Mohamed Sheikh

Herein, Fe₃O₄ core-TiO₂/mesoSiO₂ and Fe₃O₄ core-mesoSiO₂/TiO₂ double shell nanoparticles were prepared by first (R1) and second (R2) routes and applied for the removal of methylene blue. The reported adsorption capacities for R1-0.2, R1-0.4 and R2 samples were 128, 118 and 133 mg.g⁻¹, respectively, which were obtained after 80 min as equilibrium contact time, and pH of 6 using a methylene blue concentration of 200 ppm. The adsorption of methylene blue using the prepared Fe₃O₄ core-meso SiO₂/TiO₂ double shell was analyzed by kinetic and isotherms models. In addition, thermodynamic investigations were applied to assess the spontaneous nature of the process. The obtained results confirmed that the pseudo-second order model is well fitted with the adsorption data and the Freundlich-isotherm assumption suggested a multilayer adsorption mechanism. In addition, results of the thermodynamic investigation indicated that ΔG° was in the range of −2.3 to −6.8 kJ/mol for R1-0.2, −2.8 to −6.3 kJ/mol for R1-0.4 and −2.0 to −5.2 kJ/mol for R2. In addition, the ΔH° and ΔS° values were found in the range of 26.4 to 36.19 kJ.mol⁻¹ and 94.9 to 126.3 Jmol⁻¹ K⁻¹, respectively. These results confirm that the surfaces of Fe₃O₄ core-mesoSiO₂/TiO₂ and Fe₃O₄ core-TiO₂/mesoSiO₂ double shell exhibit a spontaneous tendency to adsorb methylene blue from the aqueous solutions. The achieved performance of Fe₃O₄ core-meso SiO₂/TiO₂ and Fe₃O₄ core-TiO₂/meso SiO₂ double shell as adsorbent for methylene blue removal will encourage future research investigations on the removal of a broad range of contaminants from wastewater.

Spiny-like spherical copper metal–organic frameworks (SSC-MOFs) were prepared and characterized via SEM, TEM, EDS, XRD, FTIR and the BET surface area. The fabricated SSC-MOFs were applied to develop a procedure for the microextraction of trace arsenic(III) for preconcentration. The results show that a copper- and imidazole-derived metal–organic framework was formed in a sphere with a spiny surface and a surface area of 120.7 m²/g. The TEM confirmed the perforated network structures of the SSC-MOFs, which were prepared at room temperature. The surface functional groups were found to contain NH and C=N groups. The XRD analysis confirmed the crystalline structure of the prepared SSC-MOFs. The application for the process of microextracting the arsenic(III) for preconcentration was achieved with superior efficiency. The optimum conditions for the recovery of the arsenic(III) were a pH of 7 and the use of a sample volume up to 40 mL. The developed SSC-MOF-derived microextraction process has an LOD of 0.554 µg·L⁻¹ and an LOQ of 1.66 µg·L⁻¹⁰. The developed SSC-MOF-derived microextraction process was applied for the accurate preconcentration of arsenic(III) from real samples, including food and water, with the promised performance efficiency.

Water pollution with dyes is a critical environmental issue because off the huge amount of dyes disbarred annually which cause severe damage for the ecosystem and human life. On the other hand, the core-shell based magnetic materials have showed amazing character for controlling the material synthesis with targeted structure to enhance the adsorptive-removal of pollutants. Herein, Fe3O4 core-TiO2/mesoSiO2 and Fe3O4 core-mesoSiO2/TiO2 double shell nanoparticles were prepared by first (R1) and second (R2) routes. The preparation procedure is controlled to prepare the magnetic core with further coating layers from silica and titania for the uptake of methylene blue from aqueous solutions. The reported adsorption capacities for R1-0.2, R1-0.4 and R2 samples were 46, 38 and 50 mg/g respectively at pH 6 after 80 min contact time form 50 ppm methylene blue solution. The adsorption process of methylene blue onto Fe3O4core-meso SiO2/TiO2 double shell was well fitted with the pseudo-second-order kinetic model and Freundlish isotherm which suggested the quick and multilayer adsorption mechanism. In addition, results of thermodynamic investigation indicated that the surfaces of Fe3O4 core-mesoSiO2/TiO2 and Fe3O4 core-TiO2/mesoSiO2 double shell exhibit spontaneous tendency to adsorb methylene blue from the aqueous solutions. These results will encourage the further application of Fe3O4 core-meso SiO2/TiO2 and Fe3O4 core-TiO2/meso SiO2 double shell for removal of other dyes and pollutants from wastewater.

