Thermal transformation of resorcinol-formaldehyde into hollow carbon nanospheres enhances adsorption of emerging contaminants from water

Abstract

The pollution of water systems by emerging contaminants (ECs) has caused severe environmental and human health impacts, necessitating the development of advanced nanomaterials to remove them from water efficiently. This study fabricated 3D hollow carbon nanospheres (HCNSs) utilising a water-in-oil (W/O) microemulsion method. In a novel approach, the adsorptive performance of HCNSs was compared with that of their corresponding resorcinol-formaldehyde hollow nanospheres (RF-HNSs) to assess the effect of carbonisation on adsorption behaviour. The hollow spherical nanostructure and textural properties were determined by electron microscopy and N 2 /CO 2 adsorption-desorption experiments, respectively. The HCNS-800 (carbonised at 800 °C) had an outer diameter of 52 ± 7 nm and a shell thickness of 6 ± 1 nm and exhibited a surface area of 1225 m 2 g −1 , significantly higher than those of HCNS-600 (600 m 2 g −1 ) and RF-HNSs (1.8 m 2 g −1 ). The adsorptive performance of the materials was evaluated against acetaminophen (ACT), atenolol (ATE), carbamazepine (CBZ), and lamivudine (LMD) using batch adsorption experiments. HCNS-800 demonstrated superior adsorption performance toward the target pharmaceuticals due to its larger accessible adsorption surface. The material exhibited high maximum adsorption capacities ranging from 60.3 mg g −1 to 155.9 mg g −1 , and adsorption equilibrium was rapidly reached within 6–15 min. The estimated costs for removing 1.0 g of ACT, ATE, CBZ, and LMD from water were USD 64.29, USD 35.10, USD 45.41, and USD 90.74, respectively, with the five-cycle reusability factored in. These findings demonstrate that HCNSs are promising, sustainable, and cost-effective adsorbents for removing pharmaceutical contaminants from water.