Gemini Surfactant-Modified Activated Carbon for Remediation of Hexavalent Chromium from Water

Abstract

Gemini surfactants, with double hydrophilic and hydrophobic groups, offer potentially orders of magnitude greater surface activity compared to similar single unit molecules. A cationic Gemini surfactant (Propyl didodecyldimethylammonium Bromide, PDDDAB) and a conventional cationic surfactant (Dodecyltrimethylammonium Bromide, DTAB) were used to pre-treat and generate activated carbon. The removal efficiency of the surfactant-modified activated carbon through adsorption of chromium(VI) was investigated under controlled laboratory conditions. Fourier-transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) were used to investigate the surface changes of surfactant-modified activated carbon. The effect of important parameters such as adsorbent dosage, pH, ionic strength and contact time were also investigated. The chromium(VI) was adsorbed more significantly on the Gemini surfactant-modified activated carbon than on the conventional surfactant-modified activated carbon. The correlation coefficients show the data best fit the Freundlich model, which confirms the monolayer adsorption of chromium(VI) onto Gemini surfactant-modified activated carbon. From this assessment, the surfactant-modified (especially Gemini surfactant-modified) activated carbon in this study showed promise for practical applications to treat water pollution.

Adsorption of Methylene Blue in Water onto Activated Carbon by Surfactant Modification

“…In wastewater treatment, activated carbon modified by surfactant is used as an adsorbent to remove various pollutants, including organic pollutants [26,27], reactive dyes [15,21,28,29], and heavy metals [30,31]. Surfactants are classified into anionic, cationic, non-ionic, and amphoteric ions according to the type and performance of the hydrophilic group [22].…”

Sepiolite-Based Adsorbents for the Removal of Potentially Toxic Elements from Water: A Strategic Review for the Case of Environmental Contamination in Hunan, China

“…Whilst adsorption capacities for, for example, sepiolite may be an order of magnitude lower than synthetic systems [ 18 ] (there are many examples of studies of these materials for the treatment of metals by adsorption that show useful level of performance [ 19 , 20 ]. The focus for the future development of adsorption based systems should be on identifying adsorbent materials that are cheap and effective adsorbents in the context of the treatment scenarios (for example, at point source or to deal with diffuse pollution), to improve the effectiveness of these treatments and to ensure that no secondary pollution is produced [ 21 , 22 , 23 , 24 ]. Secondary tasks include the need for good solid/water separation and the regeneration of adsorbent.…”

Synthesis of Surfactant-Modified Activated Carbon (SMAC) Above Critical Micelle Concentration as Cr(VI) Ion Adsorbent

“…The zeta potential analysis (Table 3) proved that SMAC was more stable than activated carbon. This suggested that SMAC adsorption would be persistent and hard to remove, supported by the Cr(VI) adsorption mechanism involving electrostatic interactions [18].…”

“…NH4 + adsorption efficiency Figures 4 and 5 indicate only a 10% difference in Cr(VI) and NH4+ cation adsorption between SMAC-T and SMAC, implying that SMAC-T's positive and negative sites were nearly identical. Adsorption of NH4 + ions and Cr(VI) ions through the process of electrostatic interaction[18], Cr(VI) ions would be adsorbed on a positive charge and NH4 + on a negative charge.…”