C. T. Hong Huyen, N. Thi Hong, and N. Thu Huyen, “Study On Factors Affecting the Adsorption Performance of Municipal Solid Waste-Derived Biochar for Pb²⁺ And Cr⁶⁺ Removal from Aqueous Solutions”, etj, vol. 11, no. 06, pp. 10768–10673, Jun. 2026.