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Removal of metsulfuron methyl by Fenton reagent
Javeed Mohammed Abdul,Mahintha Kumar,Jaya Kandasamy,Saravanamuthu Vigneswaran 한국공업화학회 2012 Journal of Industrial and Engineering Chemistry Vol.18 No.1
The removal of metsulfuron methyl (MeS)—a sulfonyl urea herbicide from contaminated water was investigated by advanced oxidation process (AOP) using Fenton method. The optimum dose of Fenton reagent (Fe2+/H2O2) was 10 mg/L Fe2+ and 60 mg/L H2O2 for an initial MeS concentration ([MeS]0) range of 0–80 mg/L. The Fenton process was effective under pH 3. The degradation efficiency of MeS decreased by more than 70% at pH > 3 (pH 4.5 and 7). The initial Fe2+ concentration ([Fe2+]0) in the Fenton reagent affected the degradation efficiency, rate and kinetics. The degradation of MeS at optimum dose of Fenton reagent was more than 95% for [MeS] 0 of 0–40 mg/L and the degradation time was less than 30 min. The determination of residual MeS concentration after Fenton oxidation by UV spectrophotometry was affected by the interferences from Fenton reagent. The estimation of residual MeS concentration after Fenton oxidation by high pressure/performance liquid chromatograph (HPLC) was interference free and represented the actual concentration of MeS and does not include the by-products of Fenton oxidation. The degradation kinetics of MeS was modelled by second order reactions involving 8 rate constants. The two reaction constants directly involving MeS were fitted using the experimental data and the remaining constants were selected from previously reported values. The model fit for MeS and the subsequent prediction of H2O2 were found to be within experimental error tolerances.
Nitrogenated holey two-dimensional structures
( Javeed Mahmood ),이은광,정민복,심동빈,전인엽,배서윤,손소담,정선민,최현정,서정민,박노정,오준학,신현준,백종범 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.0
Recent graphene research has triggered enormous interest in new twodimensional ordered crystals constructed by the inclusion of elements other than carbon for band-gap opening. The design of new multifunctional two-dimensional materials with proper bandgap has become an important challenge. Here we report a layered two-dimensional network structure that possesses evenly distributed holes and nitrogen atoms and a C2N stoichiometry in its basal plane. The two-dimensional structure can be efficiently synthesized via a simple wet-chemical reaction and confirmed with various characterization techniques, including scanning tunneling microscopy. Furthermore, a field-effect transistor device fabricated using the material exhibits an on/off ratio of 107, with calculated and experimental bandgaps of approximately 1.70 and 1.96 eV, respectively. In view of the simplicity of the production method and the advantages of the solution processability, the C2N-h2D crystal has potential for use in practical applications.
Javeed Mohammed Abdul,Ho Kyong Shon,Areerachakul Nathaporn,Jaya Kandasamy,Saravanamuthu Vigneswaran 한국화학공학회 2009 Korean Journal of Chemical Engineering Vol.26 No.3
Landfill leachate is a toxic effluent of a decomposing landfill that is produced when rainwater percolates through the landfill leaching out contaminants and pollutants. Untreated leachate is a potential source for the contamination of soil, surface and ground water. In this study, the treatment processes such as granular activated carbon (GAC) adsorption/bio-sorption (batch), and advanced oxidation processes (AOP) viz. photocatalysis and Fenton’s process were evaluated and compared by using synthetic landfill leachate (SLL) as a contaminant. TiO2 was used as a catalyst in photocatalysis, and Fenton’s reagent (H2O2/Fe+2) was used in Fenton’s process. The degradation of SLL effluent by the three above-mentioned processes was characterized by the % TOC removal. The % TOC removed by photocatalysis, Fenton oxidation and bio-sorption (which includes adsorption and biodegradation) was 30, 60 and 85%, respectively. The bio-sorption increased with the increasing GAC dose. The optimum dose of Fenton’s reagent in advanced oxidation was 15 and 400 milli moles of Fe+2 and H2O2, respectively. The Fenton’s process showed faster degradation kinetics compared to biodegradation and photocatalysis.
Nitrogenated two-dimensional structure, a semiconducting covalent-organic framework
Javeed Mahmood,Eun Kwang Lee,Minbok Jung,Dongbin Shin,In-Yup Jeon,Sun-Min Jung,Hyun-Jung Choi,Jeong-Min Seo,Seo-Yoon Bae,So-Dam Sohn,Noejung Park,Joon Hak Oh,Hyung-Joon Shin,Jong-Beom Baek 한국고분자학회 2016 한국고분자학회 학술대회 연구논문 초록집 Vol.41 No.2
Encapsulated cobalt oxide in 2D conjugated network polymer as a hydrogen evolution catalyst
( Javeed Mahmood ),정선민,김석진,박정민,유정우,백종범 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.0
In the hydrogen generation field, cobalt oxides have been regarded as promising catalysts, 2D network polymer-supported cobalt-oxide catalysts with good crystallinity are highly anticipated to enhance catalytic performance. Here we report the fabrication of a 2D nitrogenated network polymerencapsulated cobalt-oxide (Co@C2N) catalyst via an in situ solvothermal synthesis. Co@C2N exhibits outstanding catalytic activities for hydrogen (H2) generation from the hydrolysis of alkaline sodium borohydride (NaBH4) solutions. The rate of maximum hydrogen generation is comparable to the best reported values for catalysts containing other noble metals in alkaline solutions. Moreover, Co@C2N can also catalyze the in situ reduction of a nitro group into an amino group (4-nitrophenol to 4-aminophenol) in the presence of NaBH4. The origin of high catalytic activity with enhanced stability could be due to the strong interaction between the cobalt-oxide nanoparticle and the C2N framework, which contains a large portion of nitrogen.
