Adsorption of Pb2+ and Cu2+ in wastewater by lignosulfonate adsorbent prepared from corn straw

Abstract

The heavy metal ions contained in industrial wastewater are a great threat to human health. Exploring a adsorbent which have low-cost, green environmental friendly, high adsorption capacity, good recycle is key to solve heavy metal ions pollution. Lignin sulfonate was obtained by treating corn stover, and then modified lignin sulfonate was obtained by hydrothermal method. The porous structure makes heavy metal ions occupy more internal adsorption sites. Modified lignosulfonate adsorbent efficiency removes heavy metals in wastewater especially Cu²⁺ and Pb²⁺. The adsorption capacity of Cu²⁺ on modified lignosulfonate is 450.3 mg g^-1, Pb²⁺ is 475.4 mg g^-1. In addition, for 40 mg L^-1 Cu²⁺ and Pb²⁺ using 0.4 g L^-1, the adsorption equilibrium is only reached within 60 min. Meanwhile, the removal ratio of Pb is 83 %, Cd is 72 %, Cu is 87 %, Zn is 36 %, Mn is 25 %, Cr is 95 %, and Fe is 99 % in wastewater using 0.4 g L^-1 adsorbent in 2 h. This research develops a practical adsorbent to remove heavy metals from actual wastewater.

Keywords: Adsorption; Corn straw; Heavy metal ions; Lignosulfonate.