N-doped nano-casted carbon monolith for Pb (II) removal and photocatalytic degradation of thiamethoxam from aqueous solution

Single rock-like N-doped carbon monolith (ND-PFCM) was successfully constructed via nanocasting method. Phenol formaldehyde resin was taken as carbon source and nitrogen was incorporated in monoliths through NaNH ₂ activation. The synthesized monoliths were used for the removal of Pb (II) from aqueous solution. Various characterization techniques namely, Brunauer-Emmett-Teller (BET), Raman spectroscopy, UV-visible diffuse reflectance spectra (DRS) UV-DRS, Zeta potential, Scanning electron microscopy (SEM), TEM (Transmission electron microscopy), TGA (Thermogravimetric analysis) and XPS (X-ray photoelectron spectroscopy) were utilized to characterize synthesized monolithic samples. The different parameters such as pH, adsorbent dosage and time were enquired on the removal efficiency of monoliths towards Pb(II). ND-PFCM exhibited the highest adsorption capacity of 330.03 mg g ^− 1 in 180 min at pH 6. This is attributed to the fact that the better texture properties and presence of nitrogen functional groups enhance the uptake of Pb (II) ions on the monolith surface. In the kinetic studies, pseudo second order model fitted best with the experimental data. Furthermore, the removal of thiamethoxam (TM) from aqueous solution was done by using different weight ratios of ND-PFCM under the visible light. The maximum removal efficiency of 97.35% with rate constant of 0.02085 min ^− 1 obtained in 160 min. Moreover, monoliths exhibited good reusability for five consecutive cycles. The findings suggest that the synthesized monoliths exhibit characteristics suitable and eco-friendly for sustainable use in water treatment applications.