Volume 237, Issue 4-5

Eosin Y (EY) is a toxic dye and has adverse effects on human beings as well as on aquatic organisms. During the last few decades, various methods such as physio-chemical and biological methods have been reported for the degradation of this toxic dye. Many researchers reported degradation of EY using different polymer stabilized metal nanoparticles synthesized employing green methods. Mono-metallic nanoparticles (MNPs) stabilized by polymeric systems are the most widely used tools for the degradation of many toxic dyes including EY. Characterization as well as morphology assessment of the nanoparticles is done by different analytical techniques including UV-visible, FTIR, SEM, TEM and XRD. In this review article, synthesis, characterization, chemistry of the polymeric stabilized nanoparticles has been reported. In addition, mechanism, kinetics and thermodynamics of catalytic degradation of EY using polymeric stabilized nanoparticles, have been discussed. This review also carries the discussion on various nano catalytic systems which have been used for the degradation of EY to link the most recent work on water purification from EY dye. This review will be helpful in understanding the spectrum of already published work describing role of polymeric stabilized nanoparticles for EY degradation. It will also motivate researchers to design their future work and commercial applications of polymeric stabilized nanoparticles.

The oxidation of atrazine herbicide from water was performed by using titanium dioxide (TiO 2 ) nanoparticles synthesized via the sol-gel method. A batch-scale photocatalytic reactor was designed for experimental work. The process was monitored using a UV–visible spectrophotometer. Operational parameters such as catalyst loading and pollutant concentration were investigated. The X-ray diffraction confirmed the anatase phase and high purity of the synthesized particles. Fourier transform infrared showed the functional group of titanium (Ti–O–Ti). The morphology of synthesized nanoparticles was characterized by scanning electron microscopy and transmission electron microscopy, which exhibited the irregular shape of nanoparticles along with aggregations. The average size of TiO 2 was found to be 56.92 nm as measured from dynamic light scattering analysis. UV–visible spectrometry showed an absorbance of 0.13 (<1). The nanoparticles displayed UV light-responsive catalytic ability with a bandgap energy of 3.14 eV. Furthermore, atrazine was discovered using mass spectrometry, which revealed a clear and sharp peak at 173, 95, and 76  m/z , respectively, at collision energies of 16 and 24 eV. The photocatalytic activity of the TiO 2 nanoparticles was examined for the degradation of atrazine. Overall, the obtained results displayed the great efficiency of TiO 2 nanoparticles towards ultra-violet light, which was 92.56% at 100 mg of dosages, highlighting the great potential of the photocatalysis process for atrazine degradation. Furthermore, the process followed pseudo-first-order kinetics and the rate was seen to depend on catalyst loading.

The coal is an imperative source of energy, which on combustion, it emits sulphur dioxide, which cause air pollution. In the present study, microwave mediated desulphurization of coal was investigated and input variables were optimized by response surface methodology (RSM). The proximate analysis and ultimate analysis report indicate the sample belongs to subbituminous having sulphur (6.96%), volatile matter (34.5%) and calorific value (5099 kcal/kg). Under microwave irradiation, up to 68% of sulphur was leached in alkaline medium. The particle size of coal, concentration of potassium hydroxide (KOH), microwave exposure time and power of microwave radiation were systematically optimized for maximum desulphurization of the coal. Under optimum conditions of the process variables, 63.06% desulphurization of coal was achieved. The optimum levels of process variables are as, particle size 500 µm, irradiation time 8.54 min, radiation power 720 W and concentration of KOH 15% (w/v). Findings revealed that the microwave-assisted desulphurization under alkaline condition furnished promising efficiency, which can be employed for the desulphurization of coal.

