Abstract
To further increase the quantity and density of functional groups on adsorbent, terminal triethylenetetramine hyperbranched dendrimer-like polymer modified silica-gel (SG-TETA and SG-TETA2) was synthesized. The hyperbranched dendrimer-like polymer was successfully introduced onto silica gel and new cavities were formed, which was demonstrated by FTIR, SEM, and BET. The highest adsorption capacities of SG-TETA and SG-TETA2 obtained from Langmuir model toward Au(III) were 2.11, and 2.27 mmol g−1, respectively, indicating that SG-TETA2 possessing more functional groups had a better adsorption ability. Moreover, the adsorbents combined with Au(III) ion through chelation and electrostatic attraction mechanism, after which reduction reactions for Au(III) ion loaded on adsorbents proceeded. SG-TETA2 had better adsorption selectivity than SG-TETA in removing Au(III) in Au-existed ion solution systems. SG-TETA2 had higher overall adsorption capacities compared to silica-gel-based hyperbranched polymers functionalized by diethylenetriamine. Therefore, the effective recovery makes SG-TETA2 a practical adsorbent in removing Au(III) ion from e-wastes and industrial effluents with much prospect.
Highlights
Gold (Au) is an indispensable and important precious metals that performs many functions, as it is one of the raw materials commonly found in electronics, catalysts, anti-corrosion materials (Das, 2010; Chen et al, 2015; Vojoudi et al, 2017)
The FT-IR spectra of silica-gel, Silica gels functionalized with triethylenetetramine (SG-TETA), SG-TETA-methyl acrylate (MA), and SG-TETA2 were showed on Figure 1
In the spectrum of SG-TETA (Figure 1B), the new peaks appeared at 2,853 and 2,923 cm−1 were assigned to the symmetric and asymmetric CH2 bands, which indicated the successful attach of carbon chain of CPTSTETA on the surface of silica-gel
Summary
Gold (Au) is an indispensable and important precious metals that performs many functions, as it is one of the raw materials commonly found in electronics, catalysts, anti-corrosion materials (Das, 2010; Chen et al, 2015; Vojoudi et al, 2017). A variety of techniques such as chemical precipitation (Soylak and Tuzen, 2008; Boudesocque et al, 2014), membrane separation (Kargari et al, 2006; Wang et al, 2017), solvent extraction (Vidhate et al, 2015), and adsorption (Zhen et al, 2016; Tofan et al, 2017; Yu and Fein, 2017) have been introduced into enrich, and recover gold from waste water Among these methods, the adsorption method has been evaluated as the most effective way, with attractive features such as easy operation, low-cost, and is suitable for recovering the low level of gold which exists in industry wastewater. Nitrogen-containing adsorbents are commonly used as one of the most
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