Cyclophosphamide Neutralization in Wastewaters Using an Asymmetric Current Density Electrochemical Microreactor

HARALD BARZAN, ERIKA DIANA ARDELEAN, GABRIELA ALINA DUMITREL*, DANIEL HĂDĂRUGĂ, PETRU BÂRZAN, GABRIELA BÂRZAN, DAVID COMANICIU, VALENTIN ORDODI Babeș-Bolyai University, 7-9 Universității Str., 400084, Cluj-Napoca, Romania 2 Politehnica University of Timișoara, 2 Victoriei Sq., 300006, Timișoara, Romania 3 SC Natural Ingredients R&D SRL, 10/1Tabacari Str., 505200, Fagaraș, Romania 4 Lucian Blaga University Sibiu, 10 Victoriei Blvd., 550024, Sibiu, Romania


Fig. 1. Asymmetric current density electrochemical microreactor
The cyclophosphamide-containing sample is introduced in the microreactor through the bottom nozzle (figure 2. (2)) using a peristaltic pump controlled by the signal coming from the volume sensor (figure 2. (7)). When the reactor is full, the signal from the volume sensor stops the pump and starts the electrolysis reaction. The duration of the electrolysis reaction is 30 minutes with a constant current of 1A. After the reaction, the microreactor is drained through the bottom nozzle. The microreactor is fitted with a compressor which generates a flow of compressed air (500 mL/minute) through the reaction medium, pushing out the electrolysis gas product, which would otherwise have a corrosive effect on the reactor.

Synthetic cyclophosphamide-containing wastewater neutralization
Cyclophosphamide (C7H15Cl2N2O2P) is a chlormethine derivative and an alkylating antineoplasic agent used in the treatment of several oncological diseases: lymphoma, multiple myeloma, neuroblastoma, soft tissue sarcoma, breast and testicular tumors and some forms of leukemia are common examples. High doses of cyclophosphamide are administered in intermittent mono-chemotherapy: 40 mg/kg/day. Pharmacokinetics data suggests that 30% of administered cyclophosphamide is excreted in its non-metabolized form, via renal excretion, which gives the urine of the patients a high concentration of this cytostatic drug. Pharmacological data has showed that cyclophosphamide has leukemogenic and teratogenic effects in chronic exposure, even at low doses.
Cyclophosphamide is a white crystalline powder mildly soluble in water. For this study, a synthetic wastewater preparation was made by dissolving 100mg of cyclophosphamide in 100 ml 5% NaCl solution. The determination of cyclophosphamide concentration before and during the electrolysis reaction was made using an Agilent 1100 Series high-performance liquid chromatography (HPLC) instrument, fitted with an analytic-grade reverse-phase C18 column (Zorbax SB-C18). Mobile phase consisted of 20% acetonitrile and 80% phosphate buffer 0.1M with pH = 6 at 25 0 C. The detector is a UV-VIS spectrophotometer set at 200nm wavelength. The chromatogram acquisition duration was 23 minutes. In these conditions, the retention time of cyclophosphamide is 19.1 minutes [9,10].

Results and discussions
The experimental data shows that the electrochemical microreactor is suitable for cyclophosphamide electrodegradation within a reasonable time frame and with relatively low energy requirements. The putative mechanism for this electrodegradation cascade is presented in figure 3.

Fig. 3. Cyclophosphamide degradation via electrochemical oxidation
The synthetic wastewater sample containing 100mg/dL cyclophosphamide has undergone electro-degradation in the experimental microreactor for 30 minutes at 1A working current. The wastewater cyclophosphamide concentration was sampled during the electrochemical treatment and the samples were analyzed using the HPLC method, with results displayed in table 1.  In table 1 The coefficient of correlation value ( 2 = 0.8859) indicates that equation (1) reliably approximates the evolution of the cyclophosphamide concentration during electro-degradation [11].
The yield of the degradation (2) was calculated using the initial concentration ( ) of the synthetic wastewater before treatment and the final concentration ( ) at 10 minutes into the degradation treatment, right before the concentrations drops below the limit of detection: ℎ ℎ = 100 − * 100 = 100 − 0.03 = 99,7% (2)

Conclusions
The proposed asymmetric current density electrochemical microreactor is suitable for cyclophosphamidecontaminated wastewater treatment. Conceptually, this type of reactor has the advantage of facilitating the type of reactions we are interested inanodic electro-oxidation. The present paper justifies building the reactor at a larger scale to be used in cytostatic drug contaminated wastewater treatment.