Advanced Journal of Chemistry, Section A
Volume:3 Issue: 3, Summer 2020

Dissolved Thiocyanate in drinking water is a source of global health concern. The purpose of the present study was to remove aqueous Thiocyanate anions by using the titanium dioxide nanoparticles (TiO2 NPs). Titanium dioxide is inexpensive and non-toxic, making it an attractive choice for drinking water purification. Thiocyanate was adsorbed by the surface of nanoparticles into Fe-SCN complex and a filter was used for removing the nanoparticles. The effect of different parameters such as pH, buffer, time of stirring, the number of nanoparticles, concentration of the aqueous iron, and concentration of the electrolyte and its optimal amounts were investigated. Removal of the aqueous SCN- showed the best performance at the pH of 9, 0.5 mL of buffer, stirring for 15 min, and 0.5 g of TiO2. It was analyzed by means of spectrophotometry at ƛ=456.8 nm. Langmuir adsorption isotherm and Freundlich adsorption isotherm explained the best correlation between the Thiocyanate adsorption and equilibrium data. Langmuir adsorption isotherm showed more adaptability and the its sorption capacity was 11.6 mg/g-1 for nanoparticles. This method was tested for removing Thiocyanate from some real samples including tape water, Karoon River water, and water from petrochemical wastewater. Majority of the TiO2 NPs revealed an acceptable sorption capacity and reuse-ability in Thiocyanate anions removal in water solution.

In this study, the physicochemical parameters of the river Majowopa were determined. The parameters assessed are temperature, pH, turbidity, conductivity, total dissolved solids (TDS), total suspended solids (TSS), total solids (TS), total acidity, total alkalinity, chloride, nitrate, phosphate, sulphate, dissolved oxygen (DO), chemical oxygen demand (COD) and biochemical oxygen demand (BOD). The obtained result revealed that the average value of the parameters analysed are; temperature (27.99±0.51 °C), pH (6.76±0.08), turbidity (7.69±2.51 NTU), conductivity (124.90±18.42 uS/cm), TSS (18.29±2.27 mg/L), TDS (68.17±13.63 mg/L), TS (86.46±13.95 mg/L), total acidity (17.57±2.37 mg/L), total alkalinity (25.23±6.23 mg/L), chloride (27.91±1.92 mg/L), nitrate (10.14±2.28 mg/L), phosphate (7.62±1.85 mg/L), sulphate (32.72±0.87 mg/L), DO (1.60±0.55 mg/L), COD (23.79±5.45 mg/L), BOD (8.31±3.65 mg/L) and that these values are within the WHO allowed limits except for turbidity (7.69±2.51 NTU), nitrate (10.14±2.28 mg/L), phosphate (7.62±1.85 mg/L) and DO (1.60±0.55 mg/L). One-way analysis of variance (ANOVA) carried and the 95% confidence level revealed that the value of each parameter was significantly different (P<0.05) from one site to another. The variation of each parameter observed along the river was as a result of pollution from activities that take place along the river bank and the vicinity of the river.

In this work, the persistence of novaluron (Rimon 10% EC) in soil was studied under the humid tropical chilli pepper ecosystem. Residues of novaluron in soil were determined using the modified QuEChERS method and liquid chromatography tandem mass spectrometry. The recovery values of the novaluron were found to be in the range of 88.4-105.2% with relative standard deviation ranging from 3.8 to 15.2% at 0.01, 0.05 and 0.1 µg/mL fortification levels in soil. The soil matrix influenced the ion enhancement in a tune of 22 and 28% at 0.05 and 0.1 mg/kg, respectively. The limit of detection was 0.005 mg/kgand limit of quantitation was 0.01 mg/kg. The initial deposit of the novaluron in soil at 37.5 and 75 g.a.i./ha dosed were 0.073 and 0.151 mg/kg, respectively, which reached below the limit of quantitation (0.01 mg/kg) after 5th and 7th days after the treatment indexing a half-life of 1.85 days for lower dose and 2.13 for higher dose.

