Core–Shell Ferromagnetic Nanorod Based on Amine Polymer Composite (Fe₃O₄@DAPF) for Fast Removal of Pb(II) from Aqueous Solutions

Venkateswarlu, Sada,Yoon, Minyoung American Chemical Society 2015 ACS APPLIED MATERIALS & INTERFACES Vol.7 No.45

<P>Heavy metal ion removal from wastewater constitutes an important issue in the water treatment industry. Although a variety of nanomaterials have been developed for heavy metal removal via adsorption, the adsorption capacity, removal efficiency, and material recyclability still remain a challenge. Here, we present novel Fe<SUB>3</SUB>O<SUB>4</SUB>@DAPF core–shell ferromagnetic nanorods (CSFMNRs) for the removal of Pb(II) from aqueous solutions; they were prepared by the facile surface modification of twin-like ferromagnetic Fe<SUB>3</SUB>O<SUB>4</SUB> nanorods using a 2,3-diaminophenol and formaldehyde (DAPF)-based polymer. The crystallinity and structure of the Fe<SUB>3</SUB>O<SUB>4</SUB> nanorods were confirmed via X-ray diffraction (XRD). Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) revealed the core–shell morphology and composition of the materials. Pb(II) removal using the prepared Fe<SUB>3</SUB>O<SUB>4</SUB>@DAPF CSFMNRs was assessed, and comparable adsorption capacities (83.3 mg g<SUP>–1</SUP>) to the largest value were demonstrated. A thermodynamic study of the adsorption clearly indicated that the adsorption was exothermic and spontaneous. Due to the ferromagnetic properties with a high saturation magnetization value (56.1 emu g<SUP>–1</SUP>) of the nanorods, the nanorods exhibited excellent reusability with one of the fastest recovery times (25 s) among reported materials. Therefore, the Fe<SUB>3</SUB>O<SUB>4</SUB>@DAPF CSFMNRs can serve as recyclable adsorbent materials and as an alternative to commonly used sorbent materials for the rapid removal of heavy metals from aqueous solutions.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2015/aamick.2015.7.issue-45/acsami.5b07723/production/images/medium/am-2015-07723v_0016.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am5b07723'>ACS Electronic Supporting Info</A></P>

Facile Preparation of Ionic Liquid-coated Copper Nanowire-modified Carbon Paste Electrode for Electrochemical Detection of Etilefrine Drug

Sada Venkateswarlu,Manthrapudi Venu,Yenegu Veera Manohara Reddy,Bathinapatla Sravani,코두루말리카주나,윤민영,G. Madhavi 대한화학회 2019 Bulletin of the Korean Chemical Society Vol.40 No.6

A carbon paste electrode (CPE)/Cu nanowire (Cu NW)/poly(1-ethyl-3-methylimidazolium methyl sulfate) based sensor was successfully fabricated by the electro-polymerization of 1-ethyl-3-methylimidazolium methyl sulfate (EMIMS) onto the surface of Cu nanowires-modified carbon paste electrode. The morphology and chemical nature of Cu NWs were characterized by FTIR, FE-SEM, TEM, XRD techniques. The CPE/CuNWs/poly(EMIMS) showed an electrocatalytic activity toward the determination of etilefrine hydrochloride (ET-HCl) in the 0.11?M buffer solution of phosphate at pH 7.0. The CPE/CuNWs/poly(EMIMS) showed an excellent limit of detection (LOD) 2.3 ?M over the linear dynamic range of 0.1 to 1.3 ?M. The prepared CPE/CuNWs/poly(EMIMS) has exhibited high stability, good sensitivity, and low detection limit for the determination of ET-HCl. The validity of this advanced method was checked by applying in the blood plasma samples, with satisfactory results. This novel CPE/CuNWs/poly(EMIMS) can be an attractive material for the applications in biomedical and sensor fields.

