Abstract
The presence of heavy metals in aqueous solutions above certain limits represents a serious threat to the environment due to their toxicity and non-degradability. Thus, the removal of these metals from contaminated waters has received increasing attention during recent decades. This paper describes the removal of Cu(II) from aqueous solutions by emulsion liquid membranes, through a carrier-facilitated counter-transport mechanism, using benzoylacetone as the carrier and HCl as the stripping agent (protons as counter-ions). To optimize the Cu(II) removal process, the effect of the following operating parameters on the on the stability of the emulsion liquid membrane and on the Cu(II) removal efficiency was studied: feed pH, HCl concentration in the permeate phase, carrier and emulsifier concentration in the membrane phase, feed phase/emulsion phase and permeate phase/membrane phase volume ratios, emulsification time and speed in the primary emulsion preparation and stirring speed in the whole feed phase/emulsion phase system. Typical membrane transport parameters, such as flux and permeability, were also determined. Optimal Cu(II) removal conditions were: 5.5 feed pH, 10 kg/m3 benzoylacetone concentration in the membrane phase, 18.250 kg/m3 HCl concentration in the permeate phase, 50 kg/m3 Span 80 concentration in the membrane phase, 200 rpm stirring rate, 5 min emulsification time, 2700 rpm emulsification rate, 2:1 feed:emulsion volume ratio and 1:1 permeate:membrane volume ratio. In these optimal conditions, 80.3% of Cu(II) was removed in 15 min with an apparent initial flux and permeability of 0.3384 kg·m−3·min−1 and 0.3208 min−1, respectively.
Highlights
Illnesses related to water pollution are considered among the major causes of death in the world, and it is estimated that over two million people die each year for this reason [1]
Heavy metals are not biodegradable in natural conditions, so they tend to accumulate in living organisms, causing various diseases and disorders [2]; their presence in wastewater inhibits the biodegradation of organic pollutants, which might be present in the wastewater [3]
Emulsion breakage is determined from the ratio between the volume of internal product phase leaked into the external feed phase by splitting (V leak ) and the initial volume of the internal phase (V p ) [34]
Summary
Illnesses related to water pollution are considered among the major causes of death in the world, and it is estimated that over two million people die each year for this reason [1]. The contamination of industrial and natural waters by organic and heavy metal pollutants is recognized as one of the greatest environmental problems nowadays. Heavy metals are not biodegradable in natural conditions, so they tend to accumulate in living organisms, causing various diseases and disorders [2]; their presence in wastewater inhibits the biodegradation of organic pollutants, which might be present in the wastewater [3]. According to the World Health Organization, the metals of most immediate concern are chromium, copper, zinc, iron, mercury and lead [4]. Organization, the metals of most immediate concern are chromium, copper, zinc, iron, mercury and Metals.
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