the applicability of vinegar for acetylation of lignocellulosic fibers. Blends/composites were prepared by solution casting and their kinetics investigated in distilled water. The results indicated they could be used in outdoor applications such as, decking and packaging.
Acetylated cellulose and wood cellulose as well as untreated cellulose polyethylene blends were subjected to kinetic studies using water, 0.5 M NaOH, and 0.5 M HCl solutions in order to investigate their absorbent properties at 0.5/1.0 cellulose/wood cellulose/polyethylene matrix. The results of the absorption studies showed that the untreated cellulose and wood cellulose blends absorbed water and the acid and alkali solutions higher than the treated samples, which showed a reduction in acid, alkali, and water uptake. In this work, the effects of acetylation on the morphological studies of the polyethylene blends were obvious. The presence of acetyl groups improved the interfacial bonding between the polymer matrix and cellulose as well as the wood cellulose fibers, as evidenced by scanning electron microscopy (SEM).
Adsorption Kinetics describes the rate at which solute is adsorbed and the resident time of the adsorbates on the solid-liquid interface. Adsorption isotherms play important role in determining the interaction between adsorbate and adsorbent and the optimum adsorption capacity of adsorbent. This article considered selected adsorption kinetics and isotherms models. Pseudo first order, Pseudo second order, Elovich, Bhattacharya and Venkobachar, and Natarajan and Khalaf were adsorption kinetics reviewed on the assumption that the process behaves as heterogeneous reaction at solid-liquid interface. Adsorption kinetics equation presented takes the form of straight line, the slopes and intercepts of the plots are used to determine adsorption capacity of adsorbent, rate constant, rate of adsorption and intraparticle diffusion. Value of correlation coefficient obtained is used in determining the adsorption kinetics model that best describe the adsorption process. Langmuir, Freundlich, Radlich-Peterson, Temkin and Dubinin-Radushkevic adsorption isotherms were presented. Their slopes and intercepts provide insight on adsorption affinity, mean free energy, whether the adsorption is physisorption or chemisorptions, single or multilayer. Adsorption kinetics and isotherms reviewed provide essential information required for understanding adsorption process. Keywords: Adsorption; kinetics; isotherms; pseudo first order; Langmuir
This investigation was conducted to evaluate the adsorption capacity of nanoparticles of cellulose origin. Nanoparticles were synthesized by acid hydrolysis of microcrystalline cellulose/cellulose acetate using 64% H3PO4 and characterized using FTIR, XRD, TGA-DTGA, BET and SEM analysis. Adsorption kinetics of Pb (II) ions in aqueous solution was investigated and the effect of initial concentration, pH, time, adsorbent dosage and solution temperature. The results showed that adsorption increased with increasing concentration with removal efficiencies of 60% and 92.99% for Azeh2 and Azeh10 respectively for initial lead concentration of 3 mg/g. The effects of contact time showed that adsorption maximum was attained within 24h of contact time. The maximum adsorption capacity and removal efficiency were achieved at pH6. Small dose of adsorbent had better performance. The kinetics of adsorption was best described by the pseudo-second-Order model while the adsorption mechanism was chemisorption and pore diffusion based on intra-particle diffusion model. The isotherm model was Freundlich. Though, all tested isotherm models relatively showed good correlation coefficients ranging from 0.969-1.000. The adsorption process was exothermic for Azeh-TDI, with a negative value of -12.812 X 10 3 KJ/mol. This indicates that the adsorption process for Pb by Azeh-TDI was spontaneous. Adsorption by Azeh2 was endothermic in nature.
Nanoparticles from different cellulosic sources were prepared via hydrolysis using three different acids. Cellulose, Methylcellulose (MC), Cellulose acetate (CA), Propylcellulose (PC) and Ethylcellulose (EC) was hydrolyzed using pulp-to-liquid ratio of 4.57:1 under 1/3/6 h hydrolysis. Different particles ranging from 70 -1580 nm were obtained. The maximum yield (55.3 %) was attained at 3 h hydrolysis with H 3 PO 4 acid, and particle size decreased with increasing reaction time as revealed by SEM and fiber length histograms and BET. Most fibers had pore area around 0.41 µm2. Nanoparticles obtained from all cellulose derivative used had low crystallinity index value attributed to substituent groups. The TGA showed that the prepared nanoparticles have thermal stability at T95 and T90 (5 and 10 wt % mass loss) in the temperature range of 297.51-411.09 o C and 315-508.55 o C with Tmax, 375-525 o C respectively. An extended temperature range was observed for some samples over the whole temperature range with only 50 wt % mass loss of the nanomaterials. FT-IR spectroscopy was employed to study the characteristic functionalities found in crystalline cellulose. BET analysis of samples gave evidences of the nanoparticles possessing large surface area of between 105.698 m2/g and 250.570 m2/g. The Langmuir surface area was 10336.157 m2/g, while the pore size and pore volume, ranged from 1.324 -9.237 nm and 0.01427 -0.07939 cm3/g respectively. The three different acids used gave various yields of nanocrystals with H 3 PO 4 having the highest yield of 55.3 %, followed by HCl, (34.8 %) while H 2 SO 4 has the lowest yield of 30 %. All of these yields were obtained under the same reaction conditions during 3 h hydrolysis. All samples hydrolyzed for 6 h gave low yield, 28.2 % of nanoparticles. The 3 h hydrolysis was the optimum reaction time for the generation of nanoparticles using 4.57 mL/g solid-liquid ratio.
Effect of acetylation on pre-treated wood flour of different wood species, Boabab (Adansonia Digitata), Mahoganny (Daniella Oliveri), African locust bean (Parkia Biglobosa) and Beech wood (Gmelina Arborea), has been investigated. Acetylation was carried out in batches using acetic anhydride and then with commercial vinegar in the presence of varying amount of CaCl 2 as catalyst and at temperature of 120 °C for 3 h under reflux. The success of acetylation was determined based on Weight Percent Gains. FT-IR spectroscopy, a veritable tool was used for the analysis of both treated and untreated samples to further investigate the success of acetylation. The results showed the presence of important band such as carbonyl absorptions at 1743, 1744, 1746, 1731, 1718 and 1696 cm -1 as appeared separately in the spectra of acetylated samples, confirming esterification occurred. The purpose of this work was to investigate the applicability of vinegar for acetylation of lignocellulosic fibers. Acetic anhydride is a common acetylation reagent, but its utilization is restrictly prohibited in some countries. Using commercial vinegar as an alternative reagent was quite novel and interesting. Blends/composites were prepared by solution casting and their kinetics investigated in distilled water. The results indicated they could be used in outdoor/packaging applications.
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