Owing to the importance of explosive detection for the security of land and the environment, the exploration of new methodologies for sensing electron-deficient nitroaromatics explosives (NAEs) is urgently imperative. In this work, we... more
Owing to the importance of explosive detection for the security of land and the environment, the exploration of new methodologies for sensing electron-deficient nitroaromatics explosives (NAEs) is urgently imperative. In this work, we firstly reported a colorimetric sensor for visual detection of 2,4,6-trinitrotoluene (TNT) based on Cysteamine capped-CdSe quantum dots (QDs) decorated graphene-chitosan xerogel (GSXS), which is shown to have high signal-to-background ratio. Meisenheimer complex formation, which is a well-known sensing mechanism, is characterized by steady state and time resolved spectroscopy supported by Density-Functional-Theory (DFT). Upon Green Fluorescent Protein (GFP) illumination, this stable Meisenheimer complex actively suppresses the attributed fluorescence of QD-GSXS and thus providing a novel path for chemical sensing applications. Under optimized conditions, the sensor displayed a wide linear range from 0.0 to 311.4 μ M with a limit of detection 9.7 μ M. T...
his study puts forward the synthesis of an excellent cadmium adsorbent having unprecedented high capacity (Qmax = 5000 mg g-1) to capture cadmium ions from synthetic cadmium solution. To synthesize the adsorbent (A700), base catalyzed... more
his study puts forward the synthesis of an excellent cadmium adsorbent having unprecedented high capacity (Qmax = 5000 mg g-1) to capture cadmium ions from synthetic cadmium solution. To synthesize the adsorbent (A700), base catalyzed polymerization of tetra ethylorthosilicate (TEOS) was conducted under the sacrificial templation effect of poly(acrylamide) grafted Cassia grandis seed gum (CG) while using H2O, TEOS and EtOH in 8:1:1: ratio (v/v). The CG inspired adsorbent was characterized by FTIR, XRD and SEM, both before and after cadmium adsorption. The adsorption parameters for the synthesized adsorbent were optimized by performing the batch adsorption studies under different pH, initial cadmium concentration, adsorbent dose, and contact time. The adsorption showed pseudo second order kinetics with a rate constant of 1.55 x 10-4 g mg-1min-1 at 450 mg mL-1 Cd(II) concentration. The thermodynamic study showed that the adsorption is endothermic and spontaneous. The adsorbent could be successfully reused for three cycles. The present adsorbent is not only very efficient in cadmium uptake; it is greener than the contemporary porous silica adsorbents derived through templation of pure synthetic polymers or surfactants. Moreover the source polysaccharide used for its synthesis is abundant and cheap. This hybrid can utilized as versatile and sustainable adsorbent for cadmium recovery from industrial wastes
Clays have previously demonstrated potential as drug delivery carriers for the extended release of a variety of drugs. The objective of this study was to develop and characterise drug-containing clays in combination with natural hydrogels... more
Clays have previously demonstrated potential as drug delivery carriers for the extended release of a variety of drugs. The objective of this study was to develop and characterise drug-containing clays in combination with natural hydrogels for the preparation of lyophilised xerogels. Sulfathiazole (STH) (a hydrophobic model drug) was intercalated within the interlayer spaces of Laponite® RDS (LAP RDS) or refined montmorillonite (MMT) and then mixed with either carageenen 812 (CAR 812) or hydrohydroxy ethyl cellulose (HEC) hydrogels prior to lyophilisation. The resulting xerogels were characterised visually, using differential scanning calorimetry (DSC) and with scanning electron microscopy (SEM). Optimal geo-polymeric wafers contained 1.5% W/W CAR 812 with 2% LAP RDSand 1% W/W intercalated STH. DSC and SEM results indicated the amorphous form of STH was intercalated inLAP RDS within theleafy structure of CAR 812. This xerogel hydrated up to1700% within 40 minutes and released the STH by Higuchikinetic model.
The prominent polynuclear spin-crossover complex [Fe(NH2trz)3](2ns)2 (polymer) (NH2trz = 4-amino- 1,2,4-triazole, 2ns = 2-naphthalenesulfonate) as obtained from synthesis exists in a metastable state characterized by a columnar... more
The prominent polynuclear spin-crossover complex [Fe(NH2trz)3](2ns)2 (polymer) (NH2trz = 4-amino-
1,2,4-triazole, 2ns = 2-naphthalenesulfonate) as obtained from synthesis exists in a metastable state
characterized by a columnar hexagonal packing (Colh) of polynuclear rigid–rod complexes, and shows
considerable fluctuations in the spin-crossover temperature (between 22 and 41 °C upon heating and
between 14 and 25 °C upon cooling). This structure is converted into a more stable columnar
rectangular packing (Colr) by annealing this material at 250 °C, which is accompanied by a shift of the
spin-crossover towards higher temperatures (52 °C upon heating and 33 °C upon cooling).
Furthermore, solutions of [Fe(NH2trz)3](2ns)2 in dimethylformamide (DMF) can be converted into gels by
increasing the concentration of [Fe(NH2trz)3](2ns)2 or by addition of toluene, while preserving the spincrossover
behavior. Gels prepared by the latter method were converted into xerogels by CO2 critical point
drying, or into transparent thermochromic films by slow evaporation of the solvent. For the
xerogels an initial Colh packing is transformed into the more stable Colr packing by the same annealing
procedure applied to the powders. On the other hand, the slow evaporation of solvent used for the
manufacture of films allowed establishment of a Colr packing by annealing at lower temperatures (150 °C).
The use of gold as a promotor of alkane hydrocarboxylation is reported for the first time. Cyclohexane hydrocarboxylation to cyclohexanecarboxylic acid (up to 55% yield) with CO, water, and peroxodisulfate in a water/acetonitrile medium... more
The use of gold as a promotor of alkane hydrocarboxylation is reported for the first time. Cyclohexane hydrocarboxylation to cyclohexanecarboxylic acid (up to 55% yield) with CO, water, and peroxodisulfate in a water/acetonitrile medium at circa 50 °C has been achieved in the presence of gold nanoparticles deposited by a colloidal method on a carbon xerogel in its original form (CX), after oxidation with HNO₃ (-ox), or after oxidation with HNO₃ and subsequent treatment with NaOH (-ox-Na). Au/CX-ox-Na behaves as re-usable catalyst maintaining its initial activity and selectivity for at least seven consecutive cycles. Green metric values of atom economy or carbon efficiency also attest to the improvement brought by this novel catalytic system to the hydrocarboxylation of cyclohexane.
The use of gold as a promotor of alkane hydrocarboxylation is reported for the first time. Cyclohexane hydrocarboxylation to cyclohexanecarboxylic acid (up to 55% yield) with CO, water, and peroxodisulfate in a water/acetonitrile medium... more
The use of gold as a promotor of alkane hydrocarboxylation is reported for the first time. Cyclohexane hydrocarboxylation to cyclohexanecarboxylic acid (up to 55% yield) with CO, water, and peroxodisulfate in a water/acetonitrile medium at circa 50 °C has been achieved in the presence of gold nanoparticles deposited by a colloidal method on a carbon xerogel in its original form (CX), after oxidation with HNO₃ (-ox), or after oxidation with HNO₃ and subsequent treatment with NaOH (-ox-Na). Au/CX-ox-Na behaves as re-usable catalyst maintaining its initial activity and selectivity for at least seven consecutive cycles. Green metric values of atom economy or carbon efficiency also attest to the improvement brought by this novel catalytic system to the hydrocarboxylation of cyclohexane.
