Abdülkerim Karabakan

Batch removal of copper(II) and zinc(II) from aqueous solutions with low-rank Turkish coals

Abstract The removal of heavy-metal ions from aqueous solutions containing low-to-moderate levels of contamination using Turkish Beypazari low-rank coal was investigated. Carboxylic acid and phenolic hydroxyl functional groups present on the coal surface were the adsorption site to remove metal ions from solution via ion exchange. The equilibrium pH of the coal/solution mixture has been shown to be the principal factor controlling the extent of removal of Cu(II) and Zn(II) ions from aqueous solutions. The optimum pH was measured to be 4.0 and it was found that the adsorption reached equilibrium in 20 min. The maximum adsorption capacities of the metal ions from their single solutions were 1.62 mg for Cu(II) and 1.20 mg for Zn(II) per g of coal. The order of affinity based on a weight uptake by coal was as follows: Cu(II)>Zn(II). The same behavior was observed during the competitive adsorption, that is in the case of adsorption from their binary solutions. The adsorption phenomena appeared to follow a typical Langmuir isotherm. It was observed that use of low-rank coal was considerably effective in removing Cu(II) and Zn(II) ions from aqueous solutions. Higher amounts of adsorbed metal ions could be desorbed (up to 80%) using 25 mM EDTA. Low-rank Turkish coals are suitable for consecutive use for more than three cycles without significant loss of adsorption capacity.

Effect of the mineral matrix in the reactions of oil shales: 1. Pyrolysis reactions of Turkish Göynük and US Green River oil shales

The effect of the mineral matrix of Turkish Goynuk and Green River oil shales on the conversion of kerogen into organic material in pyrolysis reactions was investigated in this study. The conversion of kerogen to volatile organic material in pyrolysis reactions increased with increased reaction temperatures for the original and demineralized products of oil shales. Increasing the heating rate also caused greater kerogen conversion. It was found that pyrolysis reactions were catalyzed by alkaline earth metal cations in carbonates and inhibited by silicates. The inhibition effect of the silicates seemed to be greater than the catalytic effect of the carbonates in the pyrolysis reactions of the original Goynuk and Green River oil shales.

Metal-complexing ligand methacryloylamidocysteine containing polymer beads for Cd(II) removal

Different metal-complexing ligands carrying synthetic and natural adsorbents have been reported in the literature for heavy metal removal. We have developed a novel and new approach to obtain high metal adsorption capacity utilizing 2-methacryloylamidocysteine (MAC) as a metal-complexing ligand and/or comonomer. MAC was synthesized by using methacryloyl chloride and cysteine. Spherical beads with an average size of 150–200 μm were obtained by the radical suspension polymerization of MAC and 2-hydroxyethylmethacrylate (HEMA) conducted in an aqueous dispersion medium. Poly(2-hydroxyethylmethacrylate–methacryloylamidocysteine) p(HEMA–MAC) beads have a specific surface area of 18.9 m2 g−1. p(HEMA–MAC) beads were characterized by swelling studies, FTIR and elemental analysis. The p(HEMA–MAC) beads with a swelling ratio of 72%, and containing 3.9 mmol MAC g−1 were used in the removal of cadmium(II) ions from aqueous solutions. Adsorption equilibrium was achieved in about 15 min. The adsorption of Cd(II) ions onto pHEMA beads was negligible. The MAC incorporation significantly increased the Cd(II) adsorption capacity. Adsorption capacity of MAC incorporated beads increased significantly with pH. Competitive heavy metal adsorption from aqueous solutions containing Cd(II), Cr(III), Pb(II), Hg(II) and As(III) was also investigated. The adsorption capacities are 254 mg g−1 for Cd(II); 90.9 mg g−1 for Cr(III); 150.4 mg g−1 for Hg(II), 91.2 mg g−1 for Pb(II) and 6.7 mg g−1 for As(III) ions. These results are an indication of higher specificity of the p(HEMA–MAC) beads for the Cd(II) ions compared with other ions. Consecutive adsorption and desorption operations showed the feasibility of repeated use for p(HEMA–MAC) chelating beads.

Effect of the mineral matrix in the reactions of shales. Part 2. Oxidation reactions of Turkish Göynük and US Western Reference oil shales

Abstract The effect of the mineral matrix of Turkish Goynuk and US Green River oil shales and air diffusion on the conversion of organic material in oxidation reactions was investigated in the present study. The material washed with HCl from the original oil shales, mainly carbonates of calcium and magnesium, had a mild catalytical effect and the material washed with HF, silicate minerals, had an inhibition effect during oxidation reactions of organic material. The overall reaction orders from the kinetic analysis were found to be pseudo-first-order. The magnitude of the activation energies of oxidation reactions at equal heating rates changed as Ea (HCl washed shale)>Ea (original shale)>Ea ( HCl+HF washed shale). The rate of reaction depends on the rate of transport of the gas into the zone of reaction by diffusion. It was observed that the diffusion of oxygen into the organic matrix was the major resistance controlling the rate of oxidation reactions.

Removal of Silver(I) from Aqueous Solutions with Low-Rank Turkish Coals

The removal of silver ions from aqueous solutions containing low-to-moderate levels of contamination using Turkish Beypazari low-rank coal was investigated. Carboxylic acid and phenolic hydroxyl functional groups present on the coal surface provided adsorption sites for the removal of silver ions from solution via ion exchange. The equilibrium pH of the coal/solution mixture was shown to be the principal factor controlling the extent of recovery of Ag+ ions from aqueous solutions. The optimum pH was measured as 4.0 and it was found that the maximum removal of silver from solution was achieved within 30 min. The maximum adsorption capacity of the Ag+ ions was 1.87 mg/g coal. The adsorption phenomena appeared to follow a typical Langmuir isotherm. It was observed that the use of low-rank coal was considerably more effective in the recovery Ag+ ions from aqueous solutions. Higher amounts of adsorbed Ag+ ions could be desorbed (up to 92%) using 25 mM EDTA. Low-rank Turkish coals were suitable for consecutive use for more than 10 cycles without significant loss of adsorption capacity.

