Yes it is possible to use robots for this. However, they are expensive and need a lot of energy. So other projects are suggesting to use floating nets instead to remove plastic waste: https://theoceancleanup.com/oceans/
Yes it is very possible for robots to help us! We would need to train the robots to recognise certain colours, shapes and textures and then it could pick up rubbish in the ocean! Ideally it could be powered by renewable energy sources so we wouldn’t have to charge it. The only problem would be getting it to come home as it would need GPS to get home and as you can guess internet reception is not that good in the ocean!