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The removal of water pollutants by photocatalysis is a promising technique, mainly due to its environmentally friendly and sustainable nature. In this study, the degradation of a recalcitrant organic pollutant, malachite green (MG), was investigated in water by a microstructured silver oxide photocatalyst. The silver oxide (Ag2O) microparticles (MPs) were synthesized by a low-cost, green method, mediated by green tea leaves extract. The surface, morphological and optical properties of the synthesized Ag2O MPs were determined by scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis, X-ray diffraction (XRD) analysis, Fourier transform infrared (FTIR) spectroscopy, and ultraviolet-visible (UV-visible) spectrophotometry. The synthesized Ag2O MPs showed good photoactivity, represented by 83% degradation of malachite green (MG) ([C]0 = 0.4 mM, Ag2O loading = 0.1 g L−1) at neutral pH, in 3 h. Persulfate ions (PS) showed a strong synergistic effect on the efficiency of solar/Ag2O photocatalysis, represented by complete MG removal in 15 min, in the presence of 1.6 mM PS. The results revealed that solar/Ag2O, particularly solar/Ag2O/PS photocatalysis is a promising method for the elimination of toxic organic pollutants, such as malachite green, from the water environment.

To understand the expected mode of action, the physicochemical study on the solution properties of medicinal compounds and their interaction with deoxyribonucleic acid (DNA), under varying experimental conditions, is of prime importance. The present research work illustrates the physicochemical study and interaction of certain medicinal compounds such as; Levofloxacin, Ciprofloxacin, and Ibuprofen with DNA. Density, viscosity and surface tension measurements have been performed in order to determine, in a systematic manner, the physicochemical, volumetric and thermodynamic properties of these compounds; and most of these parameters have shown different behavior with varying concentration of solution, temperature of the medium and chemical nature/structure of the compound. In addition, these drugs showed a spontaneous surface-active and association behavior in aqueous solutions. The flow behavior, surface properties, volumetric behavior and solute–solvent interaction of these drugs were prominently influenced by experimental variables and addition of DNA to their solutions. UV–Visible spectroscopy was also used to examine the interaction of these drugs with DNA in aqueous media in detail. Calculated values of binding constants (Kb) for all complexes of drug-DNA are positive, indicating a fruitful binding process. It is seen that a smaller Kb value reflects weaker binding of the drug with DNA and vise versa. Due to the difference in the chemical structure of drugs the values of binding constant are different for various drug-DNA complexes and follow the order Kb(Levofloxacin-DNA) > Kb(Ciprofloxacin-DNA) > Kb(Ibuprofen-DNA). On the basis of spectral changes and Kb it can be said that the binding of all these drugs with DNA may be of physicochemical nature and the dominating binding force be of hydrogen bonding between oxygen of drugs and hydrogen of DNA units and the drug having more oxygen atoms showed stronger binding ability. The data further suggest a limited possibility of chemical type attachment of these drugs with DNA.

In this study, a magnetic carbon nanocomposite (MCNC) was prepared using peanut shell biomass as carbon source. The prepared adsorbent was characterised by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric/differential thermal analysis (TGA/DTA) and BET surface analysis. Batch experiments were carried out to determine the adsorption parameters of cetyl dimethylethyl ammonium bromide (CDEAB) on MCNC. Of the isotherm and kinetics models used, the Langmuir model fitted the equilibrium adsorption data best, while the kinetics data were best explained by the second-order kinetic pseudo-equation. The numerical values of enthalpy change (ΔH8 = 38 kJ mol–1) and Gibb free energy (ΔG8 = 70.95 kJ mol–1, 72.19 kJ mol–1 and 73.32 kJ mol–1 corresponding to 20°C, 30°C and 40 °C, respectively) were positive, while the value of entropy change (ΔS8 = –0.11 kJ mol–1 K–1) indicated an endothermic and non-spontaneous process. After determining the optimal adsorption parameters, the adsorbent was used in a hybrid plant with a membrane pilot plant equipped with ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (RO) membranes. In MCNC/membrane operation, an improvement in permeate flux was observed for the three selected membranes. The percentage retention of UF and NF membranes was also improved by MCNC pre-treatments in hybrid mode.

Many industries use various dyes to beautify their products and discharge the waste into the water without proper treatment. Such wastewater is not only dangerous for aquatic life but it is also toxic to human life and can cause numerous problems, such as skin diseases, and some dyes are carcinogenic or even mutagenic as well. Rhodamine-B (RhB) is one of those synthetic organic dyes which is widely used in textile, paper making, leather manufacturing, stained glass work, cosmetics, and many other industries owing to its high tinting strength, high stability, and bright colour. Therefore, it is essential to either remove or reduce its concentration before releasing it into aquatic streams, as well as to minimize or control the cause of several diseases. Several physical and chemical methods have been used for the removal of different dyes from wastewater; nevertheless, adsorption is one of the best techniques used for the removal of dyes due to its high efficiency and low cost. In this regard, we used Chamaecyparis lawsoniana (C. lawsoniana) fruit as a bio-adsorbent for the removal of RhB from an aqueous solution. An 85.42% dye adsorption was achieved at optimized conditions (pH 2, 40 ppm initial dye concentration, 105 min, and 50 mg adsorbent). Adsorption occurs by pseudo-second-order kinetics, according to kinetic studies. Several samples from various sources, including tap water, distilled water, river water, and filtered river water, were tested for RhB removal, and the study revealed good results even in river water. Thus, C. lawsoniana fruit can be used for its real-world application.

