Dual-functional luminescent Zn-MOF@MCHS nanocomposite for TNP detection and copper(II) adsorptive removal

Environmental remediation in the jurisdiction of wastewater treatment is considered a critical global priority. Evidence suggests that mesoporous carbon hollow sphere (MCHS) has been extensively employed for electrochemical applications owing to its distinctive structure and efficient mass or charge transfer abilities. The distinctive amalgamation comprising a high surface area and intrinsic porosity from the metal–organic framework (MOF) and mesoporous spherical carbon shells offer enrichment in active analytical sites. To the extent of our understanding, no sensors have yet been created using a hybrid of MOFs and MCHSs. The current study utilizes in-situ fabricated MCHS and MOF-based novel fluorescent nanocomposite (Zn-MOF@MCHS) for the proficient sensing and adsorptive removal of environmental contaminants. Field emission scanning electron microscopy, High-resolution transmission electron microscopy and several other characterizations were employed to validate the physical attributes of the synthesized nanocomposite. These attributes could be advantageous in enhancing the adsorption and sensing functionalities of a material. The proposed system adaptably detects TNP (2,4,6-trinitrophenol) and Cu(II) ions (Stern-Volmer constants, K_sv = 0.36 × 10⁶ M⁻¹ and 0.83 × 10⁴ M⁻¹ respectively) along with efficient adsorption (99 % removal) of Cu(II) ions featuring a maximum adsorption capacity (q_max) of 523.56 mg/g. The low detection limits i.e., 0.368 µM for Cu(II) ion and 0.301 µM for TNP, demonstrated outstanding selectivity and sensitivity of Zn-MOF@MCHS.

The nanocomposite pertains to a surface area of 18.600 m²/g, adheres to second-order kinetics and exhibits optimal fitting to the Langmuir isotherm model to adsorb Cu(II) ions. X-ray Photoelectron Spectroscopy and zeta-potential analysis diligently scrutinize mechanistic evidence for the sensing and adsorption studies. Through experimental outcomes, the newly proposed nanoscale fluorescent composite showed the potential to serve as a universal platform for detecting and removing metal ions and detecting nitro compounds sensitively.