Enhanced removal of Eriochrome Black T from water using biochar/layered double hydroxide/chitosan hybrid composite: Performance evaluation and optimization using BBD-RSM approach

In this research work, a novel hybrid composite consisting of biochar (B), layered double hydroxide (CuFe) and chitosan (CS) (B-CuFe-CS) was produced using an ultrasonication-assisted co-precipitation method. The resultant composite was employed for adsorptive removal of Eriochrome black T (EBT) from water. Physicochemical characterization indicated that the B-CuFe-CS containing 10 wt % CS exhibited a heterogeneous structure with better crystallographic and textural characteristics. The B-CuFe-CS with abundant surface functionalities (-C=O,-C-O, -OH, -NO3, and MMO), facilitates faster and enhanced removal of the EBT. The kinetic results showed better fitting to the pseudo-second order model, and equilibrium was achieved within 30 min. Equilibrium data was well explained by Langmuir and Redlich Peterson isotherm models (R-2 > 0.98), indicating the EBT removal onto B-CuFe-CS followed monolayer adsorption. The maximum adsorption capacity was 806.4 mg/g, which was higher than pristine B-CuFe (476.19 mg/g) and many other adsorbents. The spectroscopic analysis (FTIR and XPS) and experimental results suggested that EBT adsorption is mainly governed by electrostatic, chemical and anion-exchange interactions. It is evident from these results that coupling B-CuFe composite with bio-filler (chitosan) resulted in an efficient bio-adsorbent to effectively purify dye-contaminated water streams.

Automated summary

A novel hybrid composite consisting of biochar, layered double hydroxide, and chitosan was successfully synthesized and used for adsorptive removal of Eriochrome black T from water. The composite exhibited a heterogeneous structure with abundant surface functionalities, which facilitated faster and enhanced removal of the dye. The kinetic and equilibrium adsorption data showed good fitting to the pseudo-second order model and Langmuir and Redlich Peterson isotherm models, respectively. The spectroscopic analysis and experimental results suggested that the adsorption process was mainly governed by electrostatic, chemical, and anion-exchange interactions. This study highlights the importance of coupling composite materials with bio-fillers for efficient purification of dye-contaminated water streams.