Search results for "Freundlich equation"
showing 10 items of 32 documents
Kinetic and equilibrium study for cadmium and copper removal from aqueous solutions by sorption onto mixed alginate/pectin gel beads
2013
Abstract Kinetic and equilibrium studies have been carried out to evaluate Cd(II) and Cu(II) sorption from aqueous solution by calcium alginate and new synthesized hybrid calcium alginate/pectate gel beads with different alginate/pectate concentration ratios. Physical and chemical properties of the beads were characterized by different techniques (SEM, EDX, TGA). The best experimental pH conditions were selected on the basis of a study on the acid–base properties of pectin and alginate in aqueous solution and their ability to act as sequestering agents for copper(II) and cadmium(II) ions. Calcium released during the sorption process was determined in order to elucidate a possible ion exchan…
Enhancement of adsorption ability of calcium alginate gel beads towards Pd(II) ion. A kinetic and equilibrium study on hybrid Laponite and Montmorill…
2015
Abstract The adsorption ability of hybrid Montmorillonite and Laponite–calcium alginate gel beads towards Pd 2 + ion was studied in the pH range 2–4, in pure water and in aqueous NaCl solution at I = 0.01 mol L − 1 and T = 25 °C. The pseudo second order kinetic equation and the Langmuir and Freundlich isotherms were used to fit the kinetic and thermodynamic experimental data. A comparison of the results already published on the adsorption capacity of calcium alginate gel beads at the same experimental conditions was made. Enhancement of palladium(II) adsorption by alginate beads with the addition of the two clay minerals was obtained, with increments higher than 50% of Pd(II) ion recovered/…
Some factors affecting the removal of lead(II) ions from aqueous solution by porous hydroxyapatite: relationships between surface and adsorption prop…
2006
A porous hydroxyapatite (p-HAp) was prepared and employed for the removal of lead(II) ions at different concentrations from aqueous solution to determine the adsorption properties of p-HAp and compare them with those of a commercial hydroxyapatite (CAp) sample. The kinetic data obtained indicated that the adsorption performances of the adsorbents depended both on their specific surface area and crystallinity. Complexation of the Pb(II) ion on the adsorbent surface favoured the dissolution of hydroxyapatites characterized by a Ca/Pb molar ratio in the 0.85–1.5 range. The maximum adsorption capacity of p-Hap for Pb(II) ions at 30 ± 2°C was 2.30 mmol/g relative to 1.38 mmol/g for the commercia…
Removal of Basic Blue 41 dyes using Persea americana-activated carbon prepared by phosphoric acid action
2016
Adsorption study of Basic Blue 41 dye onto activated carbon from Persea americana nuts with phosphoric acid activation was achieved. The effect of operating parameters, the effect of pH (2–12), adsorbent amount (5–30 mg/50 mL), dye concentration (25–125 mg/L), contact time (0–200 min) and temperature (298–323 K), on the adsorption capacity was examined. The experimental isotherm data were analyzed using Langmuir and Freundlich models, which showed that the best fit was achieved by the Langmuir model with the maximum monolayer adsorption capacity at 625 mg/g. The adsorption kinetic process followed pseudo-second-order kinetics. Thermodynamic evaluation showed that the process was endothermic…
Mercury(II) removal from aqueous solution by sorption onto alginate, pectate and polygalacturonate calcium gel beads. A kinetic and speciation based …
2013
Abstract Gel beads of calcium alginate, pectate and polygalacturonate salts have been tested as sorbent materials for mercury(II) removal from aqueous solutions. Physico-chemical properties of gel beads, defined by SEM–EDX, TGA and texture and density analysis, were correlated with gel beads sorption capacity towards Hg 2+ ion. A speciation study in aqueous solution was carried out to define the strength of interaction of mercury ion with the polymers investigated and to assess the more suitable experimental conditions to achieve the best effectiveness of Hg 2+ sorption by gel beads. On the basis of the speciation study, pH values in the 3–5.5 pH range were considered appropriated for mercu…
The effect of montmorillonite clay in alginate gel beads for polychlorinated biphenyl adsorption: Isothermal and kinetic studies
2014
Beads of alginate montmorillonite have been used as sorbent for polychlorinated biphenyls from aqueous solutions.The structure and the differences between the different beads were established by IR spectroscopy (FT-IR). The adsorption at 25 °C has been studied in a batch system, following its kinetics and assessing adsorbent dose, initial PCB concentrations, and pH effects. The results show that increasing the initial concentration of the PCBs and the adsorption time favored the adsorption. Adsorption isotherm data were modeled using Chapman, Freundlich and Langmuir adsorption isotherms and the appropriate parameters were calculated.Adsorption of trichlorobiphenyls on alginate–montmorilloni…
Sorption of Pd(II) ion by calcium alginate gel beads at different chloride concentrations and pH. A kinetic and equilibrium study
2016
Abstract A kinetic and thermodynamic study on the sorption ability of calcium alginate gel beads towards Pd(II) ion was made in aqueous solution at different pH and chloride concentrations. The experimental conditions adopted in the sorption experiments were established on the basis of a speciation study on the Pd 2+ -AA system in which all the side reactions, such as the hydrolysis of Pd(II), the protonation of alginate and the interactions of the ligand and the metal ion with ions of ionic medium were taken into account. In the pH range 2–5 and at chloride concentration in the range 0 ⩽ C Cl - /mmol L −1 ⩽ 10 the gel beads showed good sorption ability towards Pd(II) ion as confirmed by k…
Effect of EDTA on divalent metal adsorption onto grape stalk and exhausted coffee wastes
2007
In the present work, two industrial vegetable wastes, grape stalk, coming from a wine producer, and exhausted coffee, coming from a soluble coffee manufacturer, have been investigated for the removal of Cu(II) and Ni(II) from aqueous solutions in presence and in absence of the strongly complexing agent EDTA. Effects of pH and metal-EDTA molar ratio, kinetics as a function of sorbent concentration, and sorption equilibrium for both metals onto both sorbents were evaluated in batch experiments. Metal uptake was dependent of pH, reaching a maximum from pH around 5.5. EDTA was found to dramatically reduce metal adsorption, reaching total uptake inhibition for both metals onto both sorbents at e…
The removal of sulphate from mine water by precipitation as ettringite and the utilisation of the precipitate as a sorbent for arsenate removal.
2016
Abstract The aim of this research was to investigate sulphate removal from mine water by precipitation as ettringite (Ca6Al2(SO4)3(OH)12·26H2O) and the utilisation of the precipitate as a sorbent for arsenate removal. The mine water sulphate concentration was reduced by 85–90% from the initial 1400 mg/L during ettringite precipitation depending on the treatment method. The precipitation conditions were also simulated with MINEQL + software, and the computational results were compared with the experimental results. The precipitated solids were characterised with X-ray diffraction and a scanning electron microscope. The precipitated solids were tested as sorbents for arsenate removal from the…
Potential use of activated carbon derived from Persea species under alkaline conditions for removing cationic dye from wastewaters
2017
Abstract The use of Persea americana has been studied as an alternative source of activated carbon for the removal of dyes from wastewater. Chemical activation using phosphoric acid was employed for the preparation of the activated carbon (C-PAN). The BET surface area and the total pore volumes were found to be 1593 m2/g and 1.053 cm3/g, respectively. This study investigates the effect of some parameters like, dye concentration, adsorbent dose, contact time and pH for the best comprehension of the adsorption manner. Adsorption kinetic follows pseudo-second order kinetic model. Langmuir and Freundlich isotherms models were used to analyze the adsorption equilibrium data and the best fits to …