I've used these in a drybox to keep filament dry, and they work really well for that, but to actually dry filament I use what amounts to a modified food dehydrator. You really need heat and airflow to get moisture out of already wet filament. If you don't have a food dehydrator you can use, you can also try an oven, but be careful of temperature fluctuations which could cause it to get too hot and melt your filament.
I've used these in a drybox to keep filament dry, and they work really well for that, but to actually dry filament I use what amounts to a modified food dehydrator. You really need heat and airflow to get moisture out of already wet filament. If you don't have a food dehydrator you can use, you can also try an oven, but be careful of temperature fluctuations which could cause it to get too hot and melt your filament.