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Optimization of the enzymatic production of isoamyl acetate with novozym 435 from candida antarctica

In this study the production of isoamyl acetate by esterification of isoamyl alcohol and acetic acid was carried out using immobilized C . antarctica lipase (Novozym 435) as a catalyst without any organic solvent. The esterification yield was optimized with response surface methodology. This method was used with four parameters to evaluate the effects of important variables on the esterification yield. The parameters are acid/alcohol mole ratio (0.2-0.8), enzyme amount (4-12%, w/w), temperature (30-50 °C), and reaction time (4-8 hr). It was found that the most effective parameter was acid/alcohol mole ratio. As acid/alcohol mole ratio increased at any given reaction time and amount of enzyme, ester concentration, C p (mmol ester/g mixture), increased up to an acid/alcohol mole ratio of 0.7 and thereafter decreased. The model indicated the optimum conditions for maximum esterification (3.45 mmol ester/g mixture) in the acid/alcohol mole ratio of 0.52 for 8.15% enzyme at 43.2 °C and after 5.27 hr, which were in good agreement with the experimental value (3.5 mmol ester/g mixture).

Use of Aluminium Hydroxide Sludge as Adsorbents for the Removal of Reactive Dyes: Equilibrium, Thermodynamic, and Kinetic Studies

This study investigated the removal of RR-2 and RB-4 dyes from aqueous solutions by adsorption using poppy bagasse, sugar beet bagasse, aluminium hydroxide sludge, phosphogypsum, ferrochromium plant waste, and orange peel. Aluminium hydroxide sludge had the highest adsorption capacity for both dyes. The equilibrium time was 2 days. The effects on adsorption of pH, adsorbent concentration, and stirring rate were investigated. The highest removal percentage was 80.75% and 99.74% for RR-2 and RB-4, respectively. Adsorption of RR-2 was expressed better with a Freundlich adsorption equation, while adsorption of RB-4 was expressed better with a Langmuir adsorption equation. Adsorption of RR-2 agreed with the pseudo-first-order rate equation and adsorption of RB-4 followed the pseudo-second-order rate equation. Moreover, both removal processes are endothermic. Various thermodynamic parameters, such as ?G°, ?HG°, and ?SG°, were calculated.

Enhanced ethyl butyrate production using immobilized lipase

Abstract In this study, the production of ethyl butyrate was investigated by using immobilized lipase enzyme in shake flasks. In order to determine optimum conditions for the production, response surface methodology was used. The model indicated the optimum conditions for maximum conversion (9.1%) at the 0.31 M substrate concentration, acid- alcohol molar ratio of 0.49, immobilized enzyme 25% (w/v) at 35°C, for 3 hours which were in good agreement with the experimental value. At the end of the 55 hours conversion was obtained as 61.3%. When Na2HPO4 was used in reaction medium conversion increased to 90.3% for 55 hours.

Textile Azo Dyes Decolourization by Combined Ultrasonication and Microbial Removal

Textile industry involves several processes generated large quantities of wastewaters. These effluents have some properties such as strong color due to residual dyes, recalcitrance due to the presence of compounds such as dyes, surfactants and sizing agents or high salinity, high temperature and variable pH. Remediation by a combination of various physical, chemical and biological techniques of these effluents requires due to their complex and bioresistant characters. Ultrasonication is one of the advanced oxidation processes which are degradation method of organic compounds. It has the potential for use in environmental remediation due to the formation of highly concentrated oxidizing species. In this study, the decolourization of Reactive Red 2 (RR2), Reactive Blue 4 (RR4) and Basic Yellow 2 (BY2) were studied in the first step by continuous ultrasonic irradiation at 20 kHz and in the second step by microbial. The maximum decolourizations were found as 97, 89 and 46% for RR2, RB4 and BY2, respectively by an ultrasonic/ microbial combined method.