Eucommia ulmoides Oliver derived magnetic activated carbon for eliminating methylene blue from dyeing wastewater and its economic efficiency assessment

Abstract

The abundant discharge of dyes is harmful to aquatic ecosystem, it is meaningful to seek a resource-rich adsorbent to eliminate the pollution. Activated carbons (ACs) were prepared by low temperature phosphoric activation method using Eucommia ulmoides Oliver (EUO) wood as raw material, while magnetic activated carbons (MACs) were prepared by one-step (M1ACs) and two-step (M2ACs) hydrothermal methods combined with FeSO40.7 H2O and FeCl30.6 H2O for the removal of methylene blue from printing and dyeing wastewater. The specific surface area of M2ACs (1135.6 m2/g for M2AC1) prepared by two-step method was significantly higher than that of M1ACs (708.5 m2/g for M1AC1) prepared by one-step method. Impressively, the adsorptive capacity of M2AC2 stably reached the maximum value of 540 mg/g when the concentration and pH of methylene blue (MB) were 100 mg/L and 10.0, respectively. In particular, after 5 times magnetic re-adsorption experiments (79.81%), the M2ACs exhibited a strong and gratifying magnetic behavior. Therefore, the economic feasibility of the M2ACs to remove MB was relatively high than that of M1ACs. Overall, the two-step chemical activation method is a promising route to prepare high performance MACs for dyeing wastewater treatment.