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The removal of Cu2+, Ni2+, and Zn2+ 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 Cu2+ > Ni2+ > Zn2+. 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.

Natural adsorbents such as clay was used to replace expensive imported synthetic adsorbents. In this study, Scanning Electron Microscopy (SEM), Infrared spectroscopy and X-ray diffraction techniques were used to characterize the used sorbent (clays C). Batch experiments were performed to evaluate the effects of contact time, solution pH and temperature on copper removal onto used sorbent from aqueous solution. Equilibrium data were analyzed using Langmuir and Freundlich isotherm models to calculate isotherm constants. Kinetic studies showed that an equilibrium time of 1 h was required for the adsorption of Cu(II) onto Tunisian clay. Equilibrium adsorption is affected by the initial pH of the solution. The maximum adsorption capacity was obtained at pH 5. Adsorption tests in synthetic wastewater revealed that the adsorption data of this material for copper ions were better fit to the Langmuir isotherm based on correlation coefficients. The influence of temperature on the adsorption process was also evaluated. Results indicated that adsorption of Cu(II) on the sorbents is endothermic. The thermodynamic parameters (I”G°,I”H° and I”S°) for Cu(II) sorption were also determined from the temperature dependence. Results of this study suggest that used Tunisian clay may be a promising adsorbents for environmental remediation.

The contamination of soils with heavy metals is a global disaster that is related to human activities. Phytostabilization basically refers to the use of metal-tolerant plants and inexpensive mineral or organic soil amendments to reduce the concentrations or toxic effects of contaminants in the environment. Here, we tested the effects of four cost-effective amendments (CaCO3, phosphate rock, activated carbon, and exhausted olive cake ash) on Cd, Zn, and Cu leaching and uptake by ryegrass (Lolium perenne L.). The results showed that all amendments reduced Cd, Zn, and Cu leaching, mainly due to the alkalinity increase. Among all amendments tested, CaCO3 was the most effective treatment in decreasing both the heavy-metal leaching and concentrations in ryegrass shoots. Results obtained suggest the efficacy of several amendments, but further work is needed to gain insight into their possible synergetic effects.

Manganese-oxide-coated sand (MOCS) and manganese-oxide-coated crushed brick (MOCB) were characterized and employed for the removal of phosphorus ions () from aqueous solution. Scanning electron microscope (SEM), FTIR, X-ray diffraction spectrum (XRD), and BET analyses were used to study the surface properties of the sorbents. Sorption of from aqueous solutions was investigated by batch experiments. The estimated optimum pH of phosphorus ions retention for the considered sorbents was 5. Both Freundlich and Langmuir isotherms may reasonably explain adsorption of phosphorus ions. The adsorption capacities of coated sorbents obtained at pH 5 and 20°C were 1.96 and 2.08 mg/g for MOCS and MOCB, respectively. The sorption kinetics were tested for pseudo-first order and pseudo-second order reactions as well as for intraparticle diffusion model and the rate constants of the three kinetic models were calculated. The best correlation coefficients were obtained using the pseudo-second-order kinetic model, ind...

The sorption of Pb(II) ions onto activated carbon prepared from Tunisian date stones was studied in a batch process. The effects of the main parameters, such as contact time, initial concentration of Pb(II), solution pH, and temperature were studied. The kinetic data were analyzed by applying pseudo-first-order, pseudo-second-order, and Weber-Morris diffusion models. The applicability of Langmuir and Freundlich adsorption isotherms was evaluated to better understand the adsorption process. The results revealed that the equilibrium data were perfectly represented using a Langmuir isotherm. The maximum monolayer adsorption capacity was found to be 38.46 mg/g at 20°C, pH 6, contact time 120 min, and 0.5 g activated carbon. The kinetic data followed closely the pseudo-second-order model. The application of an intraparticle diffusion model revealed that the adsorption mechanism of Pb(II) is a rather complex process and that diffusion is involved in the overall rate of the adsorption process, but it is ...

Experiments were conducted to evaluate copper and nickel sorption on artificially manganese oxide-coated burned brick (MCBb), a waste by-product of brick industry. The effect of metal concentration, contact time, solution pH, and temperature on the amount of Ni(II) and Cu(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 293 K) were 2.4 mg Ni/g and 3.7 mg Cu/g for MCBb. Isotherms were also used to evaluate the thermodynamic parameters (ΔG°, ΔH°, and ΔS°) of adsorption. The sorption kinetics was tested for the pseudo-first order, pseudo-second order, and intraparticle diffusion models. Good correlation coefficients were obtained for the pseudo-second-order kinetic model, showing that nickel and copper uptake process followed the pseudo-second-order rate expression. © 2011 American Institute of Chemical Engineers Environ Prog, 2011

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.

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.