In this work, cyclic voltammetry studies for Cu (II) ion were carried out to show it`s redox behaviours in 0.1 M KBr and 4-Fluoro benzoic acid. The aim of this research study was to estimate the copper chloride and 4-fluorobenzoic acid in KBr electrolyte. The voltammetric studies involve reversible scans at various concentration of both CuCl2 and 4-Fluoro benzoic acid (FBA). Based on the measured voltammograms the different thermodynamic parameters such as the Gibbs thermodynamic energies and stability constants for the interaction CuCl2 with 4-Fluoro benzoic acid (FBA) are discussed by the formation of strong electrostatic complexes. Different Scan rates were also considered to illustrate the mechanism of the redox reactions in the solutions. The importance of this work was to explain the uses of 4-flurobenzoic acid (FBA) as a ligand.  Estimation of the different thermodynamic parameters for the interaction of CuCl2 with 4-flurobenzoic acid in 0.1 M KBr cyclic voltammetry was done. Application of the interaction of CuCl2 with 4-fluro benzoic acid for evaluation of both different cupprous, cupric and 4-flurobenzoic acid concentrations.

In this work, legume starch from Kwakil beans (Phaseolus vulgaris L.) was cross-linked with epichlorohydrin and carboxymethylated with different concentrations of sodium monochloroacetate (SMCA) (5-30% w/w of starch db). Degree of substitution (DS) of carboxymethyl group ranged between 0.02-0.063, and adsorption was enhanced as the DS increased. The native starch (NS), cross-linked starch (ECS), and the carboxymethyl derivative (ECCS-15%; DS=0.062) with optimum adsorption capacity in Pb2+ (98.51%) and Cd2+ (97.32%) aqueous solution were further characterized using FTIR and SEM-EDX. Equilibrium studies revealed that the adsorption of Pb2+ and Cd2+ from aqueous solution by ECCS increased by enhancing the pH, contact time (up to equilibrium time at 15 min), initial concentration and adsorbent dosage, but decreased with increasing the temperature and interfering ion (Na+ and Ca2+) concentrations. Pb2+ data fits pseudo-second order kinetic (R2=0.9999) and Langmuir isotherm models (R2=0.9983), and ΔH=-48.67 Kj/mol-1. This signals a chemisorption process. Pb2+ and Cd2+ can be recovered efficiently (up to 99%), and the adsorbent can be reused up to 5 cycles with sorption capacity above 75%. On application, ECCS reveals good potentials in the purification of wastewater with low heavy metal ion concentrations.

This work, the application of a surfactant-modified natural nano-clinoptilolite for the removal of several two valances heavy metal cations (i.e., Cu2+, Pb2+, Ni2+, Cd2+, Fe2+ and Zn2+) from aqueous media was discussed. Triton X-100 was used as modifier and to achieve maximum efficiency of adsorption; variables such as the concentration of surfactant, contact time, the working temperature and pH of sample solution were optimized. The results revealed that, the maximum adsorption was achieved at a solution with the pH of 6, containing 2 mL of triton X-100 and 2 g/L of clinoptilolite at 45 °C. The obtained selectivity series for the adsorption of cations were Pb2+>Cu2+>Cd2+>Ni2+ >Zn2+>Fe2+. The maximum adsorption capacity of the modified zeolite for Pb2+, Cu2+, Cd2+, Ni2+, Zn2+ and Fe2+ was 91.34, 85.71, 78.27, 76.18, 67.41 and 63.45 mg/g, respectively. The adsorption data were acceptably fitted to the both Freundlich and Langmuir isotherms.

A tridentate Schiff base ligand (E)-1-(2-hydroxy-3-methoxybenzylidene)-3-phenylurea derived from o-vanillin and phenyl urea in 1:1 molar ratio. Also, the metal complexes of Mn (II), Co (II), Ni (II), Cu (II), Zn (II) and Zr (IV) were synthesized using the microwave-assisted irradiation and conventional methods. The ligand and its complexes 1-6 were characterized using the elemental analysis, FT-IR, UV-vis, 1HNMR, mass spectroscopy as well as thermo-gravimetric analysis (TGA). The geometry structures of the complexes were confirmed using electronic spectra, electron spin resonance (ESR) and magnetic moment. Study of the thermal dehydration and decomposition of the Co (II), Ni (II), and Zn (II) complexes kinetically using the integral method applying the Coats–Redfern and Horowitz Metzger equation. The ligand and its metal complexes were screened for the antimicrobial activity against the gram-positive, gram-negative bacteria and fungi also, the cytotoxic activity was evaluated against two cell lines; human colon carcinoma (HCT-116) and breast carcinoma cells (MCF-7).

