Preparation of eco-friendly chelating resins and their applications for water treatment

In the present study, two chelating resins were prepared and used for simultaneous adsorption
of toxic metal ions, i.e., Cr3+, Mn2+, Fe3+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, and Pb2+ (MX+). In the
first step, chelating resins were prepared starting with styrene-divinylbenzene resin, a strong basic
anion exchanger Amberlite IRA 402(Cl􀀀) with two chelating agents, i.e., tartrazine (TAR) and amido
black 10B (AB 10B). Key parameters such as contact time, pH, initial concentration, and stability
were evaluated for the obtained chelating resins (IRA 402/TAR and IRA 402/AB 10B). The obtained
chelating resins show excellent stability in 2M HCl, 2M NaOH, and also in ethanol (EtOH) medium.
The stability of the chelating resins decreased when the combined mixture (2M HCl:EtOH = 2:1) was
added. The above-mentioned aspect was more evident for IRA 402/TAR compared to IRA 402/AB
10B. Taking into account the higher stability of the IRA 402/TAR and IRA 402/AB 10B resins, in a
second step, adsorption studies were carried out on complex acid effluents polluted with MX+. The
adsorption of MX+ from an acidic aqueous medium on the chelating resins was evaluated using the
ICP-MS method. The following affinity series under competitive analysis for IRA 402/TAR was obtained:
Fe3+(44 g/g) > Ni2+(39.8 g/g) > Cd2+(34 g/g) > Cr3+(33.2 g/g) > Pb2+(32.7 g/g) > Cu2+
(32.5 g/g) > Mn2+(31 g/g) > Co2+(29 g/g) > Zn2+ (27.5 g/g).While for IRA 402/AB 10B, the following
behavior was observed: Fe3+(58 g/g) > Ni2+(43.5 g/g) > Cd2+(43 g/g) > Cu2+(38 g/g) > Cr3+
(35 g/g) > Pb2+(34.5 g/g) > Co2+(32.8 g/g) > Mn2+(33 g/g) > Zn2+(32 g/g), consistent with the
decreasing affinity of MX+ for chelate resin. The chelating resins were characterized using TG, FTIR,
and SEM analysis. The obtained results showed that the chelating resins prepared have promising
potential for wastewater treatment in the context of the circular economy approach.