Efficient Lead Removal from Aqueous Solution Using Chitosan-Vermiculite Composite: Equilibrium, Kinetic and Thermodynamic Studies

Abstract

In this study, a cost effective, naturally effective adsorbent, chitosan (Ch) - vermiculite (V) composite material for the efficient removal of lead ions from aqueous solution was synthesized. The Ch-V composite was characterized by FT-IR SEM-EDX and PZC analyzes. The adsorbent properties of Ch-V composite for Pb^2​​+ were evaluated in terms of pH, concentration, kinetic (time), thermodynamic (temperature) and recovery of adsorption. The experimental data obtained are derived from the relevant parameters applied to the Radushkevich isotherm models of Langmiur, Freundlich and Dubinin. The maximum adsorption capacity was found to be 0.154 mol kg^-1 and the K_L value was 3441 Lmol^-1. Freudlich model is a measure of adsorption capacity X_F 10.3 and β surface heterogeneity is 0.537. The results showed that the experimental data fit better with the Freundlich model. The adsorption energy of Dubin Radushkevich model was found to be 9.7 kJ mol^-1, which indicates that the adsorption process is chemical. Adsorption kinetics were found to adapt to the pseudo-second model. The olduğun ΔH0 value of adsorption was found to be 5.09 kjmol-1, indicating that the adsorption is endothermic. ΔS⁰ was found as 69.7 Jmol^-1K^-1 which indicates an increase in the randomness of the biosorbent/solution interface during the adsorption process. Gibbs free energy exchange for 298.15 ⁰C was found to be -15.7 kJ mol^-1, indicating that adsorption was spontaneous. The recovery studies showed that the Ch-V composite had good adsorption/desorption performance.

Keywords

• Chitosan,Vermiculite,Composite,Adsorption,Lead

Kitosan-Vermikülit Kompoziti Kullanılarak Sulu Çözeltiden Etkin Kurşun Giderimi: Denge, Kinetik ve Termodinamik Çalışmalar

Abstract

Bu çalışmada, sulu çözeltiden kurşun iyonlarının etkin giderimi için düşük maliyetli, doğal etkin bir adsorban, kitosan (Ch) – vermikülit (V) kompozit materyali sentezlenmiştir. Ch-V kompoziti FT-IR SEM-EDX ve PZC analizleri ile karakterize edilmiştir. Pb²⁺ için Ch-V kompozitinin adsorban özellikleri adsorpsiyonun pH, derişim, kinetik (zaman), termodinamik (sıcaklık) ve geri kazanım açısından değerlendirilmiştir. Elde edilen deneysel veriler Langmiur, Freundlich ve Dubinin Radushkevich izoterm modellerine uygulanmış ilgili parametreler türetilmiştir. Langmiur eiştliğinden maksimum adsorpsiyon kapasitesi 0.154 molkg^-1 ve K_L değeri ise 3441 Lmol^-1 olarak bulunmuştur. Freudlich modelinden adsorpsiyon kapasitesinin bir ölçüsü olan X_F 10.3 ve β yüzey heterojenliği ise 0.537 bulunmuştur. Sonuçlar deneysel verilerin Freundlich modeline daha iyi uyum sağladığını ortaya koymuştur. Dubinin Radushkevich modelinden adsorpsiyon enerjisi 9.7 kJ mol^-1 olarak bulunmuştur ki bu durum adsorpsiyon sürecinin kimyasal olduğunu ifade etmektedir. Adsorpsiyon kinetiğinin yalancı ikinci derece modele uyum sağladığı görülmüştür. Adsorpsiyonun termodinamik değerlendirilmesinden ΔH⁰ değeri 5.09 kjmol^-1 bulunmuştur ki bu durum adsorpsiyonun endotermik olduğunu işaret eder. ΔS⁰ ise 69.7 Jmol^-1K^-1 olarak bulunmuştur ki bu durum adsorpsiyon sürecinde biyosorbent/çözelti arayüzündeki rastgelelikte bir artma olduğunu gösterir. 298.15 ⁰C için Gibbs serbest enerji değişimi, -15.7 kJ mol^-1 olarak bulunmuştur ve bu durum adsorpsiyonun kendiliğinden olduğunu göstermiştir. Geri kazanım çalışmaları Ch-V kompozitinin iyi bir adsorpsiyon/desorpsiyon performansına sahip olduğunu göstermiştir.

Keywords

• Kitosan,vermikülit,kompozit,adsorpsiyon,kurşun

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