Custom-tailoring loose nanocomposite membrane incorporated bipiperidine/graphene quantum dots for high-efficient dye/salt fractionation in hairwork dyeing effluent

[Display omitted] •Effective fractionation of HDE was feasible by a novel loose NF membrane.•Partial alternative and continuous incorporating of BP and GQDs were involved.•TFN-0.2 membrane exhibited superior flux, dye rejection and salt permeation.•It showed good fouling resistance and stability for HDE treatment. The complete fractionating synthetic and real dye/salt mixtures through loose nanofiltration membranes are of great significance for the textile wastewater recycling and reuse. Therefore, in this paper, a custom-tailoring loose nanocomposite membrane was fabricated to validate the feasibility of high-efficient dye/salt fractionation in the real pretreated hairwork dyeing effluent (HDE). It was observed that after partial alternative doping of 4,4′-bipiperidine and continuous incorporating of graphene quantum dots, the resultant membrane skin-layer features including smoothness, hydrophilicity and surface charge as well as nominal pore size were improved synergistically. Consequently, the optimal TFN-0.2 membrane showed outstanding fractionation and antifouling performance for synthetic dye/salt mixtures and real pretreated HDE. Specifically, for the former, the as-prepared TFN-0.2 membrane displayed the highest water permeance of 56.0 L·m−2·h−1·bar−1, retention for all selected dyes (≥99.8%) and salt permeability (≥91.2%). Besides, the antifouling indexes in terms of reversible and irreversible fouling ratios of TFN-0.2 membrane against HDE solution reduced from 13.3% and 20.7% of pristine one to 8.32% and 1.34%, respectively. While flux recovery ratio markedly enhanced from 79.1% to 98.5% in the meantime. Overall, this work provides a facile method to fabricate high-efficient loose nanofiltration membranes for sustainably and precisely fractionating dye/salt mixtures from textile wastewater.