Multifunctional sorbent and photocatalyst material for complex water remediation based on Cu/Cr doped Mg-Al LDHs

The present study focuses on the development of multifunctional sorbent/photocatalytic materials based on Mg-Al layered double hydroxides (LDHs) doped with Cu^2 + or Cr³⁺ ions as a promising path to solve rising environmental problems. The LDHs were synthesized using a simple co-precipitation method and characterized using XRD, FTIR, SEM, EDX, XPS and UV-Vis spectroscopy methods. Developed materials exhibit high efficiency in heavy metals (Cu²⁺ and Pb²⁺) sorption and photodegradation of hazardous organic dyes (Congo red). The photocatalytic activity, enhanced by oxygen vacancies and tuned electronic structure, occurs under visible light provided by a cheap LED lamp. After separate studies of sorption and photodegradation, the ability of simultaneous removal of Pb²⁺ ion and Congo red dye from distilled water as well as from a city channel water was demonstrated. The sample of Mg-Al LDH doped with Cr³⁺ ion in a city channel water shows 72 % of Pb²⁺ sorption in 1.25 mg⋅L⁻¹ solution and 80 % of Congo red photodegradation under visible light in 4 mg⋅L⁻¹ solution with following 100 % Pb²⁺ desorption in low concentrated HCl solution.