Raw date seeds, as prospective natural, broadly obtainable and low-price agricultural waste for adsorbing cationic dyes from aqueous solutions, have been studied. In this work, Iraqi date seeds were prepared and characterised using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and Brunauer–Emmett–Teller (BET) surface area analysis before being used as an efficient bio-adsorbent for methyl violet (MV) dye removal. Adsorption tests were conducted with three investigated parameters, namely, time of contact, first adsorbate concentration and adsorbent dose. Compared with the pseudo first-order model (coefficient of determination = 0.9001), the pseudo second-order model was determined to be the best-fitting model with a coefficient of determination (R²) of 0.9917. The equilibrium isotherms for MV were obtained, and their ultimate capacity of adsorption was (59.5 mg g¹). Two isotherm models, Langmuir and Freundlich, were studied to fit the equilibrium data. Compared with the Freundlich isotherm model (R² = 0.8154), the Langmuir model functioned better as an adsorption isotherm with R² of 0.9837. In addition, the adsorption process was endothermic and spontaneous. The date seeds acted as active adsorbents to remove MV from the aqueous solutions in the model experiments.

The performance of a solar photocatalysis reactor as pretreatment for the removal of total organic carbon (TOC) and turbidity from municipal wastewater was achieved by implementing an integrated system as tertiary treatment. The process consisted of ultraviolet (UV) sunlight, UV sunlight/H₂O₂, and UV sunlight/TiO₂ nanocatalysts as pretreatment steps to prevent ultrafiltration (UF) membrane fouling. The characterization of TiO₂ was conducted with X-ray diffraction spectroscopy, Fourier-transform infrared spectroscopy, scanning electron microscopy , and Brunauer–Emmett–Teller surface area analysis. This study investigated the effect of time and solar radiation using UV, UV/H₂O₂, and UV/TiO₂ to remove TOC and turbidity. The transmembrane pressure improvement was studied using a UF membrane system to pretreat wastewater with different UV doses of sunlight for 5 h and UV/H₂O₂ and UV/TiO₂. The results showed that the highest removal efficiency of the turbidity and TOC reached 95% and 31%, respectively. The highest removal efficiency of the turbidity reached 40, 75, and 95% using UV, UV/H₂O₂, and UV/TiO₂, respectively, while the optimal removal efficiency of TOC reached 20%, 30%, and 50%, respectively.

In this study, a Methyl Green (MG) dye pollutant was separated by Mobil Composition Matter No. 41 (MCM-41) in a fixed-bed continuous column with investigated three parameters, namely a bed height (2-6 cm), initial MG concentration (10-30 mgL^-1) and a process flow rate (0.8-1.6 mL min^-1). Results indicated that the highest bed capacity of 20.97 mg/g was obtained with respective to optimal values such as; 6 cm for a column height, 0.8 mL min^-1 for flow rate, and an initial MG concentration 20 mgL^-1. Furthermore, a quantity of the adsorbed pollutant decreased as the flow rate increased, while increasing the initial MG concentration yielded the opposite effect. The column apparatus was performed properly at the low flow rate, whereas both the breakthrough and exhaustion time increased with the bed depth. Thomas and Yoon-Nelson models were applied for predicting the breakthrough curves and calculating the characteristic factors of the laboratory fixed-bed adsorption column, which were beneficial for process design. Based on regression coefficient analyses, results of employing the Yoon-Nelson model was found to be superior to the Thomas one. Breakthrough performance indicated that MCM-41 was suitable for applications in continuous adsorption regimes for MG dye. The mesoporous MCM-41 was recovered effectively by calcinations and employed again for four times in the continuous system successfully.