Analytical Methods in Environmental Chemistry Journal

Adsorption of methylene blue into modified mesoporous silica from palm oil boiler ash

Shinta Ayu Kusumaningtyas — 2024-06-29

The adsorption of methylene blue dye on modified mesoporous silica based on palm oil boiler ash (MS-POBA) as an adsorbent with a methyl ester sulfonate (MES) was investigated. MS-POBA and MES as a template improved the adsorption capacity of methylene blue by increasing the pore size of boiler ash silica. The characteristics of the material were determined using FTIR, XRD, BET, and SEM-EDX analyzers. The adsorption of methylene blue on the MS-POBA adsorbent was determined using a UV-Vis spectrophotometer. The MES as a template pasted to MS-POBA, could be increased surface area, pore diameter, and volume. In optimized conditions, pH, the adsorbent mass, the adsorption time, the methylene blue concentration, the adsorption capacity, and recovery were obtained at 7.0, 0.03 g, 45 minutes, 20 mg L^–1, 15.578 mg g^–1, and 96.9%, respectively. The adsorption of methylene blue on boiler ash silica with an MES template follows the pseudo-second-order kinetic model with a value of R² = 0.999 and Langmuir isotherm adsorption model.

Direct analysis of hexavalent chromium in water samples by UV-Vis spectrophotometry: Effects of pH and the presence of foreign ions

Rayane Nadjet Fassi — 2024-06-30

The present study aims to characterize the direct UV-Vis spectrophotometric analysis of hexavalent chromium (CrVI) in aqueous solution. The effects of pH and the presence of different ions are evaluated. The results obtained show that at pH ≤ 6, Cr(VI) analysis must be carried out at 350 nm. The Beer-Lambert law is respected for a concentration lower than 100mg Cr(VI) L^-1. At pH ≥ 8, the analysis must be performed at 372 nm. In this case, the linearity range of the standard curve does not exceed the concentration of 25 mg Cr(VI) L^-1. In the pH range 6 <pH < 8, the direct Cr(VI) analysis cannot be performed. Whatever the pH of the solutions, the presence of acetate, oxalate, citrate, and tartrate with a concentration ten times higher than that of Cr(VI), has no effect. At pH 2, only the presence of Fe(II) and Fe(III) ions prevents the direct determination of Cr(VI) ions. In the presence of metallic ions [Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II)), Cr(VI)] analysis must be carried out at pH 2. At higher pH, these ions have a significant effect.

Analysis and preparation of phenolic and alkaloid compounds from Moroccan Berberis vulgaris organic extract: Molecular docking and optimization by UHPLC/DAD/ESI-MS

Zefzoufi Manal — 2024-06-29

Among the natural products, phenolic and alkaloid compounds have the most important constituents and common plant-derived secondary metabolites, and thus, analysis deserves particular attention for their therapeutic proprieties. In this study, the phenolic and alkaloid compounds were analyzed using ultra-high-performance liquid chromatography coupled with diode array detector-tandem electrospray ionization mass spectrometry (UHPLC/DAD/ESI-MS) for three extracts of Moroccan Berberis vulgaris L. Then we optimized and validated results for four phenolic compounds. To evaluate the biological activity of this species we chose the antimicrobial activity. For the antimicrobial activity of these extracts, we used molecular docking analysis of the compounds identified with DNA gyrase. The method validation results showed a good linear (R2>0.99) with the coefficient correlation and the significance of regression tests confirmed a linear relationship between x and y. Two concentrations of phenolic and alkaloid compounds (31.25 mg L^-1 and 500 mg L^-1) were determined by the UHPLC/DAD/ESI-MS and used in repeatability tests, the relative standard deviation of 10 repetitions varied to 0.35-2.33 with CV% 1.1-2%. In addition, the analytical method is sensitive, accurate, and precise (CV<5%). The analytical method successfully set for robust quality evaluation and standardization of phenolic and alkaloid compounds from B. vulgaris organic extract.

Removal of nitrate from contaminated water of river Rushikulya using natural adsorbent

Sasmita Hota — 2024-06-29

Nitrate contamination of surface water through different human activities is an alarming issue for Human sound health survivorship. So, we have attempted to estimate and remove nitrate contamination levels in water samples, collected from the Rushikulya River in Odisha, India. A detailed study is done on the impact of nitrate contamination in various aspects and their removal is absorbed through an experimental composite adsorbent that is prepared taking rice husk dust and Bagasse waste from corn (Argo-based waste product) with different proportions of each. The nitrate absorbance was analyzed with the spectrophotometric method. The efficiency of adsorbents is identified through SEM and found that with an increase in the alkaline state of water sample up to 13 and composite proportion ratio with 20% rice husk and 80% bagasse waste from corn, removes nitrate up to 95% from contaminated water sample. A maximum of 98.0% of nitrate was removed from the water at a pH of 11. Also, maintaining the COD range of 250 mgL^-1, the nitrate could be removed up to 94%. The composite of CM-9 has the highest density of 279.88 kg m^-3. These matrices are applied for the treatment of contaminated river water samples to remove nitrate.

