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Bediako, John Kwame,Park, Sang Won,Choi, Jong-Won,Song, Mung-Hee,Yun, Yeoung-Sang Elsevier 2019 Journal of environmental chemical engineering Vol.7 No.1
<P><B>Abstract</B></P> <P>We report the fabrication and application of high-performance and acid-tolerant fibers comprising polyethylenimine (PEI) and polyvinyl chloride (PVC) for platinum recovery from acidic waste solutions. The fibers were fabricated by amination of PVC with PEI and spin-extrusion via phase-inversion mechanism. Factors including the effects of chloride concentration, pH, competing ions, and amount of PEI on the adsorption performance, were studied. The adsorption mechanism was evaluated through XPS analysis, in which electrostatic binding of Pt(IV) and its partially reduced Pt(II) were revealed. The maximum Pt adsorption capacity in 0.1 M HCl was estimated by the Langmuir isotherm model as 410.53 mg/g. The fibers were applicable to Pt recovery from actual metal refining wastewater and demonstrated high efficiency of regeneration through adsorption-desorption cycles.</P> <P><B>Highlights</B></P> <P> <UL> <LI> High Pt(IV) recovery efficiency was achieved with adsorbent fibers consisting of polyethylenimine and polyvinyl chloride. </LI> <LI> The prepared fibers were self-crosslinked, thereby requiring no extra crosslinking for chemical stability and adsorption. </LI> <LI> Compared with Amberjet 4200 commercial resin and others, the Pt(IV) recovery efficiency of the prepared fibers was highest. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Bediako, John Kwame,Song, Myung Hee,Yun, Yeoung Sang Trans Tech Publications, Ltd. 2017 Diffusion and defect data. SSP. [Pt. B], Solid sta Vol.262 No.-
<P>High-capacity polyethylenimine (PEI)/Ca-alginate blended hydrogel fibers were fabricated via three steps, viz. electrostatic blending of PEI and alginate, ionotropic gelation of alginate and CaCl2, and fixing of PEI into the Ca-alginate matrix, using glutaraldehyde (GA) as a crosslinker. Two crosslinking approaches resulted in different stabilities and gold uptake capacities of the prepared sorbents. Post-crosslinking approach was more efficient than pre-crosslinking likely owing to the better crosslinking efficiency, leading to better stability and sorption capacity. Furthermore, X-ray diffraction (XRD) study revealed the reduction of Au (III) to metallic gold, Au (0) in the crosslinked fibers. The Au (0) predominancy was confirmed with a metal desorption study. The present study thus demonstrates the possibility of recovering metallic gold from aqueous solutions by direct adsorption-coupled-reduction approach using GA-crosslinked PEI/Ca-alginate fibers.</P>
Conversion of waste textile cellulose fibers into heavy metal adsorbents
John Kwame Bediako,Wei Wei,윤영상 한국공업화학회 2016 Journal of Industrial and Engineering Chemistry Vol.43 No.-
Fibrous adsorbents were prepared by carboxymethylation of waste textilefibers and were used for Cd(II)sorption in comparison with Dowex Mac-3 (DM-3). The prepared sorbents were designatedcarboxymethyl cellulose-Lyocell strands (CMC-LS) and carboxymethyl cellulose-Lyocell fabrics (CMCLF). Kinetic and isotherm studies indicated that CMC-LS had the fastest sorption rate with high affinityconstants and good column application potential. For the same packed column volume, CMC-LS reached70% of its capacity whilst DM-3 reached57%. 100% desorption was achieved using 0.1 M EDTAor HCl. This study therefore suggests a way to recycle wastefibers into adsorbents for treating heavymetal-polluted waters.
