Chitosan-functionalized supermagnetic halloysite nanotubes for covalent laccase immobilization

Kadam, Avinash A.,Jang, Jiseon,Jee, Seung Cheol,Sung, Jung-Suk,Lee, Dae Sung Elsevier 2018 Carbohydrate polymers Vol.194 No.-

<P><B>Abstract</B></P> <P>Halloysite nanotubes (HNTs) were modified with supermagnetic Fe<SUB>3</SUB>O<SUB>4</SUB> (M-HNTs) and functionalized with chitosan (CTA) (termed as M-HNTs–CTA). Furthermore, M-HNTs–CTA were cross-linked using glutaraldehyde and applied for covalent laccase immobilization (M-HNTs–CTA–<I>Lac</I>). Facile-synthesized modified HNTs were structurally characterized by scanning electron microscopy, high resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and thermogravimetric analyses. M-HNTs–CTA–<I>Lac</I> exhibited 92.74 mg/g of laccase immobilization capacity and 92% of activity recovery. Biochemical properties of M-HNTs–CTA–<I>Lac</I> exhibited higher pH and temperature stabilities, with exceptional reusability capabilities until the 11<SUP>th</SUP> cycle. Moreover, M-HNTs–CTA–<I>Lac</I> exhibited 87% of 2,2′-azinobis (3-ethylbenzthiazoline-6-sulphonic acid) (ABTS)-mediated Direct Red 80 (DR80) decolorization. By the 11<SUP>th</SUP> cycle, M-HNTs–CTA–<I>Lac</I> exhibited 33% DR80 decolorization. Therefore, M-HNTs–CTA can function as CTA-modified supermagnetic nonreactors for immobilization of biomacromolecules. The investigated M-HNTs–CTA–<I>Lac</I> are thus biocompatible and environment-friendly biocatalysts for degradation of textile waste, such as DR80, and can be rapidly retrieved from aqueous solution by a magnet after decontamination of environmental pollutants.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Chitosan (CTA)-functionalized supermagnetic HNTs (M-HNTs) were synthesized. </LI> <LI> Laccase (<I>Lac</I>) was covalently immobilized on M-HNTs–CTA. </LI> <LI> M-HNTs–CTA–<I>Lac</I> exhibited better biocatalysis than free laccase. </LI> <LI> M-HNTs–CTA–<I>Lac</I> exhibited excellent degradation of Direct Red 80 (DR80). </LI> <LI> Repeated cycles of DR80 degradation confirmed sustainable and greener biocatalysis. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Supermagnetically Tuned Halloysite Nanotubes Functionalized with Aminosilane for Covalent Laccase Immobilization

Kadam, Avinash A.,Jang, Jiseon,Lee, Dae Sung American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.18

<P>Halloysite nanotubes (HNTs) were tuned with supermagnetic Fe3O4 (M-HNTs) and functionalized with beta-aminopropyltriethoxysilane (APTES) (A-M-HNTs). Gluteraldehyde (GTA) was linked to A-M-HNTs (A-M-HNTs-GTA) and explored for covalent laccase immobilization. The structural characterization of M-HNTs, A-M-HNTs, and A-M-HNTs-GTA-immobilized laccase (A-M-HNTs-GTA-Lac) was determined by X-ray photoelectron spectroscopy, field-emission high resolution transmission electron microscopy, a magnetic property measurement system, and thermogavimetric analyses. A-MHNTs-GTA-Lac gave 90.20% activity recovery and a loading capability of 84.26 mg/g, with highly improved temperature and storage stabilities. Repeated usage of A-M-HNTs-GTA-Lac revealed a remarkably consistent relative activity of 80.49% until the ninth cycle. The A-M-HNTs-GTA-Lac gave consistent redox-mediated sulfamethoxazole (SMX) degradation up to the eighth cycle. In the presence of guaiacol, A-M-HNTs-GTA-Lac gave elevated SMX degradation compared with 2,2'-azinobis(3-ethylbenzthiazoline-6-sulfonic acid) and syrinialdehyde. Therefore, the A-M-HNTs can serve as supermagnetic aminofunctionalized nanoreactors for biomacromolecule immobilization. The obtained A-M-HNTs-GTA-Lac is an environmentally friendly biocatalyst for effective degradation of micropollutants, such as SMX, and can be easily retrieved from an aqueous solution by a magnet after decontamination of pollutants in water and wastewater.</P>

Review on Modeling of Vapor Compression Chillers: District Cooling Perspective

Kadam Sambhaji T.,Hassan Ibrahim,Rahman Mohammad Azizur,Papadopoulos Athanasios I.,Seferlis Panos 대한설비공학회 2020 International Journal Of Air-Conditioning and Refr Vol.28 No.2

