This study investigates the diesel engine emission performances using novel emission filters with varying boron contents for environmental treatment.The filters, made from materials such as waste fly ash, waste boron clay, metakaolin, talc, MgO2, Al2O3, and boric acid, are designed in an open-cell geopolymer structure.These filters are tested in a diesel engine exhaust system at speeds of 1500 rpm, 1800 rpm, and 2400 rpm.Results indicate that the filters optimize emissions, reducing CO by 25%-44 % and HC by 11%-29 %.The open-cell geopolymer filters, with over 90 % filtration efficiency, prove effective in removing soot and particulates, demonstrating their potential as diesel particulate filters.Among the filters tested, Filter-2, with 5 % boron content, shows the highest filtration efficiency (62.58 %) for CO, HC, K, and particulates, making it the most effective.The findings suggest that boron-based filters hold significant promise for reducing emissions and protecting the environment in diesel engines.Addnl., these filters combine Diesel Oxidation Catalyst (DOC) and Diesel Particulate Filter (DPF) functions into a single material, offering an innovative, efficient alternative to sep. DOC and DPF systems.