Jaromír Hoffmann

Assessing biodegradability of plastics based on poly(vinyl alcohol) and protein wastes

Research was conducted into biodegradability of mixed polymer films based on poly(vinyl alcohol), protein hydrolyzate (collagen hydrolyzate from wastes after chrome tanning) and glycerol in an aqueous aerobic environment. Evaluation of biodegradation was based on carbon dioxide produced in the gas phase. Pure PVAL was degraded by a current mixed culture for water-treatment (unadapted) only after an approx. 10-day lag phase; during breakdown of mixed film the protein component and glycerol were broken down first and PVAL degradation occurred in the second stage. Biodegradation could be well described by 1st-order formal chemical kinetics. Repeated degradation by an adapted culture proceeded in a single stage with considerably shorter lag phase (<30 h) at a simultaneously approx. 1.5-fold greater breakdown rate (rate constants). During degradation of substrates containing PVAL, microbiological tests proved an approx. 100-fold increase in numbers of PVAL-degrading bacteria. Added protein hydrolyzate + glycerol in PVAL contributed to increasing biodegradability more than followed from proportional representation of individual components.

Poly(vinyl alcohol)–collagen hydrolysate thermoplastic blends: II. Water penetration and biodegradability of melt extruded films

Abstract Water solubility of polyvinyl alcohol (PVA) is related to degree of hydrolysis, molecular weight and modification during blending in the presence of other processing additives. In the present paper the effect of collagen hydrolysate (CH), an abundant waste product of the leather industry, and glycerol on PVA water sensitivity has been investigated. This study is a continuation of the previous research on experimental design optimisation of PVA-collagen hydrolysate blends (P. Alexy, D. Bakos, S. Hanzelova, L. Kukolikova, J. Kupec, K. Charvatova, E. Chiellini, P. Cinelli, Polymer Testing 2003, 22 doi:10.1016/S0142-9418(03)00016-3) . CH content affects water penetration into the prepared blown films, affecting therefore their solubility. An increasing content of CH in PVA based blends shortens the time to the first disruption of the film after immersing in water, restraining the negative effect of glycerol on solubility. Water penetration into film is influenced by both added components—glycerol and CH, and mutual effects depend upon their proportional amounts in the blends. Pure PVA film presented limited biodegradation at low temperature (5 °C). The CH addition in the blend significantly increases biodegradation rate at that temperature. PVA/CH blends properties are of practical relevance for applications as hospital laundry bags and containers of water-soluble substances, such as chemical agents for treatment of waste and potable water, fertilizers, washing agents, sanitary products, etc.

Capillary gas chromatography of n-butyl and isobutyl-, n-amyl and isoamyl polyethylene glycol ethers and their derivatives

Abstract The influence of a branching and increase in the length of alkyl and polyoxyethylene chain in homologous series of n -butyl and isobutyl-, n -amyl and isoamylpolyethylene glycol ethers on the retention indices at linearly programmed temperatures of a capillary column was studied. Alkylpolyethylene glycol ethers were converted by derivatization reactions into acetates, trifluoroacetates, and trimethylsilyl ethers. The influence of the structure of the alkylpolyethylene glycol molecule and the influence of the functional groups introduced into a molecule of studied compounds were examined by means of increments of retention index. Calculated retention indices were used to identify residues of individual oligomers in the products of biodegradation.

Biodegradation course of oxyethylenated medium alcohols in aqueous system

A study was conducted of the biological degradation of pure tetraethylene glycol‐mono‐n‐octyl ether and technical products of oxyethylation of n‐nonyl and n‐decyl alcohol under conditions of the modified static test according to ISO 9888. The course of degradation was judged, besides group criteria (chemical oxygen demand), by analyses of individual oligomers and intermediates using capillary gas chromatography alone or combined with mass spectrometry. Results confirmed the gradual elimination of ethylenoxide groups in the hydrophile part of molecule, with formation of respective lower oligomers (ω‐hydrophile pathway, ω‐hydrophile oxidation) as the predominant process, and central scission in the place of ether bond (hydrophile‐hydrophobe scission) as a secondary degradation mechanism. These results are not in accord with published information which present central scission as the dominant process for the given type of compounds. Identified mono‐ and dicarboxylic acids provided evidence for the presence o...

Capillary gas chromatography–mass spectrometry of lower oxyethylenated aliphatic alcohols

Abstract This paper deals with the capillary gas chromatography–mass spectrometric (CGC–MS) analysis of alkylpoly(ethylene glycol) ethers in the products of the oxyethylenation of the individual lower aliphatic alcohols C4–C10, both in synthetic mixtures and as residues in water after their biodegradation. MS has been used for the acquisition of spectra and for the recording of retention times and the areas of eluted components. Particular alkylpoly(ethylene glycol) ethers have been identified by a combination of interpreting their electron impact (EI) mass spectra and by correlating their relative retention times with the structure of the molecules. Using these correlations, the length of both the poly(ethylene glycol) part and the alkyl part of a molecule were determined. Retention times of the eluted components were used for calculation of the relative retention characteristics. The peak areas were used to determine the concentration decreases of individual components as a function of the degradation time. Alkylpoly(ethylene glycol) ethers were analysed in both the non-derivatized form and after their conversion to trimethylsilyl derivatives and acetates.