Removal of Cr (VI) from aqueous solutions by the nonliving biomass of Alligator weed: kinetics and equilibrium

Abstract

The removal of Cr (VI) from aqueous solutions using Alligator weed, a freshwater macrophyte, was investigated in batch studies. Various factors including solution pH, Cr (VI) concentrations, agitation time, and temperature were taken into account and promising results obtained. An initial solution pH of 1.0 was most favorable for Cr (VI) removal. The kinetic data were analyzed using several models, including the pseudo-second-order equation, external diffusion model, and intraparticle diffusion model. The comparison gave insight about the mechanism of adsorption and potential rate controlling step. The results suggested that the Cr (VI) adsorption at all temperatures was best represented by the pseudo-second-order equation. The external film diffusion played an important role in the adsorption mechanism. The Freundlich, Langmuir and Langmuir-Freundlich isotherms for the present system were analyzed. The best interpretation for the equilibrium data at different temperatures was given by the Langmuir-Freundlich isotherm. The Alligator weed could serve as low-cost adsorbent to remove Cr (VI) from aqueous solutions.

Adsorption isotherms and Sips models of nitrogen, methane, ethane, and propane on commercial activated carbons and polyvinylidene chloride

“…The experimental results are fitted to the Sips model (Sips 1948) which is a combined form of the Langmuir and Freundlich models and is suitable for describing heterogeneous adsorption systems at a wide range of pressures (Foo and Hameed 2010;Casas et al 2012). In the current research the Sips parameters are derived by linearizing the experimental data, as was suggested by Wang et al (2008).…”

Adsorption du Cr (VI) sur la lignine activée

“…Cette adsorption, qui dépend du pH, est spontanée et exothermique. Les données ELISEO, 2008BARAL et al, 2008ABUL-HOSSAIN et al, 2005WANG et al, 2008 Notre étude SHARMA et FORSTER, 1994YOUNG et al, 2006 Tableau 6. Comparaison de la capacité maximale d'adsorption (q max ) du Cr (VI) sur différents adsorbants.…”

Adsorption Studies on Rhodamine-B Removal from Aqueous Solution Using Acid Activated Strychnos Nux-Vomica Leaf Powder

“…Pseudo-first-order and pseudo-second-order equations can be used assuming that the measured concentrations are equal to surface concentrations 13 . The pseudo-first-order rate lagergren model is 14 : dq = k 1 , ads(q e -q) dt Where, q (mg/g) is the amount of adsorbed heavy metals on the adsorbent at time t and k 1 , ads (min -1 ) is the rate constant of first-order adsorption 15 [17][18][19][20][21][22][23][24][25][26] q e the equilibrium sorption uptake, is extrapolated from the experimental data at time t = infinity. A straight line of log(q e -q) versus t suggests the applicability of this kinetic model.…”

“…The adsorption isotherm was also fitted to Langmuir model 22 . The Langmuir equation which is valid for monolayer adsorption on to a surface is given below.…”

“…Chem Sci Trans., 2018, 7(1), [17][18][19][20][21][22][23][24][25][26] Where, R is the universal gas constant (8.314 JK -1 mol -1 ), T is the absolute temperature (Kelvin) and K represents the equilibrium adsorption constants of the isotherm fits (K L , Langmuir equilibrium constant and K f , Freundlich equilibrium constant, which must be converted to SI units, by using the molecular mass of the RB dye) obtained from the isotherm plots. ∆H o and ∆S o values can be calculated from the slope and intercept of the linear plot of ln(K) versus 1/T.…”