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Effect of toluene, an immiscible pollutant, on the photocatalytic degradation of azo dye
Mohsin Nawaz,이대성,임성린,김동우,Waheed Miran,Avinash Kadam,허준,신설혜,장지선 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.30 No.-
An adverse effect of a water-immiscible pollutant, toluene, on the photocatalytic degradation of DirectRed 80 (DR80) with TiO2 in an aqueous solution was observed when toluene was added as a continuousfree layer. However, a more efficient photocatalytic system was obtained when toluene was added in thePickering emulsion (PE) form with TiO2. With only UV and two different types of TiO2 (more hydrophilicand large-sized type A TiO2 and less hydrophilic and small-sized type B TiO2), 44% and 59% color removalwas observed, respectively. Almost 20% decrease in color removal with toluene in the continuous freelayer form was observed, however, the higher color removal was obtained when toluene was added as PEstabilized with type B TiO2 than with type A TiO2. The higher color removal was owing to the goodstability of PE stabilized with type B TiO2.
Photodegradation of microcystin-LR using graphene-TiO<sub>2</sub>/sodium alginate aerogels
Nawaz, Mohsin,Moztahida, Mokrema,Kim, Jiho,Shahzad, Asif,Jang, Jiseon,Miran, Waheed,Lee, Dae Sung Elsevier 2018 Carbohydrate polymers Vol.199 No.-
<P><B>Abstract</B></P> <P>In this study, sustainable graphene oxide-TiO<SUB>2</SUB>/sodium alginate and reduced graphene oxide-TiO<SUB>2</SUB>/sodium alginate aerogels were synthesized and the potential of these aerogels was investigated for microcystin-LR degradation in aqueous solution. Along with the role of alginate in the synthesis of aerogels, effects of different concentrations of photocatalyst, photolysis, pH, and combination of TiO<SUB>2</SUB> (anatase)/Degussa P25 with graphene were investigated in lieu of microcystin-LR photodegradation.The complete degradation of microcystin-LR was attained in case of reduced graphene oxide-TiO<SUB>2</SUB>/sodium alginate aerogel—not in graphene oxide-TiO<SUB>2</SUB>/sodium alginate aerogel case—by the synergistic effect of adsorption and photodegradation. The recyclability study of reduced graphene oxide-TiO<SUB>2</SUB>/sodium alginate aerogel demonstrated high stability and photoactivity and the degradation efficiency was not much hampered during six consecutive cycles of degradation reaction. The possible fragmentation pathways were also proposed based on identified intermediate products. High adsorption and degradation synergy and ease of separation/recycling of reduced graphene oxide-TiO<SUB>2</SUB>/sodium alginate aerogel can make it a suitable option for removing microcystin-LR from water systems.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Sodium alginate helped to synthesize a robust graphene-TiO<SUB>2</SUB> aerogel. </LI> <LI> Graphene-TiO<SUB>2</SUB>/sodium alginate aerogel efficiently degraded microcystin-LR. </LI> <LI> Synthesized aerogel was highly recyclable without producing any secondary pollution. </LI> <LI> In microcystin-LR degradation pathway, significant role of OH radicals was found. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Nawaz, Mohsin,Miran, Waheed,Jang, Jiseon,Lee, Dae Sung Elsevier 2017 Applied Catalysis B Vol.203 No.-
