Use of fly ash and fly ash agglomerates for As(III) adsorption from aqueous solution (original) (raw)
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Removal of Arsenic(III) from Aqueous Solutions by Adsorption onto Fly Ash
Asian Journal of Chemistry, 2017
In this work, the ability of fly ash in removing arsenic(III) ions from aqueous solution was considered. The effect of contact time, initial As(III) concentration, fly ash dosage, stirring speed, solution pH and temperature was investigated on the adsorption rate. Experimental studies showed that the adsorption fitted well the pseudo-second order kinetic, while the equilibrium study showed that the sorption of As(III) ions onto fly ash fitted the Langmuir and Freundlich isotherms. The adsorption process is endothermic and spontaneous. Moreover, the maximum percentage removal of As(III) achieved with approx. 2.5 g fly ash mixed with 25 mL of 100 mg/L As(III) solution was 65.4 % at pH 10, 60 min contact time, temperature of 353 K and a stirring speed of 120 rpm.
Application of fly ash agglomerates in the sorption of arsenic
Polish Journal of Chemical Technology, 2007
The scope of this contribution was to investigate in detail an application of fly ash adsorbent for the removal of arsenite ions from a dilute solution. The experiments have been carried out using fly ash from black coal burning power plant "Siersza" and brown coal burning power plant "Turów" (Poland), which was wetted, then mixed and tumbled in the granulator with a small amount of cement to increase the mechanical strength of agglomerates. The measurements of arsenic adsorption from the aqueous solution were carried out in the flask (with shaking), as well as in the column (with circulation), in order to compare two different methods of contacting waste with adsorbent. The adsorption isotherms of arsenic were determined for granulated material, using the Freundlich model. Kinetics studies indicated that the sorption follows a pseudo-first-order (PFO) model (Lagergren) and the Elovich-type model.
Use of fly ash agglomerates for removal of arsenic
Environmental Geochemistry and Health, 2010
The aim of this work is to investigate the application of fly ash adsorbent for removal of arsenite ions from dilute solution (100-1,000 ppm). Experiments were carried out using material from the ''Turów'' (Poland) brown-coal-burning power plant, which was wetted, then mixed and tumbled in a granulator to form spherical agglomerates. Measurements of arsenic adsorption from aqueous solution were carried out at room temperature and natural pH of fly ash agglomerates, in either a shaken flask or circulating column, to compare two different methods of contacting solution with adsorbent. Adsorption isotherms of arsenic were determined for agglomerated material using the Freundlich equation. Kinetic studies indicated that sorption follows a pseudosecond-order model. Preferable method to carry out the process is continuous circulation of arsenite solution through a column.
Arsenic adsorption from groundwater using non-toxic waste as adsorbent
DESALINATION AND WATER TREATMENT
Millions of people in the world are exposed to arsenic-contaminated groundwater. To decrease the concentration of arsenic in water, adsorption of arsenic was performed on a simple and easily available material, that is, eggshell. Powdered eggshell (ES) was prepared and was characterized by using Brunauer-Emmett-Teller, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy, and energy-dispersive X-ray spectroscopy (EDX). It was revealed from FTIR and EDX that the presence of CaCO 3 in ES is the major reason for arsenic adsorption. Removal of As(III) and As(V) as a function of the adsorbent dose, pH, contact time, and agitation speed were studied. The adsorption capacity is strongly influenced by the pH of the solution. ES removed 68.54% of As(III) and 72.01% of As(V) under optimum conditions from 2 mg/L As(III) and As(V) solutions. ES was also carbonized at 700°C, and it could remove 70.09% of As(III) and 76.44% of As(V) under similar conditions. Adsorption isotherms and kinetics were determined for As(III) and As(V). As(III) adsorption followed the Langmuir isotherm, revealing monolayer adsorption. As(V) adsorption followed the Freundlich isotherm, revealing multilayer adsorption. Similarly, adsorption of As(III) and As(V) on carbonized eggshell followed pseudo-second-order kinetics and on ES followed Elovich kinetics, both suggesting that the adsorption process is a chemisorption process. Also, the study of the intraparticle diffusion model concluded that there was surface adsorption along with an intraparticle diffusion mechanism during the adsorption of arsenic. The best isotherm and kinetic models were selected, based on the error values using the chi-square test, root mean square error, and average percentage error.
Applied Geochemistry, 2009
Batch and column experiments were conducted on As adsorption from aqueous solution by natural solids to test the feasibility of these materials to act as adsorbents for As removal from groundwater and drinking water. The solids considered are natural hematite and natural siderite. The As species studied are As(V), As(III) and dimethylarsinic acid (DMA). Arsenic(III), As(V) and DMA were removed to different extents by the solids studied from water solutions containing these three As species, with the highest efficiency for As(V). In aqueous solutions with a mixture of As species, adsorption kinetics depend on the species. On both materials, As(V) was preferentially adsorbed in the batches and first reached equilibrium, followed by DMA and As(III). The As adsorption took place more slowly on natural hematite and natural siderite compared with ferrihydrite. The results demonstrate that the amount of As removed from As(III) batches was greater than that from As(V) batches due to a surface alteration of the solids caused by As(III) oxidation. Although the highest efficiency for As retention was observed on hematite HIO1 in the batch experiments, siderite used as column filling was more efficient in removing As from water containing the As species studied in comparison with hematite. The coating of fresh Fe(III)-oxides was much more intensive in the siderite-packed column than in the hematite-packed column. The combination of siderite and hematite would promote the column filling performance in removing As from aqueous solution.
