Performance evaluation of cellulose triacetate and cellulose diacetate hybrid membranes with carbon nanotube (CNT) for sustainable slaughterhouse wastewater treatment via forward osmosis

Abstract Slaughterhouse wastewater (SW) contains high organic matter and nutrients, requiring sustainable treatment methods like forward osmosis (FO). This study evaluates the performance of four membranes: M1 (cellulose triacetate), M2 (M1 with carbon nanotubes), M3 (cellulose triacetate/diacetate), and M4 (M3 with carbon nanotubes) for treating SW. It reports the first-time use of CNTs in a hybrid membrane (CTA/CDA) for FO applications. Characterization showed that CNTs improved the mechanical and structural properties of M1, increasing the contact angle from 68 to 75 °C and roughness from 499.59 to 542.57 nm. However, for M3, the addition of CNTs in M4 decreased the contact angle from 88 to 77° and roughness from 773.088 to 620.001 nm. While CNTs enhanced hydrophilicity, they reduced permeability and fouling resistance due to fewer water transport channels. FTIR analysis revealed distinct stretching patterns correlating with variations in contact angles and membrane performance. The evaluation of membranes in forward osmosis (FO) comprised four phases. In Phase 1, membrane M3 excelled with 91.6% water removal and 0.32 LMH flux using 0.5 M MgCl₂, outperforming M4 at 80.84% and 0.28 LMH due to Mg²⁺ ion accumulation in M4. Phase 2 confirmed M3’s superiority with MgCl₂ among the four 0.5 M draw solutions. In Phase 3, M3 demonstrated an enhancement of 93.76% and 0.33 LMH with a 1 M solution., while M4’s performance reached 90.91% with 1 M NH₄HCO₃. Overall, low water flux was attributed to the lower circulation rates of feed and draw solutions. Phase 4 showed that M3’s water flux supported the growth of Dunaliella salina , while M4’s lower-salinity flux hindered it. This study explores the potential of hybrid membranes reinforced with carbon nanotubes (CNTs) for forward osmosis in treating slaughterhouse wastewater. It reveals a gap in data regarding CTA and CDA blends with CNTs, marking this as a new research area. The findings indicate that CNTs do not enhance the performance of hybrid membranes for this application; therefore, cost-effective membrane (M3) using recyclable solutes like NH₄HCO₃ present a promising solution for sustainable wastewater treatment.