High removal efficiency of tetracycline (TC) by biochar-supported zerovalent iron composite prepared by co-pyrolysis of hematite and pinewood

Abstract

There is a need to prepare a high-efficient sorbent to remove the recalcitrant tetracycline (TC) in wastewater. Herein, biochar-supported zerovalent iron (BC/ZVI) was fabricated in nitrogen ambience via one-step co-pyrolysis of hematite and pinewood. X-ray diffractometer pattern indicated pinewood catalyzed conversion of hematite to ZVI, which was otherwise transformed to FeO, Fe 3 O 4 and ZVI without biomass. Batch sorption results indicated that TC removal capacities at pH 5 were 8.02, 177.70 and 301.39 mg g −1 by BC, ZVI and BC/ZVI, respectively. Overall, BC/ZVI showed excellent TC removal capacity through the complexation with Fe ions, surface adsorption and degradation. Thus, the agricultural and industrial wastes were converted via a one-step co-pyrolysis to a value-added product for highly efficient removal of TC in wastewater.

Efficient removal of tetracycline in water using modified eggplant straw biochar supported green nanoscale zerovalent iron: synthesis, removal performance, and mechanism

“…S1 in the ESI † ) were successfully synthesized and immobilized on ESBC surfaces, which was helpful to inhibit the agglomeration of nZVI. 2 The EDS element mapping spectra of P-nZVI/ESBC composite ( Fig. 1C ) reveal that Fe was uniformly distributed on the composite surface.…”

“…Five different adsorption kinetic models including pseudo-first-order (eqn (4)), pseudo-second-order (eqn (5)), Avrami fractional-order (eqn (6)), intra-particle diffusion (eqn (7)), and liquid film diffusion (eqn (8) and (9)) models were used to establish the kinetic predictions for TC adsorption with P-nZVI/ESBC composite. These models are expressed as follows: 2,3,39,40 q t = q e (1 − e − k 1 t ) q t = q e [1 − e −( k 3 t ) n ] q t = k 4 t 1/2 + C Ln(1 − F ) = − k 5 t where, k 1 (min −1 ), k 2 (g mg −1 min −1 ), k 3 (min −1 ), k 4 (mg g −1 min −1/2 ), and k 5 (min −1 ) represent the adsorption rate constants of pseudo-first-order, pseudo-second-order, Avrami fractional-order, and intra-particle diffusion models, respectively; C (mg g −1 ) is the intercept of intra-particle diffusion model; F represents the equilibrium fractional achievement at reaction time t .…”

“…1,8,17,18 Generally, biochar was prepared by hydrothermal carbonization and pyrolysis routes. 2,19,20 Compared to pyrolysis route (400-800 °C), hydrothermal carbonization can yield more biochar solids at mild temperature (180-350 °C), and the fresh raw materials do not require further drying treatment. [19][20][21] However, these biochar materials generally have relatively small specic surface areas and poor pore structures, 17 resulting in the limited adsorption performance for pollutants.…”

“…Anchoring nZVI onto biochar can not only disperse nZVI well and prevent agglomeration, but also enhance the electron migration of nZVI and retard the oxidation of nZVI. 2 The combination of dispersed nZVI and modified biochar may improve the removal performance for TC in water. In addition, most of iron-based composites were synthesized by potassium/sodium borohydride reduction.…”

“…Tetracycline (TC), an important antibiotic, is widely used in human medicine, livestock and poultry industry because of its excellent antibacterial properties and low price. 1,2 It was previously reported that about 60-90% of TC was excreted into the environment in the form of parent compound and its incomplete metabolic products via urine and feces, 3 and the total emissions are increasing year by year. 4 TC has high water solubility; a large fraction of discharged TC ends up in water bodies, sediment and soil.…”