Multi-component adsorption of copper, nickel and zinc from aqueous solutions onto activated carbon prepared from date stones.

The removal of Cu(2+), Ni(2+), and Zn(2+) ions from their multi-component aqueous mixture by sorption on activated carbon prepared from date stones was investigated. In the batch tests, experimental parameters were studied, including solution pH, contact time, initial metal ions concentration, and temperature. Adsorption efficiency of the heavy metals was pH-dependent and the maximum adsorption was found to occur at around 5.5 for Cu, Zn, and Ni. The maximum sorption capacities calculated by applying the Langmuir isotherm were 18.68 mg/g for Cu, 16.12 mg/g for Ni, and 12.19 mg/g for Zn. The competitive adsorption studies showed that the adsorption affinity order of the three heavy metals was Cu(2+) > Ni(2+) > Zn(2+). The test results using real wastewater indicated that the prepared activated carbon could be used as a cheap adsorbent for the removal of heavy metals in aqueous solutions.

Retention of nickel from aqueous solutions using iron oxide and manganese oxide coated sand: kinetic and thermodynamic studies.

In this study, the removal of nickel ions from aqueous solutions using iron oxide and manganese oxide coated sand (ICS and MCS) under different experimental conditions was investigated. The effect of metal concentration, contact time, solution pH and temperature on the amount of Ni(II) sorbed was studied and discussed. Langmuir and Freundlich isotherm constants and correlation coefficients for the present systems at different temperatures were calculated and compared. The equilibrium process was well described by the Langmuir isotherm model: the maximum sorption capacities (at 29 K) were 2.73 mg Ni/g and 3.33 mg Ni/g of sorbent for ICS and MCS, respectively. Isotherms were also used to evaluate the thermodynamic parameters (deltaG degrees, deltaH degrees, deltaS degrees) of adsorption. The sorption kinetics were tested for the pseudo-first-order, pseudo-second-order and intra-particle diffusion models. Good correlation coefficients were obtained for the pseudo-second-order kinetic model, showing that the nickel uptake process followed the pseudo-second-order rate expression.

Studies of lead retention from aqueous solutions using iron-oxide-coated sorbents.

In this research, experiments were conducted to study Pb(2+) sorption onto engineered iron-oxide-coated sand (IOCS) and iron-oxide-coated crushed brick (IOCB), as well as onto naturally iron-oxide-coated sand (NIOCS). Optical and scanning electron microscopy (SEM) analyses were realised to investigate the surface properties and morphology of the coated sorbents. Infrared spectroscopy and X-ray diffraction techniques were also used to characterise the sorbent structures. Adsorption of lead from synthetic aqueous solutions was investigated by batch experiments. Results show that adsorption is slightly dependent on pH. The maximum adsorption capacity obtained at pH 6 was 5, 5.5 and 2.9 mg g(-1) for IOCS, IOCB and NIOCS, respectively. Both Freundlich and Langmuir isotherms can describe experimental data. The influence of temperature on the adsorption process was also evaluated. Results indicated that adsorption of Pb(2+) on the three sorbents is endothermic. The thermodynamic parameters (DeltaG(degrees), DeltaH(degrees) and DeltaS(degrees)) for Pb(2+) sorption on all considered sorbents were also determined from the temperature dependence. All considered sorbents could be an alternative emerging technology for water treatment without any side effects or treatment process alterations. However, IOCB has the best performances due to its greater capacity for the retention of lead.

Removal of nickel and cadmium from aqueous solutions by sewage sludge ash: study in single and binary systems.

Sewage sludge ash can potentially be used for the removal of metal ions from wastewater because its chemical composition is similar to that of fly ash. The aim of this work was to investigate the adsorptive characteristics of this material, including specific surface area and pH of zero point of charge (pH zpc), and to assess the possibility of removing nickel and cadmium from aqueous solutions by this sorbent. The effects of agitation time, pH, initial metal ion concentration and temperature on the removal of these metals were studied. In order to study the sorption isotherm, two equilibrium models, the Langmuir and Freundlich isotherms, were analysed. The effect of solution pH on the adsorption on to sewage sludge ash was studied in the pH range from 2 to 8. The adsorption was endothermic and the computation of the parameters, delta H0, delta S0 and delta G0, indicated that the interactions were thermodynamically favourable. Experiments with Ni and Cd adsorption measured together showed that Cd severely interfered with Ni adsorption to sewage sludge ash and vice versa.

Adsorption of nickel and copper onto natural iron oxide-coated sand from aqueous solutions: study in single and binary systems.

Natural iron oxide-coated sand (NCS), extracted from the iron ore located in North-West of Tunisia, was employed to investigate its capacity to remove copper and nickel from aqueous solutions. The aim of this work was to characterize the considered sorbent (NCS) and to assess the possibility of removing nickel and copper from aqueous solutions by this sorbent. The effects of agitation time, pH, initial metal ion concentration and temperature on the removal of these metals were studied. In order to study the sorption isotherm, two equilibrium models, the Freundlich and Langmuir isotherms, were analyzed. The effect of solution pH on the adsorption onto NCS was studied in the pH range from 2 to 7 and 2 to 9 for copper and nickel respectively. The adsorption was endothermic and the computation of the parameters, DeltaH degrees, DeltaS degrees and DeltaG degrees, indicated that the interactions were thermodynamically favourable. Experiments with Cu and Ni adsorption measured together showed that Cu severely interfered with Ni adsorption to the NCS and vice versa under the conditions of the two coexisted ions adsorption.

Phosphorus removal from aqueous solution using iron coated natural and engineered sorbents.

New filtration materials covered with metallic oxides are good adsorbents for both cation and anion forms of pollutants. Sfax is one of the most important industrial towns in Tunisia. Its phosphate manufacture in particular is causing considerable amounts of water pollution. Therefore, there is a need to find out a new way of getting rid of this excessive phosphate from water. This work is aimed to examining the potential of three sorbent materials (synthetic iron oxide coated sand (SCS), naturally iron oxide coated sand (NCS) and iron oxide coated crushed brick (CB)) for removing phosphate ions from aqueous solutions. According to our literature survey CB was not used as adsorbent previously. Phosphate ions are used here as species model for the elimination of other similar pollutants (arsenates, antimonates). Optical microscope and scanning electron microscope (SEM) analyses were used to investigate the surface properties and morphology of the coated sorbents. Infra-red spectroscopy and X-ray diffraction techniques were also used to characterize the sorbent structures. Results showed that iron coated crushed brick possess more micro pores and a higher surface area owing to its clay nature. The comparative sorption of PO4(3-) from aqueous solutions by SCS, CB and NCS was investigated by batch experiments. The estimated optimum pH of phosphate ion retention for the considered sorbents was 5. The equilibrium data were analysed using the Langmuir and Freundlich isotherms. The sorption capacities of PO(4)3- at pH 5 were 1.5 mg/g for SCS, 1.8 mg/g for CB and 0.88 mg/g for NCS. The effect of temperature on sorption phenomenon was also investigated. The results indicated that adsorption is an endothermic process for phosphate ions removal. This study demonstrates that all the considered sorbents can be used as an alternative emerging technology for water treatment without any side effect or treatment process alteration.