Tris asetamid modifiye çapraz bağlı sülfonamid esaslı reçinenin sentezi ve cıva tuzlarının sulu ortamlardan uzaklaştırılmasında kullanılması

In this study, crosslinked chlorosulfonated polystyrene resin (CSPS) was prepared starting from crosslinked polystyrene-divinyl benzene (DVB) resin. The CSPS was reacted with excess tris (2-aminoethyl) amine to obtain resin1. And then, the resin 1 was amidated with excess of acetyl chloride to obtain sulfonamide based tris amide containing resin (resin 2). Resin 1 and Resin 2 were characterized by using analytical methods and FT-IR. HgCl2 was used in mercury adsorption experiments. The mercury sorption capacities of the sorbent were determined by mixing weighed amount of polymer sample (0.1 g) with 10 mL aqueous Hg (II) solutions (0.1-0.00625 M). The mercury loading capacities were calculated from the initial and final Hg (II) contents of the solutions. Also, the resin 2 was interacted with HgCl2 depending on pH. According to the results obtained mercury adsorption capacity of the resin increased by increasing pH. Mercury sorption capacity of the resin 2 was found as 4.33 mmol/g resin at pH=6. Because of proton releasing during the binding, pH values closer to neutral condition are much favorable. Sorption capacities of the other metal ions were studied and sorption capacity was found between 2.20-1 mmol/g resin. Batch kinetic sorption experiment was performed by using HgCl2 solution (1.0x10-4 M). The rate constant of adsorption was studied with the help of the pseudo-first-order rate expression of Lagergren model and the pseudo-second-order kinetic rate expression of Ho and McKay. The pseudo-first-order equation assumes that the adsorption rate decreases linearly as the adsorption capacity increases, which is suitable especially for low concentrations. Also, the pseudo-second-order kinetic model assumes that the rate limiting step is the interaction between two reagent particles. To examine the nature of the diffusion process for the adsorption of mercury onto the resin attempts were made to calculate the pore diffusion coefficients as intra-particle transport is supposed to be the rate-controlling step. According to result of the kinetic models, the pseudo-first-order kinetic model having a low value for R2, does not present a good fit with experimental data. In contrast, in the case of pseudo-second-order kinetic model, the high values of correlation coefficients showed that the data fitted well to the pseudo-second-order rate kinetic. Adsorption isotherm models were applied. Three theoretical isotherm models Langmuir, Freundlich and Dubinin–Radushkevich were used to analyze the experimental data. One of the most widely used isotherm equations for modeling adsorption data is the Langmuir equation. Based on the Langmuir equation; Ce is the equilibrium concentration of mercury in solution (mmol/L), qe is the equilibrium amount of mercury adsorbed on the beads at time t (mmol/g). qm is the maximum adsorption capacity of the beads (mmol/g) and b (i.e., the adversely of dissociation constant of the ligand/surface interaction, Kd, or equal to association constant, Ka, (b = Ka = (1/Kd)) is the energy of adsorption dissociation constant. The Freundlich expression is an empirical equation based on adsorption on a heterogeneous surface. Based on the Freundlich equation; KF and n are the Freundlich constants characteristic of the system. KF and n are indicator of the adsorption capacity and adsorption intensity, respectively. The slope and the intercept of the linear Freundlich equation are equal to 1/n and ln KF, respectively. The linear plots of ln q versus ln C showed that the Freundlich isotherm can be representative for the mercury adsorption. The magnitude of KF and n values of Freundlich model showed easy uptake of mercury from aqueous medium with a high adsorption capacity of the beads at room temperature. Values of n>1 for affinity beads indicates positive cooperativity in binding. The Dubinin–Radushkevich (D–R) isotherm is also widely used in adsorption studies because it does not assume a homogeneous surface or constant adsorption potential. The Dubinin–Radushkevich (D–R) constant can give the valuable information regarding the mean energy of adsorption. The adsorption behavior might be predicted the physical adsorption in the range of 1–8 kJ/mol of the mean adsorption energies (E), and the chemical adsorption in more than 8 kJ/mol of the mean adsorption energies (E), respectively. E value was calculated as 2.016 kJ/mol for mercury, and found to be in the range of a typical free energy attributed to physical adsorption. So, the D–R isotherm also is a model which describes the experimental data compared to other applied isotherm models.