Photocatalytic assessed adsorptive removal of tinidazole from aqueous environment using reduced magnetic graphene oxide-bismuth oxychloride and its silver composite.

Antibiotics (tinidazole (TNZ)) in wastewater, exhibit adverse effects on humans and ecosystem. The current study was aimed to synthesize photocatalysts mrGO/BiOCl and mrGO/BiOCl/Ag. mrGO was coupled with BiOCl by hydrothermal method and Ag was deposited over it. The synthesized mrGO/BiOCl and mrGO/BiOCl/Ag were confirmed by Pzc analysis (5.5 and 4.4 for mrGO/BiOCl and mrGO/BiOCl/Ag, respectively), surface area analysis (380 m2 g-1, 227.7 m2 g-1, 220 m2 g-1 for mrGO, mrGO/BiOCl and mrGO/BiOCl/Ag respectively), elemental analysis (Ag, O, Bi, Fe), surface morphology (rough ball like sphere of mrGO/BiOCl and cubic Ag nanoparticles in mrGO/BiOCl/Ag), functional groups and band gap (Eg) determination. The Eg was determined using Kubelka-Munk equation as 3.5 and 2.8 eV for mrGO/BiOCl and mrGO/BiOCl/Ag respectively. During the adsorption study, the best experimental conditions for various operating parameters such as pH (2), contact time (5 min for mrGO/BiOCl and 10 min for mrGO/BiOCl/Ag under UV irradiation), TNZ concentration (18 µgL-1) and catalyst dosage (0.001 g) were achieved. Kinetic study revealed that both composites followed pseudo second order kinetics (R2 = 0.9979 and 0.9986, respectively). Data of rGO/BiOCl was fitted to Freundlich adsorption model (R2 = 0.9687) and rGO/BiOCl/Ag fitted to Langmuir adsorption model (R2 = 0.9994). Moreover, thermodynamic parameters confirmed that a photodegradation phenomenon was spontaneous and exothermic. The results confirmed that rGO/BiOCl and rGO/BiOCl/Ag are appropriate composites for TNZ removal from the aqueous environment with removal efficiency of 97 and 24%, respectively.

Exploration of solid waste materials for sustainable manufacturing of cementitious composites.

The problem of disposing and managing solid waste materials has become one of the major environmental, economic, and social issues. Utilization of solid wastes in the production of building materials not only solves the problem of their disposal but also helps in the conversion of wastes into useful and cost-effective products. In the present study, solid waste materials of organic and inorganic nature were applied in the production of sustainable cementitious composites (CC) and studied the effect of incorporated wastes on physical and mechanical properties of the resultant CC. The selected solid waste materials were cotton, polyester, PET, carpet, glass, and granulated blast furnace slag (GBFS). These wastes were incorporated in CC in different proportions and form the tuff tiles using moulds (12.5″ × 6″ × 2.5″). The various physical (fineness, setting time, bulk density, and water absorption capacity) and mechanical (flexural strength) properties of all the specimens were determined after curing period of 3, 7, and 28 days. The results show that the incorporation of solid wastes in CC did not much affect their physical characteristics. However, the CC incorporated with the selected solid waste materials have a pronounced effect of their flexural strength and found to be higher (12-875%) compared to the plain CC. Similarly, the incorporation of the selected inorganic wastes (302-715 psi) in CC exhibit much higher flexural strength compared to the organic wastes (136-235 psi). The maximum flexural strength was observed when GBFS was utilized as a solid waste. The present work will provide a reliable step for the solid waste management and conversion of such wastes into useful commercial products for concrete manufacturing.

Efficient removal of selected fluoroquinolones from the aqueous environment using reduced magnetic graphene oxide/polyaniline composite.

