Micro-milling of spent granular activated carbon for its possible reuse as an adsorbent: Remaining capacity and characteristics
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Adsorption with activated carbons for water treatment is simple and cost effective. In addition, dissolved air flotation (DAF) process has advantages including short treatment time, small facility area, and easy to eliminate floating particles. Here, super-powdered activated carbon and activated carbon prepared from Miscanthus sacchariflorus (MS) were compared. For this, adsorption isotherm and kinetics data of methylene blue on porous carbons were obtained. Results showed that the experimental data were well fitted with Langmuir and pseudo-second-order-models, respectively. The flotation efficiency of superpowdered activated carbon and activated carbon powders was evaluated in DAF process under the wide range of pH 1 to pH 14. We found that the simultaneous removal of both porous carbon fine particles and organics (i.e., methylene blue) dissolved in water can be achieved by using the hybrid processes of adsorption-DAF.
Methylene blue
Carbon fibers
Langmuir adsorption model
Dissolved air flotation
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The response surface methodology has been used to optimize the preparation conditions of activated carbon from nut oil cake by phosphoric acid activation. The Doehlert design and Desirability function were applied to determine the optimal conditions. The yield in carbon, the adsorption of methylene blue and iodine have been studied and represented in all experimental regions of activation temperature and impregnation ratio, which are the most influential factors in the preparation of activated carbon. The increase in activation temperature and impregnation ratio increases the adsorption capacity of methylene blue and iodine. The optimal conditions for the preparation of activated carbon have been identified to be an activation temperature of 465 °C and impregnation ratio of 1.63. The characteristics of activated carbon obtained under these experimental conditions were determined using adsorption capacity of methylene blue and iodine, X-ray powder diffraction, SEM/EDX, surface functions based on FTIR and pH pzc . The maximum adsorption capacity of methylene blue and iodine was found to be 270.38 mg.g -1 and 582.35 mg.g - 1 respectively. The produced activated carbon had a well developed porous structure and a pH pzc of 4.6. The FTIR analysis indicates presence of variety of functional groups on the surface of activated carbon. These results demonstrated that the nut oil cake is a suitable precursor for the production of activated carbon.
Methylene blue
Phosphoric acid
Carbon fibers
Specific surface area
BET theory
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Despite the many articles about activated carbon with different precursors in adsorption process, no in-depth research has been carried out to understand the causes of the difference in surface adsorption characteristics of activated carbon with different precursors and different activation processes. In this work, the ability of two active carbon adsorbents made of walnut shell and peach kernel by two chemical and physical methods (totally 4 different types of activated carbon) in treatment of oily wastewater including diesel, gasoline, used oil or engine lubricant has been compared. The results show that the chemical activated peach carbon active with 97% hardness has provided the highest hardness and physical activated walnut carbon active has obtained the lowest hardness value (87%). It is also found that peach activated carbon has a higher iodine number than walnut activated carbon, and this amount can be increased using chemical methods; Therefore, the highest amount of Iodine Number is related to Peach activated carbon that is made by chemical method (1230 mg/g), and the lowest amount of iodine number is seen in walnut activated carbon that is made by physical method (1020 mg/g). moreover, the pore diameter of physical activated carbon is lower than chemical activated carbon in all cases. So that the pore diameter of chemical activated peach carbon active is equal to 22.08 μm and the measured pore diameter of physical activated peach carbon active is equal to 20.42 μm. These values for walnut are obtained as 22.74 μm and 21.86 μm, respectively. Furthermore, the temperature and pH effects on the adsorption of different synthesized oily wastewater was studied and it was found that a decrease in adsorption can be seen with an increase in temperature or decreasing the pH value, which can be referred to this fact that the process of adsorption is an exothermic process. Finally, to analyze the compatibility of adsorption isotherms with experimental data and to predict the adsorption process, three different isotherms named Langmuir, Temkin, and Freundlich isotherms were applied and their parameters were correlated. The correlation results show that the Langmuir isotherm had the best correlation in all cases compared to the Freundlich and Temkin isotherms, based on the correlation coefficient, and the calculated R 2 values which was greater than 0.99 in all the studied cases.
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This study basically compared the adsorptive efficacies of powdered activated carbons (PACs) produced from palm empty fruit bunches (EFB) in the treatment of a non-simulated biotreated palm oil mill effluent (BPOME). Each of the PACs was produced from two different methods namely steam- and CO2-activation routes. This test was performed with the main aim of obtaining an appropriate activated carbon suitable for the treatment of BPOME. The steam activated PAC was found to possess higher adsorptive strength as compared with that of CO2 activation with the operating conditions of 150 rpm agitation for 60 min with varying dosage of PAC from 0.5 – 5.0 g. The steam activated PAC performed better than the CO2 activated PAC with a record uptake of up to 81%, 92% and 89% for Chemical Oxygen Demand (COD), Manganese (Mn) and Hydrogen Sulfide (H2S) respectively as compared with the uptake of 67%, 90% and 87% from the CO2-activated PAC. Furthermore, a 2-level full factorial design of experiment was utilized to assess the effects of three factors on adsorption. The highest removal efficiencies for COD, Mn and H2S were found to be 83.1%, 93.6% and 89.8% at adsorbent dosage 5 g, agitation speed 200 rpm and contact time 60 min.
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To prepare activated carbon,sawdust was impregnated in phosphoric acid,then activated in high temperature.The main parameters such as temperature,holding time and the concentration were studied to show the effect on the adsorption capabilities of the activated carbon.It was found that with the increase of temperature and holding time,methylene blue,iodine,benzene adsorption values of activated carbon showed overall upward trend.With the increase of the concentration of phosphoric acid,the methylene blue and iodin adsorption values of activated carbon decreased to a low value and then increased.Under optimized experimental conditions,the adsorption values of methylene blue,iodine and benzene of activated carbon were 330 mg·g-1,1 015.7 mg·g-1 and 59.2%,respectively.
Phosphoric acid
Methylene blue
Sawdust
Methylene
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Particle (ecology)
Carbon fibers
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Researches and applications of activated carbon for advanced water treatment of potable water in recent years in China such as ozone-activated carbon method and ozone-biological activated carbon method,as well as adsorption treatment of paroxysmal pollution of water source by activated carbon powder,were summarized.Some problems focused on advanced water treatment by activated carbon were also discussed.
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