Adsorption of cadmium onto modified nanosized magnetite: kinetic modeling, isotherm studies, and process optimization

Abstract

In this study, adsorptive removal of cadmium(II) from aqueous solutions using sodium dodecyl sulfate-modified magnetite nanoparticles was modeled. To this aim, central composite design as one of the most favorable designs in response surface methodology (RSM) was employed to optimize the removal of Cd(II) from solution under different variables such as adsorbent dosage (0.1-0.55 g), initial ion concentration (6-90 mg/L), and reaction time (5-30 min). Furthermore, the experimental data of Cd(II) adsorption were tested with various kinetic and isotherm models at various initial ion concentrations of 10-50 mg/L and adsorbent dosages of 0.1-0.25 g. The adsorption process followed the intra-particle diffusion model (R 2 > 0.94) very well. The equilibrium adsorption data were analyzed using various isotherm models. The results showed that Freundlich isotherm, with a relatively high coefficient of determination (R 2 > 0.96), fits well with the experimental results of Cd(II) adsorption. Ultimately, the optimum Cd(II) ions removal of 91.07% was obtained at the reaction time of 30 min, the adsorbent dosage of 0.35 g, and the initial ion concentration of 30 mg/L.

Environmental implications and applications of engineered nanoscale magnetite and its hybrid nanocomposites: A review of recent literature

“…Poly(1-vinylimidazole)-grafted Fe3O4@SiO2 magnetic NPs remove both free Cd 2+ and nitrilotriacetic acid (NTA) complexed Cd 2+ at pH 5-11, and the adsorbent could be regenerated with 10 mM HCl in 10 min, and the removal of both types of Cd 2+ maintains above 95% in five consecutive adsorption/regeneration cycles [344]. Sodium dodecyl sulfate-modified MNPs also show good Cd 2+ removal [345].…”

Catalytic Activity of Iron Doped Hexagonal Mesoporous Silica (Fe-HMS) for Degradation of Reactive Green-19 Dye in Water

“…Both samples show typical type-IV isotherm in Figure 2b, mainly due to the capillary condensation and desorption of nitrogen. According to IUPAC classification [19][20][21][22][23][24][25][26], this type of hysteresis with loop and the shift of sharp inflection of P/P 0 are typical for 2D-hexagonal mesoporous material.…”

“…Iron nitrate (Fe(NO) 3 .9H 2 O) and tetraethyl orthosilicate (TEOS) were used as the iron precursor and silicon, respectively. Meanwhile, the non-ionic amphiphilic triblock copolymer PluronicP 123 , (EO) 20 (PO) 70 (EO) 20 acted as the structuredirecting template and the hydrochloric acid solution was used as the acidic medium for the synthesis.…”

“…The specific surface area and pore size distribution were calculated by using the Brunauer-Emmett-Teller Method (BET) and Barrett-Joyner-Halenda Method (BJH) respectively; in which adsorption branch of the isotherms is in the BJH method. The pore volume was then determined from the plotted graph of nitrogenadsorbed volume against relative pressure [20,21].…”

“…Mesoporous silica in the form of two-dimensional hexagonal structure is formed from the arrangement of silica and the uniform mesopores with the presence of triblock copolymer PluronicP 123 , (EO) 20 (PO) 70 (EO) 20 as the structure-directing template [13]. The template is later removed by calcination process to create a material porous structure.…”