Efficient heavy metal removal from industrial melting effluent using fixed-bed process based on porous hydrogel...

High adsorption capacity, fast adsorption kinetics, good reusability and low cost are highly demanded for adsorbents used in practical adsorption process. In this study, a porous double network Jute/Polyacrylic acid (Jute/PAA) gel was prepared using simple free-radical polymerization of acrylic acid in Jute aqueous solution. The high permeability of Jute/PAA hydrogel with about 80 wt% water made internal adsorption sites fully expose to metal ions. The Jute/PAA gel adsorbent could efficiently adsorb heavy metals in melting wastewater, especially Cd²⁺ and Pb²⁺. The adsorbent showed very high adsorption capacities of 401.7 mg/g for Cd²⁺ and 542.9 mg/g for Pb²⁺. Moreover, the adsorption equilibrium reached within only 10 min for 40 mg/L of Cd²⁺ and Pb²⁺ using 1 g/L adsorbent. Meanwhile, the removal efficiencies reached 81.0% for Pb (C₀ = 3.825 mg/L), 79.3% for Cd (C₀ = 6.075 mg/L), 83.4% for Cu (C₀ = 9.325 mg/L), 29.8% for Zn (C₀ = 188.6 mg/L), 22.3% for Mn (C₀ = 17.05 mg/L), 96.2% for Cr (C₀ = 0.25 mg/L) and 99.8% for Fe (C₀ = 9.75 mg/L) in melting wastewater using 1 g/L adsorbent in 2 h. In particular, the concentrations of Pb, Cd and Cr decreased below 0.001 mg/L using 4 g/L adsorbent. In the fixed-bed column experiments, the treatment volume of melting wastewater reached 2900 BV (32.8 L) only producing 50 BV (565 mL) eluent. This work develops a highly practical adsorption process based on hydrogel adsorbents for the removal of heavy metals in actual wastewater.