Showing papers on "Sawdust published in 2012"

Levulinic acid production from waste biomass

Abstract: The hydrothermal conversion of waste biomass to levulinic acid was investigated in the presence of homogeneous acid catalysts. Different cheap raw materials (poplar sawdust, paper mill sludge, tobacco chops, wheat straw, olive tree pruning) were employed as substrates. The yields of levulinic acid were improved by optimization of the main reaction parameters, such as type and amount of acid catalyst, temperature, duration, biomass concentration, and electrolyte addition. The catalytic performances were also improved by the adoption of microwave irradiation as an efficient heating method, allowing significant energy and time savings. The hydrothermal conversions of inulin and wheat straw were carried out in the presence of niobium phosphate, which up to now have never been employed in these reactions. The preliminary results appeared to be in need of further optimization.

Selectively Improving the Bio-Oil Quality by Catalytic Fast Pyrolysis of Heavy-Metal-Polluted Biomass: Take Copper (Cu) as an Example

Abstract: Heavy-metal-polluted biomass derived from phytoremediation or biosorption is widespread and difficult to be disposed of. In this work, simultaneous conversion of the waste woody biomass into bio-oil and recovery of Cu in a fast pyrolysis reactor were investigated. The results show that Cu can effectively catalyze the thermo-decomposition of biomass. Both the yield and high heating value (HHV) of the Cu-polluted fir sawdust biomass (Cu-FSD) derived bio-oil are significantly improved compared with those of the fir sawdust (FSD) derived bio-oil. The results of UV–vis and 1H NMR spectra of bio-oil indicate pyrolytic lignin is further decomposed into small-molecular aromatic compounds by the catalysis of Cu, which is in agreement with the GC-MS results that the fractions of C7–C10 compounds in the bio-oil significantly increase. Inductively coupled plasma-atomic emission spectrometry, X-ray diffraction, and X-ray photoelectron spectroscopy analyses of the migration and transformation of Cu in the fast pyrolysi...

Conversion of biomass from an invasive species into activated carbons for removal of nitrate from wastewater

Abstract: Development of activated carbons targeted at nitrate ion removal is investigated by chemical activation of sawdust from the invasive species Parkinsonia aculeata wood. Phosphoric acid and potassium hydroxide are comparatively used as activating agent. Its effect on main physico-chemical properties and on the effectiveness of the activated carbons in nitrate removal is compared with those determined for a commercial sample. Activated carbons developed with the base show the best effectiveness in nitrate removal, as determined from application of the Langmuir model to the experimental isotherms. The behavior is consistent with the development of surface basic groups and the more basic character of these carbons. Noticeable improvement in nitrate uptake for all the carbons is attained after treatment with a saturated urea solution, with removal levels of ∼80–90%, despite reductions in porous structures. Nitrate adsorption onto the urea-treated carbons is in direct correlation with their enhanced contents of elemental nitrogen.

Sorptive removal of ciprofloxacin hydrochloride from simulated wastewater using sawdust : kinetic study and effect of pH

Abstract: The present work describes dynamic uptake of the antibiotic drug ciprofloxacin hydrochloride (CH), by using a cost-effective agricultural by-product . sawdust (SD). The sawdust was characterised by FTIR and SEM analysis. The sorbent particles were highly porous with average pore diameter of nearly 10 ƒEm. The optimum pH and solid/liquid ratio for sorption of CH were found to be 5.8 and 2.0, respectively. The dynamic drug uptake data was applied to various kinetic models and their order of fitness was found to be pseudo second order > Elovich equation > power function model, as indicated by their regression values. The experimental equilibrium uptake values (qe) were in close agreement with those evaluated from the pseudo second order equation for initial sorbate concentrations of 10 and 20 mgE.-1 at 33‹C. The drug uptake mechanism was found to be attractive non-electrostatic interactions, involving H-bonding interactions between H atoms and other electronegative species such as F, O and N of the drug molecule. The mechanism is discussed on the basis of pHpzc of sawdust and zwitterionic nature of drug CH. Mass transfer analysis was carried out using the drug uptake data obtained with sorbate concentrations of 10 and 20 mgE.-1. The used sorbent could be regenerated using 1.0 molE.-1 HCl solution with a regeneration efficiency of nearly 85%.

Highly Efficient Adsorption of Anionic Dyes from Aqueous Solutions Using Sawdust Modified by Cationic Surfactant of Cetyltrimethylammonium Bromide

Abstract: In the present study, the adsorption behavior of Congo Red (CR) dye from aqueous systems onto sawdust modified by cetyltrimethylammonium bromide, CH3(CH2)15N(CH3)3Br (CTAB) was attempted. Adsorption experiments were carried out using both batch and column modes under various operating conditions. The effects of some important parameters such as solution pH, adsorbent dosage, initial dye concentration and contact time were investigated. Treatment of the equilibrium data obtained in batch experiments was carried out using Langmuir and Freundlich isotherm equations. Based on the isotherm analysis, it was found that the adsorption of CR dye onto SD fits well to the Langmuir model and the adsorption pattern on CTAB modified sawdust (CTAB/SD) followed the Freundlich isotherm which is indicative of heterogeneity of the adsorption sites on the surfactant-modified sawdust. The maximum adsorption capacity of SD and CTAB/SD were found to be 5.2 and 9.1 mg g−1, respectively, according to the Langmuir model. However, much higher differences in sorption capacities were observed for CTAB/SD and SD in the column system (66.73 mg g−1). In order to find out the possibility of the exhausted column for frequent use, a regeneration study was also carried out. It was found that the dye uploaded column can be easily regenerated with a high performance using ethanol as the washing solution.

