Eco-friendly Production of Chemicals 1. Improvement of Enzymatic Production of Acetophenone by Direct Extraction

Acetophenone can be enzymatically produced by conversion of methylbenzylamine using transaminase. The enzymatic process is strongly affected by the product inhibition, thus requiring the acetophenone removal from the media during its synthesis. In this purpose, the individual and selective extraction of acetophenone and methylbenzylamine with the biocompatible solvent nheptane containing 1-octanol, D2EHPA or TOA has been analyzed at three values of pH (5, 7, and 9). Regardless of the solvent used and pH-value, the highest efficiency has been reached for extraction of acetophenone, the difference between the extraction yields of acetophenone and methylbenzylamine being amplified during the separation of these compounds from their mixture. On the basis of the experimental selectivity factors and taking into consideration both the possible loss of substrate from the media and the pH required for enzymatic reaction, pH = 7, it has been concluded that the optimum solvent combination is the mixture between n-heptane and 1-octanol. This solvent mixture allowed reaching high selectivity factor of 315, corresponding to the extraction yield of acetophenone of 94.5 % and of methylbenzylamine of only 0.3 %

Comparison between Powders of Strontium Hexaferrite Processed by Dynamic Gas Heat Treatment and Re-Calcination

The utilization of classical ceramic technology for ferrite preparation permits to obtain strontium hexaferrite with big crystals, of micrometer size, with a smaller coercive force than the hexaferrite with submicron crystals. In this work the strontium hexaferrite was obtained with submicron crystals, by hot reduction of the hexaferrite obtained through ceramic technology in CO atmosphere, followed by the thermal re-oxidization in air. The effects of treatment in CO atmosphere and of the re-calcination treatment on the magnetic and electric properties of the strontium hexaferrite were investigated

Comparison between Powders of Strontium Hexaferrite Processed by Dynamic Gas Heat Treatment and Re-Calcination

The utilization of classical ceramic technology for ferrite preparation permits to obtain strontium hexaferrite with big crystals, of micrometer size, with a smaller coercive force than the hexaferrite with submicron crystals. In this work the strontium hexaferrite was obtained with submicron crystals, by hot reduction of the hexaferrite obtained through ceramic technology in CO atmosphere, followed by the thermal re-oxidization in air. The effects of treatment in CO atmosphere and of the re-calcination treatment on the magnetic and electric properties of the strontium hexaferrite were investigated

Electrical and Dielectric Characterization of Bi–La Ion-Substituted Barium Hexaferrites

BaLa (x) Bi (x) Fe12-2xO19 (0.0 ae x ae 0.5) hexaferrites were produced by solid-state synthesis route, and the effect of Bi3+ and La3+ substitutions on electrical and dielectric properties of barium hexaferrite material were investigated. It is noticed that ac conductivity of barium (BaM) increases slightly with ionic substitutions of both La3+ and Bi3+ and then decreases. Ac conductivity is increased with increasing frequency at lower temperatures then remains constant for higher temperatures. This type of conductivity attitude could be originated from the indication of both electronics and polaron hopping mechanisms. The dielectric properties of BaLa (x) Bi (x) Fe12-2xO19 (0.0 ae x ae 0.5) hexaferrites represent a very interesting tunability as functions of frequency, temperature, and Bi3+ and La3+ ions