Dynamic experiment on the treatment of acidic chromium-containing wastewater by lignite loaded nano FeS

Abstract

In terms of the problem of severe pollution to the ecological environment caused by the acidic chrome-containing wastewater produced in the tanning, electroplating, metallurgy, printing and dyeing and other industries, based on the good adsorbability, reducibility and other properties of heavy metals such as Cr(VI) by lignite and nano FeS, the lignite-loaded nano FeS adsorbing material (nFeS-lignite) was prepared by ultrasonic precipitation method. NFeS-lignite and lignite were used as fillers to construct 1# and 2# dynamic columns to carry out the dynamic treatment experiment of acidic chrome-containing wastewater. And nFeS-lignite and lignite were characterized by XRD, SEM and EDS to explore the regularity, long-acting properties and removal mechanism of acidic chrome-containing wastewater treated by NFeS-lignite and lignite. The results indicate that: ① during 25 days of operation, the average removal percentages of Cr(VI) in the 1# and 2# dynamic columns are 71.6% and 53.1%. The average removal percentages of total chromium in 1# and 2# dynamic columns are 54.4% and 28.8%, and the average effluent pH of 1# and 2# dynamic columns is 5.3 and 7.3. ② According to XRD, SEM, EDS and FTIR analysis, the reducing groups in the structure of nFeS-lignite, such as –CH₃, –CH₂, C–O and Ar-OH, participate in the reaction and are oxidized to CC, CO and other groups. A large number of sediment crystals appeared on the particle surface, and new diffraction peaks such as FeOOH, Cr(OH)₃ and Cr₂S₃ appeared at the same time, indicating that after Cr(VI) was reduced to Cr(III), it would be fixed on the surface of nFeS-lignite in the form of precipitation such as hydroxide and sulfide.