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Present work described the synthesis of Al-Fe-Zn oxide nanocomposite and surface properties determinations by spectrophotometric method. Homogeneous mixing of metals, size range 9–13 nm, and rough surface determined from TEM and FESEM images are discussed. The specific surface area (121.3 m2/g), crystalline nature and elemental composition were deduced from XRD and EDAX analysis. The presence of surface hydroxyl group as identified by FTIR was found responsible for complex formation with chromate ion. The batch adsorption of chromium at different experimental variables revealed an optimised condition for chromium adsorption. Adsorption data followed second-order kinetics, Langmuir, and Freundlich isotherms. The pore diffusion and complex formation for chromium adsorption mechanism were predicted on the basis of kinetic and isotherm studies. The statistical data reveal that the double-layer model best explains the adsorption behaviour and mechanism. The unique surface properties, excellent reuse efficiency signify the application of nanocomposite. [ABSTRACT FROM AUTHOR]

The latest developments in the adsorption of organic dyes by adsorbents (metal oxides, modified metal oxides) were addressed in this review study. The main goal of this paper is to sort out the dispersion information of adsorbent materials, which are often employed in organic dye adsorption. The review dedicated to the specific dyes adsorption using various adsorbent (metal oxides, modified metal oxides). The review covers the adsorption process including parameters, kinetics, and isotherms. The review gives the brief information of Congo red (CR) adsorption using metal oxide nano‐adsorbents which provide readers with massive dye specific collection. For the first time, several metal‐doped materials that absorb organic dyes are summarized and addressed. The review includes adsorption of organic dyes using single metal oxide, bimetallic oxide, trimetallic oxide, and modified metal oxide. This study also summarized the effects of critical factors such as pH, initial dye concentration, adsorbent dosage, contact time, and temperature on dye adsorption utilizing metal oxide nano‐adsorbents. In addition, the kinetic and applied isotherm models have been discussed. Finally, a few recommendations are made for further research on adsorbent materials. [ABSTRACT FROM AUTHOR]

An efficient co-precipitation followed by ultrasonication process is used for the synthesis of trimetallic MgZnFeO nanocomposites (MZFONCs) and further characterized by FE-SEM, FT-IR, XRD, EDX, etc. spectroscopic techniques. The adsorption process is applied for the removal of toxic cationic Basic Fuchsine (BF) dye using batch experiments. To enhance removal efficiency, the effect of deviation in parameters including shaking time; adsorbent dose; pH; etc. are studied. Qmax obtained by Langmuir is found to be 250 mg/g for BF on the MZFONCs surface, at pH = 6.5; 40 min of agitation time, and a small dose of nanoparticles. The best match for the adsorption of BF on MZFONCs is a double-layer method which also describes the adsorption mechanism. The 'n' parameter value (0.507–0.628) is obtained from the statistical physics model, which shows mixed-orientation type adsorption of BF molecules on MZFONCs adsorbents. The calculated energies for BF dye adsorption are found to be less than 30 KJ/mol, hence implying an endothermic and physical adsorption mechanism. [ABSTRACT FROM AUTHOR]

Pb(II) doped zinc oxide nanoparticles (Pb-ZnONPs) was synthesised using the co-precipitation method. The average size distribution of the Pb-ZnONPs is 42.8 nm and further used as an adsorbent to remove Erichrome Black T (EBT) from wastewater. The adsorption of EBT onto the Pb-ZnONPs was best fitted for pseudo-second-order kinetics model, indicating that the adsorption phenomena depend on EBT and Pb-ZnONPs, showing chemisorption phenomenon. The maximum adsorption potential of Pb-ZnONPs (qmax = 200 mgg−1) for EBT is far better than that of the already available adsorbents. The high regression coefficient of freundlich shows that the adsorption can be shown by multi-layer process. The value of ΔG° is negative and temperature increases with an increase in the absolute value increases, suggesting the adsorption of dye onto the Pb-ZnONPs is spontaneous. The decrease in the concentration of adsorbed monolayer (Q0 = nNM) from 411 to 43.55 mg/g with the change in temperature revealed that the adsorption process is exothermic in nature. The Pb-ZnONPs have exhibited a variation of about 7–8% of adsorption compared to the fresh sample after 5th regeneration. [ABSTRACT FROM AUTHOR]

