Extraction and preconcentration capacity of bifunctionalized diamine-thiol polysiloxane immobilized ligand system towards some divalent cations

Abstract

Porous solid bi-organofunctionalized diamine-thiol polysiloxane immobilized ligand system of the general formula P-(CH 2 ) 3 -X, (where P represents [Si-O] n siloxane network and X represents a mixture of diamine; -NH(CH) 2 NH 2 and thiol; -SH functional groups) has been prepared by hydrolytic polycondensation of TEOS with a mixture of 3-mercaptopropyltrimethoxysilane and 3-(2-aminoethylimino)propyltrimethoxysilane agents. The ligand system was evaluated for extraction and preconcentartion of a series of divalent metal ions from aqueous solutions including: Co 2+ , Ni 2+ , Cu 2+ , Zn 2+ , Cd 2+ and Pb 2+ . Both batch and dynamic methods were used to examine maximum sorption capacity. The maximum binding capacity followed the sequence; Cu 2+ ! Pb 2+ ! Cd 2+ ! Ni 2+ ! Zn 2+ ! Co 2+ at pH 5.5. Measurement of variation of sorption of metal ions with temperature yielded negative values of 'G° and positive values of 'S° and 'H° indicating a spontaneous and endothermic process of binding metal ions to the ligand system.

Immobilized Thiosalicylic Ligand System Potentials for the Detoxification of Some Heavy Metals from Tannery Wastewater

“…EDX data of functionalized 3-CPP with immobilized thiosalicylic acid ligand gives 7.14 wt% of S (Table 2). This is in agreement with the suggested structure of the targeted system and is an indication of successful polymerization by nucleophilic displacement of a halide anion by Brad B [21], which the sulphur atom was originally not on the polymer framework with 7.14 wt %, within the range of 6.1-10.4 wt % reported by Issa M. E. [7]; 8.0 wt %, [6]; 4.30-11.30 wt % El-Nahhal I. M [22]; 3.90-6.80 wt % [23] for similar synthesis. The value of 7.14 wt% was obtained because of the availability of reactive sites in Figure 3, which assisted in the immobilization process, with particle size of 3.4397 ± 1.5659 nm.…”

“…The methods of [13,8,14], were adopted. 3-Chloropropylpolysiloxane (CPPS) was prepared by reacting tetraethylorthosilicate (0.1 mol, 20.8 g) with 3chloropropyltrimethoxysilane (0.05 mol, 9.936 g) in the presence of methanol (35 cm 3 ) in a solution of sodium hydroxide (NaOH, 0.42 mol/dm 3 , 4.95 cm 3 ) [6], stirred for 5 min at 40°C and pH 10 (Tricolour Universal pH Paper). Gelation formed after 40 min.…”

“…Not more than 20% of the chemicals are absorbed by leather; the remainder flows out with the effluent [4]. Conventional methods used have limitations such as production of toxic sludge [5] and inability to remove heavy metals at trace level, this prompted the use of polymeric modified surfaces with good thermal, mechanical and chemical stability properties such as polysiloxane immobilized with ligands [6] have been employed as a recyclable extractants for heavy metals. These immobilized ligand system could be synthesized directly by sol gel or by chemical modification of the prepared functionalized polysiloxane [6].…”

“…Conventional methods used have limitations such as production of toxic sludge [5] and inability to remove heavy metals at trace level, this prompted the use of polymeric modified surfaces with good thermal, mechanical and chemical stability properties such as polysiloxane immobilized with ligands [6] have been employed as a recyclable extractants for heavy metals. These immobilized ligand system could be synthesized directly by sol gel or by chemical modification of the prepared functionalized polysiloxane [6]. A variety of analytical techniques have been employed such as Fourier Transform Infra-red (FTIR) [7,8], Nuclear Magnetic Resonance (NMR), Scanning Electron Microscopy (SEM) [9,10] and Energy Dispersive X-ray Analysis (EDX) [9,10].…”

Characterization of Tannery Wastewater and Detoxification Potentials of Polysiloxane Immobilized Ligand Systems on Selected Heavy Metals

“…Conventional methods used in the tannery wastewater treatments have limitations such as production of toxic sludge [22] and inability to remove heavy metals at trace level. There is need for innovative technologies which require low maintenance, high energy efficiency, low cost and better operational techniques than the conventional methods, this prompted the use of polymeric modified surfaces with excellent thermal, mechanical and chemical stability properties such as polysiloxane functionalized or immobilized with ligands [23] have been employed as a recyclable extractants for heavy metals.…”