Abstract
Sulfate-radical-based advanced oxidation processes are highly effective in the degradation of antibiotics in water and wastewater. The activation of sulfate radicals occurs with the use of biochar, a low-cost carbon material. In this work, the preparation of biochar from rice husk for the degradation of various antibiotics was studied, and the biochar was compared with another biochar prepared at a different pyrolysis temperature. The biochar was prepared at 700 °C under limited O2. It had a high specific surface area of 231 m2 g−1 with micropores, a point of zero charge equal to 7.4 and a high silica content. The effect of different operating conditions on the degradation of organic compounds was studied. Increases in biochar dosage and sodium persulfate concentration were found to be beneficial for the degradation. In contrast, an increase in antibiotic concentration, the complexity of the water matrix and the existence of radical scavengers all had a detrimental effect on the activity. The comparison of the results with those from a biochar prepared at a higher temperature (850 °C) revealed that the preparation conditions affect the performance. The biochar pyrolyzed at 700 °C exhibited different behavior from that prepared at 850 °C, demonstrating the importance of the preparation route. The studied reaction was surface-sensitive and followed radical and non-radical pathways. The adsorption of the organic contaminant also played a significant role. The carbon phase characteristics determined the dominant pathway, which was radical formation, in contrast with the biochar prepared at higher temperature, where the degradation followed mainly non-radical pathways.
Highlights
The valorization of biomass has been receiving increasing attention in recent decades because (i) it presents a viable waste management solution and (ii) it offers raw materials at a reduced cost [1]
2 O2 and bonate) and the degradation the antibiotic (i.e., SMX, AMP and NOR, representing study, we aimed to verify the of capability of the RHB700 to degrade antibiotics, proposing sulfonamides, β-lactams and fluoroquinolones, respectively)
energy-dispersive X-Ray (EDX) with results presented in the while the inorganic phase In canaccordance be either amorphous or crystalline, crystallites of differfollowing paragraphs, the amorphous can be presented attributed in to the the following silica conent dimensions
Summary
The valorization of biomass has been receiving increasing attention in recent decades because (i) it presents a viable waste management solution and (ii) it offers raw materials at a reduced cost [1]. Rice husk (RH) valorization has been carried out in various ways including fuel and electricity/heat production and industrial and agricultural uses. Industrial uses include the production of chemicals, construction materials and biochars [2]. Biochars (BCs) were initially known as fertilizers or fuels, but in recent years they have been used in many applications, such as adsorbent materials [3,4,5], supercapacitors [6,7], catalysts or supports for catalysts [8], etc. An interesting application is the use of BCs as activators of oxidizing agents such as persulfate [9,10,11,12]. A review on persulfates activation by functional biochars for the removal of organic contaminants was recently published [13]
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