Manganese oxide-coated sand (MOCS) and manganese oxide-coated crushed brick (MOCB) were characterized and employed for the removal of Pb(II) ions from aqueous solution. Scanning electron microscopy (SEM), FT-IR, X-ray diffraction (XRD) methods and BET analyses were used to study the surface properties of the adsorbents. Adsorption of Pb(II) ions from aqueous solutions was investigated by batch experiments. The estimated optimum pH for Pb(II) ion retention by the considered adsorbents was 5. Both the Freundlich and Langmuir isotherms provided a reasonable fit to the experimental data for the adsorption of Pb(II) ions. The adsorption capacities of the coated adsorbents at a pH value of 5 and a temperature of 20 °C were 0.029 mmol/g and 0.030 mmol/g for MOCS and MOCB, respectively. The adsorption kinetics were tested using the pseudo-first-order and pseudo-second-order equations as well as the intraparticle diffusion model, with the rate constants from the three kinetic models being calculated. The best correlation coefficients were obtained using the pseudo-second-order kinetic model. Results from this study suggest that the manganese oxide-coated sorbent is potentially suitable for the removal of Pb(II) ions from aqueous solutions.

The removal characteristics of cadmium (Cd(II)) and nickel (Ni(II)) ions from aqueous solution by exhausted olive cake ash (EOCA) were investigated under various conditions of contact time, pH, initial metal concentration and temperature. Batch kinetic studies showed that an equilibrium time of 2 h was required for the adsorption of Ni(II) and Cd(II) onto EOCA. Equilibrium adsorption is affected by the initial pH (pH0) of the solution. The pH0 6.0 is found to be the optimum for the individual removal of Cd(II) and Ni(II) ions by EOCA. The adsorption test of applying EOCA into synthetic wastewater revealed that the adsorption data of this material for nickel and cadmium ions were better fitted to the Langmuir isotherm since the correlation coefficients for the Langmuir isotherm were higher than that for the Freundlich isotherm. The estimated maximum capacities of nickel and cadmium ions adsorbed by EOCA were 8.38 and 7.32 mg g−1, respectively. The thermodynamic parameters for the adsorption process data were evaluated using Langmuir isotherm. The free energy change (ΔG°) and the enthalpy change (ΔH°) showed that the process was feasible and endothermic respectively. As the exhausted olive cake is discarded as waste from olive processing, the adsorbent derived from this material is expected to be an economical product for metal ion remediation from water and wastewater.

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.

The use of natural adsorbent such as phosphate rock to replace expensive imported synthetic adsorbent is particularly appropriate for developing countries such as Tunisia. In this study, the removal characteristics of lead, cadmium, copper and zinc ions from aqueous solution by activated phosphate rock were investigated under various operating variables like contact time, solution pH, initial metal concentration and temperature. The kinetic and the sorption process of these metal ions were compared for phosphate rock (PR) and activated phosphate rock (APR). To accomplish this objective we have: (a) characterized both (PR) and (APR) using different techniques (XRD, IR) and analyses (EDAX, BET-N(2)); and, (b) qualified and quantified the interaction of Pb(2+), Cd(2+), Cu(2+) and Zn(2+) with these sorbents through batch experiments. Initial uptake of these metal ions increases with time up to 1h for (PR) and 2h for (APR), after then, it reaches equilibrium. The maximum sorption obtained for (PR) and (APR) is between pH 2 and 3 for Pb(2+) and 4 and 6 for Cd(2+), Cu(2+) and Zn(2+). The effect of temperature has been carried out at 10, 20 and 40 degrees C. The data obtained from sorption isotherms of metal ions at different temperatures fit to linear form of Langmuir sorption equation. The heat of sorption (DeltaH degrees), free energy (DeltaG degrees) and change in entropy (DeltaS degrees) were calculated. They show that sorption of Pb(2+), Cd(2+), Cu(2+) and Zn(2+) on (PR) and (APR) an endothermic process. These findings are significant for future using of (APR) for the removal of heavy metal ions from wastewater under realistic competitive conditions in terms of initial heavy metals, concentrations and pH.

In the present work, the abilities of sewage sludge and pomace ashes to remove copper (Cu(2+)) ions from aqueous solutions are compared. Batch adsorption experiments were performed in order to evaluate the removal efficiency of these materials. Effect of contact time, solution pH, ash concentration and temperature on the removal of Cu(2+) was investigated. The results of batch equilibrium studies showed that the solution pH was the key factor affecting the adsorption characteristics. In general, the amount of Cu removed increased as the solid concentration and pH increased, and then it remained constant over a wide pH region. The adsorption test of applying sewage sludge and pomace ashes into synthetic wastewater revealed that the adsorption data of these materials for copper ions were better fitted to the Langmuir isotherm since the correlation coefficients for the Langmuir isotherm were higher than that for the Freundlich isotherm. The estimated maximum capacities of copper adsorbed by sewage sludge and pomace ashes were 5.71 and 6.98 mg g(-1), respectively. Experimental results indicated that the adsorption was favorable at higher pH and higher temperature. Values of DeltaG degrees ranging from -4.64 to -5.13 kcal mol(-1) for sewage sludge ash and from -4.97 to -5.53 kcal mol(-1) for pomace ash suggest that the adsorption reaction is a physical process enhanced by the electrostatic effect. The values of DeltaH degrees and DeltaS degrees are, respectively, 4.27 kcal mol(-1) and 30.6 cal K(-1)mol(-1) for sewage sludge ash and 4.33 kcal mol(-1) and 31.3 cal K(-1)mol(-1) for pomace ash. The mechanisms of copper removal by these materials included adsorption and precipitation. The sewage sludge and pomace ashes are shown to be effective adsorbents for this metal.

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 PO 4 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.