Initially, the Diesel Particulate Filters (DPF) were standardized in 2009 and were added to the vehicles emissions legislation.
The DPF usually removes the diesel particulate matter that is generally termed as soot from the exhaust gas of the diesel vehicle. This ultimately helps in reducing the particulate emissions in the vehicle. The DPF usually helps in removing more than 85% of the soot from the exhaust gas of majorly diesel vehicles.
Role of DPF:
Just similar to the exhaust silencer the DPF works by forcing engine gasses in order to flow through the complex ceramic honeycomb structure. The gasses are generally forced to flow through the cell walls in order to exit the filter as the channels of the filter are blocked at the alternate ends.
Besides that, the particulate matter gets deposited gets trapped in the filter while ensuring that only clean exhaust gasses are exiting from the system. Thus, this is how DPF helps in preventing soot with the vehicle emissions.
Source: https://hydraulicsaustralia.blogspot.com/2017/11/a-definitive-guide-on-role-of-diesel.html