The adsorption of fluoride from aqueous solutions by Fe, Mn, and Fe/Mn modified natural clinoptilolite and optimization using response surface methodology

Abstract

Natural clinoptilolite was modified using iron, manganese, or iron-manganese for adsorption of fluoride from aqueous solutions. Natural and modified clinoptilolite samples were characterized by X-ray fluorescence spectrometry, scanning electron microscope, X-ray diffraction, and Brunauer-Emmett-Teller. For all modified clinoptilolite samples, the time required to reach equilibrium was determined as 5 hr. The effects of adsorbent dose, pH, and initial fluoride concentration for fluoride adsorption were determined using the Box-Behnken Design. Maximum fluoride removal efficiency was 80.23% at the solution pH of 11, iron-modified clinoptilolite amount of 1.08 g/50 ml and at the initial fluoride concentration of 2 mg/L. Fluoride adsorption on iron-modified clinoptilolite showed good compatibility with the Freundlich isotherm and the pseudo-second-order kinetic model. The adsorption capacity of iron-modified clinoptilolite was found to be 1.72 mg/g for the initial fluoride concentration of 50 mg/L. This study has shown that BBD is an effective and dependable method in determining the optimum conditions for fluoride adsorption. © 2020 Water Environment Federation • Practitioner points • Response surface methodology is effective in determining the optimum conditions for fluoride adsorption using modified clinoptilolite. • Fluoride adsorption on iron-modified clinoptilolite is well described Freundlich isotherm and follows pseudo-second-order kinetic model. • Fluoride removal percentage not only depends on the adsorbent dose, but also depends on the initial fluoride concentrations. • Regeneration process using acid solution is not very effective for desorption of ironmodified zeolite. • The natural clinoptilolite is an effective and economical adsorbent for adsorption of fluoride.

Editorial: April 2021

“…April's issue of Water Environment Research presents new research on topics important to water quality engineers and scientists: biodegradation of hazardous organic compounds (Lee & Ulrich, 2020) and microconstituents (Rao et al, 2020), removal of fluoride (Bilici Baskan & Biyikli, 2020), membrane fouling (Liu et al, 2020), and electrochemical disinfection (Qing et al, 2020), among others. The issue also includes original research on nutrient removal from around the world: the microbial communities involved in anammox from Las Barrillas estuary, Mexico (Ronzón Bravo et al, 2020), impact of COD/TN on anammox for influents simulating those from Vietnam (Nguyen & Tran, 2020), and electrocoagulation for ammonia removal from landfill leachate in Malaysia (Hamid et al, 2020).…”