The extraction of phenolic compounds from apples was optimised using response surface methodology (RSM). A Box-Behnken design was conducted to analyse the effects of solvent concentration (methanol or acetone), temperature and time on the extraction of total phenolic content, total flavonoids and antioxidant capacity (FRAP and DPPH). Analysis of the individual phenolics was performed by HPLC in optimal extraction conditions. The optimisation suggested that extraction with 84.5% methanol for 15 min, at 28 °C and extraction with 65% acetone for 20 min, at 10 °C were the best solutions for this combination of variables. RSM was shown to be an adequate approach for modelling the extraction of phenolic compounds from apples. Most of the experiments with acetone solutions extracted more bioactive compounds, and hence they had more antioxidant capacity, however, chlorogenic acid and phloridzin had higher yields (32.4% and 48.4%, respectively) in extraction with methanol.

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-A novel orange peel adsorbent developed from an agricultural waste material was characterised and utilised for the removal of Remazol Brilliant Blue from an artificial textile-dye effluent. The adsorption thermodynamics of this dye-adsorbent pair was studied in a series of equilibrium experiments. The time to reach equilibrium was 15 h for the concentration range of 30 mg L -1 to 250 mg L -1 . The adsorption capacity decreased with increasing temperature, from 9.7 mg L -1 at 20 °C to 5.0 mg L -1 at 60 °C. Both the Langmuir and Freundlich isotherm models fitted the adsorption data quite reasonably. The thermodynamic analysis of dye adsorption onto the orange peel adsorbent indicated its endothermic and spontaneous nature. Thus, the application of orange peel adsorbent for the removal of dye from a synthetic textile effluent was successfully demonstrated.

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