The Potential Use of Low-Grade Phosphate Rocks as Adsorbent (original) (raw)
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Oriental Journal of Chemistry
The capacity of using WPR as an unused future adsorbent for the elimination of copper ions from synthetic watery solution was carried out in batch mode. The adsorption ability of Cu2+ by WPR was estimated in accordance with: initial concentration, time of contact, temperature and pH. The temperature rise resulted a higher adsorption of Copper ions by the waste of phosphate rock (WPR). The data collected was tested by using Langmuir and Freundlich isotherms. The non-linear regression procedure was the way to obtain the parameters of adsorption isotherms. The errors analysis was finalized to find out if the model was best to adapt with the experimental protocol. In the light of the obtained results and the various previous researches carried out and published in this sense, the different conclusions were proposed about the adsorption mechanism. The thermodynamic parameters were estimated. The ΔH of adsorption was positive so the process is endothermic and ΔG was negative Therefore the...
Study of adsorptive removal of copper (II) capacity from aqueous solutions on phosphates
2014
Natural products like phosphates have varied physico-chemical and textural properties. They are able of establishing connections with various sizes of organic or inorganic molecules. Recent studies showed that these materials in the natural or synthetic state can eliminate many compounds present in waste water. In this work, we have tried to estimate the efficiency of elimination of copper by adsorption on natural phosphates and synthetic materials. Activated carbon is used as a reference. The kinetics of adsorption is followed by UV-visible spectroscopy. Several parameters are controlled and studied using experimental design (pH, temperature and the initial concentration of pollutant and phosphates). Physical treatment is made to increase the adsorption capacity of these materials. The obtained results show that the adsorption follow Langmuir model and the capacity of adsorption of these materials is equal to the activated carbon.
Texila International Journal of Academic Research, 2022
Heavy metal pollution of water bodies is a common problem in Zambia, whose economy depends on copper mining. Removal of Cu 2+ ions from the solution via adsorption using iron oxide ore was investigated. The composition of the adsorbent was determined by XRF and ICP-OES. Iron oxide had predominantly Fe2O3 at 60 % with less than 3% of SiO2 and Al2O3. The Cu 2+ ion concentrations were measured before and after adsorption using Atomic Absorption Spectroscopy (AAS). The effects of initial concentration, pH, acid activation, and thermal activation of the adsorbent on adsorption were investigated. A decrease in the adsorption of Cu 2+ ions with an increase in the initial concentration of adsorbate (Cu 2+) was observed. The adsorption of Cu 2+ ions on acid-activated Iron oxide compared to thermally activated iron oxide ranged from 83-73%, respectively. Adsorption of Cu 2+ ions was pH dependent with an optimum pH of 7. Acid activation of the adsorbent had better absorptivity since acids cause mineral dissolution, which increases the surface area and porosity of the adsorbent. Iron Oxide adsorbents have the potential to the removal of Cu 2+ ions from aqueous solutions.
Heavy metal removal from aqueous solutions by activated phosphate rock
Journal of Hazardous Materials, 2008
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 1 h for (PR) and 2 h 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 • 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 ( H • ), free energy ( G • ) and change in entropy ( S • ) were calculated. They show that sorption of Pb 2+ , Cd 2+ , Cu 2+ and Zn 2+ on (PR) and (APR) an endothermic process.
Treated Martil sand (TMS) is proposed as a mineral sorbent for removal of copper ions from aqueous solutions. TMS was characterized by different techniques such as XRF, XRD, FTIR, SEM, and BET. The effects of pH, adsorbent dosage, ionic strength, temperature, and contact time were investigated. Binding Cu(II) was found to be highly pH dependent. The thermodynamic analysis indicated that the adsorption was endothermic and the computation of the parameters, H°, S° and G°, indicated that the interaction was thermodynamically favorable. In general, the results indicated that TMS is suitable as a sorbent material for adsorption of Cu(II) from aqueous solutions for its high effectiveness and low cost.