Cadmium (II) and mercury (II) removal from aquatic solutions with low-rank turkish coal

Removal of heavy metal ions from aqueous solutions containing low-to-moderate levels of contamination using Turkish Beypazari low-rank coal was investigated. Carboxylic acid and phenolic hydroxyl functional groups on the coal surface were the adsorption sites for heavy metal ions via the ion-exchange mechanism. The equilibrium pH of the coal-solution mixture was the principal factor controlling the extent of removal of Cd(II) and Hg(II) from aqueous solutions. The optimum pH was 4.0, and the adsorption reached equilibrium in 30 minutes. The maximum adsorption capacities of the metal ions from their single solutions were 1.55 mg for Hg(II) and 1.42 mg for Cd(II) per g of coal. Based on a weight uptake by coal, Hg(II) was found to have a greater affinity for the adsorption sites than does Cd(II). The same behavior was observed during competitive adsorption, that is, adsorption from binary solutions. The adsorption phenomena followed a typical Langmuir isotherm. The maximum adsorption capacities (q m) were calculated as 2.03 mg/g and 1.70 mg/g for Hg(II) and Cd(II), respectively. The K d values were 8.2 mg/L for Cd(II) and 9.8 mg/L for Hg(II). The use of low-rank coal was considerably effective in removing Hg(II) and Cd(II) from aqueous solutions. High amounts of adsorbed metal ions could be desorbed (up to 90%) with 25 mmol/L EDTA. Low-rank Turkish coals are suitable for use in more than 10 cycles without experiencing significant loss of adsorption capacity.

RECOVERY OF ORGANIC MATERIAL BY SUPERCRITICAL TOLUENE FROM TURKISH GÖYNÜK OIL SHALE. 2. KINETIC COMPARISON WITH U.S.WESTERN REFERENCE OIL SHALE

Abstract Kinetic studies of supercritical extraction experiments to recover organic material from Turkish Goynuk and U.S. Western Reference oil shales were carried out. Solubilization curves of both shales were studied in two regions; a sharply rising part reaching an intermediate state solubilization and a part where gradual changes were observed at extended periods. Organic material recovered from demineralized oil shales when the intermediate state was attained was much lower than the percentage of organic material recovered from the original oil shale. Kinetic analysis indicated that the interaction in the first region produced primary products from the organic material of the shale while the interaction in the second region contained secondary reactions among the primary products obtained before the intermediate state was attained.

Interaction of kerogen and mineral matrix of göynük oil shale in an air atmosphere

Abstract The oxidation behaviour of Goynuk oil shale and its demineralization products up to 500°C, in an air atmosphere was investigated. The kerogen of a Turkish shale was isolated by successive HCl and HF demineralization procedures. The products obtained after each demineralization step were oxidized in an air atmosphere at different reaction temperatures. The weight-loss data was recorded and the effect of carbonates and silicates on the total yield of oxidation products was determined. The spent shale after the oxidation experiments were analysed by infrared spectroscopy. The results indicated that the oxidation reactions are catalysed by carbonates and inhibited by silicates.

Response surface approach for optimization of Hg(II) adsorption by 3-mercaptopropyl trimethoxysilane-modified kaolin minerals from aqueous solution

The optimization of Hg(II) adsorption conditions from aqueous solutions with 3-mercaptopropyl trimethoxysilane-modified kaolin (MMK) used as a new adsorbent was analyzed by response surface methodology (RSM) approach. The MMK adsorbent was characterized by means of energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). According to the quadratic model obtained from central composite design (CCD) in RSM, the optimal conditions for adsorption were found to be 30.83 mg/L, 0.1 g, 7.44 and 31.41 °C for Co, adsorbent dosage, initial pH, and T (°C), respectively. With the obtained model, the maximum amount of adsorbed Hg(II) and %Hg(II) removed was calculated to be 30.10 mg/g and 98.01%, respectively. Langmuir and Dubinin-Radushkevich isotherms fitted well the experimental results. Thermodynamic studies revealed that the adsorption was physical, exothermic, spontaneous. The results indicate that MMK a new adsorbent has great potential for the removal of Hg(II) from aqueous media.

Decarboxylation of Beypazari lignite by the catalytic effect of Cr3+ and Fe3+ ions

The catalytic effect of the transition metal ions Cr 3+ and Fe 3+ on the decarboxylation of Beypazari lignite was investigated in terms of the change in calorific values of the decarboxylated lignite samples obtained after the decarboxylation process and activation energies of the decarboxylation processes. The optimum temperature to run the decarboxylation experiments was determined as 150°C and 2% Cr 3+ or Fe 3+ loadings for the raw coal samples and 1% Cr 3+ or Fe 3+ metal loadings for the demineralized coal samples were found to be the optimum values to obtain the highest calorific value coal after decarboxylation reactions. Addition of Cr 3+ or Fe 3+ to raw and/or demineralized coal samples decreased the activation energies of the decarboxylation reactions by about 40% (raw coal samples) and 30% (demineralized coal samples). Activation energies calculated for experiments with Cr 3+ loaded coal samples were lower than those for Fe 3+ loaded coal samples, indicating higher catalytic activity of Cr 3+ as a catalyst.