Waste wood (biomass) is one of the most valuable and multifunctional environmental, long term resources of Earth. The aim of this paper was to study the possibilities for obtaining pellets from Juniperus. excelsa M. Bieb. biomass by a single-screw extrusion pre-treatment method. Biomass obtained after aqueous distillation of J. excelsa was used. The sample was grounded and sieved into dp ⩽ 500 μm and dp ⩽ 500 μm particle in size. The experiments were carried out on a single-screw laboratory extruder “Brabender 20 DN”. According to our results, the pellets with dp < 500 μm particle size were characterized with the following indicators: the mass flow rate (1.92 kg/h), sectional expansion index (1.03), specific mechanical energy (215.65 kJ/kg), density of the extrudates (0.44 g/cm3) and volumetric flow rate (4337.58 cm3/h). The samples obtained with dp > 500 μm particle size showed the following characteristics: the mass flow rate (1.30 kg/h), sectional expansion index (1.09), specific mechanical energy (535.23 kJ/kg), density of extrudates (0.48 g/cm3) and volumetric flow rate (2719.78 cm3/h). The biomass was a potential source for biofuel production. Pellets produced from biomass with a particle size dp > 500 μm had a higher density and sectional expansion index than those with a particle size dp ⩽ 500 μm. However, their production was more economically impractical, which is due to their lower mass and volumetric flow rate, as well as higher specific mechanical energy.
The main goal of present study was to examine the performance of biomass from Greek juniper needles (Juniperus excelsa M. Bieb), obtained after distillation of the raw material, for its ability to remove Cr (VI) ions from aqueous solution. The used biomass was characterized by FT-IR analysis. Batch experiments were conducted and the effects of different biosorption process parameters were determined. Maximum removal efficiency (99.58 ± 0.31 %) was obtained at pH = 1.0, adsorbent dose 0.5 g L-1, agitation speed 250 rpm, initial Cr (VI) concentration 50 mg L-1, temperature 30.0 ± 1.0°C and contact time of 30 min. The pseudo-second order model was found to provide the best fit to experimental kinetics data (R2 = 1.000) and the calculated value of equilibrium metal uptake agree quite well with the experimental value. Results indicated that the Freundlich (R2 = 0.975) and the Langmuir (R2 = 0.976) isotherm models correlated very well to the experimental equilibrium data for Cr (VI) removal. Finally, the applied biomass could be used as a cheap biosorbent for the removal of Cr (VI) ions from aqueous solutions with high maximum adsorption capacity (qmax = 143.0 mg g-1), compared to other biosorbents reported in the literature.
The aim of the present study was to investigate the possibilities for obtaining pellets by single-screw extrusion of black pine (Pinus nigra Arn.) biomass. Two fractions of black pine needles – 1) with dp ≥ 500 μm and bulk density ρn = 0.243 g/cm3 and 2) black pine twigs with d ≥ 500 μm and ρn = 0.297 g/cm3, were obtained. Wheat bran with dp ≥ 500 μm and bulk density ρn = 0.258 g/cm3 in a ratio of 1:1 was added to the obtained fractions. The experiments showed that getting pellets by single-screw extrusion of biomass from twigs and needles of black pine was possible when mixing them in a 1:1 ratio with wheat bran. The addition of wheat bran improved the smoothness and homogeneity of the produced pellets and increased their density. High-density pellets with a low sectional expansion index were produced during extrusion. The productivity of extruding mixtures of black pine twigs with wheat bran was 30% higher than that made from a mix of black pine needles and wheat bran. The pellets obtained after mixing biomass from black pine and wheat bran had over 13% higher density than those produced entirely from wheat bran. The presence of black pine biomass increased the quality of the final product while at the same time having a positive effect on both productivity and specific energy consumption.
The aim of the present study was to determine the thermodynamic and kinetic parameters of biomass obtained from black pine (Pinus nigra Arn.). The biomass, consisting of twigs with needles and needles alone of black pine, was used. Ultimate analysis with the elemental composition of the biomass with respect to the main components such as carbon (C), hydrogen (H), nitrogen (N), and sulfur (S) of the biomass before and after water distillation was made. The high heating value (HHV) and low heating value (LHV), energy density and fuel value index were determined. Thermodynamic (Gibbs energy, enthalpy, and entropy) and kinetic (activation energy, the rate constant of the process, and reaction order) parameters of the biomass were calculated.
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