Removal of cadmium ion using micellar-enhanced ultrafiltration (MEUF) and activated carbon fiber (ACF) hybrid processes: adsorption isotherm study for micelle onto ACF

Abstract

A B S T R A C TMicellar-enhanced ultrafiltration (MEUF) was applied to remove cadmium ion from wastewater using sodium dodecyl sulfate (SDS) as a micelle in this study. Investigations were carried out on operational parameters such as initial permeate flux, retentate pressure, initial cadmium concentration, pH solution, molecular weight cut-off (MWCO), and molar ratio of cadmium to SDS. Removal efficiency of cadmium increased with increase in retentate pressure, pH solution, and molar ratio of cadmium to SDS and decreased with increase in initial permeate flux. Higher removal efficiency of cadmium was achieved using lower MWCO. In optimized experimental condition, cadmium removal efficiency reached 75% within an hour. With MEUF-ACF hybrid process, removal efficiencies of cadmium and SDS were found to be over 99 and 90%, respectively. Freundlich isotherm equation fitted better with experimental results on adsorption of SDS by ACF than Langmuir isotherm equation. Overall SDS removal efficiency of ACF unit in series was 90%.

Experimental and neural network modeling of micellar enhanced ultrafiltration for arsenic removal from aqueous solution

“…3(c). Arsenic removal decreases with increasing As concentration of feed solution [11,30,31] and similar trend for other heavy metals including cadmium, chromium and nickel was presented in the literature [28]. The concentration of arsenic in product water was increased proportionally to As concentration of feed solution because lesser micelle surface area was available to adsorb higher metal concentrations electrostatically [26].…”

“…3 (a) was 92.87, 96.13, 97.01 and 97.20% at pressure of 1.5, 1.8, 2.2 and 2.5 bar, respectively, at molar ratio of CPC to As 5:1. The similar results regarding effect of pressure were presented for other heavy metals including, chromate, nickel and cadmium removal from aqueous solution [26][27][28][29]. It is evident that high pressure causes to increase the gel layer thickness on membrane surface and eventually removal of metal micelle complex was higher.…”

“…This improvement occurred due to more micelles formation at higher CPC concentration, which increases the available micelle surface area for attracting arsenic ions electrostatically. Previously done studies supported these results [26][27][28][29][30]. The optimum molar ratio was noted as 5:1 that provides 96.13% average removal of arsenic at 1.8 bar pressure without any pH adjustment.…”

“…It is evident that high pressure causes to increase the gel layer thickness on membrane surface and eventually removal of metal micelle complex was higher. On the contrary, concentration polarization happens because of high pressure that results in reduction of permeate flux [26][27][28][29]. Experimentally observed optimum pressure was 1.8 bar for As removal from aqueous solution at molar ratio of 5:1 without any adjustment of pH.…”

“…The experimental studies were tested for As removal from aqueous solution as presented in Table 2, these values of pressure were selected on the basis of previous studies [6,[26][27][28][29]. Average As removal percentage as shown in Fig.…”