On the biosorption, by brown seaweed, Lobophora variegata, of Ni(II) from aqueous solutions: equilibrium and thermodynamic studies

Abstract

The biosorption equilibrium isotherms of Ni(II) onto marine brown algae Lobophora variegata, which was chemically-modified by CaCl(2) were studied and modeled. To predict the biosorption isotherms and to determine the characteristic parameters for process design, twenty-three one-, two-, three-, four- and five-parameter isotherm models were applied to experimental data. The interaction among biosorbed molecules is attractive and biosorption is carried out on energetically different sites and is an endothermic process. The five-parameter Fritz-Schluender model gives the most accurate fit with high regression coefficient, R (2) (0.9911-0.9975) and F-ratio (118.03-179.96), and low standard error, SE (0.0902-0.0.1556) and the residual or sum of square error, SSE (0.0012-0.1789) values to all experimental data in comparison to other models. The biosorption isotherm models fitted the experimental data in the order: Fritz-Schluender (five-parameter) > Freundlich (two-parameter) > Langmuir (two-parameter) > Khan (three-parameter) > Fritz-Schluender (four-parameter). The thermodynamic parameters such as DeltaG (0), DeltaH (0) and DeltaS (0) have been determined, which indicates the sorption of Ni(II) onto L. variegata was spontaneous and endothermic in nature.

Heavy Metal Adsorption ontoKappaphycussp. from Aqueous Solutions: The Use of Error Functions for Validation of Isotherm and Kinetics Models

“…In general, mechanistic or empirical equations are used to express heavy metal adsorption capacities of different types of biosorbents using batch or column method [ 18 ]. Available literature reports confirm that nearly two dozens of empirical models involving 2, 3, 4, or even 5 parameters have been used to fit batch equilibrium isotherm curves to biosorbents [ 18 , 19 ]. Besides, kinetic models have been described by several authors elsewhere [ 20 – 22 ].…”

Adsorption of Ni(II) ions from aqueous solution onto a fungusPleurotus ostreatus

“…Moreover, the decrease in negative DG values with increase in temperature shows that the uptake of Ni(II) by P. ostreatus is favored at lower temperature which is strongly supported by the negative DH value. Basha et al [29] reported similar results for Ni(II) adsorption by Variegata. Moreover, Ho and Ofomaja [24] also reported negative DH value while studying the biosorption of cadmium by coconut copra.…”

Is the Frumkin (Fowler–Guggenheim) adsorption isotherm a two- or three-parameter equation?

“…Some authors have made the incorrect claim that the Frumkin isotherm is only valid for θ < 0.6 [49,50]. The second misconception concerns the use of the Frumkin isotherm and the Fowler-Guggenheim isotherm to fit the same isotherm data [51][52][53][54][55][56][57]. As noted above, the Frumkin isotherm is mathematically analogous to the Fowler-Guggenheim isotherm.…”