In this study, the synthesis process of TiZnPbO nanocomposite and its use for the removal of Basic Fuchsin (BF) dye from wastewater was studied. The influence of contact duration (90 min), concentration (200 mg/L), solution pH (3.0), and adsorbent dosage (0.2 g) on adsorption studies were thoroughly examined. The kinetic models (pseudo‐first‐order and pseudo‐second‐order) and isotherm models (Langmuir and Freundlich) are used to understand the adsorption mechanism and behavior of BF over adsorbents. According to the kinetic data, the models fit a pseudo‐second‐order equation which is an indication of a heterogeneous chemisorption process. The Langmuir isotherm is best fitted with R2 of 0.999 and a maximum adsorption capacity of 208.33 mg/g. It was determined that the values of n for the adsorption of BF on TiZnPbO at 298 K were less than unity (n=0.516, 0.504, and 0.501). This finding showed that the BF dyes should be adsorbed on this adsorbent in a non‐parallel orientation. As for BF adsorption on TiZnPbO, the isotherm data indicated that it behaved more like a multilayer than a monolayer. The TiZnPbO adsorbent showed high recyclability at least 5 times. [ABSTRACT FROM AUTHOR]

Highlights: [•] We synthesized a fluorescence receptor (2) and report it as a photoinduced electron transfer (PET) cation sensor. [•] The association constant (K) of receptor (2) with Fe3+ ions was calculated at 1.4±0.2×104 M−1. [•] The 1:1 stoichiometry of the host guest relationship was realized from the Job’s plot. [ABSTRACT FROM AUTHOR]

[Display omitted] • CV adsorption onto FeTiPbONCs was interpreted using statistical physics model. • The Nm values obtained 355.85, 50.91 and 26.815 mg/g at temp. 298, 308 m, and 318 K. • The adsorption energy ε 1 (16.95 to 30.39 kJ/mol) and ε 2 (7.98 to 13.02 kJ/mol). • The double layer model best explain the adsorption behavior and mechanism. In this study, Crystal Violet (CV) adsorption isotherm on FeTiPbONC was simulated and interpreted using the conventional methods as well as statistical physics two energies double layer model. This model was formalized based on the statistical physics. The following parameters are added in this pattern: steric and energy-sensitive parameters relevant to the adsorption mechanism. The findings of the mathematical model at temperatures 298, 308 , and 318 K givethe values of receptor site density (Nm) as 355.85, 50.91 and 26.815 mg/g, which reveals that maximum adsorption was achieved at lower temperature. The adsorption energies ε 1 (from 16.95 to 30.39 kJ/mol) and ε 2 (from 7.98 to 13.02 kJ/mol) increases as temperature rises, showing that the CV-FeTiPbONC contact is stronger than the CV-CV interaction. The results showed that FeTiPbONC might be employed as a nanoadsorbent for the removal of organic contaminants from an aqueous matrix. [ABSTRACT FROM AUTHOR]

Fe-Mn-Zn oxide trimetal alloy nanocomposite (FMZONC) fabricated and surface properties of the composite material revealed via several characterization methods. Porous nature and alloy type mixing of metals deduced from transmission electron microscopy analysis. Field emission scanning electron microscopy image revealed composite material is of size between 7 and 16 nm. The adsorption properties investigated through isotherm and kinetic experiments. In addition, pH effects and desorption properties were also studied. Maximum adsorption capacity (q max) 149 mg/g for phosphate removal observed at pH 6 and 0.20 g/L of adsorbent. Chemical interaction between metal hydroxide and phosphate elaborated from Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). [ABSTRACT FROM AUTHOR]

Recently composite metal oxides have gained significant attention to be used as adsorbent because of their synergetic effects. Particularly Manganese containing composite oxides are useful for removal of inorganic oxyacids such as phosphate or arsenate. In present study fabrication of Mn-Zn-Ti Oxide adsorbent for phosphate removal carried out via co precipitation method. Surface properties deduced by TEM, FESEM, EDAX and XRD, revealed nanosized composite material has a porous nature constitute of alloy type mixing of the metals. Size of the nanocomposite found to be as small as 6 nm. Adsorption capacity for phosphate estimated at different pH, time and adsorbent dose by batch mode. In addition desorption properties and thermodynamic study also carried out. Several isotherms and kinetic models applied to observe adsorption properties of the Mn-Zn-Ti Oxide nanocomposite. Adsorption capacity found to be 151 mg/g at pH 6, time 90 min, adsorbent dose 0.20 g/L and phosphate concentration of 200 mg/L. Adsorption data fitted to second order kinetics and Freundlich isotherm. Formation of complex between nanocomposite and phosphate predicted from FTIR and supported by pH kinetic and isotherm studies. Desorption and reusability found to be well maintained over five cycles. [ABSTRACT FROM AUTHOR]

