A mini review of recent findings in Cellulose-, Polymer- and Graphene-based membranes for Fluoride removal from drinking water

Effective fluoride removal from water is a persistent global concern both for drinking water and wastewater treatment. According to World Health Organization (WHO) standards the maximum contaminant level in drinking water cannot be higher than 1.5 mg F− L-1 since affects the skeletal and nervous systems of humans. Various technologies have been developed to decrease fluoride concentration from waters, such as adsorption, coagulation, precipitation and membrane separa-tion. Membrane technology found to be a very effective technology, significantly reducing fluo-ride to desired standards levels; however, has received less attention than other technologies because it is apparent as a costly process. This review aims to discuss the recent studies using modified membranes for fluoride removal. Emphasis is given on cellulose, polymer and gra-phene based membranes and is further discussing the modification of membranes with several metals that have been developed in the last years. It was observed that the main focus of the to-tal publications, has been on the use of polymer based membranes. Most of the membranes ap-plied for defluoridation exhibit greater efficiency at pH values close to that of drinking water (i.e., 6–8).and maximum treatment capacity was obtained with the use of a cellulose modified membrane Fe-Al-Mn@chitosan with a permeate flux of 2000 L m-2 h-1, following the carbon based amyloid fibril nano-ZrO2 composites (CAF-Zr) 1750 L m-2. A technical-economic comparison study of NF and RO is also referred, concluding that NF membrane is slightly less expensive.