ABSTRACT
Cellulose-agar (CAB) composite hydrogel beads were generated for the uptake-release kinetics studies of Se(VI) and selenomethionine (SeMt) from water medium. The objective of this work is to analyze the surface structure, gel properties, thermal stability and chemical functionalities responsible for the adsorption of Se(VI) and SeMt. We propose here a possible mechanism for the adsorptions. Adsorption isotherms are in good agreement with the Freundlich model, yielding a high adsorption capacity for the CAB composite. Maximum adsorption capacity of Se(VI) and SeMt were found to be 7.083â¯mgâ¯g-1 and 34.639â¯mgâ¯g-1 respectively. The mean free energy of adsorption (E*) value was found to be 0.0423â¯kJâ¯mol-1 and 0.329â¯kJâ¯mol-1 of Se(VI) and SeMt respectively. 1â¯M HCl and 0.1â¯M HCl were able to desorb Se(VI) and SeMt respectively from CAB. The adsorption of Se(VI) was significantly reduced if As(III), Cr(III) and Hg(II) were present as complementary ions in the medium. Similar studies with pristine cellulose beads (CB) yielded insignificant uptake properties.
Subject(s)
Agar/chemistry , Cellulose/chemistry , Hydrogels/chemistry , Selenic Acid/chemistry , Selenic Acid/isolation & purification , Selenomethionine/chemistry , Selenomethionine/isolation & purification , Adsorption , Hydrogen-Ion Concentration , Kinetics , Thermodynamics , Water/chemistry , Water Pollutants, Chemical/chemistry , Water Pollutants, Chemical/isolation & purificationABSTRACT
The cooperative influence of operational variables for fluoride adsorption on cerium loaded cellulose nanocomposite bead (CCNB) was assessed using Taguchi design tool. The percentage contribution of each operational variable was determined. The solution pH, with a maximum contribution of 80.78%, indicates its highest influence on the response, the adsorption percent of fluoride. The quality and validity of the experimental design were assessed from ANOVA and subsequently by the confirmation experiment. The equilibrium adsorption data showed that the Temkin isotherm is the most suited one compared to the Langmuir and Freundlich model. It is found that almost 90% adsorbed fluoride can be eluted with 0.01 (N) NaOH and the regenerated bead can successively be reused for at least three times.