Energy consumption and its associated consequences can be reduced by implementing district cooling strategies that supply low temperature water to a wide range of end users through chillers and distribution networks. Adequate understanding, performance prediction and further optimization of vapor compression chillers used widely in district cooling plants have been a subject of intense research through model-based approaches. In this context, we perform an extensive review of different modeling techniques used for predicting steady-state or dynamic performance of vapor compression liquid chillers. The explored modeling techniques include physical and empirical models. Different physical models used for vapor compression chillers, based on physics laws, are discussed in detail. Furthermore, empirical models (based on artificial neural networks, regression analysis) are elaborated along with their advantages and drawbacks. The physical models can depict both steady- and unsteady-state performance of the vapor compression chiller; however, their accuracy and physical realism can be enhanced by considering the geometrical arrangement of the condenser and evaporator and validating them for various ecofriendly refrigerants and large system size (i.e., cooling capacity). Apparently, empirical models are easy to develop but do not provide the necessary physical realism of the process of vapor compression chiller. It is further observed that DC plants/networks have been modeled from the point of view of optimization or integration but no efforts have been made to model the chillers with multiple VCR cycles. The development of such models will facilitate to optimize the DC plant and provide improved control strategies for effective and efficient operation.

Catalyst-free silylation of alcohols and phenols by promoting HMDS in CH₃NO₂ as solvent

Kadam, Santosh T.,Kim, Sung Soo Royal Society of Chemistry 2010 GREEN CHEMISTRY Vol.12 No.1

<P>An uncatalyzed method for the silylation of alcohols and phenols with HMDS in CH<SUB>3</SUB>NO<SUB>2</SUB> at rt is developed. A diverse range of aromatic and aliphatic alcohols as well as phenols undergo the silylation in very short reaction time with excellent yield. The uncatalyzed reaction requires neither elevated temperature nor high pressure for the silylation.</P> <P>Graphic Abstract</P><P>A novel and efficient uncatalyzed method for the silylation of alcohols and phenols is developed. A variety of aromatic and aliphatic alcohols as well as phenols undergo the silylation in very short reaction time with excellent yield. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=b913398d'> </P>

Mild and efficient silylation of alcohols and phenols with HMDS using Bi(OTf)₃ under solvent-free condition

Kadam, Santosh T.,Kim, Sung Soo Elsevier 2009 Journal of organometallic chemistry Vol.694 No.16

<P><B>Graphical abstract</B></P><P>A very efficient and mild silylation of alcohols and phenols with (Me<SUB>3</SUB>Si)<SUB>2</SUB>NH at rt is developed using Bi(OTf)<SUB>3</SUB> as the catalyst. Variety of aromatic and aliphatic alcohols and phenols produce corresponding silylether in excellent yield. This reaction may require the lowest catalyst quantity and relatively short reaction time of all the previous studies in recent years.</P><ce:figure></ce:figure> <P><B>Abstract</B></P><P>A very efficient and mild silylation of alcohols and phenols with hexamethyldisilazane (HMDS) at rt is developed using Bi(OTf)<SUB>3</SUB> as the catalyst. Primary, secondary and tertiary alcohols as well as phenols are excellently converted into corresponding TMS ethers in a very short reaction time. This procedure can also be applied to large scale silylation for industrial application.</P>

Morphological evolution of Cu doped ZnO for enhancement of photocatalytic activity

Kadam, A.N.,Kim, Taek Gon,Shin, Dong Su,Garadkar, K.M.,Park, Jinsub ELSEVIER SCIENCE 2017 Journal of Alloys and Compounds Vol.710 No.-

<P><B>Abstract</B></P> <P>The structure, morphology and chemical doping in metal oxide are important factors that can influence on its photocatalytic activity. In this work, a facile and template free reflux method has been used to synthesize ZnO nanostructures for the morphology control of cubes, maize corn seeds, and rods at low temperature. The photocatalytic activity of ZnO with different morphology was evaluated towards degradation of methyl orange under UV light illumination. Among all the morphology controlled ZnO, the maize corn seed shaped ZnO shows the superior photocatalytic activity. Moreover, the influence of Cu contents on the structural, optical, and photocatalytic activity of ZnO maize corn seed was also investigated systematically. The photocatalytic experiment towards the degradation of methyl orange revealed that the 0.5 mol% Cu doped ZnO exhibits 3.5 fold higher photocatalytic activity than pure corn seed shaped ZnO. The enhancement of photocatalytic activity by Cu ions substituting in ZnO lattices is attributed to synergetic effect of Cu and ZnO, increase the separation of photogenerated electron-hole pairs, oxygen vacancy, decrease in crystallite size and the higher surface to volume ratio. Based on scavengers test, it was found that both superoxide and hydroxyl radicals are mainly actives species involved for the degradation of methyl orange.</P> <P><B>Highlights</B></P> <P> <UL> <LI> ZnO with cube, corn seed and rod like morphology were prepared by a facile reflux method. </LI> <LI> Controlled Cu doping could be achieved at low temperature. </LI> <LI> The substitution of Cu<SUP>2+</SUP> in ZnO corn seed was confirmed by various characterization techniques. </LI> <LI> 0.5 mol% Cu doped ZnO exhibits 3.5 times higher photocatalytic activity than pure ZnO (Z5). </LI> <LI> Based on scavengers test, both superoxide and hydroxyl radicals are mainly actives species. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

TMEDA: Efficient and Mild Catalyst for the Acylation of Alcohols, Phenols and Thiols under Solvent-free Condition

Kadam, Santosh T.,Lee, Han-Bin,Kim, Sung-Soo Korean Chemical Society 2009 Bulletin of the Korean Chemical Society Vol.30 No.5

N,N,N′,N′-tetramethylethylenediamine (TMEDA) acts as a simple, mild and efficient catalyst for the acylation of alcohols, phenols and thiols at room temperature under solvent-free condition. Acylation reaction with acetic anhydride and benzoic anhydride proceeds with good to excellent yield in the presence of TMEDA as the catalyst.

