Publication: Layered double hydroxides biochar biocomposites for the adsorption of eriochrome black t dye
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Date
2022-10-01
Authors
Zubair, Mukarram
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Abstract
Azo dyes are increasingly used in the textile industry and causing major environmental water deterioration. Adsorption technology can provide sustainable and effective removal of dye pollutants from textile wastewater, but commercial adsorbents exhibit low adsorption capacity and reusability performance. Therefore, this study developed a novel sustainable layered double hydroxide-biochar biocomposite for effective adsorption of EBT as a model azo dye from water. Date palm fronds waste is utilized as feedstock material to produce biochar through pyrolysis. The layered double hydroxides and functional filler (CNC and CS) is supported with biochar through the facile ultrasonicated assisted co-precipitation method. The EBT adsorption onto biochar-LDH biocomposites was designed, modelled, and optimized using the BBD-RSM technique. Adsorption mechanism and environmental assessment was investigated using different adsorption models. Results showed that the biochar produced at 700 °C and 4h possessed better characteristics and high adsorption of EBT (309.61 mg/g in 240 min). The CuFe LDH exhibited better crystallinity and surface functionalities with higher EBT adsorption compared to other synthesized LDHs. The coupling of biochar with CuFe LDH substantially enhanced physicochemical properties and promoted improved and rapid EBT adsorption (565.32 mg/g in 60 min). The functionalization of B-CuFe with CNCs and CS (10 wt% of biochar) enriched surface functional groups and improved hydrophilicity, leading to an increase in EBT adsorption by 55% and 42%, respectively, with 30 min. The EBT adsorption system of biochar-LDH biocomposites was well described and optimized by the BBD-RSM models (R2>0.964), indicating solution pH, dye concentration, and temperature are critical parameters. The kinetics and isotherms studies for all biocomposites were better fitted with pseudo-second order and Redlich Peterson models, suggesting chemisorption and mono/multi adsorption are major adsorption mechanisms. The biocomposites showed satisfactory EBT adsorption in competitive anions and complex water environments. The biocomposites could be effectively regenerated using (0.1-0.25) M NaOH or ethanol and showed excellent reusability up to six cycles. Based on the outcomes of this research study, it can be postulated that the synthesized biochar-LDH biocomposites possess great potential to be utilized as an eco-friendly and sustainable adsorbent for the effective removal of azo dye from water and wastewater.