Studies on Transport of Vanadium (V) and Nickel (II) from Wastewater Using Activated Composite Membranes

Abstract

Third International Conference on Engineering for Waste and Biomass Valorization, May 2010, Beijing, China. The metals such as vanadium, nickel and iron are identified in the typical crude oils extracted from oil bearing rocks. The produced water contains salts, heavy metals, emulsified oil and other organics after the hot water extraction process (HWEP) of bitumen from oil sands. This is a serious environmental problem waiting for technically and economically feasible solutions. Membrane technologies such as ultra filtration, nanofiltration, and reverse osmosis are widely used in water purification and they are also applied for produced-water (wastewater stream in oil and gas production) purification. This study focuses on the transport of Vanadium (V) and Nickel (II) through activated composite membranes (ACMs) based on carrier Aliquat 336, in cyclohexane and dodecane. Reagents and materials, without further purification, and double distilled water were used. The UV-visible spectrophotometer and Atomic Absorption Spectrometer (FAAS) were utilised for measuring the concentrations of metal ions from aqueous solutions. Optimum conditions for both feed (pH 8) solutions, the influence of hydrodynamic conditions, the concentration of carrier on membrane (0.2, 0.5 and 0.7 M), the influence of aqueous feed acidity (4 < pH < 7), the influence of permeate reagents (NH3, HNO3, and Na2CO3) and the efficiency of separation process were established. The experiments were carried out at 20°C and low concentrations of V (V) and Ni (II), between 5 and 25 ppm, for modelling, as good as possible, one matrix of industrial wastewaters which contain V (V) and Ni (II) after HWEP. The coupled transport of vanadium from aqueous solutions following the reactions: $$ \left( {{\text{R}}_{ 4} {\text{N}}^{ + } {\text{Cl}}^{ - } } \right) \, _{\text{org}} \, + {\text{ VO}}_{ 2} \left( {\text{OH}} \right)_{ 2}^{ - } \rightleftarrows \left( {{\text{R}}_{ 4} {\text{N}}^{ + } {\text{VO}}_{ 2} \left( {\text{OH}} \right)_{ 2}^{ - } } \right)_{\text{org}} + {\text{ Cl}}^{ - } $$ $$ \left( {{\text{R}}_{ 4} {\text{N}}^{ + } {\text{VO}}_{ 2} \left( {\text{OH}} \right)^{ - }_{ 2} } \right)_{\text{org}} + {\text{ 2 OH}}^{ - } \rightleftarrows \left( {{\text{R}}_{ 4} {\text{N}}^{ + } {\text{OH}}^{ - } } \right)_{\text{org}} \, + {\text{VO}}_{ 3} {\text{OH}}^{ 2- } \, + {\text{ H}}_{ 2} {\text{O}} $$ The removal of V (V) and Ni (II) from wastewater samples was found to be governed by the carrier concentration used as well as the conditions of the aqueous feed and permeate solutions. The good efficiency of activated composite membranes separation was observed in case of V (V). The selectivity of Aliquat 336 based ACM toward V (V) and Ni (II) is presented and discussed. Selectivity demonstrated that vanadium ions were removable from mixtures due to the different extraction strength of Aliquat 336. Such selectivity is based on the difference of the dynamic behaviour of the metal ions transport.