Development of Ultrafiltration Kaolin Membranes over Sand and Zeolite Supports for the Treatment of Electroplating Wastewater

Abstract

A high cost of high-purity materials is one of the major factors that limit the application of ceramic membranes. Consequently, the focus was shifted to using natural and abundant low-cost materials such as zeolite, clay, sand, etc. as alternatives to well-known pure metallic oxides, such as alumina, silica, zirconia and titania, which are usually used for ceramic membrane fabrication. As a contribution to this area, the development and characterization of new low-cost ultrafiltration (UF) membranes made from natural Tunisian kaolin are presented in this work. The asymmetric ceramic membranes were developed via layer-by-layer and slip-casting methods by direct coating on tubular supports previously prepared from sand and zeolite via the extrusion process. Referring to the results, it was found that the UF kaolin top layer is homogenous and exhibits good adhesion to different supports. In addition, the kaolin/sand and kaolin/zeolite membranes present an average pore diameter in the range of 4–17 nm and 28 nm, and water permeability of 491 L/h.m2.bar and 182 L/h.m2.bar, respectively. Both membranes were evaluated in their treatment of electroplating wastewater. This was done by removing oil and heavy metals using a homemade crossflow UF pilot plant operated at a temperature of 60 °C to reduce the viscosity of the effluent, and the transmembrane pressure (TMP) of 1 and 3 bar for kaolin/sand and kaolin/zeolite, respectively. Under these conditions, our membranes exhibit high permeability in the range of 306–336 L/h.m2.bar, an almost total oil and lead retention, a retention up to 96% for chemical oxygen demand (COD), 96% for copper and 94% for zinc. The overall data suggest that the developed kaolin membranes have the potential for remediation of oily industrial effluents contaminated by oil and heavy metals.

Performance Assessment of a New Flat Sepiolite Clay-Based Ultrafiltration Membrane for the Removal of Paracetamol and Indigo Blue Dyes from Two Synthetic Aqueous Solutions

“…Contrary to the mechanical strength, as shown in Figure 7, the porosity decreased with an increasing in sintering temperature. This result is consistent with the trends found in the literature [38,44], indicating that an increase in the sintering temperature promotes particle fusion and compaction, thereby reducing the overall porosity of the sepiolite membrane. This densification leads to a decrease in the volume of void spaces within the material, resulting in a more compact and homogeneous structure which reduces the porosity.…”

“…A higher FDR value indicates a greater decrease in the permeate flux, showing a higher susceptibility to fouling, while a higher FRR value indicates better recovery of the permeate flux after cleaning, demonstrating the membrane's ability to regain its initial performance. FDR and FRR may be calculated and compared to determine the UF membrane's capacity to resist fouling [38].…”

Preparation and Characterization of New and Low-Cost Ceramic Flat Membranes Based on Zeolite-Clay for the Removal of Indigo Blue Dye Molecules

“…For the M S50-Z50 membrane, R 2 is relatively low (<0.900); therefore, it can be deduced that the Hermia model did not correlate with the experimental data. The suggested pore-blocking model for M S10-Z90 and the retained result for M S50-Z50 were similar to the Kaolin membranes prepared in our laboratory [38]. Additionally, Beqqour et al [33] proved standard pore-blocking using a flat membrane made from natural pozzolan and micronized phosphate like our M S30-Z70 membrane.…”

“…In addition, P and S peaks are related to smectite composition. Small carbon-related peaks were detected, which may be due to impurities [38].…”

Application of coal fly ash based ceramic membranes in wastewater treatment: A sustainable alternative to commercial materials

“…Several studies have employed ceramic membranes in wastewater treatment and the search for low-cost and environmentally friendly starting materials has continued to engender research interests. Therefore, solid wastes and readily available materials rich in Al 2 O 3 and SiO 2 such as coal fly ash, natural clay, kaolin and sand can be used as starting material for ceramic membranes [ [40] , [41] , [42] , [43] ]. Studies by Hossain and Roy [ 44 ] and Sawunyama et al [ 45 ] reported that coal fly ash and bentonite clay had significant amounts of Al 2 O 3 and SiO 2 which can make them good candidates for ceramic membranes raw materials.…”