Photocatalysis is a promising process for decomposing harmful organic pollutants in water. In this study, solar/photocatalytic degradation of two model azo dyes, i.e., methylene blue (MB) and methyl red (MR), in water usinga nanostructured chitosan-modified nickel magnetite (CS-NM) bio-composite was investigated. The CS-NM bio-composite was synthesized through a co-precipitation method and characterized by Fourier transform infrared (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), thermogravimetry (TGA), and UV-Vis spectroscopy. FTIR analysis showed the uniform incorporation and conjugation of nickel magnetite (NM) into the chitosan (CS) polymer matrix. SEM showed that the average particle size was 0.5 μm. The TGA results revealed the good thermal stability of the prepared bio-composite at 300 °C. The point of zero charge was calculated as 7.5. The effect of water quality and process parameters, such as concentration of dyes, catalyst dose, solution pH, and temperatures, was investigated, for application purposes. The solar/CS-NM photocatalysis resulted in 99 and 96% degradation of individual MB and MR (C0 = 50 ppm), respectively, in 90 min. The degradation of MB and MR by solar/CS-NM photocatalysis followed pseudo-first-order kinetics, with observed rate constants (k) of 0.077 and 0.072 min−1, respectively. The CS-NM photocatalyst showed high recyclability, represented by only a 4–6% loss in the photocatalytic efficiency, after four cycles. The results showed that solar/CS-NM photocatalysis is an efficient technique for degrading recalcitrant organic pollutants, such as azo dyes, in water environments.

The current research focused on the super capacitive behavior of organic conducting polymer, i.e., polypyrrole (PPy) and its composites with gum arabic (GA) prepared via inverse emulsion polymerization. The synthesized composites material was analyzed by different analytical techniques, such as UV-visible, FTIR, TGA, XRD, and SEM. The UV-Vis and FTIR spectroscopy clearly show the successful insertion of GA into PPy matrix. The TGA analysis shows high thermal stability for composites than pure PPy. The XRD and SEM analysis show the crystalline and amorphous structures and overall morphology of the composites is more compact and mesoporous as compared to the pure PPy. The electrochemical properties of modified solid state supercapacitors established on pure polypyrrole (PPy), polypyrrole/gum arabic (PPy/GA) based composites were investigated through cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge–discharge (GCD). The specific capacitance of the PPy modified gold electrode is impressive (~168 F/g). The specific capacitance of PPy/GA 1 electrode has been increased to 368 F/g with a high energy density and power density (~73 Wh/kg), and (~599 W/kg) respectively.

The presence of dyes in water stream is a major environmental problem that affects aquatic and human life negatively. Therefore, it is essential to remove dye from wastewater before its discharge into the water bodies. In this study, Banyan (Ficus benghalensis, F. benghalensis) tree leaves, a low-cost biosorbent, were used to remove brilliant green (BG), a cationic dye, from an aqueous solution. Batch model experiments were carried out by varying operational parameters, such as initial concentration of dye solution, contact time, adsorbent dose, and pH of the solution, to obtain optimum conditions for removing BG dye. Under optimum conditions, maximum percent removal of 97.3% and adsorption capacity (Qe) value of 19.5 mg/g were achieved (at pH 8, adsorbent dose 0.05 g, dye concentration 50 ppm, and 60 min contact time). The Langmuir and Freundlich adsorption isotherms were applied to the experimental data. The linear fit value, R2 of Freundlich adsorption isotherm, was 0.93, indicating its best fit to our experimental data. A kinetic study was also carried out by implementing the pseudo-first-order and pseudo-second-order kinetic models. The adsorption of BG on the selected biosorbent follows pseudo-second-order kinetics (R2 = 0.99), indicating that transfer of internal and external mass co-occurs. This study surfaces the excellent adsorption capacity of Banyan tree leaves to remove cationic BG dye from aqueous solutions, including tap water, river water, and filtered river water. Therefore, the selected biosorbent is a cost-effective and easily accessible approach for removing toxic dyes from industrial effluents and wastewater.

An in-situ chemical oxidative method was used to effectively synthesize a promising supercapacitor material based on PPy/ZrO2 composites. The synthesized materials were characterized by different analytical techniques, such as UV/visible (UV/Vis) spectroscopy, Fourier-transform infra-red spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The inclusion of ZrO2 into the PPy matrix was verified by vibrational spectra and structural analyses. The (TGA) results showed that incorporating ZrO2 into the polymeric matrix improved its thermal stability. In addition, the electrochemical properties of the synthesizedmaterials were investigated byusing cyclic voltammetry (CV) and galvanostatic charge/discharge (GCD). The PPy/ZrO2 composite demonstrated excellent super capacitive performance, and high specific capacity of 337.83 F/g, with an exceedingly high energy density of 187.68 Wh/kg at a power density of 1000 W/kg. The composite materials maintain good stability after 1000 charge and discharge cycles, with 85% capacitance retention. The PPy/ZrO2 possesses a high capacitance, an attractive micro-morphology, and a simple synthesis method. The findings indicate that the PPy/ZrO2 composite could be a promising electrode material for high-performance supercapacitor applications.