Bediako, John Kwame,Reddy, D. Harikishore Kumar,Song, Myung-Hee,Wei, Wei,Lin, Shuo,Yun, Yeoung-Sang Elsevier 2017 Journal of environmental chemical engineering Vol.5 No.1
<P><B>Abstract</B></P> <P>A facile modification of waste textile cellulose Lyocell fibers with tripolyphosphate and application of the adsorbent thereof to the treatment of Pb(II)-contaminated wastewater was investigated. Characterization and batch adsorption studies were conducted to understand the characteristics of the prepared adsorbent and its metal binding mechanisms. The adsorbent showed 100% adsorptive removal efficiency of Pb(II) at initial concentrations up to 300mg/L, and the adsorption performance was significant even at low pH ranges. The adsorption isotherm followed the Langmuir model, and the kinetic was described by the pseudo-first and pseudo-second order models. By comparison, the adsorbent showed strong competitiveness to existing ones especially in terms of the adsorption capacity, pH, and kinetics of adsorption, and could be reused. Considering its cheap source and simplicity of preparation, the adsorbent could be applied as a low-cost material for heavy metal scavenging from wastewater streams.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A facile method for preparing cellulosic heavy metal adsorbent with phosphate chelating groups was presented. </LI> <LI> High selectivity of Pb(II) was found in multi-metal systems. </LI> <LI> Hundred percent adsorption efficiency of Pb(II) at initial concentrations up to 300mg/L was achieved. </LI> <LI> Adsorption capacity was very high even at low pH. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Lin, Shuo,Bediako, John Kwame,Cho, Chul-Woong,Song, Myung-Hee,Zhao, Yufeng,Kim, Jeong-Ae,Choi, Jong-Won,Yun, Yeoung-Sang Elsevier 2018 Chemical Engineering Journal Vol.345 No.-
<P><B>Abstract</B></P> <P>Metal-organic frameworks (MOFs) have successfully employed as a class of adsorbents for selective separation of CO<SUB>2</SUB> and some organics from gas and liquid phases; however, little attention has been paid to MOFs applications for selective adsorption of ionic targets from aqueous solutions. Besides, selective separation of precious metals is of great importance from the standpoint of realizing a new sustainable development concept of “urban mining”. While, separation of precious metals is challenging, as they are often present in acidic solutions with many interfering metal ions. Herein, Zr(IV)-cluster-based MOFs were synthesized in this study for the selective adsorption of Pd(II), as a model precious metal ion, from acidic aqueous solutions containing Co(II), Ni(II), Pd(II), and Pt(IV). Among the various Zr-MOFs synthesized (i.e. UiO-66, UiO-66-NH<SUB>2</SUB> and UiO-66-NHCOCH<SUB>3</SUB>), UiO-66-NH<SUB>2</SUB> showed the highest Pd(II) selectivity, with the Pd(II) uptake in the mixture-metals solution being around 181 times higher than that of Pt(IV). The Pd(II) selectivity of UiO-66-NH<SUB>2</SUB> was attributed to higher binding affinity of the protonated amino groups (–NH<SUB>3</SUB> <SUP>+</SUP>) for PdCl<SUB>4</SUB> <SUP>2−</SUP> and more convenient diffusion of the PdCl<SUB>4</SUB> <SUP>2−</SUP> through the apertures (pores) of the UiO-66-NH<SUB>2</SUB> – which have the appropriate inner sizes befitting PdCl<SUB>4</SUB> <SUP>2−</SUP> penetration – than for Pt(IV) ions (PtCl<SUB>6</SUB> <SUP>2−</SUP>).</P> <P><B>Highlights</B></P> <P> <UL> <LI> This is the earliest report of selective MOFs (UiO-66-NH<SUB>2</SUB>) for an ionic target (PdCl<SUB>4</SUB> <SUP>2−</SUP>). </LI> <LI> The protonated amino groups show high affinity for PdCl<SUB>4</SUB> <SUP>2−</SUP>. </LI> <LI> The convenient diffusion of the PdCl<SUB>4</SUB> <SUP>2−</SUP> through the apertures of the UiO-66-NH<SUB>2</SUB> are found. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Removal of Cd(II) by poly(styrenesulfonic acid)-impregnated alginate capsule
Wei, Wei,Bediako, John Kwame,Kim, Sok,Yun, Yeoung-Sang ELSEVIER SCIENCE B.V.; AMSTERDAM 2016 JOURNAL- TAIWAN INSTITUTE OF CHEMICAL ENGINEERS Vol.61 No.-
