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Jung, Kyung-Won,Choi, Brian Hyun,Song, Kyung Guen,Choi, Jae-Woo Elsevier 2019 CHEMOSPHERE - Vol.215 No.-
<P><B>Abstract</B></P> <P>This study focuses on the optimization of synthetic conditions for preparing marine macroalgae-derived activated carbon/iron oxide magnetic composites (AC/Fe-MC) and its feasibility for the removal of acetylsalicylic acid from aqueous media. Response surface methodology coupled with a 3<SUP> <I>k</I> </SUP> Box-Behnken design was applied to determine the optimal conditions (independent variables: impregnation ratio, activation temperature, and activation time) towards two response variables (production yield and adsorption capacity). According to the analysis of variance and numerical desirability function approaches, the optimal conditions were impregnation ratio of 2.62:1, activation temperature of 727 °C, and activation time of 129 min. Physicochemical properties of the prepared composite revealed that AC/Fe-MC possesses a porous structure and superparamagnetic property, which substantially contributed to the effective adsorption capacity and separation from the solution using an external magnetic field. Adsorption kinetics and equilibrium studies delineated that the pseudo-second-order and Sips isotherm models represent the adsorption behavior of AC/Fe-MC accurately. The maximum adsorption capacity of AC/Fe-MC was found to be around 127 mg/g at 10 °C, as fitted by Sips isotherm model, which is higher than that of other adsorbents reported in the literature. Intraparticle diffusion and Boyd models suggested that the adsorption process was mainly controlled by film diffusion mechanism. Lastly, thermodynamic and isosteric heat of adsorption analyses demonstrated that the adsorption process was controlled by physisorption and exothermic mechanisms.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Activated carbon/iron oxide magnetic composites (AC/Fe-MC) were prepared. </LI> <LI> Preparation conditions were statistically optimized by RSM with a 3<SUP> <I>k</I> </SUP> BBD. </LI> <LI> Superparamagnetic property of AC/Fe-MC enabled simple separation by a magnetic field. </LI> <LI> AC/Fe-MC acts as an excellent adsorbent of acetylsalicylic acid (ASA) from solution. </LI> <LI> ASA adsorption on AC/Fe-MC was an exothermic and multiple mechanistic pathways. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Kim, Ki-Pal,Song, Kyung-Guen,Ahmed, Zubair,Paeng, Ki-Jung,Ahn, Kyu-Hong The Society of Chemical Engineers, Japan 2008 Journal of chemical engineering of Japan Vol.41 No.6
<P>Reclaimed water for stream augmentation or landscape impound requires low phosphorus contents to avoid eutrophication. A synthetic compressible media filtration system was previously developed for the purpose of wastewater reclamation. However, the filtration system was limited for removal of soluble matters in secondary treated wastewater, such as phosphorus. The objective of this study is to evaluate the optimum coagulation conditions for removal of phosphorus in effluent from a wastewater treatment plant (WWTP) using the filtration system combined with coagulation. Coagulation conditions including selection of coagulant, coagulant dose, mixing conditions were determined through jar-test. Also a field-test with the coagulation–filtration system was conducted to evaluated operation factors such as compression rate of media and periodic backwash. Polyaluminum chloride (PAC) demonstrated the best performance in terms of total phosphorus (TP) removal efficiency and stability of pH among coagulant used in this experiment. Since the change in mixing conditions had little effect on TP removal, in-line coagulant supplying could be feasible for the coagulation–filtration system. Increasing the compression rate of the filter media from 0 to 50% increased the TP removal efficiency within only 10%. This made great changes in the filtration pressure and the flow rate, which is related to operating cost of the system, simultaneously. Compared to the filtration system with no addition of coagulation, the addition of coagulant enhanced the removal of phosphorus along with turbidity, but decreased the operation time between each backwashing cycle. One needs to consider the various operation parameters examined in this study as well as the requirement of phosphorus removal, when operating the coagulation–filtration system. Consequently, the coagulation–filtration system, which requires a small area, can effectively reduce the phosphorus contents of WWTP effluent, and make it suitable for reuse purposes.</P>