Modelling of fluoride sorption from aqueous solution using green algae impregnated with zirconium by response surface methodology

Abstract

In the present work, an economical, more selective and a bio-compatible fluoride removal technique has been developed by using zirconium impregnated Chlorella protothecoides and Nannochloropsis oculata, which represents a combination of biological and physiochemical methods. The optimization of the effect of various factors such as pH, initial fluoride concentration, biosorbent dose and contact time was carried using a central composite design of response surface methodology. A maximum removal of fluoride ions of 92.2% was observed using zirconium-doped C. protothecoides. The adsorption isotherms and kinetics of the adsorption process were studied. The Langmuir isotherm model well expressed fluoride biosorption onto zirconiumdoped N. oculata and the Freundlich isotherm model fitted well the data of zirconium-doped C. protothecoides. The correlation coefficients indicate that the fluoride biosorption onto zirconiumdoped N. oculata, and C. protothecoides biosorbents correlated well with the pseudo-second-order kinetic model. The existence of co-anions decreased fluoride removal from aqueous solution. The biosorbent was regenerated using NaOH, distilled water and HCl and used for four cycles.

Pilot-Scale Field Demonstration of Environmental Nanotechnology for Groundwater Defluoridation

“…A shift of 0.3 eV occurred in the Zr 3d spectra after fluoride uptake, mainly arising from the strong interaction between HZO and fluoride. Moreover, two new bands appeared at around 184.0 eV and 186.4 eV, due to the formation of the Zr–F bond. , The XPS Zr 3d spectrum of the regenerated HZO@D201 turned almost identical to the fresh HZO@D201, further confirming ligand exchange as the main mechanism for the adsorption of fluoride by nano-HZO.…”

Removal of Metals by Sorption with Metal Concentration Colour Sensitive Azotized Polyethylene Terephthalate Adsorbent

“…The pH of the medium was adjusted by using either sodium acetate solution or 0.1 M nitric acid dropwise. The content of the metal ions adsorbed were calculated using equations 1 and 2 for the adsorption capacity and removal e ciency respectively [20].…”