Showing papers on "Sawdust published in 2018"

Adsorption of ammonium in aqueous solutions by pine sawdust and wheat straw biochars

Abstract: Ammonium (NH4 +) is a common form of reactive nitrogen in wastewater, and its discharge to water bodies can lead to eutrophication. This study was conducted to understand NH4 + adsorption mechanisms of pine sawdust and wheat straw biochars in aqueous solutions and the factors affecting NH4 + removal. Biochars were produced by pyrolysing pine sawdust at 300 °C (PS300) and 550 °C (PS550) and wheat straw at 550 °C (WS550). Pseudo-second-order and Redlich-Peterson models best fitted the adsorption data. The PS300 showed the highest NH4 + adsorption capacity (5.38 mg g−1), followed by PS550 (3.37 mg g−1) and WS550 (2.08 mg g−1). Higher H/C and O/C ratios of PS300 (0.78 and 0.32, respectively) indicated the greater presence of functional groups on the biochar’s surface as compared to PS550 (0.35 and 0.10, respectively) and WS550 (0.36 and 0.08, respectively), resulting in different NH4 + adsorption through electrostatic interactions. The dominant mechanism for NH4 + adsorption by the biochars was likely chemical bonding and electrostatic interaction of NH4 + with the surface functional groups. Lower pyrolysis temperature resulted in a higher NH4 + adsorption capacity by the pine sawdust biochar. At the same pyrolysis temperature (550 °C), the biochar made with pine sawdust as the feedstock had a higher NH4 + adsorption capacity than biochar made from wheat straw. We conclude that biochars can be efficient absorbents for NH4 + removal from wastewater, and the removal efficiency can be optimised by selecting different feedstocks or the pyrolysis condition for biochar production.

A simple flash carbonization route for conversion of biomass to porous carbons with high CO2 storage capacity

Abstract: This work offers a new, and simpler, method for the carbonisation of biomass that involves flash carbonisation of biomass at relatively low temperature (< 400 o C). We successfully converted the biomass precursor (eucalyptus sawdust) to carbonaceous matter via flash heating for a short period of time (5 –10 minutes) under a flow of air. On activation, the flash carbonized carbon offers high yields of activated carbons with higher microporosity compared to sawdust derived activated carbons prepared via hydrothermal carbonization or conventional pyrolysis. Depending on the level of activation, the flash carbonized sawdust-derived activated carbons retain some ‘woody’ morphology preserved from the sawdust. The porosity of the carbons can be tailored towards being predominantly microporous, which generates adsorbents that exhibit very attractive CO2 uptake (up to 5.0 mmol g-1) at 1 bar and 25 o C. Moreover, depending on the level of activation, it is possible to tailor the porosity of the carbons such that they simultaneously exhibit high post combustion (< 1 bar) and pre-combustion (20 bar) CO2 capture capability. The carbons exhibit exceptional performance for low pressure swing adsorption (PSA) with working capacity of up to 8.3 mmol g-1 for a pure CO2 stream (6 to 1 bar) and up to 5.6 mmol g-1 for flue gas (1.2 to 0.2 bar), while the working capacity for vacuum swing adsorption (VSA) reaches 5.3 mmol g-1 under pure CO2 (1.5 to 0.05 bar), and 2.1 mmol g-1 for flue gas (0.3 to 0.01 bar) conditions.

Potential of Wheat Straw, Spruce Sawdust, and Lignin as High Organic Carbon Soil Amendments to Improve Agricultural Nitrogen Retention Capacity: An Incubation Study.

Abstract: Plants like winter wheat are known for their insufficient N uptake between sowing and the following growing season. Especially after N-rich crops like oilseed rape or field bean, nitrogen retention of the available soil N can be poor, and the risk of contamination of the hydrosphere with nitrate (NO3-) and the atmosphere with nitrous oxide (N2O) is high. Therefore, novel strategies are needed to preserve these unused N resources for subsequent agricultural production. High organic carbon soil amendments (HCA) like wheat straw promote microbial N immobilization by stimulating microbes to take up N from soil. In order to test the suitability of different HCA for immobilization of excess N, we conducted a laboratory incubation experiment with soil columns, each containing 8 kg of sandy loam of an agricultural Ap horizon. We created a scenario with high soil mineral N content by adding 150 kg NH4+-N ha-1 to soil that received either wheat straw, spruce sawdust or lignin at a rate of 4.5 t C ha-1, or no HCA as control. Wheat straw turned out to be suitable for fast immobilization of excess N in the form of microbial biomass N (up to 42 kg N ha-1), followed by sawdust. However, under the experimental conditions this effect weakened over a few weeks, finally ranging between 8 and 15 kg N ha-1 immobilized in microbial biomass in the spruce sawdust and wheat straw treatment, respectively. Pure lignin did not stimulate microbial N immobilization. We also revealed that N immobilization by the remaining straw and sawdust HCA material in the soil had a greater importance for storage of excess N (on average 24 kg N ha-1) than microbial N immobilization over the 4 months. N fertilization and HCA influenced the abundance of ammonia oxidizing bacteria and archaea as the key players for nitrification, as well as the abundance of denitrifiers. Soil with spruce sawdust emitted more N2O compared to soil with wheat straw, which in relation released more CO2, resulting in a comparable overall global warming potential. However, this was counterbalanced by advantages like N immobilization and mitigation of potential NO3- losses.