A colorimetric and fluorescent 'on-off' chemosensor 1 was developed for the selective and sensitive detection of Cu2+ over the other examined metal ions. Upon addition of Cu2+, sensor 1 exhibits moderate enhancement in the absorbance intensity with a naked-eye detectable colour change from colourless to yellow in DMSO/H2O (50:50, v/v). Also, the emission of 1 was selectively quenched in the presence Cu2+ with fast response and the detection limit was found to be 50 nM. [ABSTRACT FROM AUTHOR]

Urea based fluorescent chemosensor 1 was synthesized. Receptor 1 shows unique selectivity for the Feion and no such significant response was noticed with other metal ions (Cr, Mn, Co, Ni, Cu, Zn, Cd, Hg, Pb and Bi) in DMSO/HO (50:50,v/v) semi-aqueous solution. The binding features have been established by absorption and fluorescence spectroscopic methods. The binding constant (K) values obtained from Benesi-Hildebrand, Scatchard and Connor plot for receptor 1 is (8.3 ± 0.3) × 10 M and has good detection limit 0.7 μM. The stoichiometry of 1.Fe complex was confirmed by mass spectroscopy and Job's plot. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Hybrid nanoparticles (NPs) were designed by adsorbing a (13 E ,19 E )-N 1 ′,N 3 ′-bis[4-(diethylamino)-2-hydroxybenzylidene]malonohydrazide ( L ) motif, on Fe 3 O 4 @SiO 2 distorted hexagonal and cubic NPs. Electronic images of the synthesized hybrid NPs revealed distorted topographies with size of ∼50–70 nm. We exploited key in vitro features, topographies, thermal behaviours, spectroscopic data, magnetic properties and heavy metal ion extraction efficiencies of the prepared hybrids. Additionally, the discrete discussion on the surface areas of the synthesized NPs tackled with BET, are introduced. Characterization with FT-IR, SEM, TEM, XRD, BET, VSM, TGA, particle size analysis and Raman spectroscopic techniques revealed that the organic scaffold L is attached to the prepared Fe 3 O 4 @SiO 2 NPs surface via adsorption or covalent interactions or some sort of charge/proton transfer. Antibacterial tests depicted that, L and Fe 3 O 4 @SiO 2 NPs exhibited moderate to good antifungal activity against C. albicans , while synthesized key hybrids has shown good to high antibacterial activity against Gram-positive bacterium, S. aureus , two Gram-negative bacteria's, E. coli and P. aeruginosa , and antifungal activity against C. albicans . Also, the Zn 2+ ion extraction efficiency of the key hybrids was tackled and validated with commercial pharmaceutical tablet analysis. [ABSTRACT FROM AUTHOR]

A fluorescent based receptor (4Z)-4-(4-diethylamino)-2-hydroxybenzylidene amino)-1,2dihydro-1,5-dimethyl-2-phenylpyrazol-3-one (receptor 3 ) was developed for the highly selective and sensitive detection of Cu 2+ and Zn 2+ in semi-aqueous system. The fluorescence of receptor 3 was enhanced and quenched, respectively, with the addition of Zn 2+ and Cu 2+ ions over other surveyed cations. The receptor formed host-guest complexes in 1:1 stoichiometry with the detection limit of 5 nM and 15 nM for Cu 2+ and Zn 2+ ions, respectively. Further, we have effectively utilized the two metal ions (Cu 2+ and Zn 2+ ) as chemical inputs for the manufacture of INHIBIT type logic gate at molecular level using the fluorescence responses of receptor 3 at 450 nm. [ABSTRACT FROM AUTHOR]

A new fluoride selective fluorescent receptor (13E,19E)-N1',N3'-bis[4-(diethylamino)-2-hydroxybenzylidene]malonohydrazide (1) was designed and synthesized. Receptor 1 showed a highly selective fluorescent 'turn-on' response towards F- among the various tested anions such as F-, Cl-, Br-, I-, HSO4-, H2PO4-, NO2- and CN- in CH3OH:H2O (50:50, v/v), due to the formation of hydrogen bonding host-guest complex in 1:1 stoichiometry with a detection limit of 45.7 nM and association constant of 1.0 x 104 M-1. The nature of interactions between the receptor 1 and F- was investigated by ¹H NMR and the probable structure of the 1⋅F- complex was predicted by B3LYP/6-31G** method. [ABSTRACT FROM AUTHOR]

