The present disclosure provides a particulate matter comprising a combination of crystalline manganese oxide and amorphous manganese oxide, the crystalline form being present and forms passages throughout a cross section of said particulate matter, wherein said crystalline form define a specific surface area that is greater than the outer surface of said particulate matter. Also provided herein is a process for removing chemical contaminants from flowing water making use of the particulate matter and a device and a system comprising the particulate matter.