Algal biomass as adsorbents for heavy metal sorption from aqueous solutions
Danish J. Malik
2134/7196
https://repository.lboro.ac.uk/articles/thesis/Algal_biomass_as_adsorbents_for_heavy_metal_sorption_from_aqueous_solutions/9239618
This thesis evaluates the performance of marine algal-based biosorbents in treating
trace metal bearing aqueous solutions. Native seaweed varieties (Ascophyllum
nodosum, Lessonia flavicans, Durvillea potatorum and Laminaria hyperborea) were
selected on the basis of their varying algin composition as well as their characteristic
mannuronic/guluronic acid content. Dealginated seaweed residues, i.e. waste
materials arising during algin extraction from brown marine algae were also evaluated
as potential metal biosorbent materials. The biosorbents showed significant metal
sorption capacity for copper, cadmium, nickel and zinc from synthetic single metal
and multi-metal bearing aqueous solutions. The equilibrium biosorption process may
be described using a surface complex formation model. Copper biosorption involved
chelation-type surface reactions as well as ion exchange whereas nickel and zinc
biosorption may be described by simple ion exchange and electrostatic interactions
between metal ions and the negatively charged algal surface. Evidence of
stoichiometric release of protons upon metal biosorption has been found. Metal
biosorption was found to be dependent upon transport limitations due to intraparticle
diffusion.
Surface functional groups within algal biosorbents that are responsible for metal-ion
binding were identified in an attempt to understand the mechanisms of metal
biosorption. Physical and chemical characterization techniques such as potentiometric
titrations and esterification were used for surface acidity measurements, nitrogen
sorption porosimetry for surface area and pore size distribution analysis and FT-IR
spectroscopy to identify carboxyl groups attached to structural polysaccharides in
algae.
Performance of native and dealginate algal fixed-bed mini-columns provided
optimum operating conditions for dynamic exchange between metal ions in solution
and the algal biomass. Selected biosorbents were successfully employed to treat real
industrial metal-plating rinse waters. The most efficient eluants for regeneration of
metal-laden biosorbent columns were also identified.
2010-11-17 09:59:08
Biosorbents
Seaweed
Marine
Chemical Engineering not elsewhere classified