Cu2O/Biochar-Styrene acrylic double layer composite coatings modified by NaCl: Special surface and antifouling performance

[Display omitted] •Cu2O/BC/SA-SA double-layer coatings were designed and prepared.•Cu2O/BC-SA coating was prepared and modified by NaCl for porous structure.•Efficiency layer has a faster release rate of Cu2+.•Large capacity photobioreactor was designed to test antifouling property.•3 wt% NaCl modifying coating has the best antifouling property against microalgae. In order to pursue optimize antifouling performance and protect the metal substrate from direct contact with external environment, the sodium chloride (NaCl) modified cuprous oxide (Cu2O)/Biochar (BC)/styrene-acrylic (SA)-SA double-layer coatings with the effective and controllable release rate of Cu2+ were prepared. The NaCl particles were dispersed and dissolved in the Cu2O/BC/SA layer (the functional layer) as the pore-forming agent, which can increase the contact between Cu2O/BC and external environment in order to control the release rate of Cu2+ of coatings. A large capacity photobioreactor was designed to conduct adhesion tests of marine microalgae Nannochloropsis oceanica (N. oceanica) and fresh Chlorella vulgaris (C. vulgaris) on the coatings, aiming to evaluate the antifouling performance. Results show that the Cu2O/BC/SA-SA coating modified with 3 wt% NaCl possesses the best antifouling property, which is 63.7 % higher than that of unmodified coating and 92.8 % higher than that of pure SA membrane.