A thiourea base receptor 1 was synthesized and characterized with ¹H NMR, 13C-NMR, and mass spectroscopy. The receptor 1 has shown judicious fluorescence enhancement in the intensity (at 385 nm) on binding with the sodium cation compared to other surveyed metal ions. The rationale behind the design of sensor lies in the fact that the sensor has sodium-binding recognition site, coupled with a fluorophore having the correct spectral and electron-accepting properties. Thus, the thiourea compound is a promising system for the development of new fluorescent probes for the detection of Na+ cation. [ABSTRACT FROM AUTHOR]

A linear Schiff-based receptor (L) containing two imino phenol units was developed for the selective fluorescent sensing of Zn2+ with a discriminating enhancement of 12-folds over the other surveyed cations. Within the huge plethora of Zn2+ receptors, this receptor is quite worth to mention because of its simple synthesis, low cost, no interference of Cd2+ and the judicious response availed with discernment. The spectroscopic (UV-Vis, fluorescence and mass) results, few mathematical models for determining analytical parameters such as binding constant (Ka), binding stoichiometry, detection limit, etc. and the frontier molecular orbitals were analyzed to explore the sensing ability of L and the mechanism. [ABSTRACT FROM AUTHOR]

Abstract: A malonohydrazide derivative bearing an imine and phenolic group was synthesized and had a high affinity and selectivity towards Zn2+. The recognition properties of receptor 1 were evaluated using absorbance and fluorescence spectroscopy. The 1:1 stoichiometry of 1.Zn2+ was confirmed from job׳s plot, mass spectra and density functional theory (DFT). The detection of Zn2+ in intracellular environment of HeLa cell through confocal microscopy was successfully applied for live cell imaging. [Copyright &y& Elsevier]

A dipodal ligand 2,2′-((ethane-1,2-diylbis(azanediyl))bis(ethane-1,1-diyl))diphenol was synthesized through a condensation reaction and was characterized with IR, 1H NMR, 13C-NMR, and mass spectroscopy. The receptor 2 has shown marked enhancement in fluorescence intensity (emission signal at 341 nm) on binding with Zn2+ as compared to other surveyed metal ions. The sensor has shown dramatic changes in dual channel fluorescence emission with λmax at 300 and 341 nm. The successive addition of Zn2+ to the solution of the sensor led to a blue shift of the peak maxima and interestingly upon addition of higher equivalents of Zn2+ quenched the fluorescence intensity of the sensor, and ultimately the original fluorescent profile of sensor was restored. The structures of 2 and 3 were optimized with B3LYP/LanL2DZ basis sets. The receptor 2 successfully detect the Zn2+ ion in HeLa cells cultured in Zn2+ enriched medium. [ABSTRACT FROM AUTHOR]

Highlights: [•] Preparation of a novel fluorescent sensor for sensitive and selective determination of Zn2+ ions. [•] Highly selective, sensitive and rapid recognition of Zn2+ ion. [•] Zn2+ ion detection limit as low as 1.74µM. [ABSTRACT FROM AUTHOR]

The noncyclic 2,2′-[ethane-1,2-diylbis (iminomethanediyl)]diphenol ( 4) fluorescent receptor bearing two amine and hydroxyl groups have been designed and investigated for their binding properties towards various cations. The fluorescent spectral measurements revealed that receptor 4 is a selective fluorescent sensor for Fe ions but not for metal ions such as Cr, Mn, Co, Ni, Cu, Zn, Cd, Hg, Pb and Bi. The binding ability was confirmed with spectroscopic methods and density functional theory calculation (DFT). This straightforward and cost effective receptor provides rapid detection of Fe ions at concentrations as low as 2.5 μM and expected to be useful to design efficient chemically and biological sensor. [ABSTRACT FROM AUTHOR]

Abstract: A novel cell-permeable urea-linked dipodal naphthalene-based fluorescent receptor 1 (1,1׳-(1,5,5-trimethyl-3-oxocyclohexane-1,2-diyl)bis(3-(naphthalen-2-yl)urea) was designed and synthesized. The cation recognition ability of 1 was evaluated with a library of metal ions in DMSO/H2O (9:1, v/v). The receptor showed a selective chromogenic and fluorescent turn-off response towards Hg2+ among the surveyed metal ions. The developed sensor was successfully applied to image intracellular Hg2+ in living cells and also for the determination of Hg2+ content in real water samples. Moreover, the DFT calculations were performed to complement the experimental evidences. [Copyright &y& Elsevier]

