Study of cellulolytic enzyme immobilization on copolymers of N-vinylformamide.

This study was focused on finding of effective carriers suitable for the immobilization of cellulase. Copolymers of N-vinylformamide (NFV) and divinylbenzene (DVB) were synthesized by free radical crosslinking polymerization in inverse suspension. Methyl silicone oil was used as the continuous phase. Three polymeric carriers based on P(NVF-co-DVB) with varying degrees of crosslinking and spherical particles with different grain sizes were obtained. The formamide groups in these carriers were hydrolyzed to amino groups, yielding three P(VAm-co-DVB) polymers with vinylamine units. Enzyme, cellulase (Novozym® 476), was immobilized onto carriers with vinylamine (through glutaraldehyde) and vinylformamide groups (without glutaraldehyde). The efficiency of the enzyme immobilization was determined based on the enzymatic activity of the enzyme during the catalytic reaction relative to that of the native enzyme. All tested carriers were found to be effective carriers for the immobilization of cellulase. However, the catalytic activity of cellulase immobilized on the P(VAM-co-DVB0.27)/2000/350 carrier was higher than that for the native enzyme. In addition, two molecular spectroscopy methods, Fourier-transform absorption infrared spectroscopy (FT-IR) and Fourier-transform Raman spectroscopy (FT-Raman), were used to analyze the carriers. These studies provided complete information regarding the structure of the studied copolymers.

Preparation of a new Cd(II)-imprinted polymer and its application to determination of cadmium(II) via flow-injection-flame atomic absorption spectrometry.

A new cadmium(II)-imprinted polymer based on cadmium(II) 2,2'-{ethane-1,2-diylbis[nitrilo(E)methylylidene]} diphenolate-4-vinylpyridine complex was obtained via suspension polymerization. The beads were used as a minicolumn packing for flow-injection-flame atomic absorption spectrometry (FI-FAAS) determination of cadmium(II) in water samples. Sorption effectiveness was optimal within pH range of 6.6-7.7. Nitric acid, 0.5% (v/v) was used as eluent. Fast cadmium(II) sorption by the proposed material enabled to apply sample flow rates up to 10mLmin(-1) without loss in sorption effectiveness. Enrichment factor (EF), concentration efficiency (CE) and limit of detection (LOD, 3sigma) found for 120-s sorption time were 117, 39.1min(-1) and 0.11microgL(-1), respectively. Sorbent stability was proved for at least 100 preconcentration cycles (RSD=2.9%). When compared to non-imprinted polymer the new Cd(II)-imprinted polymer exhibited improved selectivity towards cadmium(II) against other heavy metal ions, especially Cu(II) and Pb(II), as well as light metal ions. Accuracy of the method was tested for ground water and waste water certified reference materials and fortified water. The method was applied to Cd(II) determination in natural water samples.