The present study is aimed at the synthesis and exploring the efficiency of a novel activated carbon incorporated polyindole (AC@PIN) composite for adsorptive removal of Malachite Green (MG) dye from aqueous solution. An AC@PIN hybrid material was prepared by in situ chemical oxidative polymerization. The physico-chemical characteristics of the AC@PIN composite were assessed using Fourier-transform infrared spectrometer, X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, ultraviolet visible spectroscopy, and determination of point of zero charge (pHPZC). A series of adsorption studies was conducted to evaluate the influence of operational parameters such as pH, contact time, initial dye concentration, AC@PIN dosage, and temperature on dye adsorption behavior of developed composite. A maximum dye removal percentage (97.3%) was achieved at the pH = 10, AC@PIN dosage = 6.0 mg, initial dye concentration 150 mg L−1, and temperature = 20 °C. The kinetic studies demonstrated that the adsorption of MG on AC@PIN followed pseudo-second-order model (R2 ≥ 0.99). Meanwhile, Langmuir isotherm model was founded to be the best isotherm model to describe the adsorption process. Finally, the recyclability test revealed that the composite exhibits good recycle efficiency and is stable after 5 cycles. The obtained results suggest that AC@PIN composite could be a potential candidate for the removal of MG from wastewater.

Ferene is the most commonly used chromogenic agent for the determination of serum iron in blood. In this work we have successfully synthesized Ferene-S-conjugated silver nanoparticles (Ferene-S-AgNPs) for the first time characterized by UV-visible, Fourier-Transform Infrared Spectroscopy (FTIR), and Matrix-Assisted Laser Desorption/Ionization-Time Of Flight (MALDI-TOF) mass spectrometry techniques. Particle size of the synthesized nanoparticles was determined by atomic-force microscopy and scanning electron microscopy techniques with size ranges from 10–90 nm in diameter. Ferene-S-AgNPs were explored for their chemosensing potential with various metal ions such as Sb3+, Pb2+, Ca2+, Fe2+, K+, Co2+, Ba2+, V5+, Cu+, Cd2+, Hg2+, Ni2+, Cu2+, Fe3+, Mg2+, Mn2+, Al3+, and Cr3+. Ferene-S-AgNPs were found to show selective quenching effects and slight bathochromic shifts to the surface plasmon resonance absorption band after treatment with Fe2+. Furthermore, the developed chemosensor also exhibited substantial selectivity towards Fe2+ in the presence of other competitive ions. We observed that Ferene-S-AgNPs mimic the selectivity of the parent compound of Ferene towards Fe2+. The system obeyed Beer’s law over concentration ranges of 110–190 nM. The detection limit was found to be 110 nM.

Magnetic carbon nanocomposite (MCNC) was prepared from peanut shells and then characterized by FTIR, SEM, TGA/DTA and BET surface area. The removal of cetyltrimethyl ammonium bromide (CTAB) surfactant from aqueous solution was carried out by MCNC and membrane. The effect of contact time, initial concentration of CTAB and the temperature on the adsorption of CTAB was also investigated. Initially, the adsorption of CTAB on MCNC was rapid up to 20 min and then gradually slowed down. Different kinetic models i. e. 2nd pseudo order kinetics, power function and intraparticle diffusion were applied to determine different kinetic parameters. Intraparticle diffusion model showed that the adsorption of CTAB is a diffusion controlled process. Thermodynamic parameters i. e. ΔH° (–33.74 kJ/mol), ΔS° (0.98 J/mol K) and ΔG° (–62.91 kJ/mol, −64.37 kJ/mol and −66.33 kJ/mol) were calculated and the process was found to be exothermic and spontaneous in nature. The prepared adsorbent (MCNC) was used for controlling fouling of ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (RO) membranes caused by CTAB. Improved permeate fluxes and percent retention of CTAB were observed for MCNC crossbreed membrane. About 100 % retention with no effect on permeate flux was observed with RO membrane when MCNC pretreatment was applied.

The use of indigenous natural materials and their modification toward fruitful application is one of the important subjects. Thermal modification of Rice Husk at 400 oC resulted into Rice Husk Char (RHC) which was chemically modified with KOH and was labeled as KOH Modified Rice Husk Char (KMRHC). Both RHC and KMRHC were characterized by using, Fourier transformed infrared (FTIR), scanning electron microscopy (SEM), energy dispersive X-rays (EDX) and X-ray diffraction (XRD) before and after their use as adsorbents. The prepared material was applied for the removal of toxic dyes, Direct Blue (DB) and Titan Yellow (TY) from aqueous media. The maximum adsorption capacity of DB and TY dyes on KMRHC were inspected as 30.9 mg/g and 28.6 mg/g, respectively at pH 4 using initial dye concentrations of 80 mg/L containing 2500 mg/L of the adsorbent dose with agitation speed of 240 rpm at 303 K. At the same experimental conditions the highest percentage removal of DB and TY on the adsorbent were observed as 96.6% and 89.3%, respectively. Thermodynamics studies of the adsorption of DB and TY dyes on KMRHC inferred for exothermic and spontaneous process. The value of ΔS is negative which suggested that randomness decreases at the interface of adsorbent-adsorbate during the adsorption. The kinetics study indicated that the experimental data of the adsorption process for both dyes, best fits to pseudo-second order kinetic model. The equilibrium data was tested on Langmuir, Freundlich and Temkin adsorption isotherm models. It was observed that the data are best fit to the Langmuir isotherm model (R2 > 0.99), which suggested that the adsorption process is dominated by chemisorption approach. The overall results suggest that various parameters of the adsorption process were not only affected by the variation in experimental conditions but also by the chemical structure of the adsorbate molecules for the same adsorbent.