Removal of cadmium (II) from aqueous solutions by adsorption using meranti wood

Abstract: Meranti wood, an inexpensive material, has been utilized as an adsorbent for the removal of cadmium (II) from aqueous solutions. Various physico-chemical parameters such as equilibrium contact time, solution pH, initial metal ion concentration, and adsorbent dosage level were studied. Langmuir, Freundlich, Dubinin-Radushkevich (D-R) and Temkin isotherms were used to analyze the equilibrium data at different temperatures. The experimental data fitted well with the Langmuir adsorption isotherm, indicating the monolayer adsorption of the cadmium (II). The monolayer adsorption capacity of meranti wood for cadmium (II) was found to be 175.43, 163.93 and 153.84 mg/g at 30, 40, and 50°C, respectively. The thermodynamics of cadmium (II) adsorption on meranti wood indicates its spontaneous and exothermic nature. Kinetic studies showed that the adsorption followed a pseudo-second-order kinetic model. The results indicated that the meranti wood could be an alternative for more costly adsorbents used for cadmium (II) removal.

Design of process parameters for the production of xylose from wood sawdust

Abstract: Meranti wood sawdust (MWS) is a cheap and widely available lignocellulosic biomass, which can be a potential source of xylose. This xylose can be an economic raw material for the production of a wide variety of specialty chemicals, mainly xylitol. It is particularly important to establish rapid hydrolysis conditions, which can yield xylose-rich hydrolysate that do not require further treatment. The aim of this research was to study the effect of residence time, temperature, acid concentration, and liquid to solid ratio (LSR) on the formation of xylose and byproducts. Batch hydrolysis was performed using different levels of residence time (10–120 min), temperature (105–130 °C), H 2 SO 4 concentration (2–12%), and LSR (8–20 g/g). One-factor-at-a-time (OFAT) method was followed to select the optimum level of parameters. The residence time, temperature, and acid concentration were found to be the major factors affecting xylose production with the effective level of 60 min, 125 °C, and 4%, respectively. In these conditions, the xylose concentration was 17.9 g/l, corresponding to a yield of above 86% of the potential concentration.

A new valorisation strategy of olive mill wastewater: Impregnation on sawdust and combustion

Abstract: The disposal of olive mill wastewater (OMWW) by-product is one of the principal environmental problems of the olive oil industry. Therefore, several treatments have been proposed to reduce their environmental impacts; however, the high cost and the antibacterial effect of polyphenols are limiting factors for the different processes. A new valorisation strategy of OMWW based on absorption on sawdust followed by combustion has been studied. Two OMWW/sawdust blends, named impregnated samples (IS) with different mass ratios of OMWW in the mixture were prepared. In order to study the thermal behaviour of IS samples, combustion experiments were performed in a fixed bed reactor under isothermal conditions in a temperature range of 500–700 °C. In order to estimate the efficiency of the thermal process, emission factors of carbon oxides and oxygen consumption were measured. The thermal behaviours of IS were compared with that of the original sawdust under the same experimental conditions.

Use of Sagaun sawdust as an adsorbent for the removal of crystal violet dye from simulated wastewater

Abstract: Removal of dye crystal violet from wastewater by a low-cost abundantly available adsorbent was investigated. By varying the parameters such as agitation time, dye concentration, adsorbent dose, pH and temperature, potential feasibility for the removal of crystal violet by Sagaun sawdust was explored. The adsorption efficiencies were found to be pH dependent. A greater percentage of dye was removed with a decrease in the initial concentration of dye and increase in the amount of adsorbent. Characterization of the adsorbent by infrared spectroscopy was undertaken. Kinetic study showed that the adsorption of dye on sawdust was a gradual process. The equilibrium adsorption capacity of adsorbent for dye removal was measured which followed Langmuir isotherm. The dimensionless factor, RL revealed that the adsorption process is favorable in nature. © 2011 American Institute of Chemical Engineers Environ Prog, 2011

Metal ion sorption to birch and spruce wood

Abstract: Sorption of metal ions from aqueous solutions to birch wood and spruce heartwood and sapwood has been studied. Functional groups in wood were determined by acid-base titrations. The sorption of metal ions to wood of the different tree species was investigated by a column chromatographic technique. The mechanism of sorption is mainly ion exchange by complexation of metal ions to the functional groups, e.g. carboxyl groups and phenolic hydroxyl groups, in the wood phase. By combination of the sorption experiments with four different metal ion mixtures, the following affinity order was established for spruce sapwood particles: Fe3+>>Pb2+>>Cu2+>>Fe2+>Cd2+>Zn2+>Ni2+>Mn2+≥Ca2+≥Sr2+≥ Ba2+>>Mg2+>>K+>Na+≈Li+. For all three types of stemwood studied, the affinity orders were almost the same. The ion exchange properties of wood were comparable to those of a weakly acid cation exchanger. The affinity order obtained for the synthetic resin was quite similar to the order given above for wood. The metal sorption properties of wood materials imply that they could be a potential material for removal of metal ions from aqueous solutions.