It　has　been　verified　that,　as　an　emerging　contaminant,　microplastics　are　capable　of　adsorbing　certain　traditional　contaminants　like　the　heavy　metal　Cd.　However,　the　majority　of　previous　studies　only　focused　on　certain　types　of　virgin　microplastics,　especially　for　PE　and　PS.　In　addition,　this　adsorption　process　might　be　affected　by　microplastics　inevitably　undergoing　aging　and　consequent　changes　in　the　natural　environment.　Unfortunately,　the　relevant　reports　on　aging　effects　were　mainly　about　organic　pollutants,　rather　than　heavy　metals.　By　far,　there　have　been　few　comprehensive　and　mechanistic　studies　on　the　key　aging　effects　on　the　Cd　adsorption　by　various　types　of　microplastics.　In　this　study,　five　representative　types　of　microplastics　(i.e.,　PS,　ABS,　PP,　PVC,　and　PET)　were　selected　for　aging　by　ultraviolet　radiation,　and　the　physicochemical　properties　of　virgin　and　aged　microplastics　were　thoroughly　compared,　including　specific　surface　area,　crystallinity,　surface　functional　groups,　and　surface　elements.　Accordingly,　the　changes　in　adsorption　isotherms　of　Cd　by　microplastics　were　discussed.　The　results　showed　that:　aging　induced　non-significant　changes　in　specific　surface　area　but　a　significant　decrease　in　crystallinity.　Surface　functional　groups　also　changed,　including　the　emergence　of　a　CFY=,　1O　functional　group　on　PS　and　ABS,　the　decrease　in　CFY=,　1C　absorption　peak　intensity　on　ABS,　and　the　increase　in　absorption　peak　intensities　of　CFY=,　1O,　C-O,　and　polar　ester　groups　on　PET.　Regarding　surface　C　content,　CFY=,　1C/C-C　decreased,　whereas　C-O　and　O-CFY=,　1O　increased.　The　total　O　content　and　O/C　significantly　increased　as　well.　The　Langmuir　model　well-fitted　the　adsorption　isotherms　of　Cd　by　virgin　and　aged　microplastics.　Aging　significantly　expanded　the　adsorption　capacity　of　Cd　by　microplastics,　as　the　order　of　saturated　adsorption　capacity　before　aging　was　ABS　(0.228　4　mg•g-1)＞PVC　(0.136　0　mg•g-1)＞PS　(0.128　6　mg•g-1)＞PP　(0.100　5　mg•g-1)＞PET　(0.046　2　mg•g-1)　and　then　became　PS　(0.276　8　mg•g-1)＞ABS　(0.258　6　mg•g-1)＞PVC　(0.177　6　mg•g-1)＞PP　(0.172　1　mg•g-1)＞PET　(0.095　1　mg•g-1)　after　aging.　Both　crystallinity　and　surface　functional　groups　played　key　roles　in　the　adsorption　of　Cd　by　microplastics.　As　for　virgin　microplastics,　crystallinity　was　negatively　correlated　with　the　saturated　adsorption　capacity　of　Cd,　because　the　amorphous　regions　contributed　most　to　Cd　adsorption.　Aging　brought　about　the　decrease　in　crystallinity　and　the　increase　in　amorphous　regions,　which　further　promoted　the　oxidation　reaction　on　microplastics.　Consequently,　oxygen-containing　functional　groups　increased　on　the　surface　and　eventually　expanded　the　adsorption　capacity　of　Cd　by　microplastics.　Note　that　certain　specific　functional　groups　of　various　microplastics　also　had　impacts　on　the　adsorption　process.　These　results　provide　valuable　information　about　the　environmental　behaviors　and　interactions　of　microplastics　and　heavy　metals　in　nature.　©　2022,　Science　Press.　All　right　reserved.