The present study is focused on the thermal decomposition of Levofloxacin in the absence and presence of different excipients (sodium starch glycolate, magnesium stearate, microcrystalline cellulose and lactose using Thermogravimetry (TG). Fourier Transform Infra Red Spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC) were used to study the possible drug – excipient interaction. It has been shown that the interaction of the first three excipients (sodium starch glycolate, magnesium stearate, and microcrystalline cellulose) with Levofloxacin is physical in nature. Lactose was shown to decrease the degradation temperature to a maximum extent. This indicates a strong chemical interaction between the drug and lactose. The activation energies in the former case were found almost similar but deviated considerably in the latter case.

Sugarcane bagasse is an inexpensive and eco-friendly natural biosorbent for the removal of various organic pollutants. The adsorption of Remazol Brilliant Violet-5R (RBV-5R) dye on sugarcane bagasse (SCB) was studied. Biosorbent was characterized using EDX and FTIR. The effect of various experimental parameters, such as pH, biosorbent dosage, initial dye concentration, contact time, adsorption with shaking and without shaking, and the temperature, was optimized. At pH 6, maximum biosorption of 92.22% was achieved using 0.15 g of SCB. The equilibrium was attained within 30–40 min for the removal of RBV-5R. The initial dye concentration of 10 µg/mL was determined as an optimum concentration for maximum removal of RBV-5R at 30 °C. Langmuir and Freundlich adsorption isotherms were applied, and it was found that the biosorption of RBV-5R follows Freundlich adsorption isotherms. Kinetic studies were also carried out and it was found that the proposed method followed the pseudo-second-order kinetic model (R2 = 0.98). From desorption study, it was found that maximum desorption in the increasing order was obtained using ethanol, methanol, and 0.2 M sodium hydroxide (NaOH). The biosorption study was applied to actual textile waste effluent to pave way for the practical usage of this technology on a larger scale and the results were found effective.

Methyl red (MR) dye, one of the azo dyes, is mutagenic and its persistence has negative effects on the environment and people’s health. The current work is the first to demonstrate that methyl red dye can be removed effectively and sustainably, utilizing biomass derived from the bark of the Dodonaea viscosa (Hopbush) plant. The Hopbush bark shows effective adsorption of MR, upto 73%, under optimized conditions in an aqueous medium. The experimental conditions were optimized by examining the effect of time, initial dye concentration, pH and ionic strength on the adsorption process in an aqueous medium. Maximum (i.e., 73%) adsorption of MR removal (500 ppm) was observed in highly acidic conditions (pH = 1) at a contact time of 75 min. The pseudo-second-order kinetic model and Freundlich adsorption isotherm appeared to be the most appropriate for characterizing the MR’s adsorption onto the bark of the D. viscosa plant. Furthermore, it was shown that bark powder outperformed animal charcoal, silica gel, and powdered flowers, as well as the leaves of the same species, in terms of adsorption capacity. Thus, a natural adsorbent that is inexpensive and readily available—the bark of the D. viscosa plant—can be used to effectively remove harmful dyes from contaminated water and protect water resources from harmful pollutants.

Partially biodegradable polymer nanocomposites Poly(3-Hydroxybutyrate) (PHB)/MultiwalledCarbon Nanotubes (MWCNTs)/Poly(Methyl Methacrylate) (PMMA)and non-biodegradable nanocomposites (MWCNTs/PMMA) were synthesized, and their thermal, electrical, and ammonia-sensing properties were compared. MWCNTs were chemically modified to ensure effective dispersion in the polymeric matrix. Pristine MWCNTs (p-MWCNTs) were functionalized with –COOH (a-MWCNTs) and amine groups (f-MWCNTs). Then, PHB grafted multiwalled carbon nanotubes (g-MWNTs) were prepared by a ‘grafting to’ technique. The p-MWCNTs, a-MWCNTs, f-MWCNTs, and g-MWCNTs were incorporated into the PMMA matrix and PMMA/PHB blend system by solution mixing. The PHB/f-MWCNTs/PMMA blend system showed good thermal properties among all synthesized nanocomposites. Results from TGA and dTGA analysis for PHB/f-MWCNTs/PMMA showed delay in T5 (about 127 °C), T50 (up to 126 °C), and Tmax (up to 65 °C) as compared to neat PMMA. Higher values of frequency capacitance were observed in nanocomposites containing f-MWCNTs and g-MWCNTs as compared to nanocomposites containing p-MWCNTs and a-MWCNTs. This may be attributed to their excellent interaction and good dispersion in the polymeric blend. Analysis of ammonia gas-sensing data showed that PHB/g-MWCNTs/PMMA nanocomposites exhibited good sensitivity (≈100%) and excellent repeatability with a constant response. The calculated limit of detection (LOD) is 0.129 ppm for PHB/g-MWCNTs/PMMA, while that of all other nanocomposites is above 40 ppm.

