A study of the adsorption of Fe (III) ions on natural sand collected from a tank in Ramanathapuram, India (original) (raw)
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IOP Conference Series: Materials Science and Engineering, 2019
After the water adsorption process, the content of Fe (II) ion meets drinking water standard below 0.3 ppm. Based on the kinetic indicator of the absorption coefficient of correlation (R2), the adsorption rate constant k1 and k2 and the calculated qe and qe extrapolation data can be concluded the content of Fe (II) ions in groundwater above 0.3 ppm can cause serious problems for human health. A relatively effective, efficient, safe, environmentally friendly separation method is the adsorption method. The mechanism of adsorption of Fe (II) ions in the well water can be studied using pseudo-first-order and pseudo-second-order. Based on the experimental design, fixed variables consisted of 50 g of adsorbent, 20 mesh particle size, 10-liter adsorbate volume, 4liters/min flow rate and operating temperature at room temperature. The independent variable consists of contact time and the type of treatment of the adsorbent. Variation of contact time 0; 30; 60; 90; 120; 150; 180; 210; 240 minu...
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The present work investigates the removal of Fe(III) ions from an aqueous solution by kaolinite, montmorillonite and their acid activated forms. The specific surface areas of kaolinite, acid activated kaolinite, montmorillonite and acid activated montmorillonite were 3.8, 15.6, 19.8 and 52.3 m 2 /g respectively whereas the cation exchange capacity (CEC) was measured as 11.3, 12.2, 153.0, and 341.0 meq/100 g for four clay adsorbents respectively. Adsorption increased with pH till Fe(III) became insoluble at pH > 4.0. The kinetics of the interactions is not certain, but the second order kinetics (k 2 = 4.7 × 10 −2 to 7.4 × 10 −2 g mg −1 min −1 ) appears to give a better description. Langmuir and Freundlich isotherms were applied and isotherm coefficients were computed. The Langmuir monolayer capacity of the clay adsorbents was from 11.2 to 30.0 mg g −1 . The process was exothermic with H in the range of −27.6 to −42.2 kJ mol −1 accompanied by decrease in entropy ( S = −86.6 to −131.8 J mol −1 K −1 ) and decrease in Gibbs energy. The results have shown that kaolinite, montmorillonite and their acid activated forms could be used as adsorbents for separation of Fe(III) from aqueous solution. Acid activation enhanced the adsorption capacity compared to the untreated clay minerals.
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Water pollution by heavy metal ions has become a serious environmental issue especially due to their toxicity and tendency to bioaccumulation. Natural smectite clay was treated using sulfuric acid to improve its adsorption capacity for the removal of iron ions from aqueous solutions. The results showed that adsorption was favoured at pH 3 and room temperature. Experimental adsorption capacity of Fe(III) is 12.86 mg/g and 19.25 mg/g for natural and acid-activated clay, respectively. From all of our data, we conclude that the treated clay by sulfuric acid investigated in this study showed a good potential for iron removal from aqueous solutions.
Chemosphere, 2000
This study was conducted to develop a heating process for coating hydrated iron oxide on the sand surface to utilise the adsorbent properties of the coating and the ®ltration properties of the sand. BET and scanning electron microscope (SEM) analyses were used to investigate the surface properties of the coated layer. An energy dispersive X-ray (EDAX) technique of analysis was used for characterising metal adsorption sites on the iron-coated sand surface. The results indicated that the iron-coated sand had more micropores and higher speci®c surface area because of the attachment of iron oxide. Copper ions could penetrate into the micropores and mesopores of iron oxide on sand surface, and the regeneration of the iron-coated sand could be achieved by soaking with pH 3.0 acid solution. Besides, the results of EDAX analysis showed that copper ions were chemisorbed on the surface of iron-coated sand. Results of the study developed an innovative technology for coating iron oxide on sand surface for the treatment of heavy metal in water.
Adsorption of As(III) from aqueous solutions by iron oxide-coated sand
Journal of Colloid and Interface Science, 2005
Arsenic is a toxic element and may be found in natural waters as well as in industrial waters. Leaching of arsenic from industrial wastewater into groundwater may cause significant contamination, which requires proper treatment before its use as drinking water. The present study describes removal of arsenic(III) on iron oxide-coated sand in batch studies conducted as a function of pH, time, initial arsenic concentration, and adsorbent dosage. The results were compared with those for uncoated sand. The adsorption data fitted well in the Langmuir model at different initial concentration of As(III) at 20 g/l fixed adsorbent dose. Maximum adsorption of As(III) for coated sand is found to be much higher (28.57 µg/g) than that for uncoated sand (5.63 µg/g) at pH 7.5 in 2 h. The maximum As(III) removal efficiency achieved is 99% for coated sand at an adsorbent dose of 20 g/l with initial As(III) concentration of 100 µg/l in batch studies. Column studies have also been carried out with 400 µg/l arsenic (pH 7.5) by varying the contact time, filtration rate, and bed depth. Results of column studies demonstrated that at a filtration rate of 4 ml/min the maximum removal of As(III) observed was 94% for coated sand in a contact time of 2 h. The results observed in batch and column studies indicate that iron oxide-coated sand is a suitable adsorbent for reducing As(III) concentration to the limit (50 µg/l) recommended by Indian Standards for Drinking Water. 2005 Elsevier Inc. All rights reserved.
