Abstract
Developing green, sustainable, and low-cost adsorbents for removing heavy metals from wastewater while recycling food wastes can avoid secondary environmental damage. In this work, artificial humic acid (A-HA) was prepared through biological fermentation using food wastes as raw materials with the goal to remove Pb (II) and Cd (II) from aqueous solution. The results showed that Pb (II) adsorption by A-HA was superior to that of Cd (II). Electrostatic interaction, surface complexation, ion exchange, and π – π interaction played key roles in the adsorption and desorption of A-HA for Pb (II) and Cd (II). The Langmuir isothermal adsorption model was more suitable for the adsorption of Pb (II) and Cd (II) by A-HA, and at 45 °C, maximum adsorption capacities were 37.6 mg/g and 3.33 mg/g, respectively. The adsorption kinetics of Pb (II) and Cd (II) by A-HA showed good fit with the pseudo-first-order kinetic model. The adsorption capacities of A-HA for Pb (II) and Cd (II) first increased gradually and finally stabilized with increasing initial concentration of adsorbate. In the pH range of 1–7, the adsorption capacities of A-HA for Pb (II) and Cd (II) first increased and remained stable. However, the adsorption capacities were inhibited by increasing ionic strength. Under optimal adsorption conditions, very little Pb (II) and Cd (II) were desorbed. In summary, A-HA might be a promising and effective adsorbent for metal removal because of its environmental friendliness, low cost, and its origin from food wastes as raw materials. • Food wastes as the rawmaterials of Artificial humic acid aligning to concepts of sustainable development of green chemistry. • Artificial humic acid showed an effective adsorption for Pb (II)/Cd (II). • Artificial humic acid had a better adsorption for Pb (II) than Cd(II). • Adsorption and desorption mechanism were electrostatic interaction, complexation, ion exchange and π – π interaction. • Adsorbate initial concentration, pH, and ionic strength had obvious effects on adsorption and desorption.
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