In this study, Ailanthus altissima sawdust was chemically activated and characterized by Scanning Electron Microscopy (SEM), Fourier Transform Infrared (FTIR), Energy Dispersive X rays (EDX), and surface area analyzer. The sawdust was used as an adsorbent for the removal of azo dye, Acid Yellow 29 (AY 29) from wastewater. Different kinetic and equilibrium models were used to calculate the adsorption parameters. Among the applied models, the more suitable model was Freundlich with maximum adsorption capacities of 9.464, 12.798, and 11.46 mg/g at 20 °C, 30 °C, and 40 °C respectively while R2 values close to 1. Moreover, the kinetic data was best fitted in pseudo second order kinetic model with high R2 values approaching to 1. Furthermore, adsorption thermodynamics parameters such as free energy, enthalpy, and entropy were calculated and the adsorption process was found to be exothermic with a value of ∆H° = −9.981 KJ mol−1, spontaneous that was concluded from ΔG° values which were negative (−0.275, −3.422, and −6.171 KJ mol−1 at 20, 30, and 40 °C respectively). A positive entropy change ∆S° with a value of 0.0363 KJ mol−1 indicated the increase disorder during adsorption process. It was concluded that the activated sawdust could be used as a suitable adsorbent for the removal of waste material, especially dyes from polluted waters.

The selective oxidation of alcohols to aldehydes has attracted a lot of attention because of its potential use in agrochemicals, fragrances, and fine chemicals. However, due to homogenous catalysis, low yield, low selectivity, and hazardous oxidants, traditional approaches have lost their efficiency. The co-precipitation method was used to synthesize the silver-cobalt bimetallic catalyst supported on functionalized multi-walled carbon nanotubes (Ag-Co/S). Brunauer Emmet Teller (BET), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and X-ray diffraction (XRD) were used to characterize the catalyst. For the oxidation of cinnamyl alcohol (CA) with O2 as an oxidant, the catalyst’s selectivity and activity were investigated. The impacts of several parameters on catalyst’s selectivity and activity, such as time, temperature, solvents, catalyst dosage, and stirring speed, were comprehensively studied. The results revealed that in the presence of Ag-Co/S as a catalyst, O2 could be employed as an effective oxidant for the catalytic oxidation of cinnamyl alcohol to cinnamaldehyde (CD) with 99% selectivity and 90% conversion. In terms of cost effectiveness, catalytic activity, selectivity, and recyclability, Ag-Co/S outperforms the competition. As a result, under the green chemistry methodology, it can be utilized as an effective catalyst for the conversion of CA to CD.

Dye-sensitized solar cells (DSSCs) are a technically and financially viable alternative to today’s photovoltaic systems using p-n junctions. The two functions are isolated here, which are unlike traditional systems where the semiconductor is thought to perform both light absorption and charge carrier transport. This article discusses the potential use of dicyanobis(bipyridine)iron(III) to oxidize iodide as a sensitizer in DSSCs. However, it is critical to understand the kinetics of this essential process in order to understand the mechanism of electron transport. The oxidation of iodide by dicyanobis(bipyridine)iron(III) in three reaction media was studied: water, 10% v/v 1,4-dioxane-water, and 20% v/v 1,4-dioxane-water. The reaction was carried out in a regular laboratory setting, with no special sensitive conditions or the use of expensive materials, making it a cost-effective and practical method. Dicyanobis(bipyridine)iron(III) oxidized iodide in selected media at 0.06 M ionic strength and constant temperature. The reaction was subjected to a spectrophotometric analysis. The data were acquired by measuring the rise in visible absorbance as a function of time after the formation of dicyanobis(bipyridine)iron(II). The reaction proceeded with an overall fractional (0.5), first order, and third order in water, 10% media, and 20% media, respectively. The presence of dicyanobis(bipyridine)iron(III) in either of the reaction media had no effect on the rate. The effect of protons (H+) on the rate constant indicated resistance in water and catalysis in dioxane-water media containing 10–20% dioxane. When the ionic strength was raised, there was no change in the rate constant in water, but there was a deceleration in both binary solvent media. In an aqueous medium, the thermodynamic parameters of activation were computed as Ea 46.23 kJ mol−1, 24.62 M s−1, ΔH# 43.76 kJ mol−1, ΔS# −226.5 J mol−1 K−1, and ΔG# 111.26 kJ mol−1 (25 °C). By increasing the rate of the reaction to its maximum, this study discovered the binary solvent media with the highest catalytic efficiency, i.e., 20% v/v 1,4-dioxane-water, which may increase the efficiency of DSSCs without using any expensive material or unusual experimental conditions.

The catalytic activity of Pd/ZrO2 was studied in terms of the degradation of rhodamine-B dye in the presence of hydrogen peroxide. Pd/ZrO2 was prepared by impregnation method, calcined at 750 °C and characterized by XRD, SEM and EDX. The catalyst showed good catalytic activity for dye degradation at 333 K, using 0.05 g of the catalyst during 5 h. The reaction kinetics followed the pseudo-first order kinetics. The Freundlich, Langmuir and Temkin isotherms were applied to the data and the best fit was obtained with Freundlich isotherm. Thermodynamic parameters, like ΔH, ΔG and ΔS were also calculated. The negative values of ΔH (−291.406 KJ/mol) and Gibbs free energy (ΔG) showed the exothermic and spontaneous nature of the process. The positive ΔS (0.04832 KJ/mol K) value showed suitable affinity of catalyst for dye degradation. The catalyst was very stable, active and was easily separated from the reaction mixture by filtration. It can be concluded from the results that the prepared catalyst could be effectively used in dyes degradation/removal from water subjected to further validation and use for various dyes.

