Evaluation of Removal Mechanisms in a Graphene Oxide-Coated Ceramic Ultrafiltration Membrane for Retention of Natural Organic Matter, Pharmaceuticals, and Inorganic Salts

Abstract

Functionalized graphene oxide (GO), derived from pure graphite via the modified Hummer method, was used to modify commercially available ceramic ultrafiltration membranes using the vacuum method. The modified ceramic membrane functionalized with GO (ceramic) was characterized using a variety of analysis techniques and exhibited higher hydrophilicity and increased negative charge compared with the pristine ceