The Effect of Methacrylic Acid and Maleic Acid on the Isothermal Kinetics of Acrylic Acid Crosslinking Co-polymerization under Conventional and Microwave Heating

The kinetics of free-radical crosslinking co-polymerization (FRCCP) of acrylic acid (AA) with both methacrylic acid (MA) (PAMA hydrogel ) and maleic acid (MAL) (PAMAL hydrogel) was investigated under the conditions of isothermal conventional heating (CH) and under the conditions of microwave heating (MWH) with controlled cooling.   The kinetics curves of FRCCP of PAMA and PAMAL hydrogels under the conditions of CH are described with the kinetics model of second order chemical reaction, whereas the kinetics curves under the conditions of CH are described with the kinetics model of Polany-Winger.  It is proved that MWH leads to the changes in the rate of  FRCCP and to the changes in the values of the kinetic parameters (activation energy (Ea) and pre-exponential factor (lnA).  It was found the existence of relationship between the values of the kinetic parameters calculated for MWH and CH for PAMA and PAMAL hydrogel synthesis process, which is well-known as compensation effect. The effect of MWH on the kinetics of FRCCP for PAMA and PAMAL hydrogel formation were explained by applying the model of activation by selective energy transfer (SET). The changes in kinetics model, rate of FRCCP and kinetics parameters, caused with the MWH can found wide application in designing novel technologies for obtaining polymers and for synthesis of polymers with  novel physico-chemical properties.  The suggested mechanism of activation for polymerisation under the conditions of MWH also enables development of novel reaction systems and technologies for polymers productions.

Mass and controlled fabrication of aligned PVP fibers for matrix type antibiotic drug delivery systems

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link

Hydrolysis of oligosaccharides over solid acid catalysts: a review

Mild fractionation/pretreatment processes are becoming the most preferred choices for biomass processing within the biorefinery framework. To further explore their advantages, new developments are needed, especially to increase the extent of the hydrolysis of poly- and oligosaccharides. A possible way forward is the use of solid acid catalysts that may overcome many current drawbacks of other common methods. In this Review, the advantages and limitations of the use of heterogeneous catalysis for the main groups of solid acid catalysts (zeolites, resins, carbon materials, clays, silicas, and other oxides) and their relation to the hydrolysis of model soluble disaccharides and soluble poly- and oligosaccharides are presented and discussed. Special attention is given to the hydrolysis of hemicelluloses and hemicellulose-derived saccharides into monosaccharides, the impact on process performance of potential catalyst poisons originating from biomass and biomass hydrolysates (e.g., proteins, mineral ions, etc.). The data clearly point out the need for studying hemicelluloses in natura rather than in model compound solutions that do not retain the relevant factors influencing process performance. Furthermore, the desirable traits that solid acid catalysts must possess for the efficient hemicellulose hydrolysis are also presented and discussed with regard to the design of new catalysts

Microbial oil produced from the fermentation of microwave-depolymerised rapeseed meal

Rapeseed meal is high in protein and carbohydrate and is a promising feedstock for microbial valorisation, however, the fibrous structure is difficult to breakdown and involves multiple chemical and enzymatic steps to release a fermentable hydrolysate. In this investigation an innovative pre-treatment of rapeseed meal was demonstrated, involving a one-step process using microwave heating and no additional chemicals or enzymes. 57% of the biomass was solubilised over just a few minutes with minimal energy input. The hydrolysate contained a mixture of monosaccharides, oligosaccharides and micronutrients. To ferment this material the oleaginous yeast Metschnikowia pulcherrima was selected and was able to metabolise the material including some of the oligosaccharides of approximately DP8 and below, producing a lipid that was highly monounsaturated. On the laboratory scale 11% lipid could be achieved from the rapeseed meal alone, with a lipid profile akin to palm oil. On the addition of glycerol to increase the C:N ratio, over 16 g/L of yeast was achieved with lipid content of 38% w/w. To demonstrate the scalability of the microbial process, the fermentation was demonstrated on depolymerised rapeseed meal with glycerol, in a 30 L pilot scale fermenter, yielding 12 g/L of yeast with 22% w/w lipid over 120 h. While the lipid production needs to be further optimized on this scale, the use of rapeseed meal as a feedstock, coupled with a one-step microwave process that does not need additional pre- and post-processing stages, is an exciting route to potential commercially viable microbial oils