Kinetic, sorption isotherms, pseudo-first-order model and pseudo-second-order model studies of Cu(II) and Pb(II) using defatted Moringa oleifera seed powder

Abstract

In the recent decades, there has been a concern on heavy metals in waste water and high cost of conventional methods of removing heavy metals, for this reason search on adsorbents of biological origin which is low cost and efficient is necessary. In this work defatted Moringa oleifera seed powder was studied as a potential alternative adsorbent for removal of Cu(II) and Pb(II) from aqueous solution. Physicochemical parameters such as pH, contact time, adsorption kinetics and initial ions concentration adsorption capacity using sorption models were evaluated. The results showed that the optimum pH for biosorption of Cu(II) was 6.5 while that of Pb(II) was 5.5. Contact time for Cu(II) was observed to occur after 30 min while that of Pb(II) occurred after 40 min. FTIR analysis revealed that defatted Moringa oleifera seed biomass had presence of amino, carboxyl, hydroxyl and carbonyl groups, these groups were responsible for biosorption of Cu(II) and Pb(II) from aqueous solution. Biosorption kinetic data fitted well with pseudo-second-order kinetic model (r2 ≤ 0.9997) giving equilibrium rate constant (k2) of 0.0350±0.0275 g mg−1 min−1 for Cu (II) loaded biomass and 0.0206±0.0114 g mg−1 min−1 for Pb (II) loaded biomass; the biosorption isotherms for the biosorbent fitted well with Freundlich isotherm model than with Langmuir isotherm model. However, the separation factor RL of Langmuir model was between 0 and 1 indicating favourable sorption process and the low value of mean sorption energy of 9.19×10-2 kJ from D-R model showed that the forces of attraction involved were Van der Waal forces indicating the process of adsorption was physical adsorption. In conclusion, the study revealed that defatted Moringa oleifera seed is an efficient biosorbent for removal of Cu(II) and Pb(II) from aqueous solution.

Dynamic Langmuir Model: A Simpler Approach to Modeling Capacitive Deionization

“…One simple model that has been used successfully to describe ion-adsorption characteristics in CDI − is the Langmuir isotherm, which describes how the saturated state of the electrode varies with the ion concentration of the input water. The Langmuir isotherm assumes that adsorption and desorption are simultaneous processes where the adsorption rate is limited by the number of free adsorption sites .…”

Kinetics and equilibriums adsorption of Cu (II) ion by chitosan and cross-linked chitosan-bentonite

“…On the other hand, the correlation coefficients of CTS-BTN for the secondorder kinetic model obtained are greater than the firstorder kinetic model, which R 2 for the second-order is 0.995 and the first-order is 0.810. These indicate that the sorption system is a second-order model and not a first-order model, based on the assumption that the sorption may be the rate-limiting step (Aksu, 2001;Robati, 2013;Kowanga, 2016).…”

“…The adsorption capacity of chitosan and efficiency of Cu(II) removal were determined using the following equations (Kowanga et al, 2016):…”

Removal of heavy metals from aqueous media by sunflower husk: A comparative study of biosorption efficiency by using ICP-OES and LIBS

“…where qe is the metal uptake at equilibrium, KF is the measure of the sorption capacity, 1/n is the sorption intensity, and ce is the final ion concentration in the solution. 23 Calibration set preparation for LIBS analysis In order to prepare a calibration, set for the LIBS analysis, a previously developed method for the matrix-matched standards was applied. 24 A 2 g of biosorbent were mixed with appropriate amounts of multielement standard.…”

“…After 5 minutes, these elements are accumulated in the large available surface binding sites making further adsorption to be slowed down. 23 Competition of these elements has also been investigated. Several multi-element models were evaluated using their removal efficiency: Cu-Ni (94.4 %, 77.…”