Polysiloxanes are characterized by silicon and oxygen backbone and are hydrophobic in nature with low moisture uptake widely used for medical applications. Polysiloxane immobilized thiosalicylic acid ligand system has been prepared through sol-gel method, gelation was observed after 40 minutes. The immobilized ligand was characterized using FTIR, the spectrum showed characteristic absorption bands (cm -1 ) at: 3377 (OH), 2981 (C-H stretch); 2631 (SH); 1587 to 1684 (C=C, C=O); 1032 to 1144 (Si -O) respectively. SEM analysis showed irregular particle sizes of the polysiloxane matrices while EDX elemental composition gave (wt %): 3-CPPS; Si (50.45), O (25.02) and Cl (24.57). F -3CPPS showed, O (58.68), Si (41.32); thiosalicylic (7.14 of S). The extraction of metal ions (Cr 3+ , Fe 3+ , Pb 2+ , Cu 2+ and Zn 2+ ) were studied using Microwave Plasma Atomic Emission Spectrophotometer (Agilent MPAES-4200) at pH 6.0. Thermodynamic range with respect to Cr 3+ , Fe 3+ , Pb 2+ , Cu 2+ and Zn 2+ yielded negative values for∆G o : Cu 2+ -(11.483 to 14.842) to Zn 2+ -(14.368 to 14.842)KJmol -1 ; positive values for ∆H o : Fe 3+ (0.000) to Pb 2+ (105.130)KJmol -1 and ∆S o : Zn 2+ (47.421) to Pb 2+ (389.328)Jmol 1 K 1 respectively, indicating spontaneous, endothermic reactions and high degree of disorderliness with respect to metal ion binding capacity to the ligand system.
A novel polymer material that is capable of adsorption of Pb2+ and Cu2+ in aqueous solutions has been synthesized. 3-Aminopropyltriethoxysilane was reacted with tetraethylethoxysilane in methanol and aqueous solution of HCl to yield 3-aminopropypolysiloxane (APP). Reacting the APP with ethylchloroacetate in triethylamine yielded a functionalized 3-aminopropypolysiloxane (FAPP). The FAPP was reacted with urea to yield urea immobilized polysiloxane. FTIR spectra of the APP showed major absorption bands (cm−1) at: 1032.5-1042.7 (Si-O-Si), while the Urea-immobilized polysiloxanes (APPU) showed major absorption bands (cm−1) at: 3200 − 3400 υ(NH), 2929 − 2957 υ(C-H), 1505-1643 (C=O, C=C, C=N), and 1032.5-1042.7 (Si-O-Si). SEM-EDX analysis of APP and APPU showed mean pore volumes (nm3) of 113.49 ± 7.91 and 44.89 ± 7.44 respectively, and elemental composition (%) as follows: APP, O (36.68), Si (39.91); FAPP, O (29.43), Si (41.64), Cl (9.06); APPU, O (32.15), Si (28.42), N (25.42). APP maximum percentage adsorption of Pb2+ and Cu2+ in simulated water were 79.44 and 74.81 respectively, while APPU maximum percentage adsorption of Pb2+ and Cu2+ were in the range of 78.36 − 85.44 and 79.63 − 82.87 respectively. The maximum percentage adsorption of Pb2+ and Cu2+ which indicate the sorption capacities of the adsorbents occurred within the pH range of 8-10, contact time between 70-90 min, metal ion concentration of 20-25 ppm, dosage of adsorbent of 0.01 − 0.03 g for Pb2+ adsorption, and 0.04 − 0.05 g for Cu(II), and at a temperature of 90°C. The statistical analyses showed significant difference in the means of the effects of pH, time and concentration as F > Fcrit, except in the case of contact time for Cu2+. Temkin isotherm gave values of R2 in the range of 0.9210 − 0.9735 and best fitted the adsorption process. The urea immobilized polysiloxane (APPU) exhibited very high potential for adsorption of Pb2+ and Cu2+ in industrial effluent up to 100 %.
Second to the wide application of different types of adhesives in various industries, offices, and homes and to the paucity of raw materials for the production of adhesives, as well as constraints in access to the conventional instruments for determination of binding strength, especially in underdeveloped and developing countries, there is a need to source and produce adhesives locally from readily available and inexpensive raw materials and to develop simple and reliable techniques to determine the binding strength. In this work, adhesives were produced from pumpkin and watermelon seeds. The binding strength of the adhesives was successfully tested using a simple technique involving a retort stand and standard objects of known mass. The adhesives were of good quality and easily applied, especially on paper, foam, footwear, and wood works. This novel technique provides a very easy and inexpensive route for the determination of binding strength as it does not require electric power, advanced technical skills, or other chemicals.
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