Adsorptive removal of antibiotics from water and wastewater: Progress and challenges

Antibiotics as emerging contaminants are of global concern due to the development of antibiotic resistant genes potentially causing superbugs. Current wastewater treatment technology cannot sufficiently remove antibiotics from sewage, hence new and low-cost technology is needed. Adsorptive materials have been extensively used for the conditioning, remediation and removal of inorganic and organic hazardous materials, although their application for removing antibiotics has been reported for ~30 out of 250 antibiotics so far. The literature on the adsorptive removal of antibiotics using different adsorptive materials is summarized and critically reviewed, by comparing different adsorbents with varying physicochemical characteristics. The efficiency for removing antibiotics from water and wastewater by different adsorbents has been evaluated by examining their adsorption coefficient (K_d) values. For sulfamethoxazole the different adsorbents followed the trend: biochar (BC)>multi-walled carbon nanotubes (MWCNTs)>graphite=clay minerals, and for tetracycline the adsorptive materials followed the trend: SWCNT>graphite>MWCNT=activated carbon (AC)>bentonite=humic substance=clay minerals. The underlying controlling parameters for the adsorption technology have been examined. In addition, the cost of preparing adsorbents has been estimated, which followed the order of BCs<ACs<ion exchange resins<MWCNTs<SWCNTs. The future research challenges on process integration, production and modification of low-cost adsorbents are elaborated.