All-Biomass Double Network Gel: Highly Efficient Removal of Pb2+ and Cd2+ in Wastewater and Utilization of Spent Adsorbents

Abstract

Besides excellent adsorption performance of adsorbents, the disposal of spent adsorbents should be considered for environmental concern. In this study, a new all-biomass double network Jute/sodium alginate (Jute/SA) gel is prepared via the simple dripping technique. 80 wt% water of Jute/SA hydrogel endows the adsorbent with high permeability for heavy metal ions diffusion onto internal adsorption sites. The Jute/SA gel adsorbent can efficiently remove heavy metals from melting wastewater, especially Pb2+ and Cd2+. The adsorbent shows high adsorption capacities of 291.3 mg g−1 for Pb2+ and 149.9 mg g−1 for Cd2+ at 298 K. The adsorption equilibrium reaches within 45 min for 45 mg L−1 Cd2+ and Pb2+ using 1 g L−1 adsorbent, showing 98% removal efficiency of Pb2+ and Cd2+. Moreover, the removal efficiencies in 45 min reach up to 99.1% for Pb2+ (7.539 mg L−1) and 89.9% for Cd2+ (4.743 mg L−1) in actual melting effluent containing Zn (43.95 mg L−1), Cu (16.50 mg L−1), Mn (19.24 mg L−1), Ni (4.90 mg L−1) and Fe (33.75 mg L−1) using 1 g L−1 adsorbent. The concentrations of Pb and Cd decrease below 0.001 mg L−1 using 4 g L−1 adsorbent. Furthermore, the adsorption efficiencies for Pb2+ and Cd2+ remain above 95% in the tenth cycle, and the desorption efficiency is up to 99%. In addition, the spent Jute/SA gel was a good organic fertilizer for plant growth. This work develops an efficient and eco-friendly biomass adsorbent for the removal of heavy metals in actual wastewater.