The purpose of this work was to develop, characterize and test new low-cost materials suitable for removing methylene blue dye from water and wastewater by adsorption. The solid materials consisted of silica gel powder (SG), silica gel mixed with eggshell powder (SG-ES) and a mixture of silica gel with sand from the western Iraqi desert (SG-SI). The samples were milled by using an electrical mixer and a ball mill, followed by a drying step. In addition, desert sand was acid-treated in order to remove impurities. The structure and chemical composition of the samples were investigated by X-ray diffraction (XRD), a scanning electron microscopy technique equipped with an energy-dispersive X-ray spectrometer (SEM-EDX), a low-temperature nitrogen adsorption (BET) technique, thermo-analytical (TG/TGA) measurements and Fourier-transformed infrared spectroscopy (FTIR). The previously mentioned materials were tested to remove methylene blue from an aqueous solution. The adsorption experiments were monitored by ultraviolet–visible (UV-Vis) spectrophotometry and showed that SG and SG-ES gave promising results for the methylene blue removal from water. After 40 min of treatment of the aqueous solution containing 10 mg/L of MB at room temperature, the tested SG, SG-ES and SG-SI materials were found to have 86%, 80% and 57% dye adsorption efficiency, respectively. Taking into consideration not only the adsorption activity of the studied material but their availability, cost and concepts of cleaner production and waste minimization, the developed silica gel with eggshell can be considered as a good, cost-effective alternative to commercially available activated-carbon-based adsorbents. Different kinetic and isotherm models were fitted to the experimental results. A pseudo-second-kinetics-order model revealed high correlation fitting, while the Freundlich model was found to appropriately describe the adsorption isotherm. The thermal stability during the possible regeneration process of the SG-ES adsorbent mixture and its interaction mechanism with cationic dye was discussed.

This paper deals with V2O5 nanoparticles adsorbents which were obtained by thermal pretreatment carried out by increasing the temperature between 90 and 750°C. In order to obtain more detailed information on the surface chemistry of the newly prepared nanoparticles, the characterisation was done by X-ray diffraction and scanning electron microscopy, Fourier Transform infrared spectroscopy and thermogravimetric investigation technique. The prepared nanoparticles were tested for methylene blue (MB) removal from modelled water solutions. The obtained results indicated that increased MB removal efficiency (93%) and adsorption capacity (27 mg/g) after 40 minutes of adsorption were obtained for V2O5 annealed at 500°C. The applicability and suitability of the two kinetic models were tested and the removal mechanism was proposed.

The influence of introducing benzothiazole and benzimidazole as a pending groups into the repeating unit of PVC has been studied on the bases of photostability measurements. The photostability of modified polymers were studied by monitoring the carbonyl Index (ICO), polyene index (Ipo) and hydroxyl index (IOH), all results obtained indicated that PAA, PSS, PNN, PSA and PNA gave lower growth rate of ICO, IPO and IOH with irradiation time with respect to unmodified PVC film (control). The following trends of photostability are obtained PAA>PSS>PNN>PSA>PNA According to the experimental results several reaction mechanisms were proposed depending on the presence of benzothiazole and benzimidazole moieties in the polymer chain. The mode of chain scission was also investigated by measuring the variation of average viscosity molecular weight with irradiation time for modified PVC. The degree of deterioration (?) and the average number of chain scission (S) values were also calculated.

In this research, manganese oxides (MnO₂) nanoparticles were prepared by hydrothermal method using KMnO₄ as a precursor. The final brown–black precipitate MnO₂ nanoparticles as prepared, and annealed at different temperatures (250, 450, and 750 °C) were characterized. The nanoparticles prepared were tested for removal of methylene blue (MB), used as a model dye from water. In order to determine the structure and the chemical nature of the MnO₂ nanoparticles prepared, the characterization was carried out by X-ray diffraction. For the surface morphological studies of nanoparticles, field emission scanning electron microscopy was used. In order to study the surface roughness atomic force microscopy was used for determination of the imaging surface structures in the nm scale. Fourier transform infrared spectrometry was used to investigate the vibrations of functional groups in MnO₂. The tests for dye removal from water using MnO₂ nanoparticles have been carried out for MnO₂ nanoparticles as prepared and annealed at different temperatures. The process parameters such as speed of shaking, reaction time, and MB concentration were studied at 25 °C temperature to determine the best removal efficiency of methylene blue from water. UV/Visible spectrophotometer was used to follow the MB removal. MnO₂ annealed at 750 °C exhibited the highest MB removal efficiency, 89%, as compared with MnO₂ nanoparticles as prepared and annealed at 250 and 450 °C.

In this research, multi-walled carbon nanotubes (MWCNTs) were functionalized by oxidation with strong acids HNO₃, H₂SO₄, and H₂O₂. Then, magnetite/MWCNTs nanocomposites were prepared and polystyrene was added to prepare polystyrene/MWCNTs/magnetite (PS:MWCNTs:Fe) nanocomposites. The magnetic property of the prepared nano-adsorbent PS:MWCNTs:Fe was successfully checked. For characterization, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and BET surface area were used to determine the structure, morphology, chemical nature, functional groups, and surface area with pore volume of the prepared nano-adsorbents. The adsorption procedures were carried out for fresh MWCNTs, oxidized MWCNTs, MWCNTs-Fe, and PS:MWCNTs:Fe nanocomposites in batch experiments. Toluene standard was used to develop the calibration curve. The results of toluene adsorption experiments exhibited that the PS:MWCNTs:Fe nonabsorbent achieved the highest removal efficiency and adsorption capacity of toluene removal. The optimum parameters for toluene removal from water were found to be 60 min, 2 mg nano-sorbent dose, pH of 5, solution temperature of 35 °C at 50 mL volume, toluene concentration of 50 mg/L, and shaking speed of 240 rpm. The adsorption kinetic study of toluene followed the pseudo-second-order kinetics, with the best correlation (R²) value of 0.998, while the equilibrium adsorption study showed that the Langmuir isotherm was obeyed, which suggested that the adsorption is a monolayer and homogenous.