Ayşe Eren Pütün

Adsorptive removal of phenol from aqueous solutions on activated carbon prepared from tobacco residues: Equilibrium, kinetics and thermodynamics

This study consists of producing high surface area activated carbon from tobacco residues by chemical activation and its behavior of phenol removal from aqueous solutions. K(2)CO(3) and KOH were used as chemical activation agents and three impregnation ratios (50, 75 and 100 wt.%) were applied on biomass. Maximum BET surface areas of activated carbons were obtained from impregnation with 75 wt.% of K(2)CO(3) and 75 wt.% of KOH as 1635 and 1474 m(2)/g, respectively. Optimum adsorption conditions were determined as a function of pH, adsorbent dosage, initial phenol concentration, contact time and temperature of solution for phenol removal. To describe the equilibrium isotherms the experimental data were analyzed by the Langmuir, Freundlich, Dubinin-Radushkevich (D-R) and Temkin isotherm models. Pseudo-first order, pseudo-second order and intraparticle diffusion kinetic models were used to find out the kinetic parameters and mechanism of adsorption process. The thermodynamic parameters such as ΔG°, ΔH° and ΔS° were calculated for predicting the nature of adsorption. According to the experimental results, activated carbon prepared from tobacco residue seems to be an effective, low-cost and alternative adsorbent precursor for the removal of phenol from aqueous solutions.

Pyrolysis of hazelnut shells in a fixed-bed tubular reactor: yields and structural analysis of bio-oil

Fixed-bed pyrolysis experiments have been conducted on a sample of hazelnut shells to determine the possibility of being a potential source of renewable fuels and chemical feedstocks. The effects of pyrolysis temperature and well-sweep gas atmosphere (N2) on the pyrolysis yields and chemical compositions have been investigated. The maximum bio-oil yield of 23.1 wt.% was obtained in N2 atmosphere at a pyrolysis temperature of 500°C and heating rate of 7 K min−1. The pyrolysis products were characterised by elemental analysis and various chromatographic and spectroscopic techniques and also compared with currently utilised transport fuels by simulated distillation. Bio-oil was then fractionated into pentane soluble and insoluble compounds (asphaltenes). Pentane soluble was then solvent fractionated into pentane, toluene, ether and methanol subfractions by fractionated column chromatography. The aliphatic and low-molecular-weight aromatic subfractions of the bio-oil were then analyzed by capillary column gas-liquid chromatography and GC/MS. Further structural analysis of bio-oil and aromatic and polar subfractions FTIR and 1H-NMR spectra were obtained. The chemical characterization has shown that the bio-oil obtained from hazelnut shells was quite similar to the crude oil and shale oil.

Biocrude from biomass: pyrolysis of cottonseed cake

Fixed-bed pyrolysis experiments have been conducted on a sample of cottonseed cake to determine the possibility of being a potential source of renewable fuels and chemicals feedstocks, in two different reactors, namely a tubular and a Heinze retort. Pyrolysis atmosphere and pyrolysis temperature effects on the pyrolysis product yields and chemical composition have been investigated. The maximumm oil yield of 29.68% was obtained in N2 atmosphere at a pyrolysis temperature of 550°C with a heating rate of 7°C min−1 in a tubular reactor.

Bio-oil production from pyrolysis and steam pyrolysis of soybean-cake: product yields and composition

The slow pyrolysis of soybean cake in a fixed-bed reactor was investigated under three different atmospheres: static, for determining the effects of pyrolysis temperature and particle size, nitrogen and steam. The liquid yield of 33.78% was attained at 550 °C pyrolysis temperature and 200 cm3/min sweeping gas flow rate with the soybean oil cake samples having 0.850<Dp<1.250 mm particle size. And the liquid yield reached a maximum value of 42.79% with a steam velocity of 1.3 cm/s. Column chromatography was used to characterize the liquid product, bio-oil. The aliphatic subfractions of the oils were then analyzed by GC/MS. FTIR and 1H-NMR spectra were used to determine structural analysis of pyrolysis oils and aromatic and polar subfractions. The H/C ratios and the structure analysis of the fractions obtained from the biocrudes show that the fractions are quite similar to currently utilized transport fuels.