Herein we have determined the heavy metals concentrations (Pb, Cd, and Ni) estimated in River Swat water, irregated soils samples, fodder plant’s parts, farmed animal milk/meat samples and human blood from two location Mingora and Barikot in District Swat, Pakistan, using atomic absorption spectrophotometer. Heavy metals such as Cd, Pb, and Ni were found 0.016 ± 0.008, 0.50 ± 0.03, and 0.022 ± 0.004 mg/L in Mingora drain water, respectively, while in the Barikot sample the aforementioned metal were in the range of 0.014 ± 0.01, 0.29 ± 0.02, and 0.108 ± 0.08 mg/L. In the field water samples of Mingora the Cd, Pb and Ni were detected in the range of 0.008 ± 0.001, 0.65 ± 0.05 and 0.032 ± 0.006 mg/L, respectively, while in the field water samples of Barikot contained Cd = 0.016 ± 0.007 mg/L, Pb = 0.48 ± 0.04 mg/L and Ni = 0.043 ± 0.003 mg/L. Drain soil of Mingora contained the highest concentrations of heavy metals, with Cd = 3.9 ± 0.62 mg/kg, Pb = 45.5 ± 3.2 mg/kg, and Ni = 19.95 ± 2.1 mg/kg, whereas field soil contained Cd = 1.6 ± 0.44 mg/kg, Pb = 54.5 ± 2.26 mg/kg, and Ni = 34.75 ± 3.2 mg/kg. Cd in the Barikot drain soil was 3.95 ± 0.71 mg/kg, while it was 0.8 ± 0.06 mg/kg in the field soil. Lead in the same drain sample was 33 ± 3.23 mg/kg, while it was 72 ± 4.15 mg/kg in the field sample. Ni concentrations in Barikot drain soil samples was 13.85 ± 1.1 mg/kg, while 6.9 ± 0.8 mg/kg was detected in field samples. From the results it can be concluded that appreciable concentrations of heavy metals are present in milk and meat samples of farmed animals whereas significant quantities are also there in human blood samples indicating the transport of the selected metals from water through fodder plants into human. However, it may not be the sole reason heavy metal contaminations in human blood other factors like inhalation etc. may also be equally responsible.

The present work aimed to study the mixed micellar behaviour of a tri-substituted imidazolium based surface-active ionic liquid (SAIL), 1-tetradecyl-2,3-dimethylimidazolium bromide [C 14 bmim][Br], with a drug Nortriptyline hydrochloride (NOT) in the water/salt (Na 2 SO 4 ) medium using surface tension measurements (298.15 K) alongwith conductivity measurements (298.15K–313.15K). Lower experimentally obtained cmc values compared to their ideal values suggest that the investigated amphiphiles interact strongly. The values of micellar mole fraction ( X 1 ) based on the several proposed models (Rubingh, Motomura, and Rodenas) and the ideal micellar mole fraction ( X id ) were assessed, and the predicted outcomes indicate that NOT has a significant contribution to the formation of mixed micelles, which increases as the [C 14 bmim][Br] mole fraction is increased. The negative values of micellization’s Gibbs free energy (ΔG m 0 ) between the examined amphiphiles were an indication of spontaneous mixed micelle formation. Micellar changes in entropy (ΔS m 0 ) and enthalpy (ΔH m 0 ) were also computed and discussed. Using surface tension measurements, surface-active parameters like surface tension at cmc ( γ cmc ), minimum surface area per IL molecule ( A min ), maximum surface excess concentration ( τ max ), effectiveness of surface tension reduction ( π cmc ), and cmc of mixed system have been estimated. The results showed an improved adsorption and micellization properties of these mixtures which will surely contribute to the tremendous rise of these mixed systems in drug delivery applications.

The residue of lambda-cyhalothrin (LCT) and thiamethoxam (TMX) insecticides are toxic systemic pyrethroid and neonicotinoid insecticides and their entrance into water bodies can have a toxic impact on aquatic and terrestrial life. Therefore, producing of economical, sustainable and effective adsorbents is immediately required for the removal of these insecticides from polluted water. In this study, the nanocomposite of graphene oxide (GO) grafted with chitosan (CS) and copper oxide nanoparticles (Cu-NPs) was synthesized, characterized and assessed, for the first time, for LCT and TMX removal from wastewater using sorption and mechanism studies. The removal of LCT and TMX was assessed by varying the adsorbent dose, initial concentrations of insecticides, pH, exposure time and temperature to achieve optimum sorption conditions. The nanocomposite provides more than 80% removal rate for 1400 mg/L of insecticides in an aqueous solution using only 100 mg of nanocomposite at 318 K in 120 min due to large surface area and pore volume. The adsorption equilibrium data best followed the Langmuir model, with an adsorption capacity of 153 and 193 mg/g for the LCT and TMX, respectively. The pseudo-second-order explained the kinetics best, and the thermodynamic study indicated that the process was spontaneous, and endothermic and proceeded with the increase in randomness. The suggested mechanisms of LCT and TMX sorption by GO-CS-Cu nanocomposite are hydrogen bonding and electrostatic attraction. The reusability study of GO-CS-Cu was executed up to five cycles and maintains its efficiency even after the considered cycles. In conclusion, the study proves the promising use of GO-CS-Cu as a stable, reusable and promising adsorbent for LCT and TMX removal from wastewater at the industrial level.

