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In this study, solubility and degradation of paracetamol were examined using subcritical water. The effect of temperature and static time was investigated during the solubility process in subcritical water at constant pressure (50 bar). The experimental results showed that temperature and static time have crucial effects on the degradation and solubility degrees. The maximal solubility of paracetamol was obtained at 403 K as (14.68±0.74)×10 3. An approximation model for the solubility of paracetamol was proposed. O 2 and H 2 O 2 were used for the degradation of paracetamol. The maximum degradation degree was found as 68.66±1.05 % and 100±0.00 % using O 2 and H 2 O 2 , respectively.

The solubility of sebacic acid in subcritical water was investigated. Response surface methodology was used to study the combined effects of the different parameters such as temperature, static and dynamic time to optimize the process conditions for the maximum solubility of sebacic acid. Solubility results of sebacic acid were observed to be highly correlated with quadratic model according to analysis of variance. The solubility of sebacic acid was found as 500 g L -1 in the optimum conditions at 400 K temperature, 4 min dynamic time and 28 min static time. Approximation models were employed for determining solubility of sebacic acid at elevated temperatures.

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The olive mill wastewater is a major environmental problem, which is waiting for effective treatment. In this study, the mineralization of olive mill wastewater was investigated using the electro/FeII/persulfate process. The central composite design was utilized to examine the effect of each experimental variables (concentration of persulphate and FeII, treatment time and constant current) on the mineralization of olive mill wastewater. The optimum chemical oxygen demand removal percentage was obtained as 71.2% where the reaction conditions were 200 mA current, 250 mM persulphate, 25 mM FeII, and 6 h reaction time. In addition, the maximum percentage of total phenolic removal and the energy consumption were 88% and 4.50 kWh/kgCOD, respectively, which were obtained at the same reaction conditions mentioned above. ANOVA test was used to examine the reliability of the experimental method. The R 2 and adjusted R 2 coefficients were obtained as 0.9634 and 0.9305, respectively. Optimum experimental parameters were determined and theoretical equations were obtained for the degradation of olive mill wastewater. For the treatment of olive mill wastewater, an environmentally friendly oxidation process was examined and the effect of each experimental variables was clearly demonstrated. The obtained data was optimized for future applications.

An environmentally friendly method to decontaminate the olive mill wastewater, which is encountered as a major environmental problem is presented in this study. The removal of both polyphenolic and aromatic content and the degradation of wastewater of olive mill supplied from Mersin/Turkey region were investigated by the subcritical water oxidation method using H 2 O 2. The central composite design of response surface methodology was used to assess the effects of temperature, treatment time, and the concentration of oxidising agent. The reliability of the employed method was proved by ANOVA. The optimum experimental parameters were determined and theoretical equations were proposed in each case. The highest chemical oxygen demand removal, dephenolisation and dearomatisation values were obtained as 85.74, 96.13 and 95.94 %, respectively.

This study was conducted to investigate the degradation of propham, which is a compound that pollutes water and seriously threatens human health, by subcritical water oxidation and using HO as an oxidising agent. The maximum total organic carbon removal rate of propham was obtained as 73.65% at 40 min of treatment time and 60 mM of HO concentration and 373 K of temperature. In addition, response surface method based on the Box-Behnken design was applied to design the degradation experiments of propham for determination of the combined effects of process variables, namely temperature, concentration of oxidising agent and treatment time. The proposed quadratic model of propham degradation, which was examined with the analysis of variance, was used for navigating the design space. The R and adjusted R values of the model were determined as 0.9921 and 0.9819 respectively. It was shown that propham was effectively degraded, thus could be removed from the water by using an environmentally friendly method.

In this paper, we investigated the mineralization of hydrochlorothiazide, a diuretic drug which is used for the treatment of hypertension, using H2O2 as the oxidizing agent in subcritical water as a medium. Response surface methodology was applied to optimize experimental parameters such as temperature, treatment time, and concentration of the oxidizing agent. The highest TOC removal was obtained as 85.22% in 147.3 minutes of treatment time at 403 K using 80 mM of hydrogen peroxide. The reliability of the performed method was evaluated by ANOVA and the theoretical equation of TOC removal of hydrochlorothiazide was proposed. F and p values of the model were determined as 62.88 and lower than 0.0001, respectively.