Zinc and cadmium adsorption on low-grade phosphate
Separation and Purification Technology, 2004
An attempt was made to utilize low-grade phosphate (LGP) as an adsorbent for Zn 2+ and Cd 2+ over a range of initial metal ions concentrations (10-50 ppm), agitation time (5-210 min), adsorbent concentration (1-7 g/l) and pH (2-6). Adsorption of both Zn 2+ and Cd 2+ increased with increased LGP concentration and reached maximum uptake at 5 g/l and pH between 4 and 6 for both metal ions. The amount adsorbed increases with time and initial metal concentrations for both metal ions. The equilibrium time was achieved for both metal ions after 30 min. The process of uptake obeys both the Langmuir and Freundlich isotherms. The affinity of LGP for H + is considerably higher than for Zn 2+ and Cd 2+ . The equilibrium uptake of zinc ions decreases with the increase in the initial cadmium ions concentration and that of cadmium ions decreases as the initial zinc ions concentration increases. Desorption of LGP with 0.1 N H 2 SO 4 was done for three cycles successfully.
The extraction of metals from supports based on calcium phosphate was investigated; we conducted experiments with metal solutions at various concentrations, and using two carriers' calcium phosphate hydroxyapatite and hydroxyapatite in the presence of polyethylene glycol polymer. The results show a metal retention of selectivity with excellent yields. The kinetic study shows that the extraction equilibrium is fast for both matrices used. The present work relates to the adsorption of metal ions of cadmium, cobalt and copper. The adsorptive capacity of calcium phosphates been interpreted in terms of adsorption isotherms by exploiting both the Langmuir and Freundlich model. The highest adsorption quantities are improved out in the presence of PEG and reached 0.7 mmol / g, 0.66 mmol / g and 0.62 mmol / g respectively for the cadmium, copper and cobalt.
Chemical Engineering Journal, 2009
The influence of equilibration conditions and hydroxyapatite (HAP) physico-chemical properties onto retention of Cu 2+ ions was studied in batch conditions. The amount of cation removed from the solution increased with increasing pH, reaching almost 100% at pH 3, 4 and 7 for 5 × 10 −4 , 10 −3 and 5 × 10 −3 mol/dm 3 solutions, respectively. Contact time necessary for reaching equilibrium was found to increase with the increase of Cu 2+ concentration. Kinetic and equilibrium data were best described by pseudo-second-order kinetic model and Langmuir theoretical model. The calculated values of separation factors and Gibbs free energy change confirmed that the sorption was spontaneous and thermodynamically feasible at room temperature. The experiments conducted using HAP samples with different physico-chemical characteristics have revealed that the amounts of sorbed Cu 2+ depended mainly on the specific surface area and crystallinity of the applied powders. Desorption of Cu 2+ was more efficient in acidic conditions than in the solution of competing cation-Ca 2+ . The samples with higher sorption capacities also demonstrated higher stability; consequently, from the aspects of both higher sorption and lower desorption, utilization of low-crystalline HAP samples with high specific surface area was superior for immobilization of Cu 2+ ions. Taking into account molar Cu/Ca ratios, observed final pH changes, copper speciation in the function of pH and the results of X-ray diffraction analyses, conclusions about sorption mechanisms at different experimental conditions were derived.
Removal of copper (II) from aqueous solution by adsorption onto low-cost adsorbents
Journal of Environmental Management, 2008
The use of low-cost adsorbents was investigated as a replacement for current costly methods of removing metals from aqueous solution. Removal of copper (II) from aqueous solution by different adsorbents such as shells of lentil (LS), wheat (WS), and rice (RS) was investigated. The equilibrium adsorption level was determined as a function of the solution pH, temperature, contact time, initial adsorbate concentration and adsorbent doses. Adsorption isotherms of Cu (II) on adsorbents were determined and correlated with common isotherm equations such as Langmuir and Freundlich models. The maximum adsorption capacities for Cu (II) on LS, WS and RS adsorbents at 293, 313 and 333 K temperature were found to be 8. 977, 9.510, and 9.588; 7.391, 16.077, and 17.422; 1.854, 2.314, and 2.954 mg g À1 , respectively. The thermodynamic parameters such as free energy (DG 0 ), enthalpy (DH 0 ) and entropy changes (DS 0 ) for the adsorption of Cu (II) were computed to predict the nature of adsorption process. The kinetics and the factors controlling the adsorption process were also studied. Locally available adsorbents were found to be low-cost and promising for the removal of Cu (II) from aqueous solution. r