To improve dye retention, there is a concurrent interest in the development and optimization of an alternative and promising method for the dye recovery in aqueous solutions. In this regard, considerable attention was paid to the polyoxometalates (POMs) assisted ultrafi ltration (POMAUF). The aim of the present study is to eliminate toluidine blue (TB) dye by ultrafi ltration membrane using keggin polyoxometalates (POMs) as complexing agents. In the fi rst step, the keggin polyoxometalates K₃[PW₁₂O₄₀]∙6H₂O(PW₁₂) and K₇[PW) were prepared. Then, the obtained powders were characterized by X-ray diffraction and infrared spectroscopies. Afterwards, the removal of toluidine blue (TB) using polyoxometalates assisted ultrafi ltration (POMAUF) was studied. Factors affecting the retention of dye and permeate fl ux such as transmembrane pressure, operating time, polyoxometalates concentration, ionic strength, surfactant and pH were investigated. All results of both compounds have been presented and discussed. The results reveal that the addition of POMs leads to an increase in dye retention from 11 to 95% for the PW 12 and to 98% for the PW . The results of this work have thus suggested the promising enhancement of ultrafi ltration membrane selectivity for the dye removal using new complexing agents such as POMs in place of polyelectrolytes and surfactants.

Surface wastewater pollution due to accidental runoff or release of oil or its products is a longstanding and common environmental problem. The aim of the study was to investigate the impact of concentrations of oil products (diesel) and suspended solids, the sorbent type, the water flow rate and the interfering factors (chlorides) on the dynamic sorption of diesel and to test regeneration of polypropylene after its use for sorption. The sorbents used for study included common wheat straw (Triticum aestivum), polypropylene and sorbents modified with hydrogen peroxide solution. Standard methods were used for the determination of the investigated parameters and an in-house procedure employing a gas chromatograph was used for the determination of diesel concentration. The following factors that impact the sorption of diesel were investigated during the study: diesel concentration, concentration of suspended solids; type of sorbent (common wheat straw (Triticum aestivum), wheat straw modified with hydrogen peroxide, and polypropylene), water flow rate; and influence of the interfering factors (chlorides). Filtration speed in the range of investigated speeds does not affect the efficiency of diesel removal. Removal efficiency does not depend on the concentration of diesel before the sorbent reaches its maximum sorption capacity. Filling containing 50% of polypropylene and 50% of wheat straw was used for the study. It was found that polypropylene and wheat straw do not remove chlorides and suspended solids from solution. The study found that the solution of hydrogen peroxide boosts the hydrophobic properties of common wheat straw, but does not affect the sorption of diesel. The recommended number of regenerations of polypropylene should be limited to two.

This study describes the creation of a low-cost silica material using a silicate extract as a precursor. This precursor is made from inexpensive palm frond waste ash through a simple calcination process at 500°C and a green extraction with water. Nitrogen adsorption-desorption, FTIR analyses, and transmission electron microscopy were used to characterize the samples. The surface area of the obtained mesoporous silica ash material was 282 m2/g1, and the pore size was 5.7 nm. For the adsorption of copper ions, an excellent adsorbent was obtained. The maximum copper ion adsorption capacity of this inexpensive silica ash-based adsorbent for removing heavy metal ions Cu(II) from aqueous solutions was 20 mg/g, and the effect of pH, temperature, and time on its adsorption capacity were also investigated. In addition, the adsorption isotherms were fi tted using Langmuir and Freundlich models, and the adsorption kinetics were evaluated using pseudo-fi rst-order and pseudo-secondorder models. The results demonstrated that the synthesized adsorbent could effectively remove heavy metal ions from aqueous solutions at pH levels ranging from 2 to 5. The adsorption isotherms followed the Langmuir model, and the kinetic data fi t the pseudo-second-order mode well. The thermodynamic results Negative values of G° indicate that the adsorption process was spontaneous, and negative values of entropy S° indicate that the state of the adsorbate at the solid/solution interface became less random during the adsorption process. According to the findings, prepared silica from palm waste ash has a high potential for removing heavy contaminating metal ions Cu (II) from aqueous solutions as a low-cost alternative to commercial adsorbents.