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Adsorption behavior of Pb(II) onto xanthated rubber (Hevea brasiliensis) leaf powder

100%
Khalir W., Hanafiah M., So'ad S., Ngah W.
Polish Journal of Chemical Technology
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2011
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vol. 13
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issue 4
84-88
EN
A plant waste, rubber (Hevea brasiliensis) leaf powder was modified with carbon disulfide (xanthation) for the purpose of introducing sulfur groups, and the adsorbent performance in removing Pb(II) ion was evaluated. Pb(II) adsorption was confirmed by spectroscopic analysis, which involved Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The amount of Pb(II) adsorbed increased with increasing pH, contact time and concentration but slightly decreased with increasing ionic strength. Adsorption equilibrium was achieved in less than 60 min and followed the pseudo-second order model. The isotherm data indicated that Pb(II) adsorption on xanthated rubber leaf (XRL) fitted well with Langmuir isotherm model. The maximum adsorption capacity computed from the Langmuir isotherm model was 166.7 mg/g. Pb(II) adsorption occurred via ion-exchange and complexation mechanisms.
2
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Equilibrium isotherm analysis of the sorption of congo red by palm kernel coat

86%
Oladoja N., Ololade I., Idiaghe J., Egbon E.
Open Chemistry
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2009
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vol. 7
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issue 4
760-768
EN
The ability of Palm Kernel Coat (PKC), a waste agricultural product, in the abstraction of Congo Red (CR), an anionic dye, from aqueous solution was studied. The effects of sorbent dose and temperature were studied using batch sorption system. Isotherm experiments were conducted and the data obtained were fitted with different equilibrium isotherm equations namely, Langmuir, Freundlich, Dubinin-Radushkevich (D-R), Temkin, Harkins-Jura and Halsey isotherm equations. The Langmuir isotherm equation gave the best description of the sorption process and the maximum saturated monolayer sorption capacity of the PKC for CR was 79.37 mg g−1. Harkins-Jura isotherm equation gave the poorest description of the sorption process. The linear form of the Langmuir equation was used to analyze the data obtained when the sorbent dosage was optimized by method of continuous variation. The results obtained showed that the equilibrium monolayer sorption capacity, qm, of the PKC for CR decreased (79.37–17.07 mg g−1) with an increase in sorbent dosage. The relationship between the dimensionless parameter, KR, and initial concentration, Co, showed that the sorption of CR was favored at higher initial dye concentration and PKC dosages than the lower ones. The thermodynamic parameters, such as change in the free energy, the enthalpy and the entropy, were also evaluated. The thermodynamic analysis showed that the sorption is spontaneous and exothermic. [...]
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Batch adsorption of malachite green dye from aqueous solution using sawdust of Swietenia macrophylla (mahogany wood)

86%
Opia C. F., Obinna N. V., Chizoruo I. F., Obinna I. B.
World News of Natural Sciences
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2023
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vol. 50
222-246
EN
Sawdust of Swietenia macrophylla waste was used as a bio-sorbent for the removal malachite green from aqueous solutions in this study. Various parameters’ effect such as contact time, pH, initial dye concentration, temperature and adsorbent dosage were studied on the bio-sorbent. Spectrophotometric technique was implemented for the measurement of dye concentration before and after adsorption. The study indicated that the quantity of dye adsorbed increased steadily with increase in the dye’s initial concentration and contact time because as the concentration increases the dye molecules available for adsorption also increases. There was a sharp rise in the quantity of dye adsorbed as the pH increases from pH 2 to pH 7, equilibrium was obtained at pH 10 after which the quantity of dye adsorbed decreased with an increased to pH 12. As the temperature increases the quantity of dye adsorbed decreased, this can be attributed to an increase in solubility as the temperature increases. The experimental data were fitted to the Langmuir and Freundlich adsorption isotherms with Langmuir isotherm showing a better fit than Freundlich isotherm model, this shows that the adsorption follows a homogenous coverage signifying saturated monolayer coverage of the solute molecules on the adsorbent surface. The adsorption kinetics data were fitted to pseudo-first and pseudo-second order kinetic model with pseudo-second order kinetic model showing a better fit than pseudo-first order kinetic model, indicating that more than one process affects the adsorption of malachite green dye onto Swietenia macrophylla. In terms of thermodynamic parameters, negative values were obtained for Gibbs free energy ∆G o, indicating a spontaneous adsorption process; also the enthalpy change ∆H° was negative signifying the adsorption is exothermic in nature. Similarly, entropy ∆S° values were negative indicating that the degree of disorderliness of malachite green reduced as it got adsorbed onto the surface of the adsorbent.
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