Abstract The goal of this study is to examine sorption capacity of chitin-glucan (ChGC) and chitosan-glucan (CsGC) biopolymer complexes extracted from the fungus Aspergillus niger mycelium which is a by-product of citric acid production. It was established that the sorption capacity of diacetylated CsGC with primary amine groups is higher against Pb2+ and Сu2+ (130-140 mg/g) as compared with ChGC (50-80 mg/g). Three abstract models of adsorption isotherms with a high correlation coefficient correspond to Langmuir (R2=0.99), Freundlich (R2=0.96) Models and Micropore Volume Filling Theory (MVF) (R2=0.95). The Langmuir Model (0.78-0.80 g-mole/kg) makes possible to establish a value of the maximum adsorption capacity more precisely. Higher values of Pb2+and Cu2+adsorption effective capacity by the Dubinin-Radushkevich equation (2.6-5.5 kJ/g-mole) indicate there is an interaction between sorbate and sorbent functional groups forming stable complex chelate structures. The study results show that production of chitin- and chitosan-glucan biopolymers from fungus Aspergillus niger mycelial by-products and their use to remove lead, copper and other heavy metals capable to form chelate compounds from aqueous solutions have highly promising future.