Thiophene-Based Porous Triazine Polyamide (Tb-PTPa) as the Next Promising and Cost-Effective Eliminator of Hg²⁺ in Aqueous Media

Research suggests that wastewater is highly polluted by Hg²⁺, threatening the sustainability of our environment and the health conditions of human beings. However, most of the existing adsorbents have a poor adsorption performance and require expensive raw materials. A low-cost adsorbent material with a very high adsorption performance is therefore an urgent need. In this work, we have successfully prepared thiophene-based porous triazine polyamide (Tb-PTPa) for the first time, using two inexpensive raw materials and a simple amidation reaction. Tb-PTPa was then used for the efficient adsorption of Hg²⁺ in the aqueous media. The adsorption capacity of Tb-PTPa for Hg²⁺ was up to 2562 mg g^-1 and the adsorption rate was 12.9 mg g^-1 min^-1. In addition, Tb-PTPa shows good selectivity for the adsorption of Hg²⁺. The removal rate is still higher than 91% after five adsorption cycles. The interfering substances present in water only slightly affect the capture of Hg²⁺ by Tb-PTPa. The combination of our experimental results and density functional theory calculations clearly shows that the introduction of amide bonds can greatly enhance the chelating ability of the N atoms of triazine and the S atoms of thiophene for Hg²⁺. Based on our extensive investigation, we have demonstrated that Tb-PTPa is a low-cost adsorbent with excellent adsorption properties. Therefore, Tb-PTPa is expected to be a new adsorbent material for the treatment of Hg²⁺ in the wastewater.