Chemical and Biochemical Engineering Quarterly 

About: Chemical and Biochemical Engineering Quarterly is an academic journal published by Croatian Society of Chemical Engineers. The journal publishes majorly in the area(s): Adsorption & Fermentation. It has an ISSN identifier of 0352-9568. It is also open access. Over the lifetime, 1180 publications have been published receiving 13411 citations. The journal is also known as: CABEQ & Chemical and biochemical engineering quartely.

Solid-State Fermentation: An Overview

Abstract: Solid-state fermentation (SSF) is defined as the growth of microbes without free flowing aqueous phase. The SSF is alternative to submerged fermentation for production of value added products like antibiotics, single cell protein, Poly unsaturated fatty acids, enzymes, organic acids, biopesticides, biofuel and aroma production. However, the advantages of SSF in various processes are found to be greater than in submerged fermentation. This paper reviews the advantages of solid-state fermentation over submerged in production of different value added products, important features of various bioreactor designs, recent developments in utilization of various agro-industrial residues as substrates and the importance of mathematical modeling. With advances through modeling and optimization techniques, production-using SSF is advantageous and appropriate for production of many value added products like enzymes, antibiotics, and organic acids. This technique not only decreases the cost of the process but also makes product cheaper for consumers.

Thermophysical Comparison of Five Commercial Paraffin Waxes as Latent Heat Storage Materials

Abstract: Thermophysical properties of phase change materials (PCM) are of utmost importance in latent heat thermal energy storage (LHTES) applications. Therefore, an experimental study is conducted in order to determine thermophysical properties of five technical grade paraffin waxes produced by major Croatian oil company, INA d.d. Rijeka. The temperatures and enthalpies of melting and solidification (latent heat capacity) and specific heat capacities of solid and liquid paraffin waxes were measured by differential scanning calorimetry (DSC). The thermal diffusivity of paraffin waxes was determined utilizing transient method. The importance of eliminating phase transformation interferences to thermophysical properties determination is addressed. The densities and the coefficient of thermal expansion were measured using Archimedes methods. A self-adopted simple and inexpensive laboratory procedure for the determination of liquid density as a temperature function is presented. Finally, the thermal conductivities have been calculated from measured densities, heat capacities and diffusivities. Based on results obtained, the investigated paraffin waxes were evaluated in regard to their applicability as PCM for LHTES.

Recent Trends in the Production, Purification and Application of Lactic Acid

Abstract: Lactic acid, a naturally occurring multifunctional organic acid, is a valuable industrial chemical used as an acidulant, preservative in the food industry, pharmaceutical, leather, and textile industries, as well as a chemical feedstock. One of the most promising applications of lactic acid is its use for biodegradable and biocompatible lactate polymers, such as polylactic acid. Lactic acid can be produced either by fermentation or by chemical synthesis but the biotechnological fermentation process has received significant importance due to environmental concerns, use of renewable resources instead of petrochemicals, low production temperature, low energy requirements and high purity. There are numerous investigations on the development of biotechnological methods for lactic acid production, with an ultimate objective to enable the process to be more efficient and economical. This review discusses the various recent fermentation technologies to produce lactic acid, different microorganisms involved in the production of lactic acid, purification and wide industrial applications of lactic acid.

Biological and Non-biological Methods for Silver Nanoparticles Synthesis

Abstract: The synthesis of metallic nanoparticles is an active area of academic and, more significantly, applied research in nanotechnology. Several methods (chemical, physical or biological) have been introduced for the synthesis of these materials. In chemical reduction methods, for example, the reducing agent is a chemical solution, whereas in biological ones, the collection of enzymes especially nitrate reductase plays this role. This study is an attempt to present an overview of silver nanoparticles (Ag NPs) preparation by various methods including biological and non-biological. Focusing on the advantages and disadvantages of each method, the paper aims to discuss some fundamental issues about biological and non-biological methods for silver nanoparticles synthesis.

Kinetic Study of Enzymatic Urea Hydrolysis in the pH Range 4-9

Abstract: The enzymatic hydrolysis of urea by jack bean urease was investigated at 25 °C over the pH range 4-9. Reaction rate data were found to be well described by a modified Michaelis-Menten equation with a pH-dependent rate coefficient and a product inhibition term. The influence of pH on activity was interpreted in terms of perturbation of the enzyme distribution among three differently protonated forms. Kinetic analysis yielded a Michaelis constant of 3.21 mmol I -1 and indicated that the inhibition mechanism was of the fully non-competitive type, with K p = 12.2 mmol l -1 . The estimated activation energy was 35.3 kJ mol -1 . The resulting kinetic expression was tested by comparing model predictions with the experimental behaviour observed in unbuffered media and over a long-term period.