In this work, the electronic band structures, total density of state, partial density of state, and optical properties were investigated using the first principle method for SnWO4 via generalized gradient approximation (GGA) based on the Perdew–Burke–Ernzerhof (PBE0). The estimated band gap was found to be 0.557 eV which is supported for good semiconductor. The density of states and partial density of the states were simulated for evaluating the nature of 5s, 4d 5p for Sn, 6s, 4f, 5d for W and 2s, 2p for O atom for SnWO4. The optical properties for instance, conductivity, dielectric function, and the loss function were calculated. The main goal of this research study was to determine the Fe doping activity on the electronics structure and optical properties by 8%, and the band gap was recorded in 0.0 eV, showing as a superconductor. Regarding the optical properties, the loss function was decreased after doping.

In this work, a total of thirty four (N=34) street dust samples were collected from four different land use zones viz., commercial, heavy traffic, residential and control (undisturbed) areas of Kathmandu, Nepal. The dust samples were analyzed for four different heavy metals (Cd, Cr, Ni, and Pb) by using the flame atomic absorption spectrophotometer (FAAS). The total organic carbon (TOC) and pH of the samples were also measured. The selected land use zones revealed their relative order based on the concentration of the elements as heavy traffic>commercial>residential>control. The average concentration of the Cd, Cr, Ni, and Pb were found to be 0.69, 77.4, 68.9, and 63.9 mg/kg (dry basis), respectively. The results of the present study were also compared against the heavy metals concentration in street dust with previous studies across the world. High amount of Ni (122.2 mg/kg), Cr (94.8 mg/kg), Pb (74.4 mg/kg), and Cd (0.84 mg/kg) was observed in heavy traffic zone compared to other land use zones. Results revealed that the street dust from the commercial and residential zones contained high concentration of Cr whereas the heavy traffic zone was mainly affected by the Ni. In addition, the dust samples from all land use zones showed alkaline nature and contained variable amount of TOC. The inter-parameter relationship expressed by Pearson’s correlation coefficient indicated their common sources of emission as well as similar fate and characteristics. A single pollution index such as contamination factor (CF) and geo-accumulation index (Igeo) revealed different classes of metal contamination in street dust of Kathmandu. The average level of metal contamination in street dust of Kathmandu was found to be 3.94, 2.64, 1.97, and 1.94 for Ni, Cr, Cd, and Pb, respectively. Health risk assessment modeling study of the HMs in street dust indicated no non-carcinogenic risks for the receptors; however, ingestion was found to be the most potential pathway for the HMs exposure and toddlers as the most likely to be a vulnerable group.

In this work, the possibility of using Raphia taedigera seed as a low-cost adsorbent to remove methylene blue (MB) dye from aqueous solutions was investigated. The activated carbon was prepared by carbonization and chemical treatment of the seed with sulphuric acid to produce acid-modified Raphia taedigera seed activated carbon (RTAC). The surface morphology and bond arrangement of the RTAC were evaluated using the scanning electron microscopy (SEM) and Fourier transforms infrared spectroscopy (FTIR), respectively. The SEM analysis results revealed that the prepared adsorbent had aggregated and rough surface structure with pores and FTIR revealed the presence of several functional groups such as –C=O, –OH, –C=C–, –N=O and –C=N–. The adsorption efficiency of the RTAC for the removal of the MB dye was assessed under different experimental conditions including, contact time, temperature, pH, adsorbent dosage, and dye initial concentration. The results gave the performances of 99.611% after 15 min, 99.635% at 303 K, 99.894% at pH 9, 99.256% with 0.9 g, and 99.743% for 40 mg/L for evaluating the effect of the contact time, temperature, pH, adsorbent dosage, and dye solutions initial concentration, respectively. The adsorption of the MB dye onto the RTAC conformed to Langmuir isotherm and fit best to pseudo-second-order kinetic models. Thermodynamic studies indicated a spontaneous, endothermic, feasible, and physisorption nature of the RTAC and MB dye interactions. The present study found the acid-modified Raphia taedigera seed activated carbon to be a promising low-cost adsorbent for the removal of MB dye from aqueous solution.