Paulownia tomentosa, a woody plant that is widely found in Pakistan and in other regions of the world, was used as a raw material to prepare activated carbon using chemical and physical activation methods. Adsorption of the dyes- acid red 4 and methylene blue onto the prepared activated carbon were analyzed by batch experiments. The impacts of different adsorption parameters such as pH, temperature, contact time, initial dye concentration and adsorbent dosage were also evaluated. Equilibrium data were fitted into various isotherm models such as: Langmuir, Temkin and Freundlich. High regression values were achieved with Langmuir isotherm model. Different kinetic adsorption models such as pseudo-first-order, pseudo-second-order and intra-particle diffusion model models were applied. The adsorption kinetics was found to be best-fitted into pseudo-second-order kinetic model. The optimum pH for acid red 4 was around 1 while for methylene blue it was 8. The optimum adsorbent dosage was 0.3 g for both dyes used. The activation energy (Ea) values were 30.57 and 3.712 kJ/mol, respectively for acid red 4 and methylene blue while the enthalpy (ΔH) and entropy (ΔS) values were correspondingly as 24.88/1.1927 kJ/mol and −2843.32/−0.329 J·mol/K for the mentioned dyes. The experimental result showed that the prepared activated carbon was the best in the removal of acid red 4 and methylene blue from aqueous media and therefore, could be preferably used as cheap adsorbent in wastewater treatment.

In the present study, we determined the levels of chlorinated pesticide residues in surface water samples collected from the Charsadda district (KPK, Pakistan). SPME-GC-ECD with COMBI PAL CTC autosampler was used for extraction and analysis of 20 organochlorine pesticides in the collected water samples. For maximum efficiency of the SPME procedure, several parameters were studied, including the extraction and desorption time of the fiber, solution pH, agitation of samples, and stirring speed, etc. This method showed good liner response, with R2 values in the range of 0.9887 to 0.9999 for all pesticides. This method also provided good percent recoveries at 1 µg L−1 (87.5 to 106.0%) and at 2 µg L−1 (88.5 to 109.2%). Lower limits of detection for all 20 chlorinated pesticides were found to be lower than their maximum permissible contamination levels. Approximately 50% of the surface water samples collected from the Charsadda district were found to be contaminated with the pesticides γ-BHC, heptachlor, aldrin and dieldrin, with maximum concentrations of 0.023, 0.108, 0.014 and 0.013 µg L−1, respectively. For adults and children, the cancer risk from water due to contamination by various pesticides ranged from 0 to 33.29 × 10−6. The non-carcinogenic risk from each pollutant in the water samples of the Charsadda district was found to be in the order of heptachlor &gt, aldrin &gt, dieldrin &gt, γ-BHC. However, the pesticides α-BHC, β-BHC, heptachlor epoxide, chlordane, endrin, 4,4′-DDD, endrin ketone, 4,4′-DDT, endosulfan sulfate and methoxychlor were not detected in any of the surface water samples of investigated in the present study.

Previous studies conducted on the pyrolysis of used rubber were either directed towards the yield and properties of liquid fuel or focused towards the generation of carbon black as end product and, hence, little attention was paid to the quantitative determination of gaseous, liquid, tar and char fractions obtained from the pyrolysis of used tire rubber. Therefore, the aim of this study was to re-utilize waste tire rubber as raw material for production of these valuable products which has substantial benefits for domestic and commercial use. Pyrolysis experiments were performed for thermal degradation of used tire rubber (UTR). The pyrolysates from the pyrolyzer were collected in separate traps on the basis of volatility into fractions like tar, liquid and gas. Influence of temperature was determined. The gaseous fraction was monitored using gas chromatography and the major hydrocarbons detected were C1–C5. The liquid fraction was analyzed by gas chromatography/mass spectrometry and the compounds detected in the range of C16 to C19. As the different fractions (gas, liquid, tar and char) were collected independently of each other, therefore, they may be used separately for useful purposes.

Photodynamic antimicrobial chemotherapy is an attractive and novel therapeutic approach to treat microbial infections. Antimicrobial peptides (AMPs) have the potential to specifically target and kill the microorganism while showing no effect toward mammalian cells. In the current study, antimicrobial peptide (GGG(RW)3), an analogue of MP-196, was conjugated to a zinc phthalocyanine (ZnPc) photosensitizer (PS) for photoinactivation assay to enhance the bacterial killing efficacy of the peptide. The AMPs showed selectivity toward the Gram-positive strain of bacteria. We observed that the conjugate ZnPc-GGG(RW)3 also displayed a photoinactivation effect against the Gram-positive strains of S. aureus. The results showed that ZnPc-GGG(RW)3 induced a 6-log reduction (i.e., 99.999% cell killing) in Gram-positive S. aureus at a light dose of 22 J/cm2 upon illumination under red light, while the peptide did not exhibit such a significant effect when tested alone at the same concentration. The conjugate also showed 50% inhibition of the bacterial strain in the dark at a higher concentration. Furthermore, the addition of potassium iodide salt to the PS at lower concentrations also significantly killed the Gram-negative E. coli strain and killed the E. coli strain with up to a 5-log reduction at a light dose of 22 J/cm2 under red light illumination. We demonstrated the efficacy of antimicrobial peptide (GGG(RW)3 enhanced by conjugation to a ZnPc photosensitizer.

