Analytical Methods in Environmental Chemistry Journal

Adsorption of methylene blue dye onto bentonite clay: Characterization, adsorption isotherms, and thermodynamics s tudy by using UV-Vis technique

2023-09-23T05:52:23+00:00

This study uses the UV-Vis technique to describe the elimination of methylene blue dye from an aqueous solution by adsorption on an Iraqi bentonite clay surface. The batch approach was used to conduct adsorption studies carried out to evaluate the influence of factors of experimental like contact time (0–90 min), clay dose (0.1–0.35 g), and initial dye concentration (10–125 mg L^-1) at the range of temperatures (25-40^oC). The Langmuir and the Freundlich isotherms were used to analyze the data; the Langmuir isotherm (R2 = 0.998) proved more appropriate for the equilibrium data. The thermodynamic properties of the adsorption process, including Gibbs free energy (ΔG^O), entropy(ΔS^O), and enthalpy (ΔH^O), were also studied. Since the (ΔG^O) and (ΔH^O) values were negative, it was clear that the adsorption process constituted an exothermic, spontaneous reaction. This investigation revealed that Iraqi bentonite clay effectively removed the dye methylene blue because of its high surface area. Methylene blue may be removed with an adsorption efficiency of up to 99.39 % at 25^oC. By employing bentonite clay as an adsorbent surface, this research offers practical adsorption technology that is affordable and effective for treating wastewater.

Determination of 2,4-dinitrophenylhydrazine using carbon paste modified with nanoparticles by cyclic voltammetry, high-performance liquid chromatography and spectrophotometry methods

2023-09-24T23:03:33+00:00

The research deals with the manufacture of an electrode using modified carbon paste to determine 2,4-dinitrophenylhydrazine (2,4-DNPHZ), The modified carbon paste electrode (NiO-NCQD/g-C₃N₄/MCPE). The results show the presence of oxidation and reduction peaks, and it is subject to a quasi-reversible system; the best value of pH is (1) using sulfuric acid with a concentration of (0.1M), and scan rate is 100 mv sec^-1, it was linearity range of (1-1000) µM for oxidation, and (100-1000) µM for reduction, with correlation coefficient (R²=0.9717) and (R²=0.9914) for each of them, respectively. The proposed electrochemical method was compared with two methods they are spectrophotometry at a wavelength 360) nm( and high-performance liquid chromatography (HPLC) at wavelengths (340 and 250) nm. It turned out that the electrochemical method (NiO-NCQD/g-C₃N₄/MCPE) was superior to the spectrophotometry method in terms of the detection limit. It turns out that there is no significant difference between (HPLC) and (NiO-NCQD/g-C₃N₄/MCPE) in terms of accuracy. The proposed electrochemical method is a new analytical method characterized by accuracy, repeatability, and reliability.

Virtual chemical analysis and machine learning-based prediction of polyethylene terephthalate nanoplastics toxicity on aquatic organisms as influenced by particle size and properties

2023-09-24T03:13:11+00:00

This study focuses on the chemical analysis and prediction of Polyethylene Terephthalate (PET) toxicity, considering the influence of particle size and properties. The effect PET of different sizes (1, 4, 9, 16 and 25 nm coded NP1 to NP5) on aquatic organisms such as Terpedo californica (electric ray fish) and Danio rerio (zebrafish) as model species was evaluated by virtual chemical techniques and machine learning methodology based on Multilayer Perceptrons Artificial Neural Networks (MLP ANN) and Support Vector Machine. The PET NPs was built and characterized in silico and then docked on the acetylcholinesterase (TcAChE) and cytochrome P450 (Zf CYP450) of the organisms, respectively. The results showed that the binding affinities of the NPs increased steadily from – 7.1 kcal mol^-1to – 9.9 kcal mol^-1for NP1 to NP4 and experienced a drop at NP5 (– 8.9 kcal mol^-1) for TcAChE. The Zf CYP450 also had a similar pattern ranging from -5.2 kcal mol^-1 to -8.1 kcal mol^-1. The MLP ANN showed an accuracy of 85.9 % and 77.3 %. In comparison, SVM showed a better PET NPs toxicity prediction with an accuracy of 99.5 % and 99.4% based on the inherent properties of TcAChE and Zf CYP450, respectively.

Starch nanocomposite containing hydroxyapatite and eggshell for absorbing methylene blue dye from aqueous solution

2023-09-24T23:09:20+00:00

Today, polymer nanocomposites (NCs) have become important as suitable candidates for nano absorbents due to their simplicity and cheapness. This research investigated a nano absorbent based on starch nanocomposite containing hydroxyapatite (HA) and eggshell inspired by nature to absorb methylene blue (MB) as a toxic cationic dye from aqueous solution. The effect of temperature, pH, and the ratio of hydroxyapatite and eggshell absorbent on the amount of absorption after immersion in an aqueous medium was measured. The samples were identified by the UV-Vis spectrophotometer, scanning electron microscope (SEM), X-ray energy dispersive spectrometry (EDS), Fourier transform infrared (FTIR), X-ray diffraction (XRD), and BET analysis. Based on the results, the biological nanocomposite of starch-containing 0.125 g hydroxyapatite and eggshell, inspired by nature, has the highest absorption (88%) of methylene blue dye from the aqueous solution quickly. Increasing temperature, increasing pH, and decreasing the amount of nano absorbent increased the absorption of methylene blue dye from the aqueous solution. The results show that starch nanocomposite containing hydroxyapatite and eggshell can absorb methylene blue dye and have good potential for various applications, especially in medical and industrial fields.

