Polyamidoamine-epichlorohydrin (PAE) resins are used in the manufacture of various paper grades and are intended to improve the wet strength of paper. During their production, various hazardous chlorinated by-products are produced, including 1,3-dichloro-2-propanol (DCP) and 3-monochlorpropan-1,2-diol (MCPD). In order to reduce their environmental impact and the associated potential risks on human health, there is a growing need in producing PAE resins with lower concentrations of hazardous by-products. This masters' thesis examined the suitability of membrane technology as a solution in lowering their concentrations in existing resinous products. By performing diafiltrations of PAE resins, different filtration classes of composite spiral wound membranes were tested: ultrafiltration, nanofiltration and reverse osmosis. Membranes’ performance in retaining PAE resins and allowing chlorinated by-products to flow through into the permeate was monitored in parallel with continuous measurements of membrane permeability changes due to fouling. It has been established that nanofiltration with pore sizes from 150-300 Daltons is the most suitable for reducing the content of by-products, meanwhile reverse osmosis is potentially suitable for concentrating them in the obtained permeate, which enables recovery of water for further diafiltration of PAE resins. Additionally, it was found that acidic water with a comparable acidity to PAE resins is the most appropriate for dilution of PAE resins and membrane rinsing. In this way, long diafiltration cycles with minimal membrane fouling can be achieved, which will be brought to a higher industrial level in the future.
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