Biosorption of heavy metal ions by chemically modified biomass of coastal seaweed community: Studies on phycoremediation system modeling and design

•A coastal seaweed community biomass was first used for the bioremoval of zinc ions.•The biosorption capacity of biosorbent was calculated as 115.198 mg g−1.•The prepared composite biosorbent has great potential for zinc biosorption.

Biosorption of heavy metals by seaweeds (marine macroalgae) is a potential environmental biotechnology technique for biotreatment of industrial effluents. However, the co-application of biomasses of different seaweeds for bioremoval of these inorganic pollutants from aqueous phase is very limited. In this study, for the first time, a coastal seaweed community composed of Chaetomorpha sp., Polysiphonia sp., Ulva sp. and Cystoseira sp. species harvested from the north coast of Turkey was first treated with sodium hydroxide and then used as natural biosorbent material for the bioremediation of zinc-containing synthetic wastewater. Batch biosorption experiments were performed to optimize the conditions of environmental parameters (pH, biosorbent quantity, heavy metal concentration and contact time). The biosorption capacity of biosorbent for zinc ions was highly affected by the operating conditions. Kinetic studies showed that the biosorption process was multistep, fast and diffusion controlled. The pseudo-second-order rate model well described the biosorption kinetics. The equilibrium data of zinc biosorption fitted best with Sips isotherm model and the maximum biosorption capacity of biosorbent from this model was calculated as 115.198 mg g−1. Thermodynamic parameters indicated that the biosorption process was physical and spontaneous. Besides, a single-stage batch biotreatment system was designed and the kinetic performance of this biosorption system was evaluated. The obtained results revealed that the prepared composite biosorbent could be used as efficient novel biosorbent for zinc removal from aqueous effluents.