SORPTION OF Fe IONS IN AQUEOUS MEDIUM BY LATERITE CLAY: A STUDY OF pH DEPENDENCY
Laterite soil was found to be an essential material for ion sorption from aqueous solutions. This study focuses on investigating the pH dependency on sorption of Fe ions using laterite by a series of batch experiments. Basic physical and chemical parameters of laterite were measured to characterize the material. The X-ray diffraction (XRD) analyses of laterite show goethite, gibbsite, and hematite as the major secondary minerals with minor occurrences of kaolinite. In the experimental design, 20 g/L adsorbate of raw laterite was used for each batch reaction. In each experiment, a 100 ml of Fe solutions (40 ppm) was reacted with the adsorbate under a range of pH levels (1-9). Samples were analyzed for removal performances at different intervals for a five-hour reaction time. Results revealed that under acidic conditions (pH < 5), Fe removal efficiencies were very low (< 1.5 %) even after 5-hours, and Fe removal efficiencies from slightly acidic to neutral pH (5 ≤ pH ≥ 7) showed diverse variation (1.5 ≤ efficiency ≥ 100 %). However, under the basic condition (pH ≤ 7), very high Fe removal efficiencies (80-100 %) were reached within a short time. The experiment further revealed that no leaching of similar behavioral elements such as Zn, Cu, Ni, Cd, and Mn from laterite to solution occurred during the Fe sorption, which may indicate absence of iron exchange activities. Results concluded that the duration of reaction time has a strong relationship with the removal performances from acidic to basic conditions and highly acidic conditions promote dissolution of Fe ions from laterites, while basic pH facilitates the sorption.
This study was undertaken to evaluate the performance of iron oxide coated sand (IOCS) as an adsorbent for the removal of heavy metals (Mn, Fe and As) from groundwater. The main parameters affecting this treatment process were examined namely the adsorbent dose, different adsorbent types and flow rate. Riverbed sand of 0.5-0.85mm was collected, dried and coated with iron oxide. The coated sand was used as an adsorbent for the removal of Iron, Manganese and Arsenic from groundwater in column experiment. The uncoated sand was used as a control. The initial concentrations of Fe, Mn and As of raw groundwater collected from Bayelsa State of Nigeria, were found to be 5.423ppm for Fe, 0.092ppm for Mn and 0.001ppm for Arsenics. The water sample was spiked with 0.715ppm Arsenic to assess the efficiency of the adsorbent in removing heavy metals. The result showed that IOCS is a good adsorbent as compared with the uncoated sand (UCS). For the removal of Arsenic, it was observed that Arsenic was reduced from 0.715ppm to 0.020 ppm for IOCS and 0.073ppm for UCS. The adsorption of Iron (Fe) and Manganese (Mn) were found to increase with decreasing flow rate from 25ml to 5ml per minute respectively. Also, it was observed that as dosage of adsorbent increases, there was an increase in the percentage adsorption of Iron and Manganese from 5g to 25g adsorbent. In summary the coated sand showed better removal efficiency when compared to uncoated sand. Therefore, the column experiment demonstrated that heavy metals (Fe, Mn and As) can be effectively removed from groundwater using locally produced coated sand. The use of coated sand for heavy metal removal is far better than uncoated sand and that the study has shown that the locally produced adsorbent is not only for treatment of drinking water but also waste water and industrial affluent.
Modelling arsenic(III) adsorption from water by sulfate-modified iron oxide-coated sand (SMIOCS)
Journal of Chemical Technology & Biotechnology, 2003
A medium developed by coating BaSO 4 and Fe on quartz sand known as sulfate-modified iron oxide-coated sand (SMIOCS) was evaluated for the removal of arsenic(III) from simulated water with an ionic strength of 0.01 M NaNO 3 during batch studies. The medium was characterised for BET surface area, alkali-resistance, acid-resistance and the presence of iron and barium on the coated surface. Two simplified kinetic models, ie active available site (AAS) and chemical reaction rate models, were tested to investigate the adsorption mechanisms. The values of rate constants for both the models were found to decrease with increasing As(III) concentrations in the solute. The inverse relationship of rate constants of the reaction rate model with BET surface area showed that As(III) adsorption on SMIOCS was not due to physisorption but to chemisorption. A study of the effect of solute temperature showed that the adsorption of As(III) on SMIOCS media was due to chemisorption. The results of isothermal studies conducted at different pH values showed that adsorption data satisfied both the Langmuir and the Freundlich isotherm models. The adsorption of As(III) on the medium was pH dependent and maximum removal was observed in the pH range of 7-9.
Removal of iron and arsenic (III) from drinking water using iron oxide-coated sand and limestone
Applied Water Science, 2013
A method for removal of iron and arsenic (III) from contaminated water using iron oxide-coated sand and limestone has been developed for drinking water. For the intended use, sand was coated with ferric chloride and used as filtering media. Limestone was added onto the coated sand and the effect of limestone addition on removal efficiency of iron and arsenic was monitored. Both batch and column experiments were conducted to investigate the efficiency of coated sand and limestone as filtering media. Maximum removal of iron (99.8 %) was obtained with coated sand at a dose of 5 g/100 ml and by adding 0.2 g/ 100 ml of limestone at pH 7.3. Arsenic (III) removal efficiency increased with the increased dose of coated sand and was best removed at pH 7.12. The maximum adsorption capacity for arsenic (III) obtained from Langmuir model was found to be 0.075 mg/g and the kinetics data followed pseudo-first order better than pseudo-second order. Energy dispersive X-ray analysis and FT-IR study proved the removal of iron and arsenic. Column experiment showed removal of iron and arsenic (III) to\0.3 mg/l and 10 lg/l, respectively, from an initial concentration of 20 mg/l (iron) and 200 lg/l (arsenic).