Experimental and modeling study on adsorption of cationic methylene blue dye onto mesoporous biochars prepared from agrowaste

<p>Oak wood, an agrowaste, was activated to prepare biochar and used as an effective biosorbent to remove methylene blue (MB) dye from aqueous solution. The properties of the adsorbent were also characterized using scanning electron microscope, Brunauer–Emmett–Teller, and Fourier Transform Infrared techniques. The adsorption process was studied in a batch system by investigating the effects of different experimental variables such as pH of solution, contact time, adsorbent dosage, initial dye concentration, temperature, and adsorbent particle size. The equilibrium time was obtained as 120 min. The adsorption process was fully described by the Liu equilibrium and pseudo-second-order kinetic models. The maximum adsorption capacity obtained was 97.55 mg/g based on the Langmuir isotherm at 50°C. The activation energy was found to be 24.2 kJ/mol, which indicated the feasibility of the adsorption process. The values of thermodynamic parameters (Δ<i>G</i>°, Δ<i>S</i>°, and Δ<i>H</i>°) showed that the adsorption of MB dye onto the biochar surfaces was spontaneous, feasible, and endothermic. The biochar was also found to enjoy a good performance for the removal of MB in real wastewater samples under optimum experimental conditions. So, it can be concluded that biochar can be utilized as a cost-effective, environmental-friendly, and promising adsorbent for the removal of dyes from colored wastewaters.</p

Additional file 1: of Silica-coated magnetite nanoparticles core-shell spheres (Fe3O4@SiO2) for natural organic matter removal

The parameters and constants of kinetics and isotherms models of HA adsorption on MNPs and SMNPs. (DOCX 72 kb

The performance of mesoporous magnetite zeolite nanocomposite in removing dimethyl phthalate from aquatic environments

<p>In this study, magnetic zeolite nanocomposite with an average diameter of 90–100 nm was synthesized through a chemical co-precipitation method, and used for the adsorption of dimethyl phthalate (DMP) from aqueous solution. The surface morphology of the adsorbent was characterized by scanning electron microscope, transmission electron microscopy, energy dispersive X-ray, vibrating sample magnetometer, dynamic light scattering, Brunauer, Emmett, Teller, and X-ray diffraction techniques. Batch system was followed to optimize the conditions for the removal of DMP. The adsorption experiments were carried out in terms of pH, contact time, various concentrations of DMP as well as nanocomposite, and temperature. The results showed that with increase in adsorbent dosage and contact time increased the adsorption efficiency. However, the efficiency decreased by increasing pH and initial DMP concentration. Experimental data were found to fit well with Langmuir isotherm (<i>R</i>² > 0.981) in all the studied temperatures. Adsorption kinetics also showed that the adsorption behavior follows the pseudo-second-order kinetic model (<i>R</i>² > 0.996). Besides, thermodynamic analysis demonstrated that the adsorption process occurs spontaneously and is inherently endothermic. The DMP adsorption efficiency did not change after 10 batch sorption–desorption reactions, indicating the potential application prospect of the synthesized adsorbent in real water treatment.</p