Data for persulfate activation by UV light to degrade theophylline in a water effluent.

The aim of this study was to degrade theophylline (TP) drug in a pharmaceutical effluent solution utilizing persulfate (PS). A simulated and a real effluent solution were used, with different conditions tested to optimize the degradation process. HPLC analyses and a modified-HPLC method were used to track concentrations of TP and PS respectively in the treatment process. Experiments were done in triplicates and treated data is presented as graphs. A detailed analyses of this study can be found in the article "Degradation of theophylline in a UV254/PS system: matrix effect and application to a factory effluent" [1] published in Chemical Engineering Journal.

Chemically and thermally activated persulfate for theophylline degradation and application to pharmaceutical factory effluent.

Degradation of PPCPs by AOPs has gained major interest in the past decade. In this work, theophylline (TP) oxidation was studied in thermally (TAP) and chemically (CAP) activated persulfate systems, separately and in combination (TCAP). For [TP]0 = 10 mg L-1, (i) TAP resulted in 60% TP degradation at [PS]0 = 5 mM and T = 60 °C after 60 min of reaction and (ii) CAP showed slight degradation at room temperature; however, (iii) TCAP resulted in complete TP degradation for [PS]0 = [Fe2+]0 = 2 mM at T = 60 °C following a pseudo-first order reaction rate with calculated k obs = 5.6 (±0.4) × 10-2 min-1. In the TCAP system, the [PS]0 : [Fe2+]0 ratio of 1 : 1 presented the best results. A positive correlation was obtained between the TP degradation rate and increasing temperature and [PS]0, and a negative correlation was obtained with increasing pH. Both chloride and humic acid inhibited the degradation process, while nitrates enhanced it. TP dissolved in spring, sea and waste water simulating real effluents showed lower degradation rates than in DI water. Waste water caused the highest inhibition (k obs = 2.6 (±0.6) × 10-4 min-1). Finally, the TCAP system was tested on a real factory effluent highly charged with TP, e.g. [TP]0 = 160 mg L-1, with successful degradation under the conditions of 60 °C and [PS]0 = [Fe2+]0 = 50 mM.

A rapid and economical method for the quantification of hydrogen peroxide (H2O2) using a modified HPLC apparatus.

H2O2 is one of the most commonly used oxidants for the degradation of recalcitrant organic contaminants in advanced oxidation processes (AOPs). However, most research aiming to optimize AOPs is missing the monitoring of the remaining H2O2, an important parameter to assess the efficiency of the process. In this work, a novel method for [H2O2] quantification was developed using simple modifications of an HPLC-DAD setup that is available in most analytical chemistry laboratories. The modifications include the use of acidified potassium iodide solution as mobile phase and replacing the reverse phase column with a series of capillary columns. This instrument configuration allowed also the quantification of organic contaminants using the same H2O2 containing sample. The method's LOD and LOQ were calculated to be as low as 8.29 × 10-4 mM and 2.76 × 10-3 mM, respectively with an LDR range of 0.01-150 mM. The cost per analysis ranged between 0.8 and 1.8 USD cents depending on the concentration tested. This analytical method was validated by a statistical comparison to a well-known titrimetric method that is commonly used for H2O2 quantification. It was also tested using standards prepared in natural matrices such as spring and seawater, and in media containing high concentration of several spectator species such as chlorides, bicarbonates, humic acids, fumaric acids and micro pollutants. The method showed excellent robustness by maintaining high regression coefficient and excellent sensitivity in all calibration curves regardless of the matrix content.

Rapid quantification of persulfate in aqueous systems using a modified HPLC unit.

Existing analytical techniques used for the quantification of persulfate (PS) in water mostly rely on polarography, reductometry or spectrophotometry. Although acceptable to a certain extent, these methods did not satisfy environmental chemists seeking rapid, reproducible and accurate quantification of PS upon the application of ISCO and AOPs technologies. Accordingly, a novel flow injection/spectroscopy analytical technique is developed via the use of an HPLC coupled to bypass capillary columns and a DAD detector. Special HPLC configuration uses concentrated KI solution as mobile phase to readily reduce PS present in the sample. The reaction takes place inside the capillary columns, under moderate pressure facilitating the production of Iodine suspension (I2), to yield finally the formation of the Triiodide anion (I3-) in the presence of an excess of I-. Triiodide absorbs at 352nm which minimizes interferences from other organic contaminants (OCs). The method was validated by comparison to traditional PS quantification methods and tested on several environmental samples. The new method proved its superiority in terms of time requirement, labor need, material consumption, sample volume and simplicity. It eliminates the inconsistency present in other idiometric methods which is caused by the delay between the PS/I- reaction and I3- measurement. The obtained LDR extends from 0.075 to 300mmolL-1 with a LOD of 6.6 × 10-3mmol L-1 and a LOQ of 2.20 × 10-2mmolL-1. The method is successfully implemented in our laboratory to rapidly and automatically monitor the variation in the concentration of PS used in different projects, which facilitates the rapid determination of the reaction stoichiometric efficiency (RSE) of the oxidation reaction, a key factor toward the optimization of the mineralization process and its sustainability.

The fate of selected pharmaceuticals in solar stills: Transfer, thermal degradation or photolysis?

The increase in demand for, and disposal of, pharmaceuticals, positively correlated with the growing human population, has led to the emergence of contaminants with high environmental and health impacts. Several developing countries that endure problems related to water sufficiency and/or quality resort to the use solar stills as an affordable water treatment method. This research is aimed at investigating the fate of five chemically distinct pharmaceuticals that might pervade solar stills; ibuprofen (IBU), diclofenac (DCF), carbamazepine (CBZ), ampicillin (AMP) and naproxen (NPX). The experiments were conducted under three conditions. The first condition studied the combined effect of temperature and light in simulated field-test-scale solar stills. The effect of temperature as a sole variable was investigated in the second while the third condition studied the effect of light only via concentrated solar power (CSP). Results show that distillates from solar stills did not contain the parent compounds for four out of the five pharmaceuticals. IBU was the only pharmaceutical that showed a transfer via vapor into the distillate with the highest recorded transfer percentage of 2.1% at 50°C when subjected to temperature alone and 0.6% under the combined effect of temperature and light. In the case of NPX and DCF, the parent compounds did not undergo transfer into the distillate phase; however their degradation by-products did. In addition, the results also showed that in the case of NPX, IBU and CBZ both high temperatures and sunlight combined were required to attain noticeable degradation. CSP accelerated the degradation of DCF, NPX and IBU with a three-minutes-degradation percentage of 44%, 13% and 2% respectively.