Erdem Yavuz

The synthesis of new polymeric sorbent and its application in preconcentration of cadmium and lead in water samples

Metal determinations at low concentration levels (</=ngmL(-1)) comprise one of most important targets in analytical chemistry. This interest also increases in different areas such as biology, medicine, environment and food samples. In spite of inherent high sensitivities obtained for electrothermal atomic absorption spectrometry (ETAAS) and inductively coupled plasma-mass spectrometry (ICP-MS), these techniques have some limitations depending on the concomitants. As a result, interest in preconcentration techniques still continues increasingly for trace metal determinations by flame atomic absorption spectrometry (FAAS) due to the high accuracy of this method. In this work, thioureasulfonamide resin was synthesized, characterized and applied as a new sorption material for determinations of cadmium and lead in water samples. The method is based on the sorption of Cd and Pb ions on the synthesized resin without using any complexing reagent. The optimization of experimental conditions was performed using factorial design including pH, amount of resin, contact time, first sample volume and final eluent volume. Using the experimental conditions defined in the optimization, the method was applied to the determination and preconcentration of Cd and Pb at ngmL(-1) level in natural water. Flame AAS was used for trace metal determinations. This method exhibits the superiority in compared to the other adsorption reagents because of the fact that there is no necessity of any complexing reagent and optimum pH of solution presents in acidic media. Consequently, 600- and 360-fold improvements in the sensitivity of FAAS were achieved by combining the slotted tube atom trap-atomic absorption spectrometry (STAT-FAAS) and the purposed enrichment method for Cd and Pb, respectively.

Poly(glycidylmethacrylate) brushes generated on poly(VBC) beads by SI-ATRP technique: Hydrazine and amino groups functionalized for invertase adsorption and purification

Crosslinked-poly(vinylbenzylchloride), poly(VBC), beads were prepared by suspension polymerization and poly(glycidylmethacrylate) was grafted by surface-initiated-atom radical polymerization (SI-ATRP) technique. Epoxy groups of the grafted poly(GMA) were reacted with hydrazine and ammonia to create an affinity binding sites. The hydrazine and amine functionalized poly(VBC-g-GMA) beads were used as an affinity support for adsorption of invertase from solution and yeast crude extract. The influence of pH, equilibrium time, ionic strength and initial invertase concentration on the adsorption capacities of both hydrazine and amine functionalized beads has been investigated. Maximum invertase adsorptions onto hydrazine and amine functionalized beads, were 86.7 and 30.4 mg/g at pH 4.0 and 5.5, respectively. The experimental equilibrium data fitted well to the Temkin isotherm model. Finally, the hydrazine functionalized poly(VBC-g-GMA) beads were used for the purification of invertase from crude yeast extract in a batch system and the purity of the eluted invertase from the hydrazine functionalized beads was determined as 92% by HPLC from single step purification protocol.

Preparation of Dicarboxylic Acid Containing Sulfonamide Based Resin and Removal of Basic Dyes

Polymer and dye interaction leading to polymer-dye complex formation exhibits many interesting and important practical features. For this purpose, dicarboxylic acid containing resin was prepared in two steps starting from poly (styrene-divinyl benzene) (PS-DVB) (10% crosslinking) based beads with a particle size of 400-590 µm, according to the synthetic protocol; chlorosulfonation, sulfamidation with iminodiacetic acid. Dye extraction experiments were carried out by contacting wetted resin samples with aqueous dye solutions at room temperature. Capacities were determined by colorimetric analysis of the residual dye content. Dye sorption capacity of the resin was found to be (0.67-0.63 g g−1 resin). This material is also able to remove the cationic dyes completely even from highly diluted aqueous dye solutions.

Preparation of the Sulfonamide Containing Block Copolymer as Polymeric Sorbent for Removal of Mercury from Aqueous Solutions

A new sulfonamide containing polymeric sorbent for the removal of mercury ions from waste waters was prepared starting from poly(glycidyl methacrylate)-b-poly(ethylene glycol)-b-poly(glycidyl methacrylate) (PGMA- b -PEG- b -PGMA) triblock copolymer prepared by using the ATRP method. Epoxy groups on the block copolymer were functionalized with amino groups. Ammonia-functionalized PGMA- b -PEG- b -PGMA was treated with excess of benzenesulfonyl chloride to obtain a sulfonamide-based polymeric sorbent. The sulfonamide containing the polymeric sorbent with a 3.5 mmol · g−1 total nitrogen content is able to selectively sorb mercury from aqueous solutions. The mercury sorption capacity of the resin is around 3.12 mmol g−1 under non-buffered conditions. Experiments performed in identical conditions with several metal ions revealed that Cd(II), Pb(II), Zn(II), Fe(III), and Fe(II) also were extractable in quantities (0–0.45 mmol/g). The sorbed mercury can be eluted by repeated treatment with 4 M HNO3 without hydrolysis of the sulfonamide groups.

Preparation of Sulfonamide Containing Cellulose Based Sorbent for Removal of Mercury Ions

A new sulfonamide containing cellulose based sorbent was prepared in three steps; poly (acrylonitrile) (PAN) grafting onto cellulose by redox polymerization method, amination of PAN grafted cellulose with ethylenediamine, and sulfamidation with benzene sulfonyl chloride. The resulting polymeric sorbent, which had a sulfonamide content of 3.4 mmol/g, was effective for the removal of mercury ions from aqueous solutions. The mercury sorption capacity of the sorbent is around 1.95 mmol/g under non-buffered conditions. The experiments performed under identical conditions with some metal ions reveal that Cd(II), Mg (II), Zn(II), and Fe(III) ions are also extractable in low quantity (0.02–0.46 mmol/g). The sorbed mercury can be eluted by repeated treatment with hot acetic acid.

Preparation of poly(acrylamide) grafted onto crosslinked poly (HEMA-MMA-EGDMA) beads for the removal of phenol

ABSTRACT Poly(acrylamide) (PAAM) was grafted onto crosslinked poly(hydroxy ethyl methacrylate) (HEMA)-based beads for the removal of phenol from aqueous solution. A beaded polymer with a PAAM surface shell was prepared in two steps: synthesis of crosslinked poly (HEMA (50% mol) - MMA (40% mol) - EGDMA (10% mol)) terpolymers spherical beads (200–420 µm) (resin 1) via the suspension polymerization method; and the grafting of PAAM was carried out by redox initiation from hydroxyl groups on resin1 by using cerium (IV) ammonium nitrate as the initiator. The resulting polymeric sorbent (resin 2) with about 82 wt.% grafted PAAM has been demonstrated to be efficient to remove phenol from water. Moreover, phenol sorption capacities of resin 1 and resin 2 were compared and sorption experiments were performed depending on the initial phenol concentration and pH. Kinetic measurements and models were studied for resin 1 and resin 2.