Two-dimensional crystals for energy conversion and storage
( Javeed Mahmood ),백종범 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.0
Despite recent explorations in 2D materials science and engineering, easy and scalable methods to produce uniformly doped 2D materials are limited. To overcome these problems, a new layered 2D network structure with uniformly distributed holes and nitrogen atoms was synthesized and its stoichiometry of basal plane is C2N1. The structure of the C2N was confirmed by scanning tunneling microscopy (STM). Its calculated and experimental band-gaps are 1.7 and 2.0 eV, respectively, in the semiconductor region, suggesting a clear advantage over conducting graphene and insulating h-BN. The C2N structure was used to encapsulate iron (Fe) and cobalt (Co) particles by in situ reduction to give Fe@C2N and Co@C2N, which were used as electrocatalysts for energy conversion and storage.
Two-dimensional polyaniline (C<sub>3</sub>N) from carbonized organic single crystals in solid state
Mahmood, Javeed,Lee, Eun Kwang,Jung, Minbok,Shin, Dongbin,Choi, Hyun-Jung,Seo, Jeong-Min,Jung, Sun-Min,Kim, Dongwook,Li, Feng,Lah, Myoung Soo,Park, Noejung,Shin, Hyung-Joon,Oh, Joon Hak,Baek, Jong-Beo National Academy of Sciences 2016 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.113 No.27
<P>The formation of 2D polyaniline (PANI) has attracted considerable interest due to its expected electronic and optoelectronic properties. Although PANI was discovered over 150 y ago, obtaining an atomically well-defined 2D PANI framework has been a longstanding challenge. Here, we describe the synthesis of 2D PANI via the direct pyrolysis of hexaaminobenzene trihydrochloride single crystals in solid state. The 2D PANI consists of three phenyl rings sharing six nitrogen atoms, and its structural unit has the empirical formula of C3N. The topological and electronic structures of the 2D PANI were revealed by scanning tunneling microscopy and scanning tunneling spectroscopy combined with a first-principle density functional theory calculation. The electronic properties of pristine 2D PANI films (undoped) showed ambipolar behaviors with a Dirac point of -37 V and an average conductivity of 0.72 S/cm. After doping with hydrochloric acid, the conductivity jumped to 1.41 x 10(3) S/cm, which is the highest value for doped PANI reported to date. Although the structure of 2D PANI is analogous to graphene, it contains uniformly distributed nitrogen atoms for multifunctionality; hence, we anticipate that 2D PANI has strong potential, from wet chemistry to device applications, beyond linear PANI and other 2D materials.</P>
An efficient and pH-universal ruthenium-based catalyst for the hydrogen evolution reaction
Mahmood, Javeed,Li, Feng,Jung, Sun-Min,Okyay, Mahmut Sait,Ahmad, Ishfaq,Kim, Seok-Jin,Park, Noejung,Jeong, Hu Young,Baek, Jong-Beom Nature Publishing Group, a division of Macmillan P 2017 Nature nanotechnology Vol.12 No.5
<P>The hydrogen evolution reaction (HER) is a crucial step in electro-chemical water splitting and demands an efficient, durable and cheap catalyst if it is to succeed in real applications(1-3). For an energy-efficient HER, a catalyst must be able to trigger proton reduction with minimal overpotential(4) and have fast kinetics(5-9). The most efficient catalysts in acidic media are platinum-based, as the strength of the Pt-H bond(10) is associated with the fastest reaction rate for the HER11,12. The use of platinum, however, raises issues linked to cost and stability in non-acidic media. Recently, non-precious-metal-based catalysts have been reported, but these are susceptible to acid corrosion and are typically much inferior to Pt-based catalysts, exhibiting higher overpotentials and lower stability(13-15). As a cheaper alternative to platinum, ruthenium possesses a similar bond strength with hydrogen (similar to 65 kcal mol(-1))(16), but has never been studied as a viable alternative for a HER catalyst. Here, we report a Ru-based catalyst for the HER that can operate both in acidic and alkaline media. Our catalyst is made of Ru nanoparticles dispersed within a nitrogenated holey two-dimensional carbon structure (Ru@C2N). The Ru@C2N electrocatalyst exhibits high turnover frequencies at 25 mV (0.67 H-2 s(-1) in 0.5 M H2SO4 solution; 0.75 H-2 s(-1) in 1.0 M KOH solution) and small overpotentials at 10 mA cm(-2) (13.5 mV in 0.5 M H2SO4 solution; 17.0 mV in 1.0 M KOH solution) as well as superior stability in both acidic and alkaline media. These performances are comparable to, or even better than, the Pt/C catalyst for the HER.</P>