Analytical study on lead elimination by anionic clays: Characterization, adsorption kinetics, isotherm, thermodynamic, mechanism and adsorption

2023-09-24T08:28:02+00:00

The co-precipitation method synthesized the synthetic anionicMg–Al and Ni-Al clays with three molar ratios (Mg/Al, Ni/Al). The samples were characterized by powder XRD, Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). No other crystalline phases were detected in the powder XRD patterns of the co-precipitated samples. The infrared spectra obtained all the functional groups that characterize these two types of anionic clays. SEM micrographs indicate the presence of particles and aggregates. The particles, or aggregates, are in the form of plates, supported by particles of acceptable sizes. The optimal pH for maximum lead adsorption is about 6.5 for both clays. The optimal adsorbent masses for the maximum percentages of lead removal are 0.2 g for Mg₃AlCO₃ and 0.25 g for Ni₃AlCO₃. The Mg₃AlCO₃ has a maximum adsorption capacity of lead, where q_m=73.42 mg g^-1. The adsorbed amount increases with increasing temperature for both types of clays studied. The equilibrium time of Pb²⁺ adsorption is reached after 5 min for both clays. The most appropriate models to describe the experimental data of adsorption kinetics and isotherms are pseudo-second-order and Langmuir. The detection limit (LOD) was 0.272 mg L^-1. The linearity range was 1 to 5 mg L^-1(R² 0.9997).

Chemical analysis of Eucalyptus and Rosemary essential oils using gas chromatography-mass spectrometry (GC-MS) and evaluation of their toxicity against the most common urban pest

2023-09-24T08:28:57+00:00

Using plant essential oils (EOs) as a pesticide alternative has gained increasing interest as a promising strategy to reduce the harmful effects of chemical pesticides. This study aims to investigate the chemical composition of Eucalyptus globulus Labill and Rosmarinus officinalis L. essential oils and evaluate their impacts against Blattella germanica L. under laboratory conditions. The essential oils were prepared from dried leaves using hydro-distillation (HD) as a chemical extraction method. The gas chromatography-mass spectrometry (GC-MS) was employed to analyze and identify their chemical compounds. Bioassays were conducted using the standard contact method recommended by the World Health Organization, and the data were analyzed using the probit regression model. By GC-MS analysis, the major components included 1,8-cineole (50.67%), alpha-pinene (17.48%), limonene (4.26%) for eucalyptus and alpha-pinene (20.67%), camphor (10.69%), 1,8-cineole (9.38%), Borneol (9.02%), comphene (7.15%), and limonene (4.88%) for rosemary. The LD₅₀ values were 9. 27, 10.54, and 3.23 %, and LD₉₅ values increased to 27.2, 22.3 %, and 14.3% for rosemary, eucalyptus, and their mixture. The EOs mixture had a higher repellent effect with a repellency rate of 98.9% at a concentration of 3% compared to 93.3% and 90% at a concentration of 5% for rosemary and eucalyptus alone.

Comparative analysis of groundnut oil quality in the north-central zone of Nigeria: Determination and evaluation of heavy metals, fatty acids, Phospholipids, and iodine values in groundnut oil

2023-09-24T09:38:03+00:00

The research presents a comparative analysis of the quality of locally produced groundnut oil (Arachis hypogaea) sold in the north-central zone of Nigeria markets (Benue, Nasarawa, Kogi, Kwara, Niger, Plateau States). The aim was to assess and compare the qualities of the oils and to know the safety of human consumption. The groundnut oil produced biodiesel, shampoo lubricants, and soap-making industries. The concentrations of the heavy metals were analyzed with atomic absorption spectrometry (AAS). It showed that the lead, zinc, and copper (Pb, Zn, Cu) were within the FAO/WHO recommended limit, while Cd (0.201-0.331 mg kg^-1) was above the limit (0.07 mg kg^-1). Also, the gas chromatography (GC-FID) results indicated that twelve fatty acids (linoleic > oleic > palmitic > stearic >lignoceric > arachidic acid > behenic > erucic> arachidonic > margaric > linolenic > palmitoleic) were obtained in the groundnut oils in all markets and fatty acids include caprylic acid, capric acid, lauric acid, and myristic acid were absent in oils. In addition, the magnitude of six Phospholipids (phosphatidylcholine > phosphatidylethanolamine> phosphatidylinositol > phosphatidylserine > phosphatidic acid > lysophosphatidylcholine) were also achieved, respectively. The iodine were below the FAO/WHO and the acid value was higher than the normal range.