The silver nanoparticles were synthesized, functionalized with afzelechin and characterized using UV-Visible spectroscopy. A difference of 20 nm was observed in surface plasmon resonance of bare and functionalized silver nanoparticles which indicates afzelechin conjugation with silver nanoparticles. The atomic force microscopy (AFM) technique was used for the determination of the size and morphology of synthesized silver nanoparticles. The afzelechin conjugated silver nanoparticles were spherical and their sizes ranged from 3 to 10 nm with an average size of 8 nm while the bare silver nanoparticles were also spherical and their sizes ranged from 3 to 10 nm with an average size of 6 nm. The average sizes were also calculated by fitting their UV-Visible absorption spectra. Fitting is based on the Mie and Mie Gans models, which deduced that afzelechin conjugated silver nanoparticles were 96.5% spherical and 3.5% spheroidal with an average size of 5 nm while bare silver nanoparticles were 100% spherical with an average size of 4 nm. Both the fitting model as well as the AFM results showed a difference of 3 nm between the sizes of afzelechin conjugated silver nanoparticles while 2 nm differences was observed for bare silver nanoparticles. The band gap energy of afzelechin conjugated silver nanoparticles and bare silver nanoparticles were calculated via Tauc’s equation and were found to be 5.1 eV and 5.4 eV, respectively. A difference of 0.3 eV was observed in band gap energies of afzelechin conjugated silver nanoparticles and bare silver nanoparticles.

The pyrolysis behavior of polyvinyl chloride (PVC) in the presence of commercially available oxides catalysts was investigated using thermogravimetry. The pyrolysis proceeded under a heating rate of 5°C/min in the temperature range of 200–650°C. The thermogravimetric properties in terms of reduction in maximum degradation temperature and percent conversion were studied. The silica gel mesoporous catalyst, with a greater pore size and surface area, was found to be the most active materials in terms of reduction in maximum degradation temperature and increase in percent conversion. The alumina acidic, silica ppt, and alumina neutral catalysts also showed good results; however, their effects were less pronounced as compared to silica gel. The effects of these different catalysts show that surface area, pore size, and number of acidic sites are found to be the major factors for the energy efficient degradation of polymers.

Pd–Ni nanoparticles supported on activated carbon (Pd–Ni/AC) were prepared using a phase transfer method. The purpose of synthesizing ternary composites was to enhance the surface area of synthesized Pd–Ni nanoparticles, as they have a low surface area. The resulting composite was characterized by scanning electronic microscopy (SEM), X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDX) for investigating its surface morphology, particle size, percentage of crystallinity and elemental composition, respectively. The XRD data and EDX analysis revealed the presence of Pd–Ni alloys impregnated on the AC. Pd–Ni/AC was used as an adsorbent for the removal of the azo dye basic blue 3 from an aqueous medium. Kinetic and isotherm models were used to calculate the adsorption parameters. The most suitable kinetic model amongst the applied models was the pseudo-second-order model, confirming the chemisorption characteristics of the process, and the most suitable isotherm model was the Langmuir model, with a maximum adsorption capacity of 333 mg/g at 333 K. Different experimental parameters, such as the adsorbent dosage, pH, temperature and contact time, were optimized. The optimum parameters reached were: a pH of 12, temperature of 333 K, adsorbent dosage of 0.01 g and optimum contact time of 30 min. Moreover, the thermodynamics parameters of adsorption, such as Gibbs free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°), showed the adsorption processes being exothermic with values of ΔH° equal to −6.206 kJ/mol and being spontaneous with ΔG° values of −13.297, −13.780 and −14.264 kJ/mol, respectively at 293, 313 and 333 K. An increase in entropy change (ΔS°) with a value of 0.0242 kJ/mol K, indicated the enhanced disorder at a solid–solution interface during the adsorption process. Recycling the adsorbent for six cycles with sodium hydroxide and ethanol showed a decline in the efficiency of the selected azo dye basic blue 3 up to 79%. The prepared ternary composite was found effective in the removal of the selected dye. The removal of other pollutants represents one of the possible future uses of the prepared adsorbent, but further experiments are required.