Surfactant-free green synthesis of Fe₃O₄ nanoparticles capped with 3,4-dihydroxyphenethylcarbamodithioate: stable recyclable magnetic nanoparticles for the rapid and efficient removal of Hg(<small>II</small>) ions from water

Venkateswarlu, Sada,Yoon, Minyoung The Royal Society of Chemistry 2015 Dalton Transactions Vol.44 No.42

<P>Mercury is considered one of the most notorious global pollutants due to its high toxicity and widespread use in industry. Although many materials have been developed for the removal of mercury for water purification, most of these materials are difficult to reuse, which may lead to an increase in the mercury handling expense. Therefore, new sustainable materials that can be easily recycled and are highly efficient for the removal of mercury are required. Herein, we report the surfactant-free green synthesis of Fe<SUB>3</SUB>O<SUB>4</SUB> magnetic nanoparticles (MNPs) using a watermelon (<I>Citrullus lanatus</I>) rind extract. The Fe<SUB>3</SUB>O<SUB>4</SUB> MNPs were further functionalized with 3,4-dihydroxyphenethylcarbamodithioate (DHPCT) and applied to the removal of Hg(<SMALL>II</SMALL>). Evaluation of the mercury removal efficiency and the amount adsorbed by DHPCT@Fe<SUB>3</SUB>O<SUB>4</SUB> MNPs demonstrated a high Hg(<SMALL>II</SMALL>) removal efficiency (98%) with a maximum Hg(<SMALL>II</SMALL>) adsorption capacity of 52.1 mg g<SUP>−1</SUP>. Systematic studies of the adsorption mechanism and selectivity suggest that the soft ligand (DHPCT) can preferentially coordinate with the soft metal ion (Hg(<SMALL>II</SMALL>)) resulting in selective mercury removal. The developed DHPCT@Fe<SUB>3</SUB>O<SUB>4</SUB> MNPs were readily recycled several times using an external magnet by exploiting their ferromagnetic character, without a significant decline in the Hg(<SMALL>II</SMALL>) removal efficiency. This study provides a new insight into the preparation of a highly efficient adsorbent for Hg(<SMALL>II</SMALL>) removal by an eco-friendly method.</P> <P>Graphic Abstract</P><P>A 3,4-dihydroxyphenethylcarbamodithioate capped biogenic Fe<SUB>3</SUB>O<SUB>4</SUB> magnetic nanocomposite has been synthesized using a watermelon rind extract for the removal of Hg(<SMALL>II</SMALL>) ions with a facile recyclability. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c5dt03155a'> </P>

Fungus-derived photoluminescent carbon nanodots for ultrasensitive detection of Hg²⁺ ions and photoinduced bactericidal activity

Venkateswarlu, Sada,Viswanath, Buddolla,Reddy, Ankireddy Seshadri,Yoon, Minyoung Elsevier 2018 Sensors and actuators. B, Chemical Vol.258 No.-

<P><B>Abstract</B></P> <P>Herein, we present a sustainable solvent-free synthetic procedure to produce carbon nanodots from common edible mushrooms (<I>Pleurotus</I> spp.). The resulting mushroom carbon nanodots (MCDs) exhibit stable blue fluorescence with high quantum yield (25%). The MCDs are highly dispersible in water because of the enormous number of oxygen- and nitrogen-containing functional groups on the surface. The MCDs can be used as an effective fluorescent probe for label-free detection of Hg<SUP>2+</SUP> ions (detection limit: 4.13nM). To improve the sensitivity, dihydrolipoic acid was attached to the surface of MCDs, resulting in ultra-sensitivity in Hg<SUP>2+</SUP> ion sensing, with a detection limit as low as 17.4 pM. In addition, the MCDs can be used for the labeling of bacteria and as a photoinduced bactericidal agent. Light irradiation of <I>E. coli</I> treated with MCDs showed excellent bactericidal activity relative to the control. These sustainable and affordable carbon materials are potentially compatible for monitoring toxic metals and as a potent visible-light-responsive bactericidal probe.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A facile chemical free synthesis of carbon nanodots using mushrooms </LI> <LI> Temperature dependent synthesis study for high yield of carbon nanodots </LI> <LI> Very stable MCDs with easy functionalization with DHLA under benign conditions </LI> <LI> Ultrahigh sensitive detection of Hg<SUP>2+</SUP> ions with a detection limit as low as 17.4 pM </LI> <LI> Excellent photo-induced reactive oxygen species generation and bactericidal activity </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Bio-inspired fluorescence probe for ultra level detection of aliphatic amines

