Hun first of all if you have damaged skin or itrrated skin then adding any sort of citric will irrtate it further and burn so please AVOID that!
Try the follwing, it really depends on what you skin is like as everyones different and only by seeing my clients i decide whats best for them
Try this
Take like a clean cloth, (facial towl) and place it in boiling water for abit and then use that cloth to put over your fce for 3-4mins… This will help relax and loosen the skin around pores. You could actially skip this if you do this straight after a shower as after a shower your skjns very soft and open pores due to temp and steam.
Anyway then take some baking powder and water and create a fine paste. Apply that paste to the areas of the blck heads and go to sleep 
wale up and wash in morning! Simple as tht… Try to do this roughly 3 times a week and inshallah u’ll be black hed free
For whiteheads just try mixing somehoney with baking soda and scrubby affected areas.
Making a pulp out of fresh garpes and rubbing that is suppse to help.
As for brightening your face use the ones i?ve told u above as they really make a huge impact.especially the carrot mask is great for brightening skin! xx hope this helps hunny
By the way if you do want to use lenon then its ur choice u can add it to the paste too its good but depends in the condition of your skin…