Toxic metal pollution is one of the most persistent environmental problems globally. This study deals with the synthesis of the p-piperdinomethyl calix[4]arene attached silica (PAS) resin and to investigate their metal ions removal efficiency from water. In batch adsorption experiment PAS resin shows good adsorption efficacy for the Cu2+ and Pb2+ metal ions. To examine the adsorption mechanism and validate the experimental adsorption data the isotherm models were applied and adsorption of the Cu2+ and Pb2+ metal ions follow Freundlich isotherm model very well with good correlation coefficient. However, the adsorption energy calculated from the D-R isotherm was at the range of 9-14 KJ/mole which describes the ion exchange nature of resin. Furthermore, breakthrough capacity of column was calculated from online adsorption as 0.027 and 0.041 mmol/g-1 for Cu2+ and Pb2+, respectively. Furthermore, thermodynamics and kinetic study revealed that, the adsorption process spontaneity and endothermic that follows the pseudo 2nd order kinetic equation with good regression coefficient.

Pyrotechnic decoy flares are the most widely used passive countermeasures for heat-seeking missiles. The development of (photoconductive) InSb-detectors with cut-off wavelength>6 μm has allowed two-color detectors working in both short (α) (1.8-2.5 μm) and mid-wave (β) (3.5-4.8 μm) bands. Thus, it is possible to determine the sensitivity ratio and to discriminate against fake targets. An attempt was made to change the spectral distribution of MTV (Magnesium-Teflon-Viton) decoy flare compositions by adding another composition to modify spectral emission based on aluminum, hexamine, potassium nitrate and ammonium perchlorate. Aluminum emission at 1.5 µm due to Al2O3. Hexamine used as flame expanders due and to provide cooling of the flame to transform radiation from a spot location to a burning zone. In this study, theoretical and experimental comparisons were made between various spectrally adapted flame compositions based on epoxy as a binder and the MTE flare which represented by sample (4). The first composition was Mg/Teflon/Epoxy (MTE) with percentage (60-80)% and the second adapted compositions with percentage (20-40)%. The temperature of the flame and the time of burning were measured using an inframetric radiometer. The radiant emission was determined using a computer program. The results show that sample (1) which contains 20% of the adapted compositions produces high flame temperature (1300 °C) and the highest radiant emittance 6.6 W/cm2/µm.

In this work, a novel chemically adsorbent based on Zn2Al-layered double hydroxide (LDH) that modified by indigo carmine (IC) (Zn2Al-LDH/IC) was synthesized. The chemical composition and morphology of the synthesized Zn2Al-LDH/IC were investigated using the X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), field emission scanning electron microscopy (FE-SEM), and energy-dispersive X-ray spectroscopy analysis. Response surface methodology (RSM) using the central composite design (CCD) is applied to optimize the adsorption process parameters for Cd(II) removal from the aqueous solution using a novel chemically modified nano Zn2Al-layered double hydroxide (Zn2Al-LDH/IC). The combined effect of adsorption parameters such as contact time, initial Cd(II) concentration, adsorbent amount and initial pH of solution were studied. The results obtained by ANOVA analysis displayed the relative significance of the process parameters in the adsorption process. The optimum conditions to remove Cd(II) from aqueous solution were at the initial Cd(II) concentration of 52 mg/L-1, pH 4.13, the adsorbent dose 0.06 g, temperature of 36.5 °C and contact time 36 min. In optimum conditions, high adsorption efficiency and maximum adsorption capacity were 47.3% and 6.11 mg/g, respectively.  Adsorption of Cd(II) by nano Zn2Al-LDH/IC could be well examined with Langmuir and Freundlich isotherms and the pseudo second-order kinetic model was fitted to the adsorption kinetic data. Furthermore, the thermodynamic data exhibited that the adsorption process of Cd(II) by nano Zn2Al-LDH/IC was spontaneously and exothermic.