Abstract: An imine-linked dipodal Zn2+ complex has been synthesized and elevated its binding affinity towards library of metal ions (Cr3+, Mn2+, Fe3+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Hg2+, Pb2+ and Bi3+). The recognition properties of receptor 4 were performed in DMSO/H2O (50:50; v/v) and showed quenching upon interaction with Fe3+, Co2+ and Cu2+ ions. A photoinduced electron transfer (PET) is potential mechanism behind quenching. The coordination of such cations with the receptor 4 at amide part of carbonyl oxygen hindered the PET process and accordingly Turn-OFF the fluorescence of the receptor 4. The photophysical properties (fluorescence and absorption spectra) and density functional theory (DFT) clearly explains the binding mode between the receptor 4 and the detected cations. The selectivity and sensitivity of the receptor 4 for Fe3+, Co2+ and Cu2+ ions were acceptable and achieving a detection limit at the nano-molar level. [Copyright &y& Elsevier]

Highlights: [•] A new fluorescent urea and thiol based chemosensor was developed and synthesized. [•] Chemosensor showed excellent selectivity for Fe3+ ions over other interfering ions. [•] Chemosensor can detect Fe3+ up to 0.1μM in semi-aqueous medium (DMSO/H2O, 8:2, v/v). [•] Experimental results have been supported by DFT calculations. [Copyright &y& Elsevier]

A dipodal fluorescent receptor, 2,2'-[ethane-1,2-diylbis(iminoethane-1,1-diyl)]diphenol (2), with amine and hydroxyl moieties as binding sites has been synthesised and characterized with spectroscopic methods and single crystal X-ray techniques. The recognition of the anions with receptor 2 was studied using UV-Vis and fluorescence spectroscopy. The 1H-NMR spectroscopic and DFT studies revealed the distinct recognition of I- ions over the other surveyed anions. [ABSTRACT FROM AUTHOR]

Abstract: The malonohydrazide based fluorescent probe (7E,8E)–N1′,N3′-bis(1-(2-hydroxyphenyl)ethylidene) malonohydrazide (receptor 5) was designed and synthesized. It was confirmed by spectroscopic methods and the single crystal X-ray method. The receptors 5 show strong intramolecular hydrogen bonding which is useful in host–guest complexation. The fluorescence spectra of receptor 5 have shown distinct enhancement with the addition of Ni2+ ion over other surveyed cations. The stability constant was obtained by Benesi–Hildebrand, Scatchard and Connor's fitting methodologies. The 1:1 stoichiometry of the host–guest complexation was confirmed by Job's continuous variation method. [Copyright &y& Elsevier]

A pyridine based imine-linked chemosensor has been synthesized and evaluated its binding affinity with library of transition metal ions. It has prominent selectivity towards Pb among other metal ions in DMF/HO (9:1, v/v) solvent system. The 1:1 stoichiometric was confirmed by job's plot and has a binding constant (K) = 5.142 × 10 M on fluorescence. A B3LYP/6-31G and B3LYP/LanL2DZ basis sets were employed for optimization of 3 and 3.Pb. [ABSTRACT FROM AUTHOR]

A huge amount of fly ash is being generated from coal-based thermal power plants (TPPs). Fly ash is a waste product from TPPs that creates environmental problems due to improper utilization or disposal. Use of coal fly ash in agriculture is a good way to dispose of fly ash, and it will improve the yield of variety of agricultural crops. In the present study a pot experiment was carried out to study the effects of fly ash as an admixture in agriculture and on the growth and accumulation of heavy metals in wheat (Triticum aestivum), mung bean (Vigna radiata), and urad beans (Vigna mungo). In this the fly ash was applied at ratios of 10-60% (w/w). It was found that the application of fly ash enhances the seed germination rate considerably, whereas in the absence of fly ash (control) rate of seed germination was very slow. The use of fly ash as an admixture in agriculture up to 60% for the wheat (Triticum aestivum), 10-20% for mung bean (Vigna radiata), and 20% for urad beans (Vigna mungo) is suitable for maximum growth and yield. Cd, Cu, Fe, Mn, Mg Ni, Pb, and Zn were accumulated in the plants under study, but at very low concentrations and below the permissible limits provided for human consumption. [ABSTRACT FROM AUTHOR]