Abstract
The effective separation of dyes and inorganic salts is highly desirable for recycling inorganic salts and water resource in printing and dyeing wastewater treatment. In this work, tannic acid (TA) and polyethyleneimine (PEI) were grafted on the PES/Fe ultrafiltration membrane via the coordination assembly and Michael addition strategy to fabricated a loose nanofiltration membrane (LNM). The effect of PEI concentration on membrane morphologies and properties was systematically investigated. The membrane surface becomes more hydrophilic and transforms into positive charge after the PEI grafting. The optimized PES/Fe-TA-PEI membrane possesses high pure water flux (124.6 L·m−2·h−1) and excellent dye rejections (98.5%, 99.8%, 98.4%, and 86.4% for Congo red, Eriochrome black T, Alcian blue 8GX, and Bromophenol blue, respectively) under 2 bar operation pressure. Meanwhile, the LNM showed a high Alcian blue 8GX rejection (>98.4%) and low NaCl rejection (<5.3%) for the dye/salt mixed solutions separation. Moreover, the PES/Fe-TA-PEI LNM exhibited good antifouling performance and long-term performance stability. These results reveal that such LNM shows great potential for effective fractionation of dyes and salts and recycling of textile wastewater.
Highlights
With the rapid development of global industrialization, the water consumption and wastewater generation increase annually, which causes serious water shortage and environmental pollution [1,2]
The loose nanofiltration membrane (LNM) were fabricated by coupling technique with NIPs method and grafting strategy
It can be found that the PES/Fe membrane exhibits yellow, while the color changed to yellow-brown after the tannic acid (TA) coordination assembly modification
Summary
With the rapid development of global industrialization, the water consumption and wastewater generation increase annually, which causes serious water shortage and environmental pollution [1,2]. Dyeing wastewater has become a serious environmental problem due to its deep chromaticity, large water quality changes, complex composition, and great harm [3,4]. In the process of dye synthesis, the introduction of inorganic salts to purify the dye products results in a large amount of salt remaining in the dye, which inevitably produces salt-containing dye wastewater [5,6]. In order to improve the dye uptake rate of the fabric, a large amount of inorganic salt is added during the dyeing process. These inorganic salts give the dye wastewater a high recycling value [7,8]. It is very important to realize the effective separation of dye and salt molecules in dyeing wastewater
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