In the present study, reduced magnetic graphene oxide/polyaniline (RmGO/PANI) composite was synthesized via in-situ oxidative polymerization method. The synthesized RmGO/PANI was characterized by fourier transform infrared, scanning electron microscope, X-ray diffraction and energy dispersive X-rays techniques. The synthesized RmGO/PANI was explored as an adsorbent for the removal of moxifloxacin (MOX) and ofloxacin (OFL) from the aqueous samples. To inflate removal efficiency of RmGO/PANI, various adsorption effecting parameters such as effect of pH (2-12), RmGO/PANI dosage (2-14 mg), analyte concentration (150-525 µg mL-1 for MOX and 15-40 µg mL-1 for OFL), contact time (10-120 min) and temperature (293-343 K) were studied. Moreover, kinetic study exhibits that adsorption of MOX/OFL using RmGO/PANI follows pseudo second order kinetic model. The adsorption of MOX/OFL well-fitted to the Langmuir adsorption isotherm which demonstrates mono-layer adsorption of MOX/OFL on the surface of RmGO/PANI with maximum adsorption capacity of 47.7 mg g-1 and 27.33 mg g-1 for OFL and MOX, respectively. Thermodynamic study indicates that the adsorption process was spontaneous and exothermic in nature with the decrease of randomness of the system during the adsorption. On account of its practical applications, RmGO/PANI is considered an excellent adsorbent with 99% and 96% removal efficacy for MOX and OFL, respectively. The synthesized RmGO/PANI was reused for ten consecutive batches as well as applied to the real samples, maintain an excellent removal capacity. The reusable nature of RmGO/PANI declare this solid medium as an innovative adsorbent for real sample applications and wastewater treatment.

A novel magnetite nanorod-decorated Si-Schiff base complex for efficient immobilization of U(vi) and Pb(ii) from water solutions.

A novel silicon Schiff base complex (Si-SBC) and magnetite nanorod-decorated Si-SBC (M/SiO2-Si-SBC) were synthesized and well characterized in detail. The synthesized materials were applied for the removal of U(vi) and Pb(ii) from water solutions under various experimental conditions. The monolayer maximum adsorption capacities of M/SiO2-Si-SBC (6.45 × 10-4 mol g-1 for Pb(ii) and 4.82 × 10-4 mol g-1 for U(vi)) obtained from the Langmuir model at 25 °C and pH = 5.00 ± 0.05 were higher than those of Si-SBC (5.18 × 10-4 mol g-1 for Pb(ii) and 3.70 × 10-4 mol g-1 for U(vi)). Moreover, DFT calculations showed that the high adsorption energies (Ead) of 7.61 kcal mol-1 for Pb2+-(Si-SBC) and 2.72 kcal mol-1 for UO22+-(Si-SBC) are mainly attributed to stronger electrostatic interactions. The results revealed that the Si-SBC and M/SiO2-Si-SBC could be used as efficient adsorbents for the effective elimination of U(vi) and Pb(ii) from contaminated wastewater. High sorption capacity and reusability indicated the practical applications of the synthesized materials in environmental pollution cleanup.

Self-assembled three-dimensional reduced graphene oxide-based hydrogel for highly efficient and facile removal of pharmaceutical compounds from aqueous solution.

Herein, self-assembled three-dimensional reduced graphene oxide (RGO)-based hydrogels were synthesized and characterized in detail. A thorough investigation on the uptake of three widely used pharmaceutical drugs, viz. Naproxen (NPX), Ibuprofen (IBP) and Diclofenac (DFC) was carried out from aqueous solutions. To ensure the sustainability of developed hydrogel assembly, practically important parameters such as desorption, recyclability and applicability to real samples were also evaluated. Using the developed 3D hydrogels as adsorptive platforms, excellent decontamination for the above mentioned persistent pharmaceutical drugs was achieved in acidic pH with a removal efficiency in the range of 70-80%. These hydrogels showed fast adsorption kinetics and experimental findings were fitted to different kinetic models, such as pseudo-first order, pseudo-second order, intra-particle and the Elovich models in an attempt to better understand the adsorption kinetics. Furthermore, equilibrium adsorption data was fitted to the Langmuir and Freundlich models, where relatively higher R2 values obtained in case of former one suggested that monolayer adsorption played an important part in drug uptake. Thermodynamic aspects were also studied and negative ΔG0 values obtained indicated the spontaneous nature of adsorption process. The study was also extended to check practical utility of as-prepared hydrogels by spiking real aqueous samples with drug solution, where high % recoveries obtained for NPX, IBP and DFC were of particular importance with regard to prospective application in wastewater treatment systems. We advocate RGO-based hydrogels as environmentally benign, readily recoverable/recyclable material with excellent adsorption capacity for application in wastewater purification.

Functionalization of magnetic chitosan with graphene oxide for removal of cationic and anionic dyes from aqueous solution.

