I did a coagulation test on leachate sample with ferric chloride. After a certain dosage and pH level, I observed a dramatic increase in the UV absorbance. Also there was no precipitation/flocculation taking place after that dosage. Even though the organic matter was reducing, the UV absorbance was increasing. I looked in some paper where I found out about humic acid-iron complexation. I would like to know whether it the complexation that is causing the increase in UV absorbance. I would appreciate if someone can suggest me a paper on a study that can help.