Mustafa Gazi

Modification of crosslinked glycidyl methacrylate-based polymers for boron-specific column extraction

Abstract Terpolymers of glycidyl methacrylate (0.4 mol) with methyl methacrylate (0.5 mol) and divinyl benzene (0.1 mol) in spherical beads form have been modified with N -methyl- d -glucamine in N -methyl pyrrolidone solvent. Polymers with (2.05 mmol g −1 ) functionality have moderate swelling ability (1.81 v / v 0 ) and show excellent boron uptake ability (2.15 mmol g −1 ) for extraction of trace quantities of H 3 BO 3 from aqueous solutions. The resinous polymer with 110–210 μm size has a reasonable breakthrough capacity (0.835 mmol g −1 ) and a sharp elution profile in the column extractions. No interferences come from Ca(II), Mg(II) and Fe(III) ions (0.1 M), though slightly in the presence of these ions due to coprecipitation of borates by the metal hydroxides formed on the resin particles. The capacity of the resin and flow rate do not change even after 20 recyclings in the column extractions. The method has been shown to be promising for large-scale boron extractions from aqueous solutions.

UV-induced synthesis of chitosan- g -polyacrylamide semi-IPN superabsorbent hydrogels

Superabsorbent hydrogels of chitosan-g-polyacrylamide with N,N′-methylene-bis-acrylamide as a crosslinker were prepared via UV irradiation in the absence of photoinitiator under homogeneous conditions. The product was characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry, and scanning electron microscopy to confirm the formation of hydrogels. The transparent hydrogels have been observed to exhibit as much as 2987% swelling in acidic solution. In addition, the hydrogel which hydrolyzed for 6xa0h (0.24xa0×xa0103xa0min) can have a water uptake of 106 times its weight (5300% swelling for 0.5xa0g hydrogel). The effect of several variables such as time, temperature, pH, acrylamide/chitosan ratio, crosslinker amount, and different media was explored. Finally, the prepared hydrogel have been used in adsorption of Zn(II) ions from water with high removal efficiency (0.636xa0meqxa0g−1 or 20.8xa0mgxa0g−1) at pHxa0=xa07. The experimental data of the adsorption equilibrium from Zn(II) solution fit well with the pseudo-second-order model.

Efficient Removal of Anionic and Cationic Dyes from an Aqueous Solution Using Pullulan-graft-Polyacrylamide Porous Hydrogel

A pullulan-graft-polyacrylamide porous hydrogel was prepared by radical polymerization in the presence of a crosslinking agent (N,N′-methylenebisacrylamide). Then, the swelling behavior of the hydrogel and the kinetics of swelling were investigated. The novel synthesized hydrogel was used as an adsorbent for removal of dyes from aqueous solutions. In this study, methylene blue (MB) and reactive blue 2 (RB) were selected as representative cationic and anionic dyes, respectively. The synthesized porous hydrogel exhibited excellent adsorption ability for both dyes. Various experimental conditions affecting the dye adsorption were explored to achieve maximum removal of both dye molecules. In addition, kinetic, thermodynamic, and adsorption isotherm models were employed to describe the dye adsorption process. The results indicated that the prepared hydrogel is an efficient adsorbent for dyes and possesses the ability to be regenerated without losing its original activity and stability for water treatment applications.

Removal of Mercury (II) from Aqueous Solution using Chitosan-graft-Polyacrylamide Semi-IPN Hydrogels

Chitosan-graft-polyacrylamide semi-interpenetrating polymer network (IPN) superabsorbent hydrogel was prepared via UV irradiation and N, N′-methylene-bis-acrylamide was used as crosslinker. The product was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), and scanning electron microscopy (SEM). The hydrogels were observed to exhibit as much as 2580.2% swelling under optimum reaction conditions. The hydrogel is an efficient selective sorbent for the removal of mercuric ions (Hg(II)) from aqueous solutions. The mercury sorption capacity under non-buffered conditions is achieved around 9.98 mmol · g−1 (or 2001.8 mg (mercury)/g (hydrogel)) via the colorimetric method. The kinetic data were fitted to the pseudo second order model. Furthermore, the influence of pH, hydrogel dose, and initial mercury concentration on adsorption capacity of the semi-IPN hydrogel was evaluated. Also, the isothermal adsorption equilibrium data was described using the Langmuir model. Finally, the mercury loaded hydrogel was regenerated without losing its original activity and stability.

Selective Liquid–Liquid Extraction of Mercuric Ions by Octyl Methane Sulfonamide

N-octyl methane sulfonamide (OMSA) has been demonstrated to be a very efficient reagent for selective extraction of Hg(II) ions, from aqueous solutions. The extraction bases on rapid reaction of OMSA with Hg(II) ions yielding mono and disulfonamido mercury compounds in ordinary conditions. Solubility of OMSA and its mercury compounds in 2-ethyl hexanol provide a clear-cut phase separation in the extraction. The solution of OMSA in 2-ethyl hexanol (0.4 mol L−1) is able to extract 82.2% of mercuric-acetate (0.4 mol L−1) in non-buffered conditions. Although the process depends on the nature of accompanying anions, the distribution coefficient is reasonably high (kd≥1.27) even in the presence of chloride ions. The extraction is strictly selective and the presence of Cd(II), Zn(II), Pb(II) do not bring any interference. The extraction system works in moderate concentrations. Extracted mercury in the organic phase can be recovered by back-extraction with concentrated HCl or H2SO4 solutions. After acid treatment, the organic solution of OMSA becomes regenerated without losing its activity due to reasonable hydrolytic stability of the sulfonamide linkage and it can be recycled for further extractions.

