The performance of carboxylated alginic acid derivatives via methyl orange and Congo red catalytic reduction

Numerous water-treatment marital have been developed during the past few years, including adsorbents., the catalytic reduction behavior of carboxylated alginic acid derivatives has been investigated against harmful organic dyes including Methyl Orange (MO) and Congo Red (CR). Alginic acid was firstly oxidized through an easy addition of KMnO₄ as an oxidizing agent. A carboxylated alginic acid (CAA) has been interacted with selected metal ions (Sn, Fe, Ni, and Zr) through coordination bonds at the value of pH = 4 to form the corresponding metal complexes namely: Sn-CAA, Fe-CAA, Ni-CAA, and Zr-CAA. The consistency of the coordination was confirmed by several spectroscopic techniques including FT-IR, XRD, SEM, and EDX. The catalytic reduction of these metal ion-based products was carried out against MO, and CR in the presence of NaBH₄ as a reducing agent under UV irradiation. All catalysts-based metal complexes showed enhanced catalytic reduction against CR compared to MO. Among all those mentioned metal complexes Sn-CAA showed the best catalytic reduction of these dyes. The time is taken by the Sn-CAA for CR, and MO is 5 and 7 min respectively. Ni-CAA was classified as the second efficient product against both dyes, where the reduction process took 20 and 9 min respectively. The other two catalysts took a long time for CR and MO reduction. Zr-CAA showed more than 80% reduction of only CR dye within 20 min. Whereas, Fe-CAA did not show any significant sign of reduction against both the dyes after the same time. The order of higher catalytic reduction was illustrated as: Sn-CAA > Ni-CAA > Zr-CAA = Fe-CAA.