Papers by Keyword: Adsorption Isotherm

Abstract: In this study the performance of regenerated spent carbon for azo dye removal was evaluated in batch and continuous column. The spent carbon was generated by thermal method through pyrolysis process and chemical method by using NaOH 6.0 M solution. Reactive Red 120 (RR120) was selected as a model of azo dye due to its common application in the industries. The regeneration of spent granular activated carbon (GAC) by pyrolysis could produce adsorbent that has the adsorption capacity closer to new GAC. The result indicated that paralysed GAC could potentially apply to replace new GAC for RR120 adsorption. In addition, the continuous adsorption operation in mini column test confirmed that the order of adsorption capacity of each GAC is as follows: new GAC, pirolysed GAC, chemical treated GAC and spent GAC.

Abstract: Adsorption experiments of carbon dioxide (CO₂) were contacted on two coal samples from Sungai Buloh and Silantek mines in Malaysia. A fixed bed adsorption unit was used to determine CO₂ adsorption capacity of the coal samples. The experiments were conducted at different pressure ranges (5-40 bar) and temperature at 25°C. The CO₂ adsorption capacity of Silantek coal sample showed adsorption capacity of 4.178 mmol/g at 40 bars and 25 °C, which is higher than Sungai Buloh sample. Different adsorption isotherms were employed to examine the experimental results, Langmuir isotherm of Silantek coal sample illustrated better correlation than Freundlich isotherm for the same sample. In contrary, Freundlich isotherm of Sungai Buloh coal sample illustrated better fitting than Longmuir isotherm correlation for the same sample. This is related to the coal rank and moisture content and ash content.

Abstract: Solution pH plays an important criterion in the biosorption system in ensuring optimum uptake of heavy metal by a biomass is achieved at the highest performance. In this study, the biosorption of lead (II) ions by the non-living biomass of P. Amaryllifolius Roxb is performed at various pH from acidic to alkaline conditions. Results show that the optimum pH for the removal of lead (II) ions from wastewater occurs at pH 5, whereby the sorption activity occurs through monolayer process as it follows the Langmuir isotherm. High removal percentage of the metal ions at various concentrations further emphasize on the viability of P. amaryllifolius Roxbto be utilized as a green resources in the wastewater treatment.

Abstract: In the paper is presented calculation of hygric properties of hollow brick block. Namely it is adsorption isotherm, water vapour diffusion resistance factor and moisture diffusivity. The brick block cavities was filled only by air. In first step the properties of brick body were measured. Then the properties of the whole brick block were calculated by using homogenisation techniques.

Abstract: In this paper, water vapor adsorption in sandstone is analyzed using different measurement setting of dynamic vapor sorption device. Basic physical properties of tested material are determined. The vapor sorption is measured using different experimental time and dm/dt setting. It is shown that the device setting can influence the results of equilibrium moisture content in high relative humidities, whereas the differences are of about 20%. The measurement also indicates that the difference in hysteresis can be up to 50% for non-equilibrium measured sample compared to the one under equilibrium state. Both measurements are compared with the steady state desiccator method. The sandstone samples containing a certain concentration of inorganic water soluble salt which just only emphasizes the low hygroscopicity of silica grains are studied as well. The measured data can be used in evaluating of results obtained by dynamic vapor sorption device under equilibrium states although the measurement takes significantly longer time.

Abstract: Combustion of fossil fuels is one of the major sources of greenhouse gas CO₂, it is therefore necessary to develop technologies that will allow us to utilize the fossil fuels while reducing the emissions of greenhouse gases. Pressure swing adsorption (PSA) is a potential technique for removing CO₂ from high-pressure fuel gas streams. Zeolites are suitable candidate sorbents for use in the PSA process. Studies of the gas adsorption of CO₂ onto zeolite 13X and zeolite 4A were conducted at a temperature of 25 °C, 35 °C, 45 °C and 60 °C up to a pressure of 1 bar. The data fitting is accomplished with the Toth and Sips adsorption models which are generally used for micro-porous adsorbents such as zeolites. Moreover, regeneration studies have been conducted in order to verify the possibility of adsorbents reutilization, to determine its CO₂ adsorption capacity within consecutive cycles of adsorption–desorption. Zeolite with higher surface area showed higher CO₂ adsorption capacity. There is no full reversibility for the two zeolites.

Abstract: Applying of low cost adsorbent for herbicide capturing is an important area of research in environmental field. The present work reports the adsorption potential of fly ash, a waste from power stations, for removal of herbicides namely paraquat and alachlor from aqueous solution. Batch experiment was employed to investigate the adsorption of herbicide in aqueous solution. The maximum capacity of the fly ash to adsorb paraquat and alachlor was found to be 2.02 and 1.70 mmole.g^-1, respectively. The coefficient of adsorption on the basis of 3 models: Freundlich, Langmuir and Sips isotherm models were found. The results shown that the equilibrium data are better fitted by three-parameter models than two-parameter models. The experimental data agree to adsorption isotherms in the order of Sips > Langmuir > Freundlich isotherms.

Abstract: Activated carbon of activated sludge and straw with pyrolysis was used as adsorbent, and its adsorption of organic matter in the leachate and influence facts were studied. The results showed that the economic and reasonable addition of straw in the raw of activated sludge was 45% and the optimum adsorption conditions were 40 min, duration of pH 4.0 and resin dosage 2%,the removal rate of COD reach 69.63%. Langmuir isotherm equation could better describe the adsorption behavior of COD on the activated carbon and it was a monolayer adsorption reaction.

Abstract: In this work, both batch method and column method were used to investigates the adsorption of Ni and Zn on different kinds of soils found in the Northeastern Thailand including clay, silt, and sand. The batch method was used to examine the adsorption isotherm and the effect of contact time, initial concentration, and temperature on the adsorption. The column method was used to simulate the real condition of wastewater adsorption. The results indicated that the adsorption isotherms were fitted with Freundlich and Langmuir isotherm. All soils adsorbed Ni better than Zn. The adsorption capacity of soils tended to increase when the temperature increased from 30°C to 50°C. Soil surface characteristic was an important factor that affected on the adsorption capacity of soils. For the column test, the adsorption decreased with the increasing amount of metal solution. Leaching of the metal occurred in a fractional volume.

Abstract: In this study granular activated carbon loaded with ferric oxide hydrate (Fe-AC) as arsenic adsorbent was prepared by impregnation method. The influence of the kinds of ferric salt solution, the concentration of ferric salt solution, impregnation time and curing temperature on its arsenic removal effect was investigated. The optimal preparation conditions of the adsorbent were determined. And its adsorption properties of arsenic in aqueous solution were studied by static adsorption experiments. Results showed that when the dipping solution is 1.0 mol/L of Fe (NO₃)₃, impregnation time is 16h and the curing temperature is 60°C, the arsenic adsorption effect of the prepared adsorbent is best. The pattern of adsorption of As (V) with Fe-AC prepared under optimal condition well fit the Langmuir adsorption model, the correlation coefficient R² is greater than 0.98, and the maximum adsorption capacity is up to 71.43 mg/g.