Many studies have been conducted on the mixed surfactants systems concerning their properties, adsorption and synergism. To date, the aggregation behavior of mixed surfactants in bulk solution and at interface has been investigated to enhance the performance and maintaining the stability. 9 Indeed, ionic-nonionic systems have been considered to offer more benefits over ionic–ionic or nonionic–nonionic systems. 8 However, the mixed surfactants systems have been reported for more advantages (synergism) than a single surfactant system. loaded cationic surfactants on AC for perchlorate adsorption. 5 Furthermore, AC-cetyltrimethylammonium chloride was applied for bromated removal 6 and cetylpyridinium chloride, cetyltrimethylammonium bromide, cetyltrimethylammonium chloride were also employed in AC modification. ![]() 4 Moreover, AC modified with sodium diethyl dithiocarbamate was studied for the removal of Zn, Cu, Cr whereas tetrabutyl ammonium iodide employed for the removal of CN − from wastewater. 3 AC modified with sodium dodecylsulphate and sodium diethyl dithiocarbamate were used for heavy metals removal from industrial phosphoric acid. Choi and coworkers investigated cationic surfactant-modified AC for Cr( VI) removal from aqueous solution. Both cationic and anionic surfactants have been employed in the functionalization of AC. Surfactants have been widely reported to induce different properties on the surface of AC, due to their aggregation behavior at the interface. This approach makes AC more effective, hydrophilic and acidic or basic due to the nature of charges. In order to improve the surface activity of AC for specific applications, imparting the cationic or anionic charges on the surface is a prerequisite, especially in inverted CDI. AC is widely used as a CDI electrode material and AC modification has been a research hotspot for the sake of enhanced surface chemistry since the charges are indispensable in the process. 2 Capacitive deionization (CDI) has become a promising technology that relies on electrosorption, for the removal of cationic and anionic pollutants from brackish water and seawater by means of the capacitive effect. However, it is basically an inert porous material which binds pollutants mostly via van der Waals or London dispersion forces, thus it is unable to bind certain chemicals including metals and most inorganic materials. 1 Noteworthy, AC has been a workhorse adsorbent for the removal of a wide variety of pollutants from wastewater. Introduction Activated carbon (AC) has been recognized as a good candidate in adsorption process due to having a high specific surface. This study demonstrates the beneficial effects of mixed surfactants on AC electrode properties and discloses the impact on electrochemical performance. The hypothetical synergistic mechanism of surfactants adsorption on the surface of AC was depicted as hydrophobic interaction and steric stabilization being the main keys for the synergy between cationic and nonionic surfactants. ![]() Moreover, the stability testing reveals a strong attachment of HDTMA in AC-T80-HDTMA than AC-HDTMA with the loss of 0.32% and 1.32%, respectively. In 5 g L −1 of NaCl, AC-T80-HDTMA (0.01 : 0.01 mM) exhibits the specific capacitance of 209.79 F g −1, at 0.8 V whereas AC-HDTMA (0.01 mM) and AC exhibited 186.5 F g −1, 178.9 F g −1, respectively. Electrochemical characterization revealed a higher specific capacitance and a decaying resistance of specific capacitance in AC-T80-HDTMA than AC-HDTMA at high concentration. Tween 80 displayed a significant size control dependence on AC particles. Isoelectric point and point of zero charge implicate heterogeneous distribution of charges and the extent of surfactants treatment. The zeta potential results unveiled the positive charge density enhancement in the mixed surfactants system. AC gained a good wettability originated from the surfactants, especially in the binary mixture (T80-HDTMA). ![]() Both field emission scanning electron micrographs and FTIR spectra indicated a successful adsorption of loaded surfactants. The synergistic effects of the mixed surfactants on AC surface activity in the light of interface behaviors were studied. Hexadecyltrimethylammonium bromide (HDTMA) and Tween 80 were employed for enhancing the surface activity of AC via synergism. Activated carbon (AC) modification has been intensively studied in order to design carbon electrodes with enhanced electrochemical performance.
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