Phosphomolybdic Acid Supported on Silica Gel as an Efficient and Reusable Catalyst for Cyanosilylation of Aldehydes

Kadam, Santosh T.,Kim, Sung-Soo Korean Chemical Society 2008 Bulletin of the Korean Chemical Society Vol.29 No.7

Phosphomolybdic acid supported on silica gel (PMA-$SiO_2$) is an efficient catalyst for the activation of TMSCN for the facile cyanosilylation of various aldehydes. Cyano transfer from TMSCN to aldehyde proceeds smoothly at rt in presence of 0.8 mol % of PMA-$SiO_2$ leading to a range of cyanosilylether in excellent yield (mostly over 93%) within short reaction time (30 min). The catalyst can be recovered and reused several times without loss of activity.

Adsorptive remediation of cobalt oxide nanoparticles by magnetized α-cellulose fibers from waste paper biomass

Kadam, Avinash,Saratale, Rijuta Ganesh,Shinde, Surendra,Yang, Jiwook,Hwang, Kyojung,Mistry, Bhupendra,Saratale, Ganesh Dattatraya,Lone, Saifullah,Kim, Dae-Youg,Sung, Jung-Suk,Ghodake, Gajanan Elsevier 2019 Bioresource technology Vol.273 No.-

<P><B>Abstract</B></P> <P>Remediation of engineered-nanomaterials is an up-coming major environmental concern. This study demonstrates adsorptive-remediation of cobalt oxide nanoparticles (CoO NPs) from the water. The α-cellulose-fibers were extracted from waste-paper biomass (WP-αCFs) and magnetized with Fe<SUB>3</SUB>O<SUB>4</SUB> NPs (M-WP-αCFs). The XRD, FT-IR, and TGA were performed for detailed characterization of the newly developed bioadsorbent. The M-WP-αCFs was then applied for adsorptive remediation of CoO NPs. The adsorptive kinetics of CoO NPs adsorption onto the M-WP-αCFs reveals the pseudo-second-order model. The various adsorption isotherm studies revealed Langmuir is a best-fit isotherm. A prominently high adsorption capacity <I>q<SUB>m</SUB> </I> (1567 mg/g) corroborated extraordinary adsorptive potential of M-WP-αCFs. Furthermore, CoO NPs were adsorbed onto M-WP-αCFs were analyzed by the XPS, VSM, and TEM. Therefore, this study gave rise WP biomass extracted and rapidly-separable nano-biocomposite of ‘M-WP-αCFs’ with a high-capacity for CoO NPs remediation and can be further applied in remediation of several other engineered-nanomaterials.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Office paper waste (WP) extracted α-cellulose fibers (αCFs) was magnetized. </LI> <LI> M-WP-αCFs presented an effective adsorptive-remediation of CoO NPs from the water. </LI> <LI> The adsorption kinetics followed a pseudo-second-order rate model. </LI> <LI> Langmuir adsorption isotherm model was best fit to the experimental data. </LI> <LI> M-WP-αCFs can be effective for remediation of engineered NPs from the water. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Facile synthesis of pectin-stabilized magnetic graphene oxide Prussian blue nanocomposites for selective cesium removal from aqueous solution

Kadam, A.A.,Jang, J.,Lee, D.S. Elsevier Applied Science 2016 Bioresource technology Vol.216 No.-

This work focused on the development of pectin-stabilized magnetic graphene oxide Prussian blue (PSMGPB) nanocomposites for removal of cesium from wastewater. The PSMGPB nanocomposite showed an improved adsorption capacity of 1.609mmol/g for cesium, compared with magnetic graphene oxide Prussian blue, magnetic pectin Prussian blue, and magnetic Prussian blue nanocomposites, which exhibited adsorption capacities of 1.230, 0.901, and 0.330mmol/g, respectively. Increased adsorption capacity of PSMGPB nanocomposites was attributed to the pectin-stabilized separation of graphene oxide sheets and enhanced distribution of magnetites on the graphene oxide surface. Scanning electron microscopy images showed the effective separation of graphene oxide sheets due to the incorporation of pectin. The optimum temperature and pH for adsorption were 30<SUP>o</SUP>C and 7.0, respectively. A thermodynamic study indicated the spontaneous and the exothermic nature of cesium adsorption. Based on non-linear regression, the Langmuir isotherm fitted the experimental data better than the Freundlich and Tempkin models.