This work focuses on the interaction of cellulose-based colloidal microgel dispersions with the anionic surfactant sodium dodecyl sulfate (SDS) at different concentrations. First, a Cellulose-P(NIPAAm-MAA)-based responsive microgel sample was prepared by a radical polymerization method using a one-pot process. The samples thus obtained were purified, characterized and used to study microgel-surfactant interactions. To this end, SDS solutions with different concentrations were prepared and the interactions of SDS in the premicellar and micelle regions with polymer microgel were investigated using different physicochemical techniques. Experiments were also performed at different temperatures to obtain the degree of binding of SDS to microgel in gel surfactant mixtures. Due to the temperature-sensitive properties of microgel, we observed significant changes in various properties of microgel-surfactant mixtures when the solution temperature changed. The overall results showed that various experimental variables, such as the polymer gel/surfactant ratio and temperature, affect the gel–surfactant interaction quantitatively and qualitatively. With increasing surfactant concentration, conductance, viscosity and absorbance values ​​increased, but a decrease in surface tension was observed. This is due to the adsorption of SDS at the air-water interface. The micellar activity of surfactants is enhanced by the addition of microgels. It was found that the strength and nature of the interaction depended not only on the gel/surfactant ratio, solvent type and test temperature, but also on the chemical structure of the surfactant used. Furthermore, the visual stability of the colloidal particles in the mixture of microgel and SDS was also noticeable over time.

In this investigation, the binary solutions of morpholine (MP) with tert-butyl acetate (TBA), iso-butyl acetate (IBA), butyl acetate (BA) and butyl acrylate (BAC) were prepared for the densities ( ρ ) and speeds of sound ( u ) measurements at T  = (303.15, 308.15, 313.15 and 318.15) K over the entire composition range and at atmospheric pressure ( P  = 0.1 MPa). From these data, excess thermodynamic properties such as excess molar volume ( V m E ${V}_{m}^{E}$ ), excess isentropic compressibility ( κ S E ${\kappa }_{S}^{E}$ ) and excess speeds of sound ( u E ${u}^{E}$ ) were calculated to elucidate the strength and types of intermolecular interactions between the component molecules. Redlich-Kister (RK) equation and Prigogine–Flory–Patterson (PFP) theory was applied to correlate the excess parameters and excess volumes, respectively. Further, intermolecular free length theory and collision frequency theory were used to correlate the speed of sound data. Shifting of bands ( δν ), bond length and hydrogen bond strength between the atoms were calculated from the experimental FTIR and DFT theoretical studies. The systematic increasing order of the intermolecular hydrogen bond strength between the two atoms in the studied binary systems as follows: TBA > IBA > BA > BAC.

Synthesis of a biocomposite based on N-maleated chitosan immobilized in amino-carbamated alginate matrix (NMC-PSC) was carried out. Facile chemical modifications of sodium alginate and chitosan were executed using maleic anhydride and 4-phenylsemicarbazide as chemical modifiers, respectively. NMC-PSC hydrogel beads were employed for Cu(II) biosorption from aqueous media. Study of surface characterization, morphology and chemical structure of the sorbent indicated the successful surface functionalization and attachment of Cu(II) ions. Sorption parameters like pH, time of contact, sorbent dosage and adsorbate content significantly influenced the sorption capacity. Kinetic results demonstrated that copper sorption on NMC-PSC was governed by chemisorption and ion-exchange rather than merely mass transfer. Equilibrium sorption data closely fitted with Langmuir model and maximum Langmuir monolayer binding capacity ( q m ) was determined as 207 mg/g. The negative Δ G o values indicated the spontaneity of Cu(II) sorption process while Δ H o and Δ S o parameters indicated the exothermic nature of sorption which proceeds with rise in entropy.

This study reports the removal of chromium (VI) from waste aqueous medium using disilver-dicopper oxide nanoparticles (Ag 2 Cu 2 O 3 NPs) as adsorbent, which were synthesized by adopting reduction route of chemical method and stabilized by emulsifier (sodium dodecyl sulfate [SDS]). Synthesized nanoparticles were further characterized using different analysis techniques such as UV–Vis for the detection of NPs via Λ max and their point-zero charge (pzc) determination also done. Whereas, FTIR and XRD were done to determine the functional groups, crystal plane (tetragonal) and crystallite size (15.19 nm) of Ag 2 Cu 2 O 3 NPs respectively. SEM was used with EDX for morphology and elemental confirmation respectively. The synthesized nanoparticles were then employed for the adsorptive removal of chromium (VI) (Cr(VI)). Different parameters including pH, temperature, agitation time, adsorbate and adsorbent’s concentration were also studied. At optimized conditions, 0.5 g adsorbent, 40 ppm concentration of Cr(VI) solution along with 1 h agitation time were studied. Maximum observed adsorption and chromium removal efficiency was 96.66319 %. Four adsorption isotherms namely; Freundlich, Langmuir, Temkin and Harkins-Jeura were employed from which Freundlich adsorption model gives best fitting on experimental results. The kinetic modelling had shown that adsorption process follows second order kinetics. The thermodynamic studies of the adsorptive removal of Cr(VI) also evaluated. The Ag 2 Cu 2 O 3 NPs adsorbent’s reusability were also determined. The study had proven that Ag 2 Cu 2 O 3 nanoparticles are efficient adsorbents for the removal of Cr(VI).

