إزالة بعض الأيونات الفلزية بواسطة ليكاند متعدد المنح مثبت على البولي سيلوكسان

Removal of some Metal Ions by Polysiloxane Immobilized polydonor Ligand System

abstract

The world is moving towards using the best scientific methods to get rid of environmental pollution. Some metallic elements are natural and industrial pollutants like Cobalt, Copper, and Nickel. Also, Rice husks are one of the pollutants produced daily in all parts of the world. Therefore, rice husks were used to produce compounds to get rid of some polluting elements, thus eliminating two types of pollutants at the same time. Sodium silicate was prepared from rice husks, then reacted with 3-aminopropyltriethoxysilane to produce RH-SiO2PrNH2 via the sol-gel method which was characterized by using the FTIR showed that the vibration NH2 and NH absorbed at 3283 and 3113 cm-1, respectively. Then RH-SiO2PrNH2 reacted with 2-amino-3,5-dibromobenzaldehyde to produce RH-SiO2PrADB which was characterized by using several techniques (FTIR, XRD, FESEM-EDX, CHN, AFM, TEM, and TGA/DTA):
The FT-IR spectrum displays azomethine group (C=N) is represented by the peak at 1642 cm-1. The XRD spectra were showed the amorphous nature of the prepared ligand. The elemental analysis of the RH-SiO2PrADB compound indicates that the percentage of carbon and nitrogen is 16.63% and 6.4%. FESEM images show an increase in the roughness of the outer surface of the sample with an increase in the rate of accumulation of nanoparticles as a result of the bonding of the RH-SiO2PrNH2 with 2-amino-3,5-Dibromobenzaldehyde compound. Also, the images of AFM confirmed a clear increase in the roughness rate to reach 16.24nm. This indicates the successful association of the RH-SiO2PrNH2 with the 2-amino-3,5-Dibromobenzaldehyde compound. While TEM images were shown, the presence of spherical clusters linked together. It was found that the average particle size is 35 nm, and this value is consistent with the results of the FESEM and XRD analysis. The TGA analysis shows that the loss percentage reached (53.48%) due to the evaporation of the adsorbed water molecules and the dissociation of the 2-amino-3,5-Dibromobenzaldehyde compound, thus breaking the silanol bonds and the success of the synthesis process and the production of a compound with high stability. The specific area and pore diameter of the RH-SiO2PrADB were using BET analysis, and it was determined to be equal to 3.818 m2/g, and 1.21 nm, respectively.
In addition, sodium silicate was treated by adding Fe3O4 to produce magnetic nanosilicates. Following the same previous method, Fe3O4@RH-SiO2PrADB was produced and characterized by several techniques (FTIR, XRD, FESEM-EDX, CHN, AFM, TEM, VSM and TGA/DTA):
The FT-IR spectrum showed an absorption band at 636.5 and 570.9 cm-1 due to Fe-O bond in addition to bands same absorptions for compound RH-SiO2PrADB. the XRD spectrum composite showed a clear displacement in the broad peak at (2θ =22.5 o -28.8o) due to the RH-SiO2PrABD compound and sharp peaks at (2θ =29.2o, 35.4o, 39.1o, 42.4o, 47.9o, 57.0o, 62.8o, 67.0o) due to the cubic structure of Fe3O4. It was noted that the prepared composite is amorphous. The VSM showed that the prepared iron oxide (Fe3O4) has ferromagnetic behavior with a saturation magnetization up to 13.39 emu g−1. While the results of the saturation magnetization value for the Fe3O4@RH-SiO2PrNH2 and Fe3O4@RH-SiO2ADB compounds showed a clear decrease in magnetism up to 3.88 and 3.87 emu g−1, respectively.
The results showed that the specific surface area value of the RH-SiO2 sample is 390.12 m²/g and has a pore size distribution of 3.469 nm. While the specific surface area value of the RH-SiO2PrNH2 sample is 0.789 m²/g and has a pore size distribution of 15.055 nm. In contrast, the surface area value in the Fe3O4@RH-SiO2PrNH2 sample decreased to up to 0.593 m²/g and has a pore size distribution of 21.078 nm. whilst the Specific area of the RH-SiO2PrADB was using BET analysis, to be equal to 3.818 m2/g, and has a pore size distribution of 36.216 nm. The specific surface area of Fe3O4@RH-SiO2PrADB was (3.576m2/g) and has a pore size distribution of 16.586 nm which was decreased compared with the specific surface area of RH-SiO2PrADB. This is due to the attachment of Fe3O4 particles to an RH-SiO2PrADB surface, which reduces the surface area
The preparation of hybrid solid ligands was used to uptake the metal ions from its aqueous solution by using various conditions such as:- exposure time, pH, metal ion concentration, and ligand mass.