Pickering Emulsion‐Based Ammonia Extraction Using MPTMS ‐Functionalized Magnetic Nanoparticles: Process Optimization and Stability Evaluation

ABSTRACT In this study, magnetite (Fe 3 O 4 ) nanoparticles surface‐modified with 3‐mercaptopropyltrimethoxysilane (MPTMS) were synthesized to develop a magnetic water‐in‐oil (W/O) Pickering emulsion system for ammonia‐containing wastewater treatment. The optimal modification conditions (pH 8.0, 5% MPTMS, 70 C, 6 h) yielded a water contact angle of 102.9° and an iron leaching rate of 0.2%. Fourier transform infrared spectroscopy (FTIR) confirmed FeOSi covalent bonding, and vibrating sample magnetometry (VSM) showed retained superparamagnetism (59.6 emu/g), enabling magnetic separation within 10 s. Under optimized emulsion conditions, the W/O Pickering emulsion achieved an ammonia extraction efficiency of 93.2% with a membrane breakage rate of only 0.5%. After five reuse cycles, the extraction efficiency remained at 82.5%, equivalent to 88.5% of the initial value. This magnetic Pickering emulsion system overcomes the limitations of conventional surfactant‐based emulsion liquid membranes and shows promise as a stable and efficient technology for ammonia wastewater treatment, even under strongly acidic conditions.