In the present study, we decorated chitosan (©) with Fe3O4 nanoparticles followed by cross-linking with GO to prepare Fe3O4 supported chitosan-graphene oxide composite (Fe3O4©-GO). Different properties of synthesized material were investigated by SEM, XRD, FTIR, TGA and EDX. Batch adsorption experiments were performed to remove toxic cationic and anionic dyes from industrial wastewater. To maximize removal efficiency of composite material, effect of pH (4-12), time (0-80min), Fe3O4©-GO dosage (2-10mg), initial dye concentration (2-30µgmL̄ (1)) and temperature (303, 313, and 323K) were studied. The uptake of dyes presented relatively fast adsorption kinetics with pseudo-second-order equation as the best fitting model. To understand the interaction of dye with adsorbent, Langmuir and Freundlich isotherm were applied. Thermodynamic studies were conducted to calculate the changes in free energy (ΔG(0)), enthalpy (ΔH(0)) and entropy (ΔS(0)). In view of practical application, the influence of ionic strength, recycling as well as investigations based on percent recoveries from spiked real water samples were also taken into account.

Modulation of diorganoyl dichalcogenides reactivity by non-bonded nitrogen interactions.

The study was designed to explore the biochemical influence of non bonding nitrogen interactions (N⋯Se/S) on organochalcogens potency. Approximately five and six times higher thiol peroxidase (TPx) like activity was observed for compound (C)-2 than C-1 and C-3, respectively. C-2 also displayed significantly (p<0.05) higher activity in 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging and deoxyribose degradation assays. All compounds, except C-4 and C-6 significantly inhibited Fe (II) and sodium nitroprusside (SNP) induced thiobarbituric acid reactive species (TBARS) production in rat's brain, liver and kidney preparations with highest activity observed for C-2. The highest C-2 activity was attributed to the presence of non-bonded nitrogen interactions which were absent in C-1 and blocked with butoxycarbonyl (BOC group) in C-3. The same structural activity analogy was extended to organosulfur compounds and it was observed that compound with non-bonding nitrogen interactions, i.e. C-5 has significantly (p<0.05) higher TPx like activity than C-6 and C-4. C-5 at the highest tested concentration significantly (p<0.05) protected against Fe (II) and SNP induced TBARS formation in rat's brain, kidney and liver preparations but did not display activity in DPPH and deoxyribose degradation assays. This study confirms the influence of not only N⋯Se interaction but also for the first time the effect of non bonded N⋯S interactions on organochalcogens potency. C-2 (with the highest activity) was also tested in vivo and was administered at three different doses, i.e. 15, 30 and 50 mg/kg to get an exact idea about its interaction with thiol containing molecules (NPSH) and enzyme α-ALA-D (sulfhydryl containing enzyme). Oxidative stress parameters, i.e. free radical concentration by dichlorofluoreseein (DCF) assay, TBARS, ascorbic acid level, hepatic (ALT and AST) and renal (urea and creatinine) toxicity markers were also estimated to get an insight about its possible toxicological profile. Our data indicates that C-2 has higher TPx and Antioxidant activity and importantly, C2 did not induce toxicity even when tested at relatively high doses, indicating that its pharmacological properties should be further explored in models of diseases associated with oxidative stress.

Synthesis of diorganyl selenides mediated by zinc in ionic liquid.

A new approach for the synthesis of diorganyl selenides is described. By using economically attractive zinc dust in BMIM-BF(4), a series of diorganyl selenides were efficiently achieved in excellent yields, under neutral reaction conditions. Compared to the usual organic solvents, BMIM-BF(4) exhibited higher performance with the advantage to be reused up to five successive runs.

DDT residue in soil and water in and around abandoned DDT manufacturing factory.

Dichlorodiphenyltrichloroethane (DDT) belongs to one of the most hazardous groups of chemicals called persistent organic pollutants. Many organochlorine pesticides including p,p(')-DDT are long lasting due to their non-degradability can travel to distant places and being fat soluble can accumulate in animals and human bodies. Due to the persistent nature of p,p(')-DDT, its adverse environmental and health impacts, the present study was undertaken to examine the residual p,p(')-DDT in and around abandoned p,p(')-DDT manufacturing factory in Amman Gharh, Nowshera, NWFP. Samples of soil, sediments and water were collected in and around the factory area, nearby p,p(')-DDT stores, main factory drain leading to river Kabul and nearby villages. Standard procedures were used for the collection, transportation and storage of samples for analyses. Extraction of each sample for p,p(')-DDT analyses was carried out in triplicates using Soxhelt extraction. p,p(')-DDT contents in the samples were analyzed by capillary GC with electron capture detector. Most of the samples collected up to half kilometer distance from the site of the DDT factory were found contaminated. Further the level of p,p(')-DDT decreased with increasing depth from top to bottom and with distance from the site. The results indicate that there is no immediate threat to underground water reservoirs.