In the present study, we successfully synthesized a series of indoles with a variety of aromatic aldehydes via one-pot route. The excellent results of the bis(indoly) methane (BIM) derivatives was obtained at the presence of 5.0 mol% p -toluene sulfonic acid in acetonitrile at room temperature using conventional process. All the as-synthesized compounds were bioactive. The synthesized BIM derivatives were evaluated for the antibacterial activity (in vitro) against the Staphylococcus aureus, and the results were compared with the standard Kanamycin. The results confirmed that, majority of the as-synthesized compounds revealed splendid antibacterial activity.

The molecular dynamics (MD) simulation of two structures of human insulin hexamers (Zn-hexamer and Znfree-hexamer) in explicit solvent was performed and the role of the Zn2+ ions in the hexamer’s cavity as it may affect the propensities of the dissociation of insulin hexamer into dimers and monomers investigated. The starting structure of the Zn-hexamer contains two cavity water molecules and two Zn2+ ions in addition to the amino acids residues of the insulin hexamer while the starting structure Znfree-hexamer is made up of only the amino acids residues of the insulin hexamer. The MD simulation was performed for 1 µs under the isothermal-isobaric conditions (NPT) conditions using the GROMACS software, amber ff99-SB force field, TIP 3P water model with periodic boundary conditions imposed on x-, y- and z- directions. Structural analyses of the two experimental structures were carried out and root mean square deviations (RMSD) and root mean square fluctuations (RMSF) computed from the referenced initial structures. The average RMSD value of the backbone atoms for the Zn-hexamer is 0.293 nm and Znfree-hexamer is 0.785 nm. The structural analysis revealed that, there were dimer’s dissociation and pronounced fluctuations of the amino acids residues in the Znfree-hexamer compared to the Zn-hexamer during the MD simulation. This is evident in the higher inter-dimer distances of the six glutamate-13(β) residues in the Znfree-hexamer which confirmed the influence of the removal of the Zn2+ ions and cavity water molecules on dissociation of the insulin hexamer.

In this research study, the detection and removal of nalidixic acid by boron nitride nanocluster (B12N12) were investigated using the DFT, infra-red (IR), natural bond orbital (NBO) and frontier molecular orbital (FMO) computations. The calculated negative values of adsorption energy, Gibbs free energy changes, and great amounts of thermodynamic equilibrium constants demonstrated nalidixic acid adsorption on the surface of B12N12 was spontaneous, irreversible and experimentally feasible. The values of adsorption enthalpy changes and specific heat capacity (CV) revealed that, the interaction of the adsorbate and adsorbent was exothermic and B12N12 was an ideal nanostructure for the construction of new thermal sensors for detection of nalidixic acid. The influence of temperature on the thermodynamic parameters was also investigated and the results demonstrated that, the adsorption process was more favorable at room temperature. The NBO results indicated in all of the studied configurations covalent bonds were formed between nalidixic acid and B12N12 and their interaction was chemisorption. The density of states (DOS) spectrums showed that, the bandgap of boron nitride nanocage after the adsorption of nalidixic acid decreased from 14.864 (eV) to 7.314 (eV), indicating that the electrical conductivity of B12N12 improved significantly in the adsorption process and B12N12 is an appropriate sensing material for developing novel electrochemical sensor to nalidixic acid determination. The important structural parameters including chemical hardness, chemical potential, dipole moment, electrophilicity and maximum charge capacity were also computed and discussed in detail.

Thermal insulators based on ethylene propylene diene terpolymer (EPDM) is an effective class of extreme temperature thermal insulators due to their outstanding heat, mechanical and ablative characteristics. This classed insulator is often reinforced by Kevlar pulp and fumed silica. Ammonium sulfate and antimony trioxide combination have been added as a flame retardant. To improve the elastomer ablative characteristics, multi-walled carbon nanotubes (MWCNTs) were added. We have studied different MWCNT concentrations. In this work, we investigated the effect of the MWCNTs content on the characteristics of the selected insulating formulation based on EPDM. The maximum improvement of tensile strength was 60%. Thermal stability increased by 27% through thermal gravimetric analysis (TGA-DTG), while the ablation resistivity was significantly increased by 60%. The weight loss of the 10 phr MWCNT sample decreased by 40% compared with that of the neat sample. Besides, an increase in ablation rate by 60% was recorded with the same sample.

