Solmaz Karabulut

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.

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.

Recent Advances in the Applications of Electrochemically Generated Molybdenum and Tungsten-Based Catalysts for the Olefins Metathesis

Catalytic olefin metathesis has quickly emerged as one of the most often-used transformations in modern chemical synthesis. One class of catalysts that has led the way to this significant development are the electrochemically produced tungsten- and molybdenum-based species. In this review, some of the discovery, developments and applications of electrochemically generated tungsten- and molybdenum-based metathesis catalysts are outlined.

ADMET Polymerization Activities of Electrochemically Reduced W-Based Active Species for Ge- and Sn-Containing Dienes

In the last 20 years metal atom-containing polymers have become important classes of polymers [1]. Properties like high thermic stability, electric, and photo conductometry make them very interesting for producing films, fibers, and coating [2]. Many of these compounds can be synthesized by conventional methods [3]. For producing metal-containing polymers anionic, cationic, and radicalic polymerizations were used [4–6]. Metal-containing polymers were also synthesized via acyclic diene metathesis (ADMET) polymerization that is facilitated by Schrock’s molybdenum alkylidene, or Grubbs’ ruthenium carbene catalyst [7–9]. In 1979, Gilet and coworkers succeeded in synthesizing metathetically active species from electrochemical reduction of WCl6 and MoCl5 [10,11]. In the light of these works, we have showed that electrochemically generated tungsten-based active species (WCl6-e–Al–CH2Cl2) catalyzes various metathesis-related reactions [12–16].

Olefin Metathesis in Air Using Latent Ruthenium Catalysts: Imidazole Substituted Amphiphilic Hydrogenated ROMP Polymers Providing Nano-Sized Reaction Spaces in Water

Imidazole substituted hydrogenated amphiphilic ROMP polymers were used as both surfactants and ligand precursors for olefin metathesis reactions in water. Amphiphilic ROMP polymers were synthesized using a two-step procedure. Firstly, dimethyl-5-norbornene-2,3-dicarboxylate was polymerized using ring-opening metathesis polymerization (ROMP)/cross-metathesis (CM) in the presence of allyl-PEG5000 methyl ether and a Grubbs 3rd generation (G3) catalyst. Secondly, a one-pot hydrogenation/aminolysis protocol was used for the post-polymerization modification of PEG end-capped polynorbornene derivatives. Hydrogenation reactions were carried out using residual G3 in the presence of formic acid/sodium formate in THF at 70 °C. The aminolysis reaction was carried out without isolation of the hydrogenated polymer, using triazabicyclodecene (TBD) and 1-(3-aminopropyl)-imidazole, forming imidazole substituted hydrogenated amphiphilic ROMP polymers (mod-Amph1) in an efficient manner. G1-mod-Amph1 formed micelle structures in water with an average particle size of 85.95 (±35) nm as determined by transmission electron microscopy (TEM) and dynamic light scattering (DLS) analysis. The diffusion of Grubbs 1st generation (G1) catalyst into the micelle structure has led to the formation of nano-sized catalysts which exhibited a latent characteristic. The diffusion of hydrophobic olefinic substrates into the nano-reaction spaces, followed by activation of the catalyst with HCl led to a very efficient catalytic system for ring-closing metathesis reactions. RCM reactions of various hydrophobic dienes can run in non-degassed water under an air atmosphere. The catalyst system exhibits similar performance under an air atmosphere even in tap water, reaching a conversion value of 90% for RCM of diethyl diallylmalonate with a catalytic loading of 1% Ru.

Acyclic Diene Metathesis (ADMET) Polymerization of Bis(4-pentenyl) dimethylstannane and Bis(4-pentenyl) diphenylstannane with an Electrochemically Activated Catalyst System

The microstructure and thermal analysis of two polycarbostannanes, obtained by acyclic diene metathesis (ADMET) polymerization in the presence of an electrochemically reduced tungsten-based catalyst system, were investigated in this study by NMR, DSC, and TGA techniques.

A Study on the Reactivity of WCl6–e––Al–CH2Cl2 with the Silicon-Containing Dienes

Although until the late 1980s very little information on effective metathesis conversion of organosilicon compounds had been reported, the use of molybdenum (Schrock) catalyst and ruthenium (Grubbs) carbene complexes as catalysts tolerating functional groups in substrates, have opened new synthetic opportunities in organosilicon chemistry. Silicon containing dienes undergo two types of metathetical transformation.