Treatment of dye wastewater by in situ hybridization with Mg–Al layered double hydroxides and reuse of dye sludge

A multi-anion dye (e.g. direct blending scarlet D-GLN) can intercalate into Mg–Al-layered double hydroxides (LDHs) which is confirmed from XRD, SEM, FTIR, DTG and ζ-potential analyses. The DGLN–LDHs hybrid with the hybridization amount 524 mg/g DGLN exhibits a high adsorption capacity to cationic dyes, e.g. 1064 mg/g for victorial blue B. The hybrid was used as a sorbent to treat cationic dye wastewater and the decoloration rate over 80% by adding only 5 g/dm3. In addition, the resulting sludge was reutilized as a colorant filled in polymer materials and it exhibited the resistance to bleeding and fire. This work provides a new approach for the treatment of dye wastewater and reutilization of dye sludge.

► A LDHs–anionic dye hybrid is proved to easily and efficiently adsorb cationic dyes.
► The product after sorption can be reused as anti-bleeding and anti-firing pigment.
► Anionic and cationic dye wastewater can replace dyes to hybridize with LDHs.
► Carbon emission is reduced by immobilizing organic carbon in wastewater into LDHs.