Check https://socratic.org/questions/why-do-aromatic-rings-absorb-light

Also check https://www.shimadzu.com/an/service-support/technical-support/technical-information/uv-ap/apl.html

Thanks a lot Chinaza. let me check

Dear Jawad, thanks for posting this very interesting technical question. In addition to the important general information provided by Chinaza Godswill Awuchi you might be interested in reading the following article in which a practical application of the UV light absorption of humic and fulvic acids is reported:

Influence of humic substances on the ultraviolet disinfection of surface waters

Article Influence of humic substances on the ultraviolet disinfectio...

This article has been posted by the authors as public full text on RG. Thus you can freely download it as pdf file.

Also please have a look at the following relevant article:

The usefulness of UV–visible and fluorescence spectroscopies to study the chemical nature of humic substances from soils and composts

https://www.timacagro.com/app/uploads/sites/32/2017/11/5047-URT-06-Spain-FA-2-chemical-nature-of-humic-substances.pdf

This paper is freely available as full text from the internet (see attached pdf file).

Yet another article which provides useful information with respect to your question is the following:

The importance of aromaticity to describe the interactions of organic matter with carbonaceous materials depends on molecular weight and sorbent geometry

Article The importance of aromaticity to describe the interactions o...

This paper has not yet been posted as public full text on RG. However, six of the authors have RG profiles, so that there is a good chance that you can request the full text directly from one of the authors.

Good luck with your research and best wishes, Frank Edelmann

Thanks a lot sir Frank T. Edelmann for your valuable suggestion.