_Applied_  
_sciences_  
_Hosynthesis of Zinc Oxide Nanoparticles Using Leaf Extract of Prosopis juliflora_ as Potential Photocatalyst for the Treatment of Paper Mill Effluent  
[PERSON] 1,2,*, [PERSON] 2, [PERSON] 2, [PERSON] 2, [PERSON] 2, [PERSON] 3, [PERSON] 1,4,5, [PERSON] 5,6, [PERSON] 5,7, [PERSON] 1,6, [PERSON] 1, [PERSON] 8, [PERSON] 9 and [PERSON] 10,11,*  
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1 Biology Department, Faculty of Science, King Khalid University, Abha 61321, Saudi Arabia; [EMAIL_ADDRESS] (A.E.A. ); [EMAIL_ADDRESS] (S.A.A. ); [EMAIL_ADDRESS] (M.A.A.) \\
2 Department of Botany and Microbiology, Faculty of Science, South Valley University, Qena 83523, Egypt; sabah.hammad2@sci.siv.edu.e (S.A.H. ); [EMAIL_ADDRESS] (H.S. ); [EMAIL_ADDRESS] (L.M. ); [EMAIL_ADDRESS] (M.K.A.) \\
3 Department of Chemistry, Faculty of Science, South Valley University, Qena 83523, Egypt; [EMAIL_ADDRESS] \\
4 Department of Theriogenology, Faculty of Veterinary Medicine, South Valley University, Qena 83523, Egypt; [EMAIL_ADDRESS] (S.K.A. ); [EMAIL_ADDRESS] (M.A.T.) \\
5 Biology Department, College of Arts and Science, King Khalid University, Muhayl Asir 65259, Saudi Arabia; [EMAIL_ADDRESS] (S.K.A. ); [EMAIL_ADDRESS] (M.A.T.) \\
6 Biology Department, College of Science, Ibb University, Ibb 70270, Yemen \\
7 Botany Department, Faculty of Science, Aswan University, Awasan 51528, Egypt \\
8 Department of Horticulture, Faculty of Agriculture and Natural Resources, Aswan University, Aswan 81528, Egypt; [EMAIL_ADDRESS] \\
9 School of Engineering, University of Petroleum and Energy Studies, Bidholi, Dehradun 248007, India; [EMAIL_ADDRESS] \\
10 Physics Department, College of Science, Jouf University, Sakaka 72311, Saudi Arabia \\
11 Physics Department, Faculty of Science, South Valley University, Qena 83523, Egypt \\
* Correspondence: [EMAIL_ADDRESS] (A.M.A. ); [EMAIL_ADDRESS] (M.M.J. ); Tel: +966-540271385 (A.M.A. ); ap11231194. [[https://doi.org/10.3390/appl1231194](https://doi.org/10.3390/appl1231194)]([https://doi.org/10.3390/appl1231194](https://doi.org/10.3390/appl1231194)) \\
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and heavy metals, as well as chlorinated organics, lignin, aromatic hydrocarbons, unsaturated fatty acids. which cause aquatic and non-aquatic life to deteriorate [2; 3; 5]. As a result, untreated paper mill effluent poses harm to the natural environment, requiring the development of a treatment approach. Chemical decomposition, coagulation, adsorption, and biological processes, as well as UV radiation disinfection, are applied for treating paper mill effluent [6]. These methods, however, have several significant drawbacks, chemicals used in chemical treatment operations, for example, have a high toxicity [7]. The reagents' biocompatibility and biodegradability [3]. To combat the conventional limitations, nanotechnology has emerged as an alternative efficient and effective method for wastewater treatment [8]. The majority of nanomaterials research has concentrated on nanoparticles because they are easy to prepare. Metal nanoparticles have gotten a lot of considerable attention in recent decades because of their wide range of uses in medicine, biology, physics, chemistry, and materials science [9]. ZnO nanoparticles are recognized to be one of the more useful nano sizes. ZnO is important for industrial and medical applications due to its wide bandgap and strong excitonic binding energy [10]. Photocatalysis is a term that refers to the combination of photochemistry and catalysis [11]. It means that a chemical reaction should be started or accelerated with assistance of light and a catalyst. To put it another way, photocatalysis is the \"a photoreaction that is accelerated in the presence of a catalyst\". This definition covers photosensization, which is a process in which one chemical species undergoes a photochemical change because of radiation absorption by another chemical species known as the photosensitizer. As a result of the above, heterogeneous photocatalysis involves photoreactions that take place on a catalyst's surface.