Sequestration of thiazolyl blue tetrazolium bromide and bromophenol blue onto biochar derived from American sycamore leaves

Biochars have received much attention as efficient adsorbents for water pollutants. Besides, the chemical treatment of biochars performed to increase the adsorption capacity usually causes secondary chemical pollution and increases the cost of the process. The biomass feedstock utilised in biochar preparation impacts significantly the surface properties and adsorption capacity. Thus, the need to prepare new biochars from new feedstock with potentially high uptake capacities. Herein, we prepared new biochar (POBC) from Platanus occidentalis waste leaves (POL), which was utilised for the ultrasonic-aided adsorption of bromophenol blue (BRB) and thiazolyl blue tetrazolium bromide (TTB). The FTIR, SEM, EDX, TGA, BET, pH(pzc,) and elemental characterisations of POBC revealed potent surface characteristics desirable for efficient dye adsorption. An increase in the surface area from 14.31 m(2)/g to 31.94 m(2)/g and the pore volume from 0.0214 cm(3)/g to 0.0326 cm(3)/g was obtained after the conversion of the POL to POBC. Besides, the SEM images of POBC revealed a highly porous surface structure of the adsorbent. The Freundlich and pseudo-second-order model presented the best fit to the isotherm and kinetics based on the high coefficient of determination (R-2 > 0.9) and low sum square errors (SSE < 0.31). The heterogeneous surface nature of POBC was inferred from the independent-oriented site model. The monolayer adsorption capacity of 45.03 mg/g and 48.8 mg/g were obtained for BRB and TTB, respectively. Thermodynamics showed an endothermic, feasible, and random uptake, and POBC displayed efficient potentials to be reused. The obtained results revealed that novel POBC is an efficient low-cost biochar with high adsorption capacity for dyes.

Automated summary

A new biochar material (POBC) prepared from Platanus occidentalis waste leaves (POL) showed efficient adsorption capacity for bromophenol blue (BRB) and thiazolyl blue tetrazolium bromide (TTB). The surface characteristics and pore structure of POBC contributed to its high adsorption efficiency, as confirmed by various characterisation techniques. The Freundlich and pseudo-second-order models provided the best fit for the adsorption isotherm and kinetics, and thermodynamics indicated the endothermic and feasible nature of the adsorption process. Moreover, POBC exhibited potential for reuse, making it a cost-effective biochar option with excellent dye adsorption capacity.