Response surface-optimized removal of Reactive Red 120 dye from its aqueous solutions using polyethyleneimine enhanced ultrafiltration

Reactive red 120 retention through ultrafiltration enhanced by synthetic and natural polyelectrolytes

“…Chitosan (MW 670,000 Da), on the other hand is a natural aminopolysaccharide produced chemically from chitin, which closely follows cellulose as the second most predominant variety of bio-polysaccharide [16]. The purchased polymeric solution demonstrated competent performance, even on occasions where any form of polymer solution pretreatment was excluded, as reported a priori by a number of studies [13,17]. Hence, in the present case, the polymer solution was not subjected to any kind of pretreatment, such as diafiltration [1,17,20,23].…”

“…Hence, the polyelectrolyte to dye ratio in each of the ultrafiltration experiments was determined on the basis of their respective weights, that is, weight of the polyelectrolyte/weight of dye in the feed solution (which was 20 L × 50 mg/L = 1 g, in each case), as reported previously by a number of studies [1,17,18]. The ultrafiltration experiments were conducted at the unperturbed room temperature of 35 ± 1 • C; it is noteworthy that such high room temperatures are often encountered, especially during summers, in cases, where experiments are carried out under tropical (Indian) climatic conditions, as has been documented a priori by a number of studies [13,17]. In each case, the pH was moreover adjusted as necessary using NaOH or HCl.…”

“…The concentration of RR 120 ( max = 506 nm) in each of the permeate samples was thus determined, and the dye rejection efficiency was hence calculated as [13]:…”

“…Moreover, these scientific investigations mostly cater to the removal of cationic dyes such as methylene blue, crystal violet, and malachite green by way of PEUF technology [1,[30][31][32]. The potential use of PEUF for enabling the retention of reactive anionic dyes nonetheless has seldom been explored [13].…”

“…In this scenario, the genesis of the ingeniously configured and environmentally benign polymer enhanced ultrafiltration (PEUF) technology can be viewed as a pragmatic answer to the scientists' unflagging quest for an innocuous yet efficient coloured effluent treatment technique, which also has the potential to bring about sizable reclamation of process water in the current water stressed global arena. The futuristic PEUF technique is essentially a cost effective and energy-efficient membrane based separation process, which is suitably engineered to amalgamate the superior selectivity, usually demonstrated by the nanofiltration (NF)/reverse osmosis (RO) process, with the provision of reasonably high permeation flux, offered characteristically by the UF process [13,14]. The PEUF process can be described as a hybrid complexation-ultrafiltration process, wherein, judiciously selected high molecular weight water-soluble polymeric macroligands bind to the target ionic species, forming macromolecular complexes that are subsequently retained via ultrafiltration.…”