In this study palladium-nickel (Pd-Ni) nanoparticles supported on carbon and cerium oxide (Pd-Ni/AC-CeO2) were synthesized by a transfer phase method and characterized by scanning electronic microscopy (SEM), X-ray diffraction (XRD), and energy-dispersive X-ray spectroscopy (EDX). The XRD and SEM data concluded the presence of alloy formation between Pd and Ni. The synthesized particles were used as an adsorbent for removal of azo dye acid orange-8 (AO-8) from water and were found to be effective in removal (over 90% removal efficiency) of the selected dye. Different kinetics and equilibrium models were applied to calculate the adsorption parameters. The most suitable model that best fitted the equilibrium data was the Langmuir model and maximum adsorption capacities were 666.6, 714 and 769 mg/g at 293, 313 and 333 K, respectively, with R2 values closed to 1 while in the case of the kinetics data the best fit was obtained with a pseudo-second order kinetics model with a high R2 value. Furthermore, the adsorption thermodynamics parameters such as free energy, enthalpy, and entropy were calculated and the adsorption process was to found be exothermic with a value of ΔH° (−7.593 kJ mol−1), spontaneous as ΔG° values were negative (−18.7327, −19.4870, and −20.584 kJ/mol at 293, 313 and 333 K, respectively). A positive entropy change ΔS° with a value of 0.0384 kJ /mol K indicates increased disorder at the solid–solution interface during the adsorption process. An attempt was made to recycle the Pd-Ni/AC-CeO2 with suitable solvents and the recycled adsorbent was reused for 6 cycles with AO-8 removal efficiency up to 80%. Based on findings of the study, the synthesized adsorbent could effectively be used for the removal of other pollutants from wastewater, however, further studies are needed to prove the mechanisms.

The study aimed to assess the physicochemical parameters (pH, electrical conductivity (EC), total dissolve solid (TDS), oxidation reduction potential (ORP), Temperature) and potential toxic metals (PTMs), including Ni, Mn, Cr, Cu, Cd, Pb, Co, Fe and Zn in the groundwater of Lower Dir, Pakistan. Furthermore, the pollution sources and spatial distribution pattern of PTMs were also investigated via principal component analysis (PCA) and geographic information system (GIS) application to understand the changing behaviors of PTMs in groundwater. The average concentrations of physicochemical parameters such as pH, EC, TDS, ORP and Temperature were 7.1, 418 μS/cm, 251 mg/L, 193 mV and 25.7 ○C, while the concentrations of PTMs; Ni, Mn, Cr, Cu, Cd, Pb, Co, Fe and Zn were 0.25, 0.34, 0.09, 0.29, 0.10, 0.08, 0.10, 0.83 and 0.25 mg/L, respectively. Among the selected metals, Mn, Cr, Cd, Pb, Co and Fe were exceeded the WHO guidelines and their percentage contribution were 43%, 57%, 45%, 70%, 70% and 62%, respectively. The increasing order of PTMs were; Pb > Co > Fe > Cr > Cd > Mn > Cu > Ni > Zn in the study area. PCA represented three significant factors, which explained 76% variability in the groundwater. Whereas, clustering analysis (CA) grouped groundwater into three distinct clusters less polluted (C1), moderate polluted (C2) and highly polluted (C3). Human health risk assessment was carried out to check the suitability of groundwater for drinking and domestic uses. The HQ and HRIs values of Cd were >1, suggested that the groundwater sources are unfit for drinking and domestic purposes and may be caused potential health risk after long term ingestion.

Made available in DSpace on 2018-12-11T16:52:52Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-09-01 Higher Education Commission, Pakistan University of Peshawar This study investigated the fluoride (F−) concentrations and physicochemical parameters of the groundwater in a fluorite mining area of the flood plain region of the River Swat, with particular emphasis on the fate and distribution of F− and the hydrogeochemistry. To better understand the groundwater hydrochemical profile and F− enrichment, groundwater samples (n = 53) were collected from shallow (24–40 m), mid-depth (48–65 m) and deep (85–120 m) aquifers, and then analysed using an ion-selective electrode. The lowest F− concentration (0.7 mg/L) was recorded in the deep-aquifer groundwater, while the highest (6.4 mg/L) was recorded in shallow groundwater. Most groundwater samples (62.2%) exceeded the guideline (1.5 mg/L) set by the World Health Organization (WHO); while for individual sources, 73% of shallow-groundwater samples (F− concentration up to 6.4 mg/L), 42% of mid-depth-groundwater samples, and 17% of deep-groundwater samples had F− concentrations that exceeded this permissible limit. Assessment of the overall quality of the groundwater revealed influences of the weathering of granite and gneisses rocks, along with silicate minerals and ion exchange processes. Hydrogeochemical analysis of the groundwater showed that Na+ is the dominant cation and HCO3 − the major anion. The anionic and cationic concentrations across the entire study area increased in the following order: HCO3 > SO4 > Cl > NO3 > F > PO4 and Na > Ca > Mg > K, respectively. Relatively higher F− toxicity levels were associated with the NaHCO3 water type, and the chemical facies were found to change from the CaHCO3 to (Na–HCO3) type in calcium-poor aquifers. Thermodynamic considerations of saturation indices indicated that fluorite minerals play a vital role in the prevalence of fluorosis, while under-saturation revealed that – besides fluorite minerals – other F− minerals that are also present in the region further increase the F− concentrations in the groundwater. Finally, a health risk assessment via Dean's classification method identified that the groundwater with relatively higher F− concentrations is unfit for drinking purposes. Department of Environmental Sciences University of Peshawar Hydrogeochemistry Laboratory Department of Environmental Sciences Faculty of Biological Sciences Quaid-i-Azam University, PO 45320 Key Laboratory of Surficial Geochemistry Ministry of Education School of Earth Sciences and Engineering Nanjing University National Centre of Excellence in Geology University of Peshawar Departamento de Fısico-Quımica de Instituto Quımica Universidade Estadual Paulista (UNESP) Departamento de Fısico-Quımica de Instituto Quımica Universidade Estadual Paulista (UNESP) University of Peshawar: 5135/NRPU