Preparation of Coal Gangue-Based Porous Ceramics and Its Application on Pb[sup.2+] Cycling Adsorption

The presence of lead in wastewater poses a significant threat to human health. To address this issue, coal gangue-based porous ceramics (CGPC) were developed to remove Pb[sup.2+] in wastewater. Coal gangue (CG) waste from Lvliang City, Shanxi province in China was used as raw material, and porosity was introduced through the addition of a pore-forming agent and an extrusion molding process. Properties of CGPC were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) surface area analysis, Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA) to explore its adsorption mechanism. The researchers examined the impact of pH, dosage of adsorbent, initial concentration, duration of adsorption, and temperature on the adsorption efficiency of CGPC. The CGPC of best performance had a porosity of 32.91% and compressive strength of 20.5 MPa prepared at 800 °C under nitrogen atmosphere with 10 wt% Na[sub.2]CO[sub.3] pore-forming agent and 8 wt% CaO-MnO[sub.2] combined fluxing agent. The removal rate of Pb[sup.2+] in simulated lead-containing wastewater with a concentration of 200 mg/L reached 99.63%, and the maximum adsorption capacity was 32.15 mg/g. The adsorption process of Pb[sup.2+] by CGPC involves chemical adsorption and ion exchange. After being regenerated for seven cycles with 1 mol/L NaOH as the desorption agent, the removal rate of Pb[sup.2+] by CGPC still had 72%.