Removal of arsenic species from water by batch and column operations on bagasse fly ash
2013
Bagasse fly ash (BFA, a sugar industrial waste) was used as low-cost adsorbent for the uptake of arsenate and arsenite species from water. The optimum conditions for the removal of both species of arsenic were as follows: pH 7.0, concentration 50.0 μg/L, contact time 50.0 min, adsorbent dose 3.0 g/L, and temperature 20.0°C, with 95.0 and 89.5 % removal of arsenate and arsenite, respectively. The Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich adsorption isotherms were used to analyze the results. The results of these models indicated single-layer uniform adsorption on heterogeneous surface. Thermodynamic parameters, i.e., ΔG°, ΔH°, and ΔS°, were also calculated. At 20.0 to 30.0°C, the values of ΔG°lie in the range of −4,722.75 to −4,878.82 and −4,308.80 to −4,451.73 while the values of ΔH°and ΔS°were −149.90 and −121.07, and 15.61 and 14.29 for arsenate and arsenite, respectively, indicating that adsorption is spontaneous and exothermic. Pseudo-first-order kinetics was followed. In column experiments, the adsorption decreased as the flow rate increased with the maximum removal of 98.9 and 95.6 % for arsenate and arsenite, respectively. The bed depth service time and Yoon and Nelson models were used to analyze the experimental data. The adsorption capacity (N o) of BFA on column was 3.65 and 2.98 mg/cm 3 for arsenate and arsenite, respectively. The developed system for the removal of arsenate and arsenite species is economic, rapid, and capable of working under natural conditions. It may be used for the removal of arsenic species from any contaminated water resources.
2008 Adsorption of arsenic(V) onto fly ash A speciation-based approach (Wang).pdf
Arsenic (As) poses a significant water quality problem and challenge for the environmental engineers and scientists in the world. The large volume of coal fly ash produced around the world is a potentially significant anthropogenic source of arsenic. Currently the leaching behavior of arsenic from fly ash is not well understood. Batch methods were used in this study to investigate arsenic leaching using a raw ash, and arsenic adsorption using a clean, washed ash. Experimental results indicated that pH had a significant effect on arsenic leaching or adsorption. Between pH 3 and 7, less arsenic was in the dissolved phase. When pH was less than 3 or greater than 7, increasing amounts of arsenic were leached or desorbed from fly ash. The leaching and adsorption behavior of arsenic was interpreted with the speciation of surface sites and arsenic. In a new approach, a speciation-based model was developed to quantify the arsenic adsorption as a function of pH and surface acidity parameters. This work is important in offering insight into the leaching mechanism of arsenic from coal fly ash, and providing a robust model based upon specific, measurable parameters to quantify arsenic adsorption by other solid media in addition to fly ash.
2008a Adsorption of arsenic(V) onto fly ash A speciation-based approach (Wang).pdf
Arsenic (As) poses a significant water quality problem and challenge for the environmental engineers and scientists in the world. The large volume of coal fly ash produced around the world is a potentially significant anthropogenic source of arsenic. Currently the leaching behavior of arsenic from fly ash is not well understood. Batch methods were used in this study to investigate arsenic leaching using a raw ash, and arsenic adsorption using a clean, washed ash. Experimental results indicated that pH had a significant effect on arsenic leaching or adsorption. Between pH 3 and 7, less arsenic was in the dissolved phase. When pH was less than 3 or greater than 7, increasing amounts of arsenic were leached or desorbed from fly ash. The leaching and adsorption behavior of arsenic was interpreted with the speciation of surface sites and arsenic. In a new approach, a speciation-based model was developed to quantify the arsenic adsorption as a function of pH and surface acidity parameters. This work is important in offering insight into the leaching mechanism of arsenic from coal fly ash, and providing a robust model based upon specific, measurable parameters to quantify arsenic adsorption by other solid media in addition to fly ash.
Adsorption of arsenic(V) onto fly ash: A speciation-based approach
Chemosphere, 2008
Arsenic (As) poses a significant water quality problem and challenge for the environmental engineers and scientists in the world. The large volume of coal fly ash produced around the world is a potentially significant anthropogenic source of arsenic. Currently the leaching behavior of arsenic from fly ash is not well understood. Batch methods were used in this study to investigate arsenic leaching using a raw ash, and arsenic adsorption using a clean, washed ash. Experimental results indicated that pH had a significant effect on arsenic leaching or adsorption. Between pH 3 and 7, less arsenic was in the dissolved phase. When pH was less than 3 or greater than 7, increasing amounts of arsenic were leached or desorbed from fly ash. The leaching and adsorption behavior of arsenic was interpreted with the speciation of surface sites and arsenic. In a new approach, a speciation-based model was developed to quantify the arsenic adsorption as a function of pH and surface acidity parameters. This work is important in offering insight into the leaching mechanism of arsenic from coal fly ash, and providing a robust model based upon specific, measurable parameters to quantify arsenic adsorption by other solid media in addition to fly ash.
Removal of arsenic from water by different adsorbents
Indian Journal of Chemical Technology, 2004
Present study is carried out for the removal of As(III) from water using commonly available adsorbents such as sand, from Yamuna river ( Delhi ), as well as from Ganga river (Kolkata), activated carbon, Hametite ore and sand -iron scrap mixture. All these adsorbents are used as received but sand and activated carbon which do not show much adsorption for As(III) are modified by treating with different metal ions in order to improve their adsorption efficiency. Results of the laboratory experiments under static conditions have confirmed that iron impregnated granular activated carbon (GAC), spherical activated carbon (SAC) as well as sand - iron scrap mixture have much promise as a medium for the removal of As(III) in drinking water. Various parameters like adsorbent dose, contact time, pH and arsenic concentration are optimized. A simple and economical domestic arsenic removal kit has been designed and successfully evaluated in the laboratory using sand-iron scrap mixture as media fo...