<P><B>Abstract</B></P> <P>In this study, the three-dimensional (3D) reduced graphene oxide/TiO<SUB>2</SUB> (RGOT) aerogel was synthesized by a facile one-step hydrothermal treatment, and its photocatalytic efficiency was evaluated in the photodegradation of recalcitrant carbamazepine (CBZ) in aqueous solution. RGOT exhibited high adsorption and an almost two-fold higher photodegradation ability than bare TiO<SUB>2</SUB> as more than 99% CBZ removal was observed within 90min in 10ppm aqueous solution of the latter. The mass ratio of TiO<SUB>2</SUB> in the RGOT aerogel substantially affected CBZ adsorption and photocatalytic degradation, with the optimal TiO<SUB>2</SUB>/GO ratio in RGOT found to be 2:1. The chemical bonding between TiO<SUB>2</SUB> and GO and the effective reduction of the latter during RGOT synthesis were also considered to achieve high photocatalytic efficiency, because the physical mixture of GO and TiO<SUB>2</SUB> showed a lower photocatalytic CBZ degradation ability than bare TiO<SUB>2</SUB>. The macroporous 3D structure, abundant surface sites for anchoring the catalyst, effective charge separation, and mass transportation of CBZ near the photocatalyst surface are the attractive features of RGOT aerogels, promoting their use in resolving environmental issues.</P> <P><B>Highlights</B></P> <P> <UL> <LI> 3D reduced graphene oxide/TiO<SUB>2</SUB> (RGOT) aerogel formation is successful. </LI> <LI> Strong coupling between TiO<SUB>2</SUB> and GO is a prerequisite for RGOT aerogel synthesis. </LI> <LI> Chemically bonded RGOT aerogel is better than a physical mixture of TiO<SUB>2</SUB> and GO. </LI> <LI> RGOT (1:2) with a 1:2 mass ratio of TiO<SUB>2</SUB> to GO gives higher photocatalytic activity. </LI> <LI> CBZ photodegradation ability of RGOT (1:2) is two times higher than that of bare TiO<SUB>2</SUB> </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Shahzad, Asif,Nawaz, Mohsin,Moztahida, Mokrema,Jang, Jiseon,Tahir, Khurram,Kim, Jiho,Lim, Youngsu,Vassiliadis, Vassilios S.,Woo, Seung Han,Lee, Dae Sung Elsevier 2019 CHEMICAL ENGINEERING JOURNAL -LAUSANNE- Vol.368 No.-
<P><B>Abstract</B></P> <P>Two-dimensional (2-D) titanium carbide MXene core (Ti<SUB>3</SUB>C<SUB>2</SUB>T<SUB>x</SUB>) shell aerogel spheres (MX-SA) for mercuric ion removal were designed and fabricated with varying concentrations of Ti<SUB>3</SUB>C<SUB>2</SUB>T<SUB>x</SUB> MXene and sodium alginate (SA) using a facile method. Owing to their unique inside structures, high porosities, large specific surface areas, oxygenated functional groups of MXene nanosheets, and available active binding sites, the synthesized microspheres constitute a unique adsorbent for heavy metals removal in water. The MX-SA<SUB>4:20</SUB> spheres exhibit an exceptional adsorption capacity of 932.84 mg/g for Hg<SUP>2+</SUP>, which is among the highest value reported for adsorbents. The adsorbent exhibits high single- and multi-component removal efficiencies, with 100% efficiency for Hg<SUP>2+</SUP> and >90% efficiency for five heavy metal ions. The synthesized materials are highly efficient for Hg<SUP>2+</SUP> removal under extreme pH conditions (0.5–1.0 M HNO<SUB>3</SUB>) and have additional excellent reproducible properties. The micro-size and spherical shape of MX-SA<SUB>4:20</SUB> also allow it to be used in column-packed devices.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Ti<SUB>3</SUB>C<SUB>2</SUB>T<SUB>x</SUB> nanosheets were synthesized using a low-toxicity etching agent (NH<SUB>4</SUB>F). </LI> <LI> Core-shell of MX-SA<SUB>4:20</SUB> spheres was capable of very effectively removing heavy metals. </LI> <LI> MX-SA<SUB>4:20</SUB> spheres exhibited exceptional Hg<SUP>2+</SUP> adsorption capacity of 932.84 mg g<SUP>−1</SUP>. </LI> <LI> MX-SA<SUB>4:20</SUB> performed excellently in extreme acidic conditions. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Fabrication of MX-SA<SUB>4:20</SUB> spheres through MXene-Alginate networking and their application in Hg<SUP>2+</SUP> uptake.</P> <P>[DISPLAY OMISSION]</P>
Miran, Waheed,Nawaz, Mohsin,Jang, Jiseon,Lee, Dae Sung Pergamon Press 2017 Water research Vol.117 No.-
