Adsorption, kinetics and thermodynamics studies of methyl orange dye sequestration through chitosan composites films.

Different films comprising pure chitosan (CS) and chitosan coated sodium zeolites composites films designated as CSZ1, CSZ2, CSZ3 and CSZ4 respectively are presented here for the sequestration of MO dye. The as-synthesized films were characterized by using FSESM, XPS XRD, and TGA analysis. The sequestration of methyl orange dye (MO) was studied under various adsorption parameters i.e. pH effect, reaction temperature, catalytic dosage, interaction period, and original dye concentration in batch experiments. The adsorption power of MO dye sequestration in the presence of CSZ3 was 287 mg g-1 higher than the fine CS (201 mg g-1), and lowest for CSZ4 (173 mg g-1). The experimental data is fitted in the pseudo-second order of chemical kinetics. The Freundlich and Langmuir adsorption models were used on behalf of the analysis of experimental data that revealed multilayered adsorption of MO dye. Kinetics, equilibrium and thermodynamic process were discussed in detailed, suggesting the endothermic and spontaneous process of the adsorption of MO dye on the exterior of films. The present work is general for the MO adsorption, however, it can be applied on large scale applications and can be easily adjustable in the water purification assemblies.

Synthesis, Characterization, and Multifunctional Applications of Cu-Fe and Ni-Fe Nanomaterials.

Cu-Fe and Ni-Fe nanomaterials (NMs) were successfully obtained via a coprecipitation route. Phase analysis and the micro- and physiochemical structure studies for the as-synthesized NMs were carried out with advanced techniques such as TEM, SEM, XRD, XPS, BET, DRS, TGA, and FTIR. Particles with size ranging from 25 to 70 nm were displayed by all the characterization techniques. A surface area of ∼4.48 and 36.52m2/g and band gap energies of ∼1.79 and 1.48 eV were calculated for Cu-Fe and Ni-Fe NMs, respectively. Saturation magnetization (Ms) ∼77.95 emu/g (for Cu-Fe) and 27.70 emu/g (for Ni-Fe) revealed superparamagnetism for both the NMs. The presence of ethanol and methanol as sacrificial agents contributed effectively toward electrocatalytic H-evolution as compared to pure NMs. Furthermore, under solar light irradiations, Cu-Fe and Ni-Fe NMs displayed 85 and 91% degradation during a time interval of 50 and 110 min, respectively, for toxic industrial methylene blue (MB) dye. Different operational variables such as the catalyst amount, pH values, various scavengers, reusability, and stability were thoroughly investigated. Moreover, in situ analysis was carried out in order to determine the mechanism for degradation reactions. A detailed study about various applications categorized the synthesized NMs as efficient candidates for toxic industrial waste cleanup and energy production at an industrial level.

Electrical, Photocatalytic, and Humidity Sensing Applications of Mixed Metal Oxide Nanocomposites.

Mixed metal oxide nanocomposites (NCs) comprising Cu-Sr (CS), Sr-Cd (SC), and Cd-Cu (CC) were fabricated via a sol-gel method. Structural investigations of fabricated samples were carried out via X-ray diffraction (XRD), scanning electron microscopy (SEM), diffuse reflectance spectroscopy (DRS), and X-ray photoelectron spectroscopy (XPS). The Maxwell-Wagner model, attributing to poor conducting layers around the conducting grains, was indicated to be followed by all of the NCs while investigating the dielectric properties. The Space-charge polarization and hoping mechanism contributed to low AC conductivity at lower frequencies and high AC conductivity at higher frequencies. The as-synthesized NCs effectively degraded two toxic water contaminants, such as crystal violet (CV) and Congo red (CR). Furthermore, the NCs were also evaluated for humidity sensing measurements. All of the NCs indicated efficient response/recovery time with better stability. The extensive investigation suggested the synthesized NCs, well suited for various optical and microelectronic applications.

Synthesis of AgNPs coated with secondary metabolites of Acacia nilotica: An efficient antimicrobial and detoxification agent for environmental toxic organic pollutants.

This study concentrates on biosynthesis of Silver Nanoparticles (AgNPs) from stem extract of Acacia nilotica (A. nilotica). The reaction was completed at a temperature ~40-45 °C and time duration of 5 h. AgNPs were thoroughly investigated via advanced characterization techniques such as UV-Vis spectrophotometry (UV-Vis), Fourier Transform Infrared spectroscopy (FTIR), X-ray Diffractometry (XRD), Field Emission Scanning Electron Microscopy (FESEM), High Resolution Transmission Electron Microscopy (HRTEM), X-ray Photoelectron Spectroscopy (XPS), Thermo Gravimetric Analysis (TGA), Diffuse Reflectance Spectroscopy (DRS), Brunner-Emmett-Teller (BET), Dynamic Light Scattering (DLS), and Zeta potential analysis. AgNPs with average size below 50 nm were revealed by all the measuring techniques. Maximum surface area ~5.69 m2/g was reported for the as synthesized NPs with total pore volume ~0.0191 mL/g and average pore size ~1.13 nm. Physical properties such as size and shape have changed the surface plasmon resonance peak in UV-visible spectrum. Antimicrobial activity was reported due to denaturation of microbial ribosome's sulphur and phosphorus bond by silver ions against bacterium Methicillin Resistant Staphylococcus aureus (MRSA) and fungus Candida Albican (CA). Furthermore, AgNPs degraded toxic pollutants such as 4-nitrophenol (4-NP), 2-nitrophenol (2-NP) and various hazardous dyes such as Congo Red (CR), Methylene Blue (MB) and Methyl Orange (MO) up to 95%. The present work provided low cost, green and an effective way for synthesis of AgNPs which were utilized as potential antimicrobial agents as well as effective catalyst for detoxification of various pollutants and dyes.