Here, in this work, acid-activated bentonite and its nanocomposite with hematite nanoparticles were synthesized using the simple chemithermal and thermal coupling methods, respectively. The synthesized samples were investigated for morphological, compositional, structural, and thermal properties. Results suggested distortion in clay structure on acid activation and nanocomposite formation with improved thermal stability. Nanocomposite acts as a quencher for thermoluminescence and as an insulator in heat transfer reactions.

Nanoparticles synthesised using natural resources is a cost-effective and ecofriendly technique with a number of advantages. In current work, silver nanoparticles (AgNPs) have been synthesized using the extract of Fragaria ananassa seeds. The extract was used as a source of phytochemicals that can act as reducing and stabilizing agents. The characteristics of AgNPs were determined by UV/Visible, FTIR, SEM, XRD and Dynamic light scattering (DLS) techniques. The appearance of the distinctive absorption peak in UV-visible spectra at 430 nm confirmed the formation of AgNPs. The involvement of different bioactive functional groups with AgNPs was authenticated by FTIR studies. Particle size and morphology was confirmed by DLS, SEM and XRD analysis. The catalytic potential of AgNPs for the removal of poisonous organic dyes, brilliant green (BG) and methyl orange (MO) was also tested. Effect of different parameters including the catalyst concentration, dyes concentration and presence of different salts on the degradation of dyes was investigated. Nano-size and well-distributed nature of AgNPs, BG and MO dyes were degraded rapidly individually as well as simultaneously. The degradation process obeyed pseudo first order kinetics. Authors concluded that AgNPs synthesized using environment friendly and cost-effective method, can be used as a new tool to combat pollution caused by carcinogenic organic dyes.

Upconversion nanoparticles possess the ability to convert low energy photons to high energy photons, with the advantages of no autofluorescence, reduced photodamage, deeper tissue penetration, and extended photostability. Therefore, upconversion nanoparticles are considered ideal probes for framing potential theranostic agents. Generally, oleic acid has been used as a capping agent to fabricate high-quality upconversion nanoparticles. However, the hydrophobic oleic acid ligands on the surface of the nanoparticles continue to be a barrier when used in biological applications. Herein, we modified the surface of oleic acid coated upconversion (OA-NaGdF 4 :Yb/Er) nanoparticles to be hydrophilic using a novel one-step solvent assisted mechanochemical (SAM) milling ligand exchange strategy. Normal ligand exchange processes are tedious and take one to two days to complete, but the SAM ligand exchange strategy presented here is facile, rapid, and takes less than 1 h. This surface modified citric acid coated upconversion (CA-NaGdF 4 :Yb/Er) nanoparticles further ensures dispersibility in water and good biocompatibility, as revealed by electron microscopy, ATR-FTIR spectroscopy, zeta potential measurement, upconversion luminescence studies, and cytotoxicity assessment. Besides, the size and shape of the nanoparticles were retained after surface modification. Moreover, the monodispersed CA-NaGdF 4 :Yb/Er nanoparticles exhibit intrinsic paramagnetic behavior which makes them suitable to be used as a contrast enhancer for T 1 -weighted MRI. In addition, the measured CT numbers (in HU) increased linearly with increasing the concentration of the surface modified CA-NaGdF 4 :Yb/Er nanoparticles, indicating their plausibility as a CT contrast agent. The current findings suggest that the SAM ligand exchange strategy could be used to fabricate hydrophilic and biocompatible upconversion nanoparticles for bioimaging applications.

Graphene oxide (GO) and reduced graphene oxide (rGO) are two-dimensional material of carbon having unique optical, electrical, mechanical and thermal properties, which could form composite material with different materials. In this work, we fabricated the nanocomposite of GO and rGO with silver (Ag). Modified Hummer method was adopted for the production of GO from graphite powder. This GO was reduced into rGO using ascorbic acid. On the reduction of GO into rGO, inter-planar distance increases which enhanced the properties of rGO as compared to GO. Turkevich method was adopted to produce the nanocomposite of GO and rGO with Ag. FTIR was performed to confirm the different functional group in the desired product. XRD spectra of rGO have broad hump shaped peak which reflects the amorphous structure or lattice and proposed rGO composite as a better membrane material than GO composite for water purification. Similarly, the Raman spectra shows the lower value of D and G band for rGO than GO. Results revealed that methylene blue dye was degraded up to 79.36 % using rGO-Ag composite. Hence, it is concluded that fabricated material could possibly be employed for degradation of other toxic pollutant from industrial effluents.