A system and method to remove a polluting agent or contaminant, including but not limited to mercury, from the liquid phase of a process system using an adsorbent. In one exemplary embodiment, a magnetic or non-magnetic support with a chemisorbing or physisorbing sorbent is suspended in the liquid phase of a process system, under conditions in which the polluting agent binds to the adsorbent. The pollutant-bearing adsorbent may then be separated from the process system by either physical or magnetic means. The polluting agent may then disassociated from the adsorbent so the adsorbent is regenerated and capable of repeated use.