Biomass to Bio-Oil via Fast Pyrolysis of Cotton Straw and Stalk

Cotton straw and stalk were thermo-chemically processed by fast pyrolysis under different conditions in a fixed tubular reactor. Fast pyrolysis studies were carried out under sweeping gas atmosphere in two groups. The effects of pyrolysis temperature, heating rate, and sweep-gas rate were investigated in the experiments. The highest yield, 39.51%, was obtained at 550°C final temperature, with heating and sweep-gas rates of 550 Kmin -1 and 200 cm 3 min -1 , respectively. The pyrolysis products and the subfractions of pentane soluble were characterized by elemental analysis, gas chromatography, IR spectroscopy, and 1 H-NMR spectroscopy.

Structural analysis of bio-oils from pyrolysis and steam pyrolysis of cottonseed cake

Structural analysis and the effect of the water vapour on the structure of the products obtained by low temperature thermal destruction of biomass at atmospheric pressure has been investigated. The liquid products were fractionated into pentane solubles and insolubles (Asphaltenes). Pentane solubles were then solvent fractionated into pentane, toluene, ether and methanol subfractions by fractionated column chromatograpy. The aliphatic subfractions of the oils were then analysed by capillary column gas-liquid chromatography and GC/MS. For further structural analysis, the pyrolysis oils and aromatic and polar subfractions were conducted using FTIR and 1H-NMR spectra.

Fixed-bed pyrolysis and hydropyrolysis of sunflower bagasse: Product yields and compositions

Abstract Pyrolysis and hydropyrolysis experiments at different temperatures, heating rates and pressures have been conducted on a sample of sunflower pressed bagasse to investigate the effect of particle size, sweep gas velocity, and hydrogen pressure on the product yields and characteristics. In contrast to coal and oil shales, char and oil yields from sunflower pressed bagasse were found to be largely independent of particle size and sweep gas velocity in a Heinze retort with the oil yield of ≈ 40% w/w being the same as that from a well-swept fixed-bed reactor in which a much smaller sample size was used. The use of high hydrogen pressure ( > 50 bar) increased the oil yields by up to ≈ 10% w/w but these increases are much greater when expressed on a carbon basis due to the reduced oxygen contents of the oils. Even at low pressure, it has been estimated that ≈ 40% of the carbon aromatized during pyrolysis.

Oil production from an arid-land plant: fixed-bed pyrolysis and hydropyrolysis of Euphorbia rigida

Abstract Fixed-bed pyrolysis and hydropyrolysis experiments at different temperature, heating rates and pressures have been conducted on a sample of Euphorbia rigida to investigate the product yields and characteristics. In hydrogen at 15 MPa and 550°C, the trends in yield and product composition markedly differ from those found previously for coals and oil shales, also the oil yield of 41.5 wt% is more than double that obtained from static retorting. This increase by using high hydrogen pressure is much greater when expressed on a carbon basis, due to the reduced oxygen contents of the oils, and the carbon conversion is increased by ∼25% relative to static retorting.

Kinetics and evolved gas analysis for pyrolysis of food processing wastes using TGA/MS/FT-IR

The objective of this study was to identify the pyrolysis of different bio-waste produced by food processing industry in a comprehensible manner. For this purpose, pyrolysis behaviors of chestnut shells (CNS), cherry stones (CS) and grape seeds (GS) were investigated by thermogravimetric analysis (TGA) combined with a Fourier-transform infrared (FT-IR) spectrometer and a mass spectrometer (MS). In order to make available theoretical groundwork for biomass pyrolysis, activation energies were calculated with the help of four different model-free kinetic methods. The results are attributed to the complex reaction schemes which imply parallel, competitive and complex reactions during pyrolysis. During pyrolysis, the evolution of volatiles was also characterized by FT-IR and MS. The main evolved gases were determined as H2O, CO2 and hydrocarbons such as CH4 and temperature dependent profiles of the species were obtained.

Hydropyrolysis of Extracted Euphorbia rigida in a Well-Swept Fixed-Bed Tubular Reactor

Tubular reactor fixed-bed hydropyrolysis experiments have been conducted on a sample of extracted Euphorbia rigida to determine the possibility of being a potential source of renewable fuels and chemical feedstock. The effects of hydropyrolysis temperature and heating rate on the hydropyrolysis yields and chemical compositions have been investigated. The maximum bio-oil yield of 39.8 wt% was obtained in H 2 atmosphere at a hydrogen pressure of 150 bar, a hydrogen flow rate of 5 dm 3 min -1 , a hydropyrolysis temperature of 550°C, and a heating rate of 100°C min -1 . Then this bio-oil was characterized by elemental analysis and 1 H nuclear magnetic resonance (NMR) techniques.