Optimization of lead adsorption of mordenite by response surface methodology: characterization and modification

Havva Turkyilmaz,Sibel Yigitarslan Yildiz,Tolga Kartal

doi:10.1186/2052-336x-12-5

Havva Turkyilmaz, Sibel Yigitarslan Yildiz + Show 1 more

Open Access

https://doi.org/10.1186/2052-336x-12-5

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Abstract

BackgroundIn order to remove heavy metals, water treatment by adsorption of zeolite is gaining momentum due to low cost and good performance. In this research, the natural mordenite was used as an adsorbent to remove lead ions in an aqueous solution.MethodsThe effects of adsorption temperature, time and initial concentration of lead on the adsorption yield were investigated. Response surface methodology based on Box-Behnken design was applied for optimization. Adsorption data were analyzed by isotherm models. The process was investigated by batch experiments; kinetic and thermodynamic studies were carried out. Adsorption yields of natural and hexadecyltrimethylammonium-bromide-modified mordenite were compared.ResultsThe optimum conditions of maximum adsorption (nearly 84 percent) were found as follows: adsorption time of 85-90 min, adsorption temperature of 50°C, and initial lead concentration of 10 mg/L. At the same optimum conditions, modification of mordenite produced 97 percent adsorption yield. The most appropriate isotherm for the process was the Freundlich. Adsorption rate was found as 4.4. Thermodynamic calculations showed that the adsorption was a spontaneous and an exothermic process.ConclusionsQuadratic model and reduced cubic model were developed to correlate the variables with the adsorption yield of mordenite. From the analysis of variance, the most influential factor was identified as initial lead concentration. At the optimum conditions modification increased the adsorption yield up to nearly 100 percent. Mordenite was found an applicable adsorbent for lead ions especially in dilute solutions and may also be applicable in more concentrated ones with lower yields.

Highlights

In order to remove heavy metals, water treatment by adsorption of zeolite is gaining momentum due to low cost and good performance
Quadratic model and reduced cubic model were developed to correlate the variables to the response
A Box-Behnken Design was conducted to study the effects of three adsorption variables, namely adsorption time, temperature and initial lead ion concentration on the adsorption yield of lead

Summary

Introduction

In order to remove heavy metals, water treatment by adsorption of zeolite is gaining momentum due to low cost and good performance. Heavy metals are defined as those having higher density than 5000 g/L [1] When their concentrations reach a certain level, they cause serious damage to the environment, animals and public health. None of the studies investigated the effect of modification of mordenite on adsorption yield. Studies have shown that lead removal by mordenite is strongly dependent upon the initial concentration of lead and adsorption conditions. No study has been found in the literature for optimization of adsorption of lead ions by mordenite, neither modified nor unmodified. The objective of the present research was to optimize the adsorption conditions of lead ions by mordenite. The effects of variables including initial lead concentration, adsorption time and temperature on adsorption yield were investigated by three-variable-three-level Box-Behnken Design (BBD).

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