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Magnetic Fe3O4 nanoparticles (NPs) were successfully synthesized via co-precipitation method using ferric chloride and ferrous sulphate as the starting materials. The shape and the size of Fe3O4 NPs were controlled by using different types of additive including ammonium hydroxide and sodium hydroxide. The results revealed that by adding ammonium hydroxide, the particles attained a spherical shape with a uniform size. On the other hand, the shape of the particles turned from spherical to cubic using sodium hydroxide. The magnetic results showed that both samples attained hysteresis loop, which indicated that both samples have ferromagnetic behavior. In addition, Fe3O4 NPs with cubic shape showed higher adsorptive behaviour towards Congo red compared to spherical Fe3O4 NPs, which is attributed to the enhancement of their magnetic properties. The adsorption of Congo red onto cubic Fe3O4 NPs was best described by Langmuir isotherm model, while spherical Fe3O4 NPs followed Freundlich isotherm model.

In this work, new magnetic bentonite-based adsorbents combined with different carbon sources, namely, reduced graphene oxide and multiwall carbon nanotubes, were synthesized via co-precipitation method. The synthesized adsorbents were characterized using XRD, TGA, SEM, EDX, TEM, and BET analysis techniques. The adsorbents were then used to remove oil from aqueous solutions of water-in-oil emulsion by performing batch adsorption experiments. The experimental data were fitted to three isotherm models including Langmuir, Freundlich, and Sips models using non-linear regression and were compared using Akaike Information Criterion statistical model. The data analysis showed that Sips model best fits the experimental data for the adsorption of oil onto both adsorbents. The maximum adsorption capacity of oil from sips model were 81.65 mg/g and 77.12 mg/g for Fe3O4/Bent/rGO and Fe3O4//Bent/MWCNTs, respectively. The obtained kinetics data were fitted to pseudo-first-order, pseudo-second-order, and intraparticle diffusion models. Pseudo-second order kinetic model best fitted the kinetic data of both adsorbents. Overall, both adsorbents showed high removal efficiency reaching equilibrium in less than 50 min indicating that both adsorbents can be successfully utilized in industrial adsorption process. Graphical abstractOther Information Published in: Water, Air, & Soil Pollution License: https://creativecommons.org/licenses/by/4.0See article on publisher's website: http://dx.doi.org/10.1007/s11270-022-05641-6

To control Fe3O4 nanoparticles (Fe3O4 NPs) size, different molar ratio of Fe2+ and Fe3+ as well as ammonium hydroxide (pH) was used to synthesize Fe3O4 NPs through co-precipitation method. The Box–Behnken design was selected to explore the interaction between process parameters (factors) such as Fe2+ molar ion, Fe3+ molar ion and pH on the final size. The interactive effect between the process variables was evaluated by analysis of variance (ANOVA). The quadratic model predicted by the Box–Behnken design was significant with a P value of 2+ ion with 3.00 mol Fe3+ ion with pH at 12.00. From the experiment, the particle size was 10 ± 2 nm at optimum conditions, while the model predicted a particle size of 6.80 nm. The magnetic properties of Fe3O4 NPs were displayed typical ferromagnetic behavior with saturation magnetization value to be 49.729 emu/g. Finally, the optimized Fe3O4 NPs showed about 80% removal of Congo red (CR) dye, which confirms their applicability in adsorption process for future applications.

Despite its importance in chemical industry, 4-Nitrophenol (4-NP) is a persistent organic pollutant that has serious effects on the ecosystem. In the present study, Box–Behnken design in response surface methodology was used to optimize the adsorption process parameters for the maximum 4-NP removal at 30 ℃ using Fe3O4/Bt NC. The regression model results suggested that the optimum adsorbent dosage, initial concentration, pH and contact time were 0.3182 g, 85 mg/L, 11 and 137.2 min, respectively. The regression model showed an optimum removal of 100%, while 99.5% removal was obtained from batch experiments at the optimum conditions suggested by the regression model, which confirm the model validity. The adsorption data best fitted to Freundlich isotherm model and Pseudo second-order kinetic model suggesting the existence of physical and chemical interaction between the fabricated composite and 4-NP. FTIR analysis suggested that the adsorption mechanism included an electrostatic attraction and the formation of new chemical bonds. Obtained results suggest that Fe3O4/Bt NC can be an effective adsorbent for complete 4-NP removal at the indicated optimum conditions. Graphical AbstractOther Information Published in: International Journal of Environmental Research License: https://creativecommons.org/licenses/by/4.0See article on publisher's website: http://dx.doi.org/10.1007/s41742-022-00402-z

Membrane technologies are used intensively for desalination and wastewater treatment. Water filtration using ceramic membranes exhibited high performance compared with polymeric membranes due to various properties such as high resistance to fouling, permeability, rejection rate, and chemical stability. Recently, the performance of nanocomposite ceramic membranes was improved due to the development in nanotechnology. This article focusses on the development of porous ceramic membranes and nanomaterial functionalized ceramic membranes for water filtration applications. At the beginning, various fabrication methods of ceramic membranes were described, and the effect of surface modification techniques on the membrane intrinsic properties was reviewed. Then, the performance of nanoparticles functionalized ceramic membranes was evaluated in terms of physicochemical properties, rejection rate, and water permeability. This work can help new entrants and established researchers to become familiar with the current challenges and developments of nanoparticle-incorporated ceramic membranes for water filtration applications.

The use of conventional heating techniques in adsorbents preparation involves long synthesis time, high energy consumption, high cost and material fast firing. Recently, Microwave heating technique has been used to replace or complement the conventional heating in adsorbents preparation as it provides rapid, selective, and uniform heating. Consequently, the adsorbent microscopic structure and adsorption performance are affected significantly. The current review critically investigates the effect of using microwave heating technique on Carbon based, minerals and polymeric adsorbents’ morphology, surface chemistry, and pore structure. In addition, the adsorption performance of water pollutants using microwave synthesized adsorbents, adsorption kinetics and isotherms were included. A competitive comparison in terms of adsorbent morphology, pore structure and adsorptive behavior between adsorbent prepared by microwave and convention heating technique were discussed. Finally, challenging, and promising routes are suggested for future development of microwave prepared adsorbents for water pollutants removal. On the basis of this review, using microwave technology in adsorbents preparation is promising, however, further development and investigation are substantially still required.

The effect of temperature, time and rotation speed of FT-GTL process water on the corrosion rate of API X-120 carbon steel was investigated. Electrochemical impedance spectroscopy and potentiodynamic polarization techniques were used to determine the carbon steel corrosion rate under temperatures ranging from 293 to 323 K and rotation speed of 0, 500, 1000, 2000 rpm when the immersion time was 0.5, 1, and 2 h. The corrosion rate increased with temperature and rotation speed but decreased with immersion time. SEM, XRD, and XPS analyses of the corroded surfaces confirmed the formation of iron oxide and ferric oxide as the main components of the protective layer.