<P><B>Abstract</B></P> <P>In this study, a capsule type sorbent of poly(styrenesulfonic acid)-impregnated alginate capsule (PSSA-AC) was developed by using a simple and moderate method. PSSA was used as a model encapsulated material because of its large number of sulfonic acid groups which have high affinity toward Cd(II). PSSA-AC was prepared by dropping solution A (mixture of 10% (w/v) PSSA + 1% CaCl<SUB>2</SUB>) into B solution (0.6% (w/v) sodium alginate). Microscope images revealed that PSSA was well encapsulated inside of the alginate shell. The pH edge experiment indicated that Cd(II) sorption was influenced marginally by the experimental pH range. The maximum Cd(II) uptake by PSSA-AC was as high as 184.12 ± 6.30 mg/g. The kinetic and FTIR studies demonstrated that ion-exchange was the main sorption mechanism. The PSSA-AC could be regenerated by using 2% CaCl<SUB>2</SUB> as a desorbing agent.</P> <P><B>Highlights</B></P> <P> <UL> <LI> PSSA-AC was successfully developed using a simple and moderate method. </LI> <LI> The maximum Cd(II) uptake was 184.12 ± 6.30 mg/g using Langmuir isotherm model. </LI> <LI> The Cd(II)-loaded PSSA-AC was easily regenerated by using 2% CaCl<SUB>2</SUB> solution. </LI> <LI> The overall sorption/desorption mechanism was cation ion-exchange between Cd(II) and Ca(II). </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Song, Myung Hee,Reddy, D. Harikishore Kumar,Bediako, John Kwame,Lin, Shuo,Yun, Yeoung Sang Trans Tech Publications, Ltd. 2017 Diffusion and defect data. SSP. [Pt. B], Solid sta Vol.262 No.-
<P>Magnetic MnFe2O4 nanoparticles (MNPs) were fabricated and entrapped in amine-rich chitosan (CS) sorbents containing multi-walled carbon nanotubes (MWCNTs) or polyethyleneimine (PEI). Magnetic polymer composite sponges (MPCSs) and magnetic polymer composite fibers (MPCFs) were prepared through mixing each of MWCNT and PEI with MNPs-CS solution. The successful fabrication of MPCSs and MPCFs was confirmed through FTIR and VSM analyses. The as-fabricated MPCSs and MPCFs were used for adsorptive recovery of Pt (IV) from acidic solution. The maximum uptakes of Pt (IV) ions by the MPCSs and MPCFs were estimated to be 218.2 ± 8.3 and 371.4 ± 16.8 mg/g, respectively. Moreover, the Pt (IV)-loaded MPCSs and MPCFs were easily separated from aqueous solution under magnetic field after sorption process.</P>
Zhao, Yufeng,Choi, Jong-Won,Bediako, John Kwame,Song, Myung-Hee,Lin, Shuo,Cho, Chul-Woong,Yun, Yeoung-Sang Elsevier 2018 Journal of hazardous materials Vol.360 No.-
<P><B>Abstract</B></P> <P>Due to high mobility and specific toxic actions of the ionizable pharmaceuticals in surface water with a normal range of pH, the pharmaceuticals should be removed before being discharged. Therefore, this study investigated the adsorptive interactions between cationic pharmaceuticals and a popular adsorbent (i.e., activated charcoal) frequently used in water treatment processes. For that, we performed isotherm experiments and then the results were plotted by Langmuir model to determine the adsorption affinity (<I>b</I>) and capacity (<I>q<SUB>m</SUB> </I>). Afterwards, to interpret the adsorption behaviors, two simple prediction models were developed based on quantitative structure-activity relationships (QSAR). In the modelling, molecular weight (MW), polar surface area (PSA), and octanol-water partitioning coefficient (log <I>P</I>) were used as model parameters. In the results, the combinations of these three parameters could predict the adsorption affinity and capacity in <I>R</I> <SUP>2</SUP> of 0.85 and 0.80, respectively. The robustness of models was validated by leave-one-out cross-validation (<I>Q</I> <SUP>2</SUP> <SUB>LOO</SUB>) and the estimated <I>Q</I> <SUP>2</SUP> <SUB>LOO</SUB> values were 0.60 and 0.55 for the adsorption affinity and capacity, respectively, which are higher than the acceptability of standard i.e., 0.5.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Adsorptive interactions between cationic pharmaceuticals and activated charcoal were obtained at natural pH. </LI> <LI> Simple and easy parameters were used to predict adsorptive behavior through QSAR-based modelling. </LI> <LI> Major factors influencing the adsorption include log <I>P</I>, polar surface area, and molecular weight of pharmaceuticals. </LI> <LI> The log <I>P</I> value of pharmaceutical was the most important factor. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>