Folasegun A. Dawodu

Equilibrium, kinetic and sorber design studies on the adsorption of Aniline blue dye by sodium tetraborate-modified Kaolinite clay adsorbent

Raw Kaolinite clay obtained Ubulu-Ukwu, Delta State of Nigeria and its sodium tetraborate (NTB)-modified analogue was used to adsorb Aniline blue dye. Fourier transformed infrared spectra of NTB-modified Kaolinite suggests that modification was effective on the surface of the Kaolinite clay with the strong presence of inner -OH functional group. The modification of Kaolinite clay raised its adsorption capacity from 1666 to 2000 mg/kg. Modeling adsorption data obtained from both unmodified and NTB-modified Kaolinite clay reveals that the adsorption of Aniline blue dye on unmodified Kaolinite clay is on heterogeneous adsorption sites because it followed strongly the Freundlich isotherm equation model while adsorption data from NTB-modified Kaolinite clay followed strongly the Langmuir isotherm equation model which suggest that Aniline blue dye was adsorb homogeneous adsorption sites on the NTB-modified adsorbent surface. There was an observed increase in the amount of Aniline blue adsorbed as initial dye concentration was increased from 10 to 30 mg/L. It was observed that kinetic data obtained generally gave better robust fit to the second-order kinetic model (SOM). The initial sorption rate was found to increased with increasing initial dye concentration (from 10 to 20 mg/L) for data obtained from 909 to 1111 mg kg(-1)min(-1) for unmodified and 3325-5000 mg kg(-1) min(-1) for NTB-modified adsorbents. Thereafter there was a decrease in initial sorption rate with further increase in dye concentration. The linearity of the plots of the pseudo-second-order model with very high-correlation coefficients indicates that chemisorption is involved in the adsorption process. From the design of a single-batch adsorber it is predicted that the NTB-modified Kaolinite clay adsorbent will require 50% less of the adsorbent to treat certain volumes of wastewater containing 30 mg/L of Aniline blue dye when it is compared with the unmodified adsorbent. This will be cost effective in the use of NTB-modified adsorbent for the adsorption of Aniline blue dye from water and wastewater.

Efficient abstraction of nickel(II) and manganese(II) ions from solution onto an alkaline-modified montmorillonite

Abstract We tested alkaline-activated montmorillonite as a low-cost adsorbent for simultaneous removal of Ni(II) and Mn(II) ions from solution. The experiment was performed by batch adsorption to evaluate the effects of pH, initial metal ion concentration, particle size, adsorbent dose, contact time and temperature on adsorption. Alkaline modification of montmorillonite increased the specific surface area from 23.2 to 30.7 m2/g and the cation exchange capacity from 90.78 to 94.32 mEq/100 g. The adsorption capacity of the montmorillonite for Ni(II) and Mn(II) ions increased with alkaline modification. The adsorbent was characterized by Fourier transform infrared, X-ray diffraction and scanning electron microscopy. When four isotherms, the Langmuir, Freundlich, Temkin and Dubinin–Radushkevich models, were applied to the experimental data, the best fit was obtained with the Freundlich model. The kinetic data were analysed with pseudo-first order, pseudo-second order, Elovich and intraparticle diffusion rate equations; greater conformity was found with the Elovich equation. Thermodynamic studies revealed a spontaneous, endothermic physical adsorption process.

Physicochemical analysis of automobile effluent before and after treatment with an alkaline-activated montmorillonite

Abstract Effluents obtained from six industries were analysed for physicochemical properties. An alkaline-modified montmorillonite was used to remove heavy metals from automobile effluent. The effects of effluent pH, adsorbent dose, adsorbent particle size and contact time on adsorption were determined. Langmuir, Freundlich, Temkin and Dubinin–Radushkevich models were used to analyse equilibrium isotherms. Kinetics was analysed by the pseudo-first-order, pseudo-second-order, intra-particle diffusion and film diffusion rate equations. Thermodynamic parameters including changes in free energy, entropy and enthalpy were calculated. The alkaline-modified montmorillonite was effective for treatment of effluent contaminated with heavy metals.

Montmorillonite-rice husk composite for heavy metal sequestration from binary aqua media: a novel adsorbent

This work describes the sorption of metal ions using a montmorillonite-rice husk composite as a novel adsorbent. The adsorption capacity of the new adsorbent was compared with the unmodified, alkaline and acid treated montmorillonite. Scanning electron microscopy showed an increase in the porous nature of the adsorbent modified with rice husk. The Fourier transform infrared spectra showed an alteration of the structure of the montmorillonite-rice husk adsorbent. Brunauer–Emmett–Teller (BET) analysis showed a sharp increase in the surface area of the montmorillonite from 55.76 to 118.01 m2/g and the total pore volume from 0.0688 to 0.114 cm3/g. It showed a decrease in the average pore diameter from 49.35 to 38.64 Å and enhancement of the cation exchange capacity from 90.78 to 96.17 meq/100 g for the new adsorbent. The change in solution pH, initial metal concentration, adsorbent dosage, contact time and solution temperature affected the adsorption process. The Freundlich model gave a better fit than the Langmuir model in the equilibrium isotherm analysis for the acid, alkaline and rice husk treated adsorbents, while the latter was suitable for the unmodified form. Interestingly, the rice husk modified adsorbent recorded a higher adsorption capacity than the unmodified, acid and alkaline derivatives. Both the pseudo-first order and pseudo-second order kinetic models were applicable for the sorption on all the adsorbents and a thermodynamic study revealed a feasible, spontaneous and endothermic adsorption on the novel adsorbent.

Treatment of an automobile effluent from heavy metals contamination by an eco-friendly montmorillonite.

Graphical abstract (A) Infrared spectra, (B) X-ray diffraction, (C) initial pH and (D) particle size.