<p>The rapid growth of the electronics industry has exacerbated the issue of heavy metal–contaminated wastewater, leading to significant environmental challenges. In recent years, various methods have been developed for heavy metal removal, among which membrane technology offers a practical and efficient approach to water purification. Chitosan, an abundant, biodegradable, and non-toxic biopolymer, serves as an excellent heavy metal adsorbent due to its high adsorption capacity and its versatility in film formation. As a result, chitosan-based membranes are regarded as superior alternatives to conventional membranes for heavy metal removal due to their active functional groups. In this study, porous chitosan membranes were prepared using silica particles as pore-forming agents. The fabrication process involved: (1) ozone treatment of a thin chitosan film, (2) casting a mixture of chitosan and silica particles onto the treated film, (3) drying the composite film and immersing it in a NaOH solution to remove the silica particles and create a porous structure, and (4) crosslinking the porous membrane by immersion in an epichlorohydrin solution. To optimize membrane properties, we adjusted the silica particle stirring time during the mixing process and monitored its effect on pore size, ultimately identifying conditions that yielded a membrane with improved heavy metal adsorption efficiency. </p> Graphical Abstract <p></p>