Ag nanoparticle and 1-buthyl-3-methyl imidazolium bromide (1B3MIBr) carbon paste electrode(Ag/NP/1B3MIBr/CPE) amplified sensor was fabricated for determination of rutin in this project. The electro-oxidation of rutin occurs at a potential about 0.4 V at the surface of Ag/NP/1B3MIBr/CPE and this value is less positive than the unmodified CPE. pH = 7.0 was selected as an optimize condition for all of electrochemical investigations in this work and for evaluating electrochemical parameters such as diffusion coefficient (5.0 × 10-6 cm2/s). At the optimized condition for rutin analysis, the differential pulse voltammetry (DPV) peak currents of rutin show a wide linear dynamic range from 0.05-320 μM with a detection limit of 10 nM. Finally, the Ag/NP/1B3MIBr/CPE was used for determination of rutin in soy samples with good selectivity and high sensitivity.

The aim of the present study was to determine the cefixime (CFX) through highly sensitive and simple electrocatalytic method. The electrocatalytic oxidation of CFX was performed on the surface of the modified carbon paste electrode (MCPE) with synthesized nano-sized ZSM-5 zeolite using the cyclic chronoamperometry and voltammetry methods. Also this work probed the application of the nano-zeolite in electrode structure and prepare zeolite MCPE. Due to the porous structure of the zeolite framework, the nickel (Ni) (II) ions were embedded into the zeolite framework through the immersing MCPE with synthesized zeolite in a 1.0 M Ni chloride solution. An excellent redox activity was practically seen for the Ni2+/ Ni3+ couple on the MCPE surface in alkaline solution. The Ni ions were acted as a mediator for the oxidation of CFX and catalyzed the electron transfer in this process. The CFX molecules were successfully oxidized on the surface of proposed electrode. The chronoamperometric method was used and catalytic reaction rate constant (K) was 3.5 ×106 cm3/s-1/mol-1 for the CFX oxidation. This electrocatalytic oxidation had a good linear response in the CFX concentration range of 25×10-6– 25×10−5 M with a regression correlation coefficient of 0.993, and the detection limit (3δ) of the method was 26×10-7 M. The diffusion coefficient of CFX molecules (D=6.47×10-5 cm2/s-1) was calculated based on the chronoamperometry studies.

Separation of light hydrocarbons (LHs) is one of the most important and mostly energy intensive petrochemical processes. Several techniques have been developed industrially based on traditional separation methods such as distillation and extraction. However, they mainly suffer from high-energy consumption and low efficiency. Adsorptive separation using porous solid materials and membrane separation are the promising processes to separate the mixture of light hydrocarbons comprising paraffin/olefin mixtures of C1/C2/C3 hydrocarbons. Introducing and developing new porous adsorbents for selective separation of LHs is highly needed because of competitive adsorption and challenging separations that are arising from the similarity in some structural and physicochemical properties of LHs. In addition, separation under the mild condition is of great importance for the application in industry. In this review, we discussed some methods for separation of LHs mixtures and highlighted the recent advances in the separation techniques based on using porous structures especially metal organic frameworks in the form of porous adsorbents and membranes.

BiVO4/Hydroxyapatite (HAP) composite was synthesized successfully by combining co-precipitation process and wet-chemical method. Three composites have been prepared by varying the molar concentration of BiVO4 and HAP and were named as 1:1-BHC, 1:2-BHC and 2:1-BHC respectively. These composites were characterized by X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). SEM and TEM images of as prepared composites revealed the BiVO4 nanorods enclosed with HAP nanoflakes while XRD and FTIR results confirmed the formation of nano composites. The composites were then used as photocatalyst for the photocatalytic degradation of malachite green (MG) dye and the photocatalytic activities were compared with that of BiVO4. The 2:1-BHC showed best MG photodegradation, better than BiVO4 itself due to synergistic effects of adsorption of dye particles by HAP and subsequent photocatalytic degradation by BiVO4. The optimum catalyst dose for 2:1-BHC was found to be 0.1 g per 100 mL of 10 ppm dye concentration with initial pH of solution being 6. These results revealed that BHC-composite did possess the features of visible light active photocatalyst and could be used for the degradation of organic pollutants like dyes.