A robust self-regenerating graphene-based adsorbent for pharmaceutical removal in various water environments

Area of Science:

• Environmental Science
• Materials Science
• Chemical Engineering

Background:

• Active pharmaceutical ingredients (APIs) in wastewater pose ecological and health risks.
• Conventional adsorbents like activated carbon have limitations, including reduced efficacy with natural organic macromolecules (NOMs) and high regeneration costs.
• A need exists for stable, self-regenerative adsorbents for efficient API removal.

Purpose of the Study:

• To synthesize and characterize a novel self-generating metal oxide nano-composite (S-MGC) for API adsorption and photodegradation.
• To optimize the composition of S-MGCs containing titanium dioxide (TiO2), silicon dioxide (SiO2), and 3D graphene oxide (GO).
• To evaluate the adsorption and regeneration performance of S-MGCs in various water matrices, including those with NOMs and artificial urine.

Main Methods:

• Synthesis of S-MGCs with varying TiO2:SiO2:GO ratios, optimized using methylene blue as a model contaminant.
• Characterization of S-MGC physical and chemical properties.
• Adsorption and photodegradation studies using five model APIs (sulfamethoxazole, carbamazepine, ketoprofen, valsartan, diclofenac) in single and multi-component systems.
• Performance evaluation in complex water environments (varying NOM levels, artificial urine) and continuous fixed-bed column tests.

Main Results:

• S-MGCs demonstrated enhanced adsorption capacity compared to 3D graphene oxide (CGB) and GAC.
• Adsorption performance remained consistent in the presence of NOM and artificial urine.
• The synthesized TiO2 on GO exhibited effective photocatalytic activity for API degradation.
• S-MGCs showed robust performance in continuous flow tests and were successfully regenerated through multiple light-illumination cycles.

Conclusions:

• S-MGCs represent a promising, stable, and self-regenerative adsorbent for effective API removal from diverse water sources.
• The light-activated regeneration mechanism offers a cost-effective alternative to conventional adsorbent regeneration.
• This technology addresses the limitations of existing methods, particularly in complex environmental conditions.