Abstract
ABSTRACT. Mercury even at a trace level poses a significant threat to the environment and the ecosystem. Thus, prompting the need to develop a technology to separate mercury(II) selectively from aqueous solutions. The removal of mercury(II) from aqueous solutions using tri n-butyl phosphate (TBP) based supported liquid membrane (SLM) was investigated in this study. HCl and NaOH were used as feed and strip phases, respectively. Factors considered for designing the experiments using the Taguchi method include feed phase acid concentration, strip phase alkali concentration, carrier concentration and initial feed phase mercury(II) concentration. The results indicated that carrier concentration was the most influential factor on the removal efficiency. The percentage contribution of each factor was calculated. The results show that carrier concentration and initial feed phase mercury(II) concentration have a maximum contribution. For the maximum removal of 91.7% of mercury(II) (initial concentration - 10 mg/L) in the feed phase, the optimum conditions were 0.3 M of HCl, 0.2 M of NaOH, and 90% of TBP. SEM analysis was performed to evidence the transportation process through the membrane. The research study indicated the potential use of TBP as a carrier in the SLM system for the selective separation of mercury in trace concentration.
 
 KEY WORDS: Removal of mercury(II), Tri n-butyl phosphate, Taguchi method, Supported liquid membrane
 
 Bull. Chem. Soc. Ethiop. 2021, 35(2), 273-286.
 DOI: https://dx.doi.org/10.4314/bcse.v35i2.5
Highlights
The classical method of design for experimentation of process parameters is time-consuming as it propagates the study through a large set of runs, and the interaction between the parameters is not considered leading to less reliability [1]
"Larger the better" performance characteristics of the S/N ratio were used for obtaining the maximum removal efficiency determined by using Eq 2
tri n-butyl phosphate (TBP) based supported liquid membrane (SLM) system for the removal of mercury was successfully demonstrated by applying Taguchi method to examine the effects of parameters on percentage removal of mercury(II) in trace level of concentration (10 mgL-1)
Summary
The classical method of design for experimentation of process parameters is time-consuming as it propagates the study through a large set of runs, and the interaction between the parameters is not considered leading to less reliability [1]. Statistical techniques benefit the user by facilitating a special design that involves less time and energy [2] and is useful by considering the interaction between the parameters. The two most extensively used statistical methods are Taguchi design and response surface methodology. Response surface methodology is profusely employed to study the response influenced by several input parameters, to optimize the response [2], and to quantify the relationship between them. It finds its usefulness in modeling and analyzing engineering problems [4]
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