Effectiveness of carbon polymeric nanofiltration composite membrane in treating industrial textile wastewater

Abstract

Today, the trend is towards the use of low-cost materials to develop green processes in the aim to reduce cost and impact on environment. The use of low-cost materials of natural origin has been proven to be very promising for the fabrication of ceramic membranes for wastewater treatment. In this article, fabrication and testing of high performance microporous carbon membrane for nanofiltration (NF) separation based on mineral coal and phenolic resin are reported. The preparation of the NF composite membrane involved carbonizing a polymeric precursor deposited on a porous supported membrane, using the vacuum slip-casting process to obtain a homogeneous NF top layer almost without defects by one-step coating-carbonization cycle. To ensure a better final membrane texture, several parameters including the viscosity of the casting suspension, the casting time and the carbonization temperature were considered. A crack-free NF membrane with a thickness layer of 1.36 μm, a mean pore size of 1.1 nm, and a molecular weight cut-off of 400 Da was obtained using 1 min casting time and 45% of phenolic resin. These membranes were tested in the treatment of textile wastewater. Promising results in terms of permeate flux and pollutant retention (COD (72%), salinity (45%)) were obtained. The results further showed that the treated wastewater could be recycled into the textile industry or can be discharged into the municipal sewerage in compliance with legislations. In addition, a carbonization temperature of 650°C yielded best membranes in terms of average pores size and membrane permeability with minimum energy consumption.