Differences in adsorption mechanisms of heavy metal by two different plant biomasses: reed and brown seaweed
ABSTRACT The adsorption of Pb(II) by two different biomaterials, reed (Phragmites australis) and brown seaweed (Sargassum horneri) biomass pretreated with CaCl(2), were compared in an attempt to explain the differences in adsorption performance between the two biosorbents. A very interesting characteristic was found in their individual adsorption performances; the Pb(II) adsorption capacity of brown seaweed (Q(max)=0.45 mmol/g) was much higher than that of reed (Q(max)=0.05 mmol/g), but its adsorption affinity (b=112 L/mmol) was much lower compared with that of reed (b=471 L/mmol). To elucidate the mechanism, the elemental components, ion exchange phenomenon and roles of functional groups of these two biosorbents were compared. The higher Pb(II) adsorption by brown seaweed could be due to its richness in total functional groups and calcium contents on its surface. In contrast, the functional complexity, higher zeta potential and pK(a) value (deprotonation state) of reed are believed to lead to its high adsorption affinity.
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ABSTRACT: The removal of lead (II) and iron (III) from aqueous solutions using empty fruit bunch (EFB), oil palm leaves (OPL), oil palm frond (OPF), and oil palm bark (OPB) as biosorbents was investigated. The biosorbents were characterized through scanning electron microscopy, Brunauer–Emmett–Teller analysis, and Fourier transform infrared spectroscopy. Variables such as pH (2–12), biosorbent particle size (200–1,400 μm), adsorbent dosage (0.25–1.75 g/l), and agitation time (5–80 min) were investigated. The suitable pH range, particle size, adsorbent dosage, and agitation time for the removal of both metals were 5 to 6, 200 μm, 1 g/l, and 40 min, respectively. Under optimum conditions, OPB showed the highest adsorption efficiency of 80 % and 78 % for lead and iron, respectively. The adsorption equilibrium data were fitted to three adsorption isotherm models. The Langmuir isotherm showed the best result for both metals. The kinetics of the biosorption process was analyzed using pseudo-first-order and pseudo-second-order models. The latter showed a better fit for both metals. OPB biomass introduced the lowest chemical oxygen demand into the treated solution, with an average amount of 32.9 mg/l.Water Air and Soil Pollution 03/2013; 224(3). DOI:10.1007/s11270-013-1455-y · 1.69 Impact Factor
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ABSTRACT: The kinetics of zinc, cadmium, and lead ions removal by natural zeolite-clinoptilolite has been investigated using an agitated batch adsorber. Batch experiments at constant temperature have been performed. The influence of agitation speed, initial heavy metals concentration and particle size of the sorbent on the removal efficiency of heavy metals from liquid phase have been studied. A decrease in the initial heavy metals concentration in aqueous solutions prolongs the time needed for equilibrium. Two kinetics models according to the Vermeulen's approximation and the parabolic diffusion model have been tested with the experimental data for adsorption of heavy metals onto natural zeolite. For the systems examined, the fit of the proposed models with the experimental data was shown to be equally good using both models. The diffusion coefficients are calculated from kinetic models of heavy metal ions and they are of the order from 10(-5) to 10(-6) cm(2)/min. The diffusion coefficients depend on initial concentration for both models.Water Science & Technology 01/2010; 62(5):1136-42. DOI:10.2166/wst.2010.918 · 1.21 Impact Factor
Chapter: Algal Biosorption and Biosorbents[Show abstract] [Hide abstract]
ABSTRACT: Algae belong to the kingdom Protista which contains all the Eucaryotes organisms that cannot be classified within other eucaryotic kingdoms: Fungi, Animalia or Plantae. They are autotrophic organisms that carry out an oxygenic photosynthesis. Maybe the most well-known use of algae since ancient times is in food, especially in the Asian coast. In addition, the phycocolloid industry uses algae as raw material in the manufacture of a wide variety of additive products in the cosmetic, pharmaceutical and food industries. Lately algae have been proposed for the treatment of wastewaters due to their high heavy metal sorption capacity. Although, traditionally they have been used in less extent than other biomass, algae have important advantages such as: high efficiency metal removal, non-toxic chemical sludge and low cost. The main kinds of algae (green, red and brown) have constituents (cellulose, carrageenan and alginate, respectively) that provide binding sites such as: hydroxyl, carboxyl, amino and sulfhydryl, which are responsible for the selectivity of these biomass for heavy metals. In this way, Fucus spiralis, a brown alga very common in the Galician coast, has been proved very selective in the sorption of copper versus other heavy metals. Like for other types of biomass, one way to improve its biosorbent capacity is by pre-treatment with different reagents. KeywordsAlgae types-Binding sites-Sorption uptake-Biosorbent pretreatment01/2011: pages 159-178;