N,N-bis(2,3-Dihydroxypropyl) Octadecylamine for Liquid–Liquid Extraction of Boric Acid

N,N-bis(2,3-dihydroxypropyl) octadecylamine (BPO) has been synthesized by condensation of octadecylamine with 2 M of 1-chloro 2,3-propandiol (1-chloroglycerol) in alcohol, in high yields (88.0%). Its solution in 2-ethyl hexanol has been demonstrated to be very efficient in liquid–liquid extraction of boric acid from aqueous solutions. Two vicinal-diol functions of BPO make it versatile reagent for boron extraction. The long aliphatic chain involved provides solubility in organic solvents. At relatively low boric acid concentrations, i.e., 1.2% (w/w), about 98% of BPO involves boron chelation, in nonbuffered conditions. The role of the tertiary amine function is entrapping acidic proton resulting from possible anionic borate complexation. In the study, pH dependence of the boric acid extraction and regeneration conditions of the chelating agent has been investigated. Overall results indicate that the boron complex is stable above pH 4.7 and the presence of some common foreign ions such as Ca(II) and Mg(II) does not affect the extraction. The complexed boron can be recovered from organic phase by treating with 2 M H2SO4 solutions. Due to nonhydrolyzability of the linkages in BPO it can be recovered and may be of interest to use in continuous extraction systems.

Synthesis and Characterization of Chitosan- graft -Poly(N-Allyl Maleamic Acid) Hydrogel Membrane

A chitosan-graft-poly(N-allyl maleamic acid) hydrogel membrane was prepared by radical polymerization in the absence of a cross-linker. The product was characterized by Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), and scanning electron microscopy (SEM) to confirm the formation of hydrogels. Transparent hydrogels have been observed to exhibit as much as 223.4xa0% swelling capacity, following pseudo-second-order kinetic models. The synthesized hydrogel membrane was subsequently utilized for removal of copper ions from an aqueous solution in the presence of several different functional groups. The effects on adsorption efficiency of various parameters such as time, temperature, pH, initial concentration of copper (II) solution, and amount of hydrogel were also investigated. The maximum adsorption capacity and efficiency were found to be 50.75xa0mgxa0g−1 and 99.91xa0%, respectively, by the 0.004xa0mg adsorbent after 12xa0h of immersion in copper solution. Finally, the result showed that hydrogel membrane is pH sensitive to copper (II) adsorption and has maximum adsorption efficiency near to the pH of ground water.

Fixed-bed column sorption of borate onto pomegranate seed powder-PVA beads: a response surface methodology approach

Pomegranate seed powder (PS) was functionalized with polyvinyl alcohol (PVA) and utilized for boron removal from the aqueous system. Results of Brunauer--Emmett--Teller (BET) surface area analysis and Boehm titration indicated notable decrease in total surface area and increase in acidic surface functional groups of PS after PVA modification. Enhanced sorption is indicative of complex formation between diol groups of the pomegranate seed powder--polyvinyl alcohol (PS–PVA) and borate ions. Under column test, the saturated sorption capacity of boron was noted to be dependent on flow rate and bed height. The developed central composite design (CCD) was adequate to elucidate the sorption mechanism. Mathematical modeling of the column data was conducted, and a modified-dose-response model was the most suitable to describe the breakthrough curve and observed to be consistent with CCD analysis. This is further supported by extensive error analyses conducted between the model predicted and experimental data.

Synthesis, Characterization and Application of Cellulose Based Nano-Biocomposite Hydrogels

Nano-hydroxyapatite/cellulose-graft-polyacrylamide biocomposite hydrogels of different molar ratios were prepared to examine their potential application as a carrier for colon targeted drug delivery in vitro. The particle size of the synthesized nano-hydroxyapatite was found to be 122 nm. The swelling behavior of the composite hydrogels was observed in acidic and basic aqueous solution that simulated lower small intestine, colon and stomach fluids. The hydrogel could be applied in drug-delivery systems and acetylsalicylic acid was used as a model compound to test such a possibility. Finally, the synthesized biocomposite hydrogels with the 96.97% maximum encapsulation and 85.67% release efficiency in the basic medium were found to be a suitable candidate to carry and release of colon-targeted drugs.

Quantitative Quaternization of Poly(4-Vinyl Pyridine)

Quaternization of poly(4-vinyl pyridine), (P4-VP) by common alkyl halides can be performed with relatively low (up to 65–70%) conversion yields. Here we describe fully quaternization of P(4-VP) with activated halides such as chloro 2-propanone and 2-chloroacetamide in dimethylformamide (DMF) at room temperature.