<P><B>Abstract</B></P> <P>Wastewaters are increasingly being considered as renewable resources for the sustainable production of electricity, fuels, and chemicals. In recent years, bioelectrochemical treatment has come to light as a prospective technology for the production of energy from wastewaters. In this study, a bioelectrochemical system (BES) enriched with sulfate-reducing bacteria (SRB) in the anodic chamber was proposed and evaluated for the biodegradation of recalcitrant chlorinated phenol, electricity generation (in the microbial fuel cell (MFC)), and production of hydrogen peroxide (H<SUB>2</SUB>O<SUB>2</SUB>) (in the microbial electrolysis cell (MEC)), which is a very strong oxidizing agent and often used for the degradation of complex organics. Maximum power generation of 253.5 mW/m<SUP>2</SUP>, corresponding to a current density of 712.0 mA/m<SUP>2</SUP>, was achieved in the presence of a chlorinated phenol pollutant (4-chlorophenol (4-CP) at 100 mg/L (0.78 mM)) and lactate (COD of 500 mg/L). In the anodic chamber, biodegradation of 4-CP was not limited to dechlorination, and further degradation of one of its metabolic products (phenol) was observed. In MEC operation mode, external voltage (0.2, 0.4, or 0.6 V) was added via a power supply, with 0.4 V producing the highest concentration of H<SUB>2</SUB>O<SUB>2</SUB> (13.3 g/L-m<SUP>2</SUP> or 974 μM) in the cathodic chamber after 6 h of operation. Consequently, SRB-based bioelectrochemical technology can be applied for chlorinated pollutant biodegradation in the anodic chamber and either net current or H<SUB>2</SUB>O<SUB>2</SUB> production in the cathodic chamber by applying an optimum external voltage.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A SRB enriched (anodic chamber) bioelectrochemical system was developed. </LI> <LI> Degradation of 4-CP and current generation/H<SUB>2</SUB>O<SUB>2</SUB> production were evaluated. </LI> <LI> H<SUB>2</SUB>O<SUB>2</SUB> was produced by applying external voltage in MEC mode operation. </LI> <LI> Maximum power density of 253.3 mW/m<SUP>2</SUP> was obtained. </LI> <LI> H<SUB>2</SUB>O<SUB>2</SUB> output of 13.3 g/L⋅m<SUP>2</SUP> (974 μM) and 4-CP removal of 42.9% was achieved. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Miran, Waheed,Nawaz, Mohsin,Kadam, Avinash,Shin, Seolhye,Heo, Jun,Jang, Jiseon,Lee, Dae Sung Ecomed 2015 Environmental Science and Pollution Research Vol.22 No.17
<P>The expansion in knowledge of the microbial community structure can play a vital role in the electrochemical features and operation of microbial fuel cells (MFCs). In this study, bacterial community composition in a dual chamber MFC fed with brewery waste was investigated for simultaneous electricity generation and azo dye degradation. A stable voltage was generated with a maximum power density of 305 and 269?mW?m(-2) for brewery waste alone (2000?mg?L(-1)) and after the azo dye (200?mg?L(-1)) addition, respectively. Azo dye degradation was confirmed by Fourier transform infrared spectroscopy (FT-IR) as peak corresponding to -N=N- (azo) bond disappeared in the dye metabolites. Microbial communities attached to the anode were analyzed by high-throughput 454 pyrosequencing of the 16S rRNA gene. Microbial community composition analysis revealed that Proteobacteria (67.3?%), Betaproteobacteria (30.8?%), and Desulfovibrio (18.3?%) were the most dominant communities at phylum, class, and genus level, respectively. Among the classified genera, Desulfovibrio most likely plays a major role in electron transfer to the anode since its outer membrane contains c-type cytochromes. At the genus level, 62.3?% of all sequences belonged to the unclassified category indicating a high level of diversity of microbial groups in MFCs fed with brewery waste and azo dye.</P>