Synthesis-activated carbon based on various agri-food wastes for highly efficient removal of an anionic dye before analysis by UV-Vis spectrometry

Mohamed Ennabely, Corresponding Author — 2024-06-29

This study aims to valorize three agricultural-food (agri-food) wastes: Argan husks, dates seeds, and olive stones collected from various regions of Morocco to produce three types of activated carbons (ACah),(ACds) and (ACos) respectively. These activated carbons were used to compare their effectiveness in removing methyl orange, an organic pollutant in aqueous solutions. The precursor materials were carbonized at a temperature of T=900°C for 2 hours and subsequently chemically activated using phosphoric acid (H₃PO₄) in a weight ratio of 1:2. The obtained samples were characterized by Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and BET-analysis to determine the specific surface area. The analysis revealed that (ACah) displayed a rough surface with more pores and O-H chemical bonds, indicating its superior adsorption properties. This finding corresponds to the BET-specific surface areas obtained, which were 476 m²g^-1for ACah, 441 m²g^-1 for ACds, and 362 m²g^-1 for ACos. In all methyl orange adsorption experiments (10 mg L^-1), 60 mg of each activated carbon was used for 30 minutes, resulting in removal efficiencies of 93.87% for ACah, 91.83% for ACds, and 89.79% for ACos. The examination of adsorption kinetics and isotherm analysis demonstrated a strong alignment of the adsorption data by Langmuir models.

Dolomite utilization for removal of Zn2+ and Cu2+ ions from wastewater before determination by flame atomic absorption spectroscopy

Firas Fadhel Ali — 2024-06-30

This study aims to use dolomite to remove Zn²⁺ and Cu²⁺ from wastewater. The adsorption process of the Zn²⁺ and Cu²⁺ was performed using the batch method at various factors (such as the amount of adsorbent, contact time, particle size, pH media, temperature, and initial concentration) to investigate the optimum removal conditions. The flame atomic absorption spectroscopy (F-AAS) was used to determine Zn²⁺ and Cu²⁺ after removal steps. The LOD of Zn²⁺ and Cu²⁺ were 0.05 mg L^-1and 0.08 mg L^-1, respectively. Results showed that the adsorbent dolomite efficiently removed Zn²⁺ and Cu²⁺ with up to 98 % when 0.4 g of dolomite was used. The smaller dolomite particle size had higher removal efficiency for Zn²⁺ and Cu²⁺ ions. The results showed the removal of Zn²⁺ and Cu²⁺ was the maximum in the basic medium. Also, the removal of ions reached the maximum when dolomite had been in contact for 30 minutes with the wastewater. The experimental results of Langmuir and Freundlich adsorption isotherms show linearity where R² is more than (0.998 and 0.978) and (0.9915 and 0.9996) for Zn²⁺ and Cu²⁺, respectively. The q_max was obtained at 91.74 mg g^-1 for Cu²⁺and 44.24 mg g^-1 for Zn²⁺.

Hydrothermal synthesis of Zn2BO3 as photocatalyst for efficient removal and determination of Congo red dye from aqueous solution by UV-Vis spectroscopy

Hasan Jasim Mohmmed, Corresponding Author — 2024-06-29

This study synthesized zinc borate (Zn₂BO₃(OH), ZB) through one-step precipitation from nano Zinc oxide and boric acid. FTIR, XRD, SEM, EDX, and Zeta potential characterized the product. Due to the photocatalyst properties Congo Red Day (CRD) was removed from the aqueous solution. Effective factors on the adsorption efficiency are studied (time, amount of adsorbent, concentration, pH, and temperature). Results of the study indicated that the best amount of adsorbent was obtained at 0.1 g which was used against dye when adsorption capacities equal 6.034 mg g^-1. Also, the adsorption capacities [q_(mg/g)] were obtained at 35.556 mg g^-1 in the CRD concentration of 50 mg L^-1, and [q_(mg/g)] was equal to 20.154 mg g^-1 in 100 mL sample at pH 5.5. All adsorption processes using distilled water (DW) were analyzed using UV-Vis spectroscopy. The adsorption capacity was calculated by using Langmuir and Freundlich isotherm models, and results showed that the maximum adsorption capacity (q_max) in the Langmuir model was achieved at 212.7 mg g^-1 for Zn₂BO₃(OH). The R-squared (R²) or the low coefficient of determination for Langmuir and Freundlich isotherms adsorption were obtained at 0.98 and 0.89, respectively. The first-order and second-order pseudo coefficients were achieved at R²=0.89 and R²=0.99, respectively.