Abstract
The adsorptive removal of antibiotics from aqueous solutions is recognized as the most suitable approach due to its easy operation, low cost, nontoxic properties, and high efficiency. However, the conventional regeneration of saturated adsorbents is an expensive and time-consuming process in practical wastewater treatment. Herein, a scalable adsorbent of magnetic Fe3O4@chitosan carbon microbeads (MCM) was successfully prepared by embedding Fe3O4 nanoparticles into chitosan hydrogel via an alkali gelation-thermal cracking process. The application of MCM composites for the adsorptive removal of doxycycline (DC) was evaluated using a fixed-bed column. The results showed that pH, initial concentration, flow rate, and bed depth are found to be important factors to control the adsorption capacity of DC. The Thomas and Yoon-Nelson models showed a good agreement with the experimental data and could be applied for the prediction of the fixed-bed column properties and breakthrough curves. More importantly, the saturated fixed bed can be easily recycled by H2O2 which shows excellent reusability for the removal of doxycycline. Thus, the combination of the adsorption advantage of chitosan carbon with catalytic properties of magnetic Fe3O4 nanoparticles might provide a new tool for addressing water treatment challenges.
Highlights
In the past years, doxycycline (DC) has gradually become one of the most widely used antibiotics in the world especially in human therapy and livestock industry because of its specific antimicrobial properties and minor adverse side effects [1,2,3]
The formation of magnetic Fe3O4@chitosan carbon microbeads by alkali gelation-thermal cracking route was proposed in Scheme 1
Chitosan is insoluble in water but soluble in diluted acidic solution below its pKa (~6.3), in which the amine groups (–NH2) of chitosan can be facilely converted into the soluble protonated form (–NH3+) [28]
Summary
Doxycycline (DC) has gradually become one of the most widely used antibiotics in the world especially in human therapy and livestock industry because of its specific antimicrobial properties and minor adverse side effects [1,2,3]. Compared with the traditional chemical and biological strategies to purify the antibiotic wastewater, the adsorptive removal of antibiotic from aqueous solution is the most suitable approach for the treatment of toxic antibiotic wastewater because of its easy operation, low cost, nontoxic properties, and high efficiency [7, 8]. A series of adsorbents, such as activated carbon [9], clays [10], graphene oxide [11], and zeolites [12], have been exploited extensively and applied widely for Journal of Nanomaterials the removal of organic antibiotics. The adsorption of toxic organic compounds with activated carbon only transfers the pollutants from the wastewater to the surface of adsorbents rather than decomposing them, which limited the recycling of the adsorbents. In order to deal with such conundrums, the periodical regeneration by traditional physicochemical approaches should be executed for the pollutant-loaded adsorbents, such as thermal regeneration [16], oxidative catalytic regeneration [17], ultrasound-assisted sorbent regeneration [18], electrochemical method [19], and microwave regeneration [20]
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