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Abstract
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The removal of nitrate concentrations above international drinking water
standards is a prominent task of governments. In this regard, various
technologies such as reverse osmosis, biological denitrification, electrodialysis,
and capacitive deionization (CDI) as an electrochemical approach have been
used for nitrate removal from water. In the present research study, a novel
composite electrode named E2 was synthesized and used to improve the
efficiency of the membrane capacitive deionization (MCDI) process for
increasing the electrosorption capacity of nitrate from water. E1 as a based
electrode composed of activated carbon (AC), PVDF, and E2 as an optimal
electrode containing (AC), PVDF, ZrO2, and PANi -ES were utilized. The
morphology and structure of the composite electrode were determined using
field emission scanning electron microscopy (FESEM), Brunauer–Emmett–Teller
(BET), Fourier-transform infrared spectroscopy (TEM), X-ray diffraction (XRD),
and energy-dispersive X-ray spectroscopy (EDAX) techniques. Also, the cyclic
voltammetry (CV) and electrochemical impedance spectroscopy (EIS) methods
were applied to investigate the electrochemical behavior of the electrodes. In
the MCDI process with the presence of the E2 electrode, the amounts of
separated nitrate ion and its adsorption efficiency were 7.51 mg/g and 81.6%,
respectively; this demonstrated that the capacity of the adsorbed nitrate ion
by the MCDI process was 30.34% higher than the CDI process. On the other
hand, the E2 electrode, compared to the E1 electrode, ameliorated the
performance by almost 50% of the amount of adsorbed nitrate ion and also
ion adsorption efficiency during the CDI and MCDI processes.
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