حذف فسفات از محلول هاي آبي به وسيله بنتونيت و هيدروژل

چكيده انگليسي :

Phosphate Removal from Aqueous Solutions by Bentonite and Hydrogel Soghra Yaghoobi Rahni yaghoobi84@yahoo com January 8 2011 Department of Natural Resource Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi N Mirghaffari mnorolah@cc iut ac ir and B Rezaei rezaei@cc iut ac ir Abstract Removal and recovery of phosphorus from wastewater is important to manage the environmental and economic issues such as eutrophication of surface waters and depletion of phosphorus resources Phosphorus removal from wastewater has been widely investigated using several techniques including physical chemical precipitation and biological processes Recently the removal of phosphate from aqueous solutions by adsorption has attracted much attention due to severe emission standards and also high efficiency of this technique Adsorption is an environmental friendly simple feasible and economical method for removal of phosphate from wastewater leading to a practical recycling and reuse of phosphorus The key problem in phosphorus adsorption method is finding an efficient and low cost sorbent Clays are low cost and easily available minerals that due to their individual properties were used as general adsorbents in wastewater treatment In this study bentonite and hydrogel a commercial material produced from bentonite were used for removal of phosphate from aqueous solutions in batch and column tests Different effective parameters on phosphate removal such as equilibrium time pH initial phosphorus concentration and amount of sorbent were investigated The effect of some colloid surface modification treatments on phosphate sorption of the sorbents was also studied The sorbents were characterized by Fourier transform infrared spectroscopy FTIR X ray powder diffraction XRD X ray uorescence XRF and scanning electron microscopy SEM The raw bentonite and hydrogel had low affinity for phosphate adsorption since the negative charges of clay surfaces prevent the electrostatic attraction of phosphate anion In addition the relatively stable siloxane groups on the surfaces of clays do not permit the adsorption of phosphate through ligand exchange processes Phosphate adsorption capacity in modified adsorbent followed the order Al Fe Al Fe Ca Rewoquate surfactant Irasoft surfactant acid thermoactivation The optimum sorption capacity obtained when Fe and Al applied as 2 and 4 times the CEC for bentonite and hyrogel respectively Study of the reaction kinetics showed that phosphate sorption on bentonite and hydrogel modified by Fe Al was a fast process The initial pH of solution as well as the presence of nitrate chloride sulfate and bicarbonate anions in the solution had no effect on phosphate adsorption The adsorption of phosphate on the modified bentonite and hydrogel could be efficiently described by Langmuir isotherm model The maximum adsorption capacity was 8 33 and 14 29 mgP g for bentonite and hydrogel respectively The phosphate desorption was 87 for hydrogel while for bentonite it was 5 This indicates probably a chemisorption and or precipitation mechanism The use of modified sorbents for an urban sewage sample also showed a very high efficient P removal 99 The relatively low cost and high capacities of the modified bentonite and hydrogel introduce them as potentially attractive sorbents for the removal of phosphate from water and wastewater Key words Phosphate Adsorption isotherm Pillared Clay Bentonite Hydrogel

يعقوبي رهني، صغري

حذف فسفات از محلول هاي آبي به وسيله بنتونيت و هيدروژل

جذب , پل دار كردن , همدماي جذبي