You could try chromatography, or vacuum Short path destillation - kugelrohr for example, but i guess it might be out of reach.
However in my opinion it will be enough to recrystallise your CBD in n-pentane, avoid using alcohols such as methanol or ethanol becouse they are highly polar and so most diols are far too soluble in them for succesfull recrystallization, I’d also add activated carbon once CBD has dissolved in solvent then quick filtration (for best hot) and very slowly chill the product.
If the product remains dirty repeat procedure w/ fresh solvent.
* dont add too much activated carbon as it might trap some of your product once most off impurities are gone.
If u Have trouble understanding recrystallization, respond I’ll write down the procedure for u