Removal of Fluoride from Aqueous Solution by Using of Adsorption onto Modified Lemna Minor: Adsorption Isotherm and Kinetics Study

Background and Fluoride in drinking water can be either beneficial or detrimental to health depending on its concentration. Its high concentrations leads to dental and skeletal fluorosis and lesions of the endocrine glands، thyroid and liver. This paper describes the removal of fluoride from water using lemna minor. This research was a lab study. The lemna minor plants were collected and dried in the oven at 105 in 24 h and sieved in 18-30 mesh. The optimum values of pH، contact time and adsorbent dosage were determined and the different concentrations of fluoride were experimented in lab scale conditions for modified lemna minor. The fluoride concentration was measured in wavelength of 518 nm by spectrophotometer. Also، the found data of this research were fitted with Variety Isotherm and kinetic models. The results showed that by increasing pH solution، removal efficiency decreased and optimum pH was 5. Increasing of contact time and adsorbent dose can lead to the increase of the removal efficiency. Adsorption isotherm data show that the fluoride sorption followed the Langmuir No 2. Fluoride sorption is better agreed with pseudo- second order of Kinetics model which was well described by pseudo- second order model. The result of the present work shows that lemna minor can be used as an effective and cheap adsorbent for fluoride removal.