Danijela D. Maksin

Equilibrium and kinetics study on hexavalent chromium adsorption onto diethylene triamine grafted glycidyl methacrylate based copolymers.

Two porous and one non-porous crosslinked poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) [abbreviated PGME] were prepared by suspension copolymerization and functionalized with diethylene triamine [abbreviated PGME-deta]. Samples were characterized by elemental analysis, mercury porosimetry, scanning electron microscopy with energy-dispersive X-ray spectroscopy, and transmission electron microscopy. Kinetics of Cr(VI) sorption by PGME-deta were investigated in batch static experiments, in the temperature range 25-70°C. Sorption was rapid, with the uptake capacity higher than 80% after 30 min. Sorption behavior and rate-controlling mechanisms were analyzed using five kinetic models (pseudo-first order, pseudo-second order, Elovich, intraparticle diffusion and Bangham model). Kinetic studies showed that Cr(VI) adsorption adhered to the pseudo-second-order model, with definite influence of pore diffusion. Equilibrium data was tested with Langmuir, Freundlich and Tempkin adsorption isotherm models. Langmuir model was the most suitable indicating homogeneous distribution of active sites on PGME-deta and monolayer sorption. The maximum adsorption capacity from the Langmuir model, Q(max), at pH 1.8 and 25°C was 143 mg g(-1) for PGME2-deta (sample with the highest amino group concentration) while at 70°C Q(max) reached the high value of 198 mg g(-1). Thermodynamic parameters revealed spontaneous and endothermic nature of Cr(VI) adsorption onto PGME-deta.

Porous glycidyl methacrylate-bentonite composite

Crosslinked macroporous copolymer of glycidyl methacrylate and ethylene glycol dimethacrylate (CP) and copolymer composite with acid modified clay (CP-SA) were prepared by radical suspension copolymerization and functionalized by ring-opening reaction of the pendant epoxy groups with diethylene triamine (CP-deta and CP-SA-deta). Both SAmples were characterized by mercury porosimetry. The influence of pH, sorption time and initial 4-nitrophenol (4-NP) concentration on sorption efficiency of CP-deta and CP-SA-deta was studied in order to evaluate this material as wastewater sorbent. The isotherm data were best fitted with Langmuir model, while the sorption dynamics obeyed the pseudo-second-order kinetic model.

A novel macroporous polymer–inorganic nanocomposite as a sorbent for pertechnetate ions

A novel magnetic macroporous poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) (mPGME) was prepared by suspension copolymerization and functionalized with diethylenetriamine (mPGME-deta). The samples were characterized by Fourier transform infrared spectroscopy (FTIR) analysis, mercury porosimetry, scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), atomic force microscopy (AFM) and SQUID magnetometry. The sorption behavior of mPGME-deta toward pertechnetate ions (TcO4−) from aqueous solution was studied. Experimental results indicated relatively fast TcO4− sorption kinetics that depends on pH and ionic strength, with a high removal efficiency of 99% within 180 min in the pH range 3.0–5.0. The pseudo-second-order model yielded the best fit for the kinetic data.

Polymer-Based Monolithic Porous Composite

Porous monolithic glycidyl methacrylate (GMA) and ethylene glycol dimethacrylate (EGDMA) copolymer [PGME] and three composite samples with alumina (PGME/alumina) were synthesized by radical copolymerization in a cast and functionalized by reaction of diethylene triamine (deta) with epoxy groups in GMA. All the samples were characterized using FTIR-ATR spectroscopy, SEM, AFM, solid state NMR, thermogravimetry and mercury porosimetry. Additionally, amino functionalized PGME/alumina with the highest alumina content (PGME/alumina50-deta) was loaded with chromium [Cr(VI)] ions. Kinetics of Cr(VI) sorption was investigated in batch static experiments, at 298 K and pH = 2, for various initial concentrations (C i = 0.5, 1.5 and 2.5 mM) and analyzed using three kinetic models. Cr(VI) sorption by PGME/alumina50-deta obeys the PSO kinetic model, while IPD model suggests some degree of intraparticle pore diffusion control.

Cu(II) immobilization onto a one-step synthesized poly(4-vinylpyridine-co-ethylene glycol dimethacrylate) resin: Kinetics and XPS analysis

Synthesis of an unconventional resin based on 4-vinylpyridine (4-VP) and its Cu(II) sorption behavior were studied. Three samples of macroporous crosslinked poly(4-vinylpyridine-co-ethylene glycol dimethacrylate) [P4VPE] with different porosity parameters were prepared by suspension copolymerization by varying the n-heptane amount in the inert component. The samples were characterized by mercury porosimetry, elemental analysis and x-ray photoelectron spectroscopy (XPS). The sorption of P4VPE for Cu(II) ions, determined under non-competitive conditions, was relatively rapid, i.e. the maximum capacity was reached within 30 min. The maximum experimental sorption capacity for the sample with the highest values of pore diameter and specific pore volume (Sample 3, Qeq = 89 mg g-1) was 17.5 times higher than for the sample with the lowest values of pore diameter and specific pore volume (Sample 1, Qeq = 5.1 mg g-1). Since the values for pyridine content in all P4VPE samples were almost the same, it was concluded that the porosity parameters have predominant influence on Cu(II) sorption rates on P4VPE. The sorption behavior and the rate-controlling mechanisms were analyzed using six kinetic models (pseudo-first order, pseudo-second order, Elovich, intraparticle diffusion, Bangham and Boyd models). XPS study clarified the nature of the formed P4VPE-Cu(II) species. [Projekat Ministarstva nauke Republike Srbije, br. TR 37021 i br. III 43009]