Solar-Responsive Bi₂S₃/ZnS Heterojunction-Loaded Chitosan/Cellulose Sponges for Adsorption-Photocatalytic Degradation of Congo Red

Dye wastewater discharges threaten fragile aquatic ecosystems. Photocatalysis has been applied as an effective, viable, and economical option to achieve dye degradation. However, current photocatalysts suffer from large bandgaps, powder agglomeration, difficult recovery, and cannot be recycled. Herein, a novel Bi₂S₃/ZnS heterojunction loaded cellulose/chitosan (BiZnCCS) with highly efficient photocatalytic activities for CR pollutant degradation was designed and fabricated via a simple hydrothermal method. BiZnCCS has a large pore size of 2 μm with a high porosity of 71.62%, which increases the contact area with CR and facilitates the adsorption of CR. The pore wall was uniformly loaded with Bi₂S₃/ZnS particles, and the degradation rate of CR could reach 97.8% under simulated visible light irradiation. By adjusting the composition ratio, BiZnCCS was able to withstand a stress of about 82.45 kPa, and the CR removal rate was still maintained at about 85% after 7 cycles of testing. By creating a synergistic adsorption-photocatalytic degradation mechanism, BiZnCCS has the ability to efficiently remove CR under visible light, which provides a new material for the treatment of dye wastewater.