Introduction Deterioration of water resources due to heavy metal pollutants, such as lead and cadmium and other metals, have become an emerging concern for environmental agencies and governmental authorities around the world. The accumulation and persistence of such heavy metals in the food chain elevate its threat of toxicity, even when found at low concentrations in water [1, 2]. The increment of heavy metals pollution comes from industrial revolution and transportation activities that contribute heavily with heavy metal discharge to the environment. Different methodologies have been applied to minimize heavy metals pollution in water resources, such as precipitation, coagulation [1], nanomaterials [3] ion exchange [4], adsorption [5], oxidation/reduction [6] and biosorption methods, which is being applied in this study. In the biosorption method, pretreated natural substances such as seaweed or algae are used as sorbents of pollutants and become a promising alternative to the traditional physicochemical methods used for water treatment [7–12]. The Red Sea area features an important biodiversity hotspot for marine life organisms that is still being explored [13]. New algal species have been recorded in the western shores of Saudi Arabia over the past few decades [14, 15], especially in industrial areas such as Jeddah and Yanbu, where pollution, eutrophication and overfshing occur [16, 17]. Pol. J. Environ. Stud. Vol. 28, No. 5 (2019), 3589-3596 Original Research Removal of Lead and Cadmium Ions from Water Using Cladophora Biomass Abdulaziz N. Amro 1 *, Mohammad K. Abhary 2 1 Chemistry Department, Faculty of Science, Taibah University, Al Madinah Al Munawwarah, Kingdom of Saudi Arabia 2 Biology Department, Faculty of Science, Taibah University, Al Madinah Al Munawwarah, Kingdom of Saudi Arabia Received: 12 April 2018 Accepted: 26 August 2018 Abstract Cladophora biomass has been treated and used for the removal of Lead and Cadmium ions from water, and the characterization of Cladophora biomass by Fourier transform infrared (FTIR) and energy- dispersive x-ray analysis (EDS) indicate the presence of functional groups of different components such as polysaccharides, amino acids, fatty acids and others. Scanning electron microscopy (SEM) and surface area analysis (BET) confrm nonporous algal biomass with small surface area. The parameters affecting metal ions removal from water such as adsorbent-solution contact time, pH of metal ion solution, algal biomass dose and mesh sizes have been studied. Isothermal study has been applied using Freundlich and Langmuir models. Keywords: Cladophora biomass; water treatment; lead; cadmium; isothermal study *e-mail: abdulazizamro@yahoo.com DOI: 10.15244/pjoes/94622 ONLINE PUBLICATION DATE: 2019-05-03