Removal of lead from aqueous solution by non-living rhizopus nigricans

Removal of heavy metals (Pb 2? , Zn 2? ) from aqueous solution by dried biomass of Spirulina sp. was investigated. Spirulina rapidly adsorbed appreciable amount of lead and zinc from the aqueous solutions within 15 min of initial contact with the metal solution and exhibited high sequestration of lead and zinc at low equilibrium concentrations. The specific adsorption of both Pb 2? and Zn 2?increased at low concentration and decreased when biomass concentration exceeded 0.1 g l -1 . The binding of lead followed Freundlich model of kinetics where as zinc supported Langmuir isotherm for adsorption with their r 2 values of 0.9659 and 0.8723 respectively. The adsorption was strongly pH dependent as the maximum lead biosorption occurred at pH 4 and 10 whereas Zn 2? adsorption was at pH 8 and 10.

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“…The metal adsorption (q) by the alga and bioremoval efficiency (R) were calculated by the following formulae [20,21].…”

Section: Lead and Zinc Sorption Experimentsmentioning

confidence: 99%

Biosorption of Pb2+ and Zn2+ by Non-Living Biomass of Spirulina sp.

et al. 2010

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“…The rate constant of adsorption is determined using Lagergren first order rate expression Namasivayam & Ranganathan, 1995;Zhang et al, 1998):…”

Section: Adsorption Dynamicsmentioning

confidence: 99%

Adsorption of zinc onto bed sediments of the River Ganga: adsorption models and kinetics

Jain¹

2001

Hydrological Sciences Journal

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A laboratory study was performed to study the effects of various operating factors, viz. initial metal ion concentration, solution pH, amount of sediment, contact time, particle size and temperature on the adsorption of zinc ions onto the bed sediments of the River Ganga (India). The equilibrium time was found to be of the order of 60 min. The adsorption curves are smooth and continuous leading to saturation, suggesting the possible monolayer coverage of zinc ions on the surface of the adsorbent. The extent of adsorption increases with an increase of pH. Furthermore the adsorption of zinc increases with increasing amount of adsorbent and decreases with adsorbent particle size. The important geochemical phases, iron and manganese oxide act as the active support material for the adsorption of zinc ions. The adsorption data have been analysed with the help of Langmuir and Freundlich adsorption models to determine the mechanistic parameters associated with the adsorption process. An attempt has also been made to determine thermodynamic parameters of the process, viz. free energy change, enthalpy change and entropy change. The negative values of free energy change (AG") indicated the spontaneous nature of the adsorption of zinc onto the bed sediments and positive values of enthalpy change (Aff°) suggest the endothermic nature of the adsorption process. The intraparticle diffusion of zinc in the adsorbent was found to be the main rate-limiting step.Key words River Ganga; adsorption; Langmuir model; Freundlich model; kinetics; thermodynamic parameters Adsorption du zinc par les sédiments du lit du Gange: modèles et cinétiques d'adsorptionRésumé Les effets de plusieurs facteurs -la concentration ionique initiale, le pH de la solution, la quantité de sédiments, le temps de contact, la taille des particules et la température-sur l'adsorption des ions zinc par les sédiments du lit du Gange (Inde) ont été étudiés en laboratoire. Le temps d'équilibre identifié est de l'ordre de 60 min Les courbes d'adsorption sont régulières et continues jusqu'à saturation, suggérant une adsorption surfacique mono-couche des ions zinc sur les particules. Le degré d'adsorption augmente avec le pH. Il augmente également avec la quantité de sédiments, mais décroît avec la taille des particules. Les oxydes de fer et de manganèse s'avèrent être les supports actifs de l'adsorption des ions zinc. Les données d'adsorption ont été analysées avec les modèles de Langmuir et Freundlich, pour déterminer les paramètres mécaniques associés au processus d'adsorption. Une tentative a aussi été faite pour déterminer les paramètres thermodynamiques du processus, c'est-à-dire les variations d'énergie libre, d'enthalpie et d'entropie. Les valeurs négatives de la variation de l'énergie libre (AG°) mettent en évidence la spontanéité de l'adsorption du zinc par les sédiments du lit, tandis que les valeurs positives de la variation de l'enthalpie (Aff°) suggèrent un processus de nature endothermique. La diffusion intra-particulaire du zinc dans les sédiment...

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“…From the above findings it was proved that microbial biosorption of heavy metals from aqueous solutions depends on properties of adsorbent and molecules of adsorbate transfer from the solution to the solid phase. It has been also reported that biosorption capacities for heavy metals are strongly pH sensitive and that adsorption increases as solution pH increases [49]. The low bioaccumulation capacity at low pH is attributed to the competition of hydrogen ion with the metal ion on the sorption site.…”

Section: Effect Of Ph and Temprature Variationsmentioning

confidence: 99%