fig1

Figure 1. (A) The molecular structure characteristics of ARS, PHS, and SBS; (B) UV-Vis spectra of ZnSO₄, ZnSO₄ + ARS, and ARS, respectively; (C) NMR spectra, (D) Raman spectra, and (E) hydrogen-bonding ratio of ZnSO₄, ZnSO₄ with ARS/PHS/SBS, and ARS (0.02 mM aqueous solution); The binding energy of (F) H₂O and (G) Zn²⁺ to H₂O, ARS, PHS, and SBS, respectively. ARS: Alizarin red S; SBS: sodium benzenesulfonate; NMR: nuclear magnetic resonance; UV-Vis: ultraviolet-visible; PHS: sodium p-hydroxybenzenesulfonate.