Thermal treatment is applied for the direct conversion of palm stalk waste to Fe₃O₄ (np)@carbon sheets (Fe₃O₄ (np)@CSs). The effect of conversion temperature was investigated. The TEM examination of the prepared magnetic Fe₃O₄ (np)@CSs showed the formation of Fe₃O₄ (np) in a matrix of carbon sheets as a coated layer with surface functional groups including carbonyl and hydroxyl groups. Removal of dyes such as methyl orange, methylene blue, and neutral red was achieved using fabricated Fe₃O₄ (np)@CSs which were prepared at 250 °C, 400 °C, and 700 °C in a weak acidic medium. By studying the contact time effect for the adsorption of methylene blue, neutral red, and methyl orange, using the fabricated Fe₃O₄ (np)@CSs which were prepared at 250 °C and 400 °C, equilibrium occurred between 120 min and 180 min. In addition, the first-order and second-order kinetic models were applied to the adsorption data. The results revealed that the adsorption data fit better with the second-order kinetic model. Furthermore, the Freundlich model was found to be more suitable for describing the process of the separation of the dyes onto Fe₃O₄ (np)@CSs which were prepared at 250 °C and 400 °C, suggesting heterogenous surfaces and multi-layer adsorption.

Developing and improving adsorbent materials for wastewater treatment have become crucial for achieving recyclable water and keeping the environment safe. Carbon materials are modified with alumina (Al₂O₃) using various doping ratios and a solvothermal treatment. The process aims to combine the advantages of stable carbon and alumina materials with an efficient adsorbent for methylene blue removal. Fabricated materials including carbon and carbon/alumina derivatives were characterized with TEM, SEM, EDS, XRD, and FTIR, revealing successful surface modifications. The carbon materials exhibited pore diameters between 23 and 39 µm, while the modified ones showed pore diameters between 1.68 and 6.08 µm. The alumina nanoparticles were formed on a carbon surface with a particle size between 174 nm and 179 nm. Fabricated adsorbents were applied for the removal of methylene blue by adsorption at pH 4. The equilibrium and steady state adsorption stage was achieved after 2 h of reporting fast adsorption behavior. Low ratio carbon doping with alumina improved the adsorption capacity for methylene blue removal, while the excessive doping of carbon materials with alumina led to a reduction in adsorption efficiency. The application of pseudo-first-order and pseudo-second-order kinetic models indicated a fast adsorption mechanism, which agreed with the second-order model. The adsorption capacity for methylene blue was found to be 234 mg/g. Adsorption-isotherms including the Langmuir and Freundlich models were applied to investigate the adsorption mechanism. The results indicate that the Langmuir model fits with the adsorption data, which suggests a monolayer adsorption process.

In this work, metal organic frameworks (A100 Al-based MOFs) were used in dispersive solid-phase microextraction (DSPME) for the isolation and preconcentration of the carbaryl from vegetable, fruit and water samples. The A100 Al-based MOFs showed excellent behavior for the adsorption of carbaryl from a water–ethanol solution; additionally, carbaryl was easily desorbed with ethyl acetate for detection by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-TMS). The analytical process of DSPME together with UPLC-TMS provides the accurate monitoring of trace carbaryl residues. The results show that the optimal recovery% of carbaryl was obtained at a sample apparent pH of 5, with the application of 1 mL of ethyl acetate to elute the carbaryl from the A100 Al-based MOFs. The limit of detection (LOD) and the limit of quantification (LOQ) were 0.01 mg.L⁻¹ and 0.03 mg.L⁻¹, respectively. The RSD% was 0.8–1.9, and the preconcentration factor was 45. DSPME and UPLC-TMS were successfully used for the isolation and detection of carbaryl in food and water samples.

A biomass-derived adsorbent was simply prepared and applied as efficient and low-cost solid-phase supports. The adsorbent material was characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), surface area analysis and Fourier transform infrared (FTIR) spectroscopy. The amorphous structure of the prepared adsorbent was indicated from the XRD. The prepared adsorbent exhibited surface functional groups such as carbonyl and hydroxyl groups, which enhance the application of DSPE. An accurate separation and preconcentration of Cr(III), Fe(III), Co(II) and Ni(II) prior to ICP-MS detection was achieved using the biomass-derived adsorbent. The extraction process was performed at pH 4 using 1 mL of 0.5 N nitric acid for elution and recovery of ions. The prepared biomass-derived adsorbent showed efficient performance for extraction application, exhibiting a preconcentration factor of 50 and LODs of 1.4, 2.4, 1.9 and 3.0 µg.L⁻¹ for Cr(III), Fe(III), Co(II) and Ni(II), respectively, while the LOQs were reported as 4.1, 7.3, 5.7 and 8.9 µg.L⁻¹ for Cr(III), Fe(III), Co(II) and Ni(II), respectively. The DSPE procedure presented was successfully applied to the determination of the Cr(III), Fe(III), Co(II) and Ni(II) contamination in some food samples.