Enhanced Xylooligosaccharides Yields and Enzymatic Hydrolyzability of Cellulose using Acetic Acid Catalysis of Poplar Sawdust

Abstract: To increase the value and promote the utilization of woody processing residues, poplar sawdust was used to produce xylooligosaccharides (XOS) with polymerization degrees of 2–6 by acetic acid catal...

Liquid Deposition Modeling: a promising approach for 3D printing of wood

Abstract: Liquid Deposition Modeling is introduced as a promising technology for 3D printing of wood. Specimens were printed using different paste-like suspensions made from ground beech sawdust and methylcellulose dissolved in water. The wood content could be increased up to 89% in dry mass. Physical properties were influenced by binder/water ratio and wood particle size. Shrinkage due to drying was 17.3–20.0%. Density values (r12) lay between 0.33 and 0.48 g/cm3. Bending strength and modulus of elasticity ranged from 2.3 to 7.4 and from 284.8 to 733.1 N/mm2, respectively. Density, MOR and MOE increased with increasing viscosity of dissolved methylcellulose and decreased with increasing particle size.

Oils sorption on hydrophobic nanocellulose aerogel obtained from the wood furniture industry waste

Abstract: Vegetable fibers have been used for a long time for oil sorption during spills. But the hydrophilic nature of plant fibers reduces their capacity to sorb oils. Cellulose aerogels have become a product of great interest in this area due to their high porosity, low specific mass and high surface area, in addition to cellulose’s abundance and sustainability. The objective of this study was to develop a hydrophobic aerogel from cellulose nanofibers obtained from furniture industry wastes (Pinus elliotii) processed via steam explosion acid hydrolysis for oil sorption. The work started with processing the waste (sawdust) by steam explosion with a mixture of nitric and acetic acid. The cellulose-rich fraction was then washed, ground and lyophilized. The obtained aerogel was made hydrophobic by vapor-phase deposition of methyltrimethoxysilane (MTMS). Sorption tests were performed for pure petroleum, pure vegetable oil and petroleum on water (heterogeneous medium). The cellulose-rich fraction had more than 90% of the original cellulose of the wood waste, while hemicellulose and lignin were completely removed. After lyophilization an aerogel of specific mass 0.046 ± 0.0013 g cm−3 and porosity 97.08 ± 0.08% was obtained. Hydrophobization yielded a contact angle of 138.78° ± 0.78°. The aerogel showed a high sorption capacity to both medium. Kinetic models in non-linear form indicated a better fit for experimental data by the pseudo-nth order model (n = 0.95) for petroleum and by pseudo-first order for vegetable oil. For heterogeneous medium (petroleum + water) the kinetic models showed that the sorption rate is governed by liquid film diffusion.

Adsorption kinetics and surface modeling of aqueous methylene blue onto activated carbonaceous wood sawdust

Abstract: In this work, Sawdust was used to develop a new low-cost adsorbent and study its application to remove methylene blue dye from aqueous solution. Sawdust was calcined under air atmosphere at three different temperatures (300°C, 400°C, and 500°C) using phosphoric acid (H3PO4) as an activating agent. The structure, morphology, surface functions and the chemical composition of adsorbent were characterized by Fourier Transform Infrared spectra (FTIR), X-ray fluorescence (XRF), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), specific surface area (BET) and Boehm method. Different operational parameters such as pH, adsorbent loading, contact time and were investigated to evaluate experimental data. The adsorption of MB on SD-300, SD-400, and SD-500 show that the pseudo-second-order and Langmuir models fitted better the experimental results of MB adsorption onto all adsorbents. The maximum capacities based on the Langmuir model were 416.7 mg.g−1 for SD-300, 526.3 mg.g−1 for SD-40...

Chemical composition of bio-oils produced by fast pyrolysis of two energy biomass

Abstract: In this study, bio-oils from fast pyrolysis of West African cordia (Cm) and Africana birch (Al) sawdust were analyzed using a gas chromatography-mass spectrometry (GC-MS) analyzer. The chemical com...

Kinetics, isotherms, and thermodynamic studies of lead, chromium, and cadmium bio-adsorption from aqueous solution onto Picea smithiana sawdust.

Abstract: Lead (Pb), chromium (Cr), and cadmium (Cd) removal capacity of sawdust (Picea smithiana) from aqueous solution was investigated by conducting batch experiments. Thermodynamic parameters, like change in standard free energy (ΔGΘ), enthalpy (ΔHΘ) and entropy (ΔSΘ) during bio-adsorption process were estimated using the Van’t Hoff equation. The maximum metals adsorption was observed at pH 8, 20 g L−1 bio-adsorbent and at 60 min of contact time. The metal adsorption kinetics was examined by fitting the pseudo-first-order as well as four forms of pseudo-second-order kinetic models. Type 1 pseudo-second-order equation described adsorption kinetics better than others. Langmuir model and Freundlich equations were used for calculation of sorption parameters. The Langmuir maximum adsorption capacity of Pb, Cr, and Cd was 6.35, 3.37, and 2.87 mg g−1 at room temperature, respectively. The values of the separation factor (RL) were in between 0 and 1, indicating that bio-adsorption was favorable. Thermodynamics study revealed that the Pb, Cr, and Cd uptake reactions were endothermic and spontaneous. Results of the study asserted that the removal of heavy metal ions from aqueous solution is viable and the sawdust could be used in the treatment of effluents from industries, thereby reducing the level of water pollution.