Surfactant Chain Length’s Impact on Hexavalent Chromium Adsorption by Magnetite Nanoparticles

The effect of cationic surfactant chain length on chromium VI (Cr(VI)) adsorption behavior on Magnetic NanoParticles (MNPs) was examined in this work. To alter the surface of MNPs, we used a variety of alkyl trimethylammonium bromide surfactants, such as cetyltrimethylammonium bromide (C16TAB), tetradecyl trimethylammonium bromide (C14TAB), and decyl trimethylammonium bromide (C10TAB). Aqueous solutions containing known amounts of Cr(VI) were used in the adsorption studies. Fourier Transform InfraRed (FT-IR) spectrophotometry, transmission electron microscopy (TEM), and powder X-ray diffractometry (XRD) were used to analyze the Functionalized MNPs (CnTAB@MNPs). In order to evaluate the impacts of several parameters on chromium removal efficiency (RE), we conducted statistically planned batch experiments. These parameters included surfactant chain length, initial chromium concentration, solution pH, interaction time, adsorbent dose, and added salt. Our findings showed that the adsorption capacity of magnetic nanoparticles for Cr(VI) was considerably impacted by the chain length of the cationic surfactant. Compared to MNPs functionalized with shorter alkyl chains, those functionalized with longer alkyl chain surfactants showed better adsorption capabilities. Additionally, we found that the adsorption efficiency was influenced by a number of variables, including pH, the chemical reduction of Cr(VI) to Cr(III), and the interactions between the negatively charged Cr(VI) ions and the cationic surfactant via electrostatics. Using CnTAB@MNPs, Cr(VI) was effectively removed at low pH values; however, removal was negatively impacted by a rise in pH. After 7 minutes and 30 seconds of contact time, we reached an Cr VI, RE of 95.77% at pH = 4, nanoparticles dosage = 12 g/L, and initial [CrVI]= 98 mg/L.