Panda, Atanu,Venkateswarlu, Sada,Reddy, Ankireddy Seshadri,Yoon, Minyoung Elsevier 2018 Dyes and pigments Vol.156 No.-

<P><B>Abstract</B></P> <P>The detection of trace amounts of amines is essential to mitigate toxicity and health risks. Various chemical probes have been reported for the detection of amines, which are expensive, difficult to handle, and toxic. In this study, we have developed a bio-inspired fluorescent probe for ultra-level detection of amines in liquid solution. Diatoms, which are silicified algae were used strategically for the detection of aliphatic amines. The presence of an electron-deficient moiety in diatoms improves the ability of diatoms to detect electron-rich organic amines. When an organic amine binds to the pyrolyzed diatom, enhanced photoluminescence and a color change under UV irradiation were observed. Interestingly, fluorescence analysis revealed that the diatoms can selectively detect aliphatic amines with sensitivity up to the pM level, even in the presence of other volatile organic compounds. Among the given analytes, only the electron-rich aliphatic amines significantly enhanced the fluorescence intensity. In contrast, aromatic amines and other organic solvents did not exhibit a fluorescence signal for detection. In particular, ethylenediamine (EDA) contributes the most apparent enhancement effect, with a detection limit of 116 pM. Therefore, diatoms were proved it potential as a tool for monitoring toxic organic molecules.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Developed a bio-inspired 'turn-on' fluorescence probe, a pyrolyzed diatom, for the detection of aliphatic amines in the liquid phase. </LI> <LI> The diatom has excellent selectivity towards aliphatic amines better than aromatic amines. </LI> <LI> The sensitivity of the probe is achieved up to pM level of aliphatic amines. </LI> <LI> Facile identification of the sensing properties by visual color analysis. </LI> <LI> This low-cost material could be an attractive fluorescent probe for the detection of electron-rich molecules. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Turn-on diatom fluorescence towards aliphatic amine binding.</P> <P>[DISPLAY OMISSION]</P>

Bio-inspired self-propelled diatom micromotor by catalytic decomposition of H₂O₂ under low fuel concentration

Panda, Atanu,Reddy, Ankireddy Seshadri,Venkateswarlu, Sada,Yoon, Minyoung The Royal Society of Chemistry 2018 Nanoscale Vol.10 No.34

<P>Recently, active bubble-propelled micromotors have attracted great attention for fuel applications. However, for generating bubble-propelled micromotors, additional catalysts, such as Pt, Ag, and Ru, are required. These catalysts are expensive, toxic, and highly unstable for broad applications. To overcome these issues, in this study, we present an innovative methodology for the preparation of self-propelled motor machines using naturally occurring diatom frustules. This natural diatom motor shows effective motion in the presence of a very low concentration (0.8%) of H2O2 as a fuel at pH 7. Due to the unique 3D anisotropic shape of the diatom, the self-propelled motor exhibited unidirectional motion with a speed of 50 μm s<SUP>−1</SUP> and followed pseudo first-order kinetics. It was found that a trace amount of iron oxide (Fe2O3) in the diatom was converted into Fe3O4, which can act as a catalyst to achieve the facile decomposition of H2O2. Interestingly, “braking” of the unidirectional motion was observed upon treatment with EDTA, which blocked the catalytically active site. These results illustrate that diatom catalytic micromotors have opened a new era in the field of catalysis and bioengineering applications.</P>