Thermodynamic Profile of Some Heavy Metal Ions Adsorption Onto Biomaterial Surfaces

Abstract

The adsorption of Co²⁺, Zn²⁺, Pb²⁺ and Hg²⁺ onto dried non-living biomass (NB) of different Pseudomonas strains has been investigated in detail. Maximum adsorption of these cations is achieved at optimum pH values from 3.5 to 4.5 to avoid hydrolysis, polymerization and precipitation of metal cations in the treatment solutions. The experimental data obtained at different temperatures were fitted to the Langmuir model at different temperatures from 283 to 323 K. Metal ions adsorption occurs in multi detectable steps (i=A, B, C). Binding of Pb(II) to NB occurs in one detectable step labeled A, where two detectable binding steps were observed for the other cations; A and B for Zn(II), A and C for Co(II), B and C for Hg(II), respectively. Site capacities, υi are found to be temperature-independent in the whole investigated temperature range. The thermodynamic parameters (∆Hi, ∆Si and ∆Gi) for the adsorption processes were calculated for each binding step i and the results suggest that the nature of adsorption is endothermic and the process is spontaneous and favorable. Thermodynamic data pairs (∆Hi , ∆Si) for metal binding are linearly correlated for all sites in the investigated biosorption systems

Equilibrium and kinetic studies in adsorption of heavy metals using biosorbent: A summary of recent studies

“…This is opposing the real condition as a small to modest increase [2,25,33,47,54,59,63,67,69,80,81] and decrease [20,[82][83][84][85] in saturation capacity with temperature is generally observed as exposed in Table 2. It is the expected case indeed, if the saturation limit is associated with the surface functional groups rather than a set of identical surface sites.…”

Removal of heavy mercury(II), cadmium(II) and zinc(II) metal ions by live and heat inactivated Lentinus edodes pellets

“…Biosorption with microbial biomasses has become an alternative to traditional methods of industrial wastewaters treatment, such as precipitation, adsorption, coagulation, etc. [9,10] and it is relatively inexpensive, non-hazardous, and may permit recovery of the metals from the adsorbing biomass [11][12][13]. Biosorption is the non-specific term used to denote the complex process whereby biomass, usually microbial, is utilized to remove solutes during water treatment.…”

Copper Ions Biosorption Properties of Biomass Derived from Algerian Sahara Plants

“…Within the Langmuir model, the saturation capacity qmax is supposed to coincide with saturation of a fixed number of identical surface sites and as such, it should logically be independent of temperature. The decrease of b value with temperature rise signifies the exothermicity of the adsorption process (physical adsorption) [Shaker, 2007], while the opposite trend indicates that the process needs thermal energy (endothermic), leading to chemisorption [Dundar et al, 2008;Vilar et al, 2008]. In physical adsorption, the bonding between heavy metals and active sites of the biosorbent weakens at higher temperature in contrast with chemisorption bonding which becomes stronger.…”