Facile Synthesis, Characterization of Poly-2-mercapto-1,3,4-thiadiazole Nanoparticles for Rapid Removal of Mercury and Silver Ions from Aqueous Solutions

Shaojun Huang; Chengzhang Ma; Chao Li; Chungang Min; Ping Du; Yi Xia; Chaofen Yang; Qiuling Huang

doi:10.3390/polym10020150

Facile Synthesis, Characterization of Poly-2-mercapto-1,3,4-thiadiazole Nanoparticles for Rapid Removal of Mercury and Silver Ions from Aqueous Solutions

Polymers (Basel). 2018 Feb 6;10(2):150. doi: 10.3390/polym10020150.

Authors

Shaojun Huang¹, Chengzhang Ma², Chao Li³, Chungang Min⁴, Ping Du⁵, Yi Xia⁶, Chaofen Yang⁷, Qiuling Huang⁸

Affiliations

¹ Research Center for Analysis and Measurement, Kunming University of Science and Technology, Kunming 650093, China. huangshaojun1975@163.com.
² School of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093, China. mcz219@yeah.net.
³ School of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093, China. lichao2527@yeah.net.
⁴ Research Center for Analysis and Measurement, Kunming University of Science and Technology, Kunming 650093, China. minchungang@163.com.
⁵ Research Center for Analysis and Measurement, Kunming University of Science and Technology, Kunming 650093, China. dupin515@163.com.
⁶ Research Center for Analysis and Measurement, Kunming University of Science and Technology, Kunming 650093, China. xiayi0125@163.com.
⁷ Research Center for Analysis and Measurement, Kunming University of Science and Technology, Kunming 650093, China. yangmlh@163.com.
⁸ Research Center for Analysis and Measurement, Kunming University of Science and Technology, Kunming 650093, China. hql1975@eyou.com.

Abstract

Industrial pollution by heavy metal ions such as Hg²⁺ and Ag⁺ is a universal problem owing to the toxicity of heavy metals. In this study, a novel nano-adsorbent, i.e., poly-2-mercapto-1,3,4-thiadiazole (PTT), was synthesized and used to selectively adsorb mercury and silver ions from aqueous solutions. PTT nanoparticles were synthesized via chemical oxidative dehydrogenation polymerization under mild conditions. Oxidant species, medium, monomer concentration, oxidant/monomer molar ratio, and polymerization temperature were optimized to obtain optimum yields. The molecular structure and morphology of the nanoparticles were analyzed by ultraviolet-visible (UV-Vis), Fourier transform infrared (FT-IR), matrix-assisted laser desorption/ionization/time-of-flight (MALDI/TOF) mass and X-ray photoelectron (XPS) spectroscopies, wide-angle X-ray diffraction (WAXD), theoretical calculations and transmission electron microscopy (TEM), respectively. It was found that the polymerization of 2-mercapto-1,3,4-thiodiazole occurs through head-to-tail coupling between the S(2) and C(5) positions. The PTT nanoparticles having a peculiar synergic combination of four kinds of active groups, S⁻, ⁻SH, N⁻N, and =N⁻ with a small particle size of 30⁻200 nm exhibit ultrarapid initial adsorption rates of 1500 mg(Hg)·g^-1·h^-1 and 5364 mg(Ag)·g^-1·h^-1 and high adsorption capacities of up to 186.9 mg(Hg)·g^-1 and 193.1 mg(Ag)·g^-1, becoming ultrafast chelate nanosorbents with high adsorption capacities. Kinetic study indicates that the adsorption of Hg²⁺ and Ag⁺ follows the pseudo-second-order model, suggesting a chemical adsorption as the rate-limiting step during the adsorption process. The Hg²⁺ and Ag⁺-loaded PTT nanoparticles could be effectively regenerated with 0.1 mol·L^-1 EDTA or 1 mol·L^-1 HNO₃ without significantly losing their adsorption capacities even after five adsorption⁻desorption cycles. With these impressive properties, PTT nanoparticles are very promising materials in the fields of water-treatment and precious metals recovery.

Keywords: adsorption; characterization; heavy metal ions; mercury; nanoparticles; poly-2-mercapto-1,3,4-thiadiazole; silver; synthesis.

Abstract

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