Low-temperature conversion of Fe-rich sludge to KFeS2 whisker: a new flocculant synthesis from laboratory scale to pilot scale

Abstract

Herein, a KFeS2 whisker was formed in mass production at a low temperature, with waste cold-rolling sludge as Fe source, which exhibited good performance in the removal of Zn/Ni from real electroplating effluent. At laboratory scale, KFeS2 was generated at 80 °C by the hydrothermal method, and KFeS2 whisker grew radially with the extension of the reaction time. This method was applied at pilot scale, where a similar KFeS2 whisker was also produced with waste cold-rolling sludge as Fe source, and a residual brownish supernatant was observed after the reaction and then completely recycled in the next round for KFeS2 synthesis. After recycling five times, the produced KFeS2 whisker did not change. The drying and storage of KFeS2 have also been verified. Freeze drying and vacuum drying were applicable, whereas air drying was not profitable. Moreover, the efficiency of Zn/Ni removal using undried KFeS2 was similar to that of dried KFeS2. The efficiencies of Zn/Ni removal using KFeS2 were apparently higher those of common reagents for wastewater treatment.

Chemical exfoliation of 1-dimensional antiferromagnetic nanoribbons from a non-van der Waals material

“…33 An alternative bottom-up synthesis in solution results in ''whiskers'' of KFeS 2 . 34 In addition to determining the feasibility of using liquid exfoliation to make these compounds, we also sought to determine whether the magnetic properties could be preserved. Magnetic studies on bulk KFeS 2 show that it is antiferromagnetic (AFM) within the chains, with a Ne ´el temperature (T N ) of 250 AE 5 K; there are ferromagnetic (FM) interactions between the chains, but due to the significantly larger spacing between inter-chain Fe ions (6.6 Å) versus intra-chain Fe ions (2.7 Å), these interactions are less significant.…”

Density Functional Theory Approach to the Vibrational Properties and Magnetic Specific Heat of the Covalent Chain Antiferromagnet KFeS2

“…Ternary potassium-iron sulfide, KFeS 2 , belongs to the family of quasi-one-dimensional compounds with the general chemical composition AFeCh 2 (where A-K or Rb; Ch-S or Se) [1,2]. These compounds share a common structural motif, i.e., a chain of edge-sharing chalcogen tetrahedra with iron ions inside (see Figure 1) [1][2][3]. Because of the strong intra-chain antiferromagnetic exchange interaction between the iron ions, these compounds are considered as model ones to study the magnetic properties and thermal behavior of a one-dimensional antiferromagnetic chain.…”