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A multistep response surface methodology (RSM) was successfully applied to optimise the medium conditions for the enzymatic polymerisation of bisphenol A (BPA). The laccase enzyme used as the catalyst was derived from Funalia trogii (ATCC 200800) yeast culture. The enzymatic polymerisation rate of BPA, based on the measurements of the initial dissolved oxygen (DO) consumption rate in a closed batch system, was studied through RSM. Initially the most effective medium factors, which are monomer concentration (mg/L), temperature (°C) and solvent content (% methanol), were determined through Plackett–Burman Design (PBD), then the steepest ascent combined with central composite design (CCD) steps were applied to evaluate the optimal reaction conditions for the enzymatic polymerisation. The optimal conditions were evaluated to be 748.46 mg/L, 32.24°C and 15.92% for monomer concentration, temperature and solvent content, respectively. A quadratic model was developed through RSM to represent DO consumption in the medium. The maximum DO consumption rate was calculated to be 0.093 mg DO/L min. Several repetitions were conducted at the optimal conditions to validate the system performance. The data evaluated from the quadratic model were in good agreement with those measured experimentally. The variations between the values did not exceed 10%. The correlation coefficient, R2, was calculated to be 0.95, which indicates that 95% of results can be explained by model.

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The tobacco roasting-process was carried out and a study was carried out on the composition of the gases released during this process. It has been determined that the amounts of substances obtained from the studied tobacco are generally less than the amounts of substances obtained in the literature. The volatile gases formed during this roasting were passed over some clay minerals and adsorbed on them. The adsorbed components were desorbed by diethyl ether extraction. Adsorption and desorption analyzes were investigated by GC and TG techniques. The components released during the tobacco-roasting process were first directly obtained and analyzed by gas chromatography. Then, the adsorbing efficiency to clay for each of the components in the vapors from tobacco was calculated by comparing the amount of the component retained in the absence of adsorbent with the amount retained after the component was passed over the adsorbent. The structure of the clay samples used as adsorbent was investigated by chemical analysis and DTA techniques. The adsorption efficiencies are discussed with the physical properties of the clays, the affinities of the volatile components, and their adsorption efficiency. Most of the volatiles adsorbed on the adsorbents were recovered by diethyl ether extraction. Especially benzaldehyde, propionic acid, furfuryl alcohol, 3-methylbutanoic acid and nicotine were recovered with good yield.