1 Page 1-9 © MAT Journals 2023. All Rights Reserved Journal of Water Resources and Pollution Studies www.matjournals.com e-ISSN: 2581-5326 Volume-8, Issue-2 (May-August, 2023) Synthesis of Zero Valent Nickel Nano Biochar Composites from Guava Leaf Extract for the Adsorption of Heavy Metals from Wastewater Michael Chika Egwunyenga 1* , Wisdom Chukwuemeke Ulakpa 2 , Lucy U. Modebe 3 , Cyril O. Anakpoha 4 1 Lecturer, Department of Chemical Engineering, Delta State Polytechnic Ogwashi –Uku, Nigeria 2,4 Lecturer, Department of Petroleum Chemistry, Delta State University of Science and Technology, Ozoro, Nigeria 3 Lecturer, Department of Chemical Engineering, University of Delta, Agbor, Nigeria * Corresponding Author: michaelchika90@gmail.com Received Date: March 17,2023 Published Date: March 27,2023 ABSTRACT Aforesaid materials has weaknesses as adsorbents, the rising demand for adsorption as a wastewater treatment approach demands the search for a suitable composite that combines the benefits of nanoparticles and porous support material. In this study, zero valent nickel nanoparticles were produced and immobilized/deposited on the zinc chloride-activated surface of Biochar for wastewater remediation. Psidium guajava Guava) leaves were gathered and the leaf extract was made; subsequently, nickel nanoparticles were biosynthesized utilizing the obtained leaf extract as the reducing agent. Furthermore, Zinc chloride-activated biochar was employed as a support medium for the inclusion of the Nickel nano biochar composite. The morphological structures, crystalline natures, and functional groups of the nickel nanoparticles (NiNPs) and nickel nano biochar composite were determined using High-Resolution Scanning Electron Microscopy (HRSEM), X-ray powder diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR), respectively. This study's findings suggest that the synthesized nanocomposite can be employed in wastewater treatment. Keywords- Adsorption, Biosynthesis, Guava leaf extract, Nanocomposite, Remediation, Wastewater INTRODUCTION Water supply pollution brought on by human industrial activity is a recent trend in environmental and aquatic concern that is causing a global water problem. The bulk of the pollutants in industrial effluents that are hazardous to the environment and the general people are heavy metals [1]. Because of their prevalence in wastewater, mercury (II) (Hg 2+ ) and chromium (VI) (Cr 6+ ), for example, have gained major global awareness and concern from researchers. Mercury is generally released into the environment through industrial activities such as pharmaceutical manufacturing, paint manufacturing, nonferrous smelting, waste incineration, pesticide production, and energy generation. Chromium is emitted by the battery, leather, electroplating, cosmetics, tanning, textiles, and plastic sectors [2]. Mercury buildup in the human body causes serious harm to the skin, liver, kidneys, thyroid, immunological system, and central nervous system [1]. Prolonged chromium exposure is also carcinogenic, and mutagenic, and causes diarrhoea, asthma, and severe brain, kidney, and liver damage [3]. As a result, removing mercury and chromium from wastewater to achieve acceptable concentrations of drinking water of 0.002 to 0.006 mg/L and 0.06 to 0.09 mg/l is an urgent challenge [4]. Though a variety of water treatment techniques, including coagulation, chemical oxidation, reverse osmosis, flocculation, ultrafiltration, bioremediation, and adsorption, have been employed for wastewater remediation over time, their shortcomings have heightened the demand for more effective wastewater remediation techniques [1]. Currently, adsorption is the most widely accepted wastewater remediation technique, thanks to its ease of operation, low cost, and reusability frequency [5]. Going forward, the