Abstract
The potential of water hyacinth—Eichhornia crassipes biomass immobilized in calcium alginate for the adsorption of Ni(II) from water was studied using the Langmuir and Freundlich adsorption models. The equilibrium adsorption data were obtained at different initial Ni(II) concentrations = 0.05 - 2 mg/L, temperature = 30˚C ± 0.2˚C, agitation rate = 150 rpm, equilibration time = 3 hr, biosorbent dose = 4 g/L, and pH range = 4 - 7.4. Langmuir isotherms gave monolayer sorption capacities ( ) of 26.5, 44.3 and 53.0 mg/g for the removal of Ni(II) in the presence of methanol, without adde d organic substance, and in the presence of acetonitrile, respectively. These findings were also confirmed by the trend in the Freundlich isotherm parameter ( m q 1 n 90%). The results from these studies indicated that E. crassipes fixed on calcium alginate beads is a viable metal enrichment media that can be used freely immersed in solution to achieve very high adsorption capacities and possible preconcentration of Ni(II) in aquatic environments.
Highlights
Biosorption of heavy metals, which is the passive uptake of the metals by dead/inactive biological materials or by materials derived from biological sources, has attracted significant attention during the past few decades as an alternative to the conventional methods of heavy metal removal from aquatic systems [1,2,3,4,5]
Desorption experiments to recover Ni(II) from the adsorbent showed that highest amounts of the metal could be removed from the adsorbent when previously adsorbed in the presence of 1-(2-Thiazolylazo)-2-naphtol (TAN) (>90%). The results from these studies indicated that E. crassipes fixed on calcium alginate beads is a viable metal enrichment media that can be used freely immersed in solution to achieve very high adsorption capacities and possible preconcentration of Ni(II) in aquatic environments
Analysis of equilibrium data on a specific adsorption isotherm is of significance for comparing different sorbents under different experimental conditions
Summary
Biosorption of heavy metals, which is the passive uptake of the metals by dead/inactive biological materials or by materials derived from biological sources, has attracted significant attention during the past few decades as an alternative to the conventional methods of heavy metal removal from aquatic systems [1,2,3,4,5]. Several advantages of biomass fixation in polymeric material have been realised when applied in packed or fluidised bed reactors These include the control of particle size, regeneration and reuse of the biomass, easy separation of biomass and effluent, high biomass loading and minimal. Among plants that have been studied for their uptake of heavy metals from aquatic systems, E. crassipes has been shown to possess the ability for the sorption of several heavy metals [15,16,17]. The present work has been addressed to the study of the effect of selected organic substances: acetonitrile, methanol and 1-(2-Thiazolylazo)-2-naphtol (TAN) on the sorption dynamics of Ni(II) ions onto E. crassipes fixed on alginate
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