Transitional metals immobilized by coordination on aminophosphonate functionalized copolymers and their catalytic properties

Cu(II) and Mn(II) Anchored on Functionalized Mesoporous Silica with Schiff Bases: Effects of Supports and Metal-Ligand Interactions on Catalytic Activity

New series of Cu(II) and Mn(II) complexes with Schiff base ligands derived from 2-furylmethylketone (Met), 2-furaldehyde (Fur), and 2-hydroxyacetopheneone (Hyd) have been synthesized in situ on SBA-15-NH₂, MCM-48-NH₂, and MCM-41-NH₂ functionalized supports. The hybrid materials were characterized by X-ray diffraction, nitrogen adsorption-desorption, SEM and TEM microscopy, TG analysis, and AAS, FTIR, EPR, and XPS spectroscopies. Catalytic performances were tested in oxidation with the hydrogen peroxide of cyclohexene and of different aromatic and aliphatic alcohols (benzyl alcohol, 2-methylpropan-1-ol, and 1-buten-3-ol). The catalytic activity was correlated with the type of mesoporous silica support, ligand, and metal-ligand interactions. The best catalytic activity of all tested hybrid materials was obtained in the oxidation of cyclohexene on SBA-15-NH₂-MetMn as a heterogeneous catalyst. No leaching was evidenced for Cu and Mn complexes, and the Cu catalysts were more stable due to a more covalent interaction of the metallic ions with the immobilized ligands.

New Polymeric Adsorbents Functionalized with Aminobenzoic Groups for the Removal of Residual Antibiotics

In this paper, we present the synthesis of new polymeric adsorbents derived from macroporous chloromethylated styrene-divinylbenzene (DVB) copolymers with different cross-linking degrees functionalized with the following aminobenzoic groups: styrene-6.7% DVB (PAB1), styrene-10% DVB (PAB2), and styrene-15% DVB (PAB3). The new polymeric products, PAB1, PAB2, and PAB3, were characterized by FTIR spectroscopy, thermogravimetric analysis, and EDX, SEM, and BET analysis, respectively. The evolution of the functionalization reaction was followed by FTIR spectroscopy, which revealed a decrease in the intensity of the γCH2Cl band at 1260 cm-1, and, simultaneously, the appearance of C=O carboxylic bands from 1685-1695 cm-1 and at 1748 cm-1. The thermal stability increased with the increase in the cross-linking degree. The data obtained from the EDX analysis of the novel cross-linked copolymers confirmed the functionalization with aminobenzoic groups through the presence and content of nitrogen, as follows: PAB1: N% = 0.47; PAB2: N% = 0.85; and PAB3: N% = 1.30. The adsorption performances of the novel polymeric adsorbents, PAB1, PAB2, and PAB3, were tested in the adsorption of three antibiotics, tetracycline, sulfamethoxazole, and amoxicillin, from aqueous solutions, by using extensive kinetic, equilibrium, and thermodynamic studies. The best adsorption capacity was demonstrated by the tetracycline. Amoxicillin adsorption was also attempted, but it did not show positive results.

New polymeric adsorbent materials used for removal of phenolic derivatives from wastewaters

Phenolic compounds are produced in thermal cracking processes, drugs and herbicides synthesis and other industrial processes. Such compounds exhibit high toxicity for aquatic environment and for aquatic life. So, due to their high toxicity is important to treat waters with phenols content. For the treatment of waste waters containing phenols or phenolic compounds several unconventional methods are applied, such as: inverse osmosis, coagulation, solvent extraction, flotation–coagulation combined processes, adsorption, and anaerobic processes. From all used remediation processes adsorption has a higher applicability degree due to its main advantages: simplicity, ease of use and operation and high efficiency. Through time activated carbon and ashes were used as adsorbent materials for phenols remediation, but such materials present the main disadvantage of low regeneration degree. Thus, it is important to develop and use new adsorbents with higher regeneration degree and longer life time. Polymeric materials have been used for removal of organic compounds and/or metal ions from contaminated water due to their versatility in functionality, morphology and texture properties. Chemical modification of polymeric matrices with pendant functional groups is a valuable method used to improve the surface and interface chemistry of polymeric adsorbents, to achieve better adsorption performance and to design tailor-made adsorbents with respect to specific pollutants. In present study new adsorbent materials were obtained starting from chloromethylated styrene-divinylbenzene copolymers with different degrees of crosslinking (6.7%, 12% and respectively 15% DVB), functionalized by reaction with 3-hydroxibenzaldehyde. The polymeric intermediates were further modified by polymer-analogous reaction with iso-propylamine and diethylphosphite with the aim to improve their adsorptive properties. The obtained polymeric adsorbents were tested for remediation of waters containing phenol (P), 2,3-dimethylphenol (2,3-DMP) and 2,4,6-trimethyl-phenol (2,4,6-TMP). Based on obtained experimental data the adsorption mechanism, process kinetics and thermodynamics were studied.

Rhodium(i) diphenylphosphine complexes supported on porous organic polymers as efficient and recyclable catalysts for alkene hydrogenation

Highly stable, chemoselective and recyclable immobilized Rh(i) homogeneous catalysts for alkene hydrogenation.

Performance of poly(styrene-co-divinylbenzene) functionalized with different aminophosphonate pendant groups, in the removal of phenolic compounds from aqueous solutions

In the present work, we describe the synthesis and characterization of styrene-6.7%-divinylbenzene copolymers functionalized with aminophosphonate groups by “one-pot” reactions. Different aminophosphonate groups were grafted on the copolymer with the aim of obtaining adsorbents for removal of phenolic compounds from aqueous solutions. Adsorption experiments were carried out in batch system. The phenolic compounds studied were phenol and 2,4,6-trimethyl-phenol. The best adsorption capacity was observed in the case of polymeric adsorbents functionalized with aminophosphonate groups in para- position of the aromatic nucleus for both phenol and 2,4,6-trimethyl-phenol. In comparison, the copolymers with the functional groups in ortho- position and respectively in meta- position were slightly less efficient. The differences in adsorption efficiency may be explained taking into account the structure of the adsorption active centers. The possible explanation is that the active functional groups responsible for the adsorption process, grafted in ortho- or meta- position could be affected by possible steric hindrance effects. The difference between the adsorption capacities of the polymers of the same series, are rather small and depending on the nature of the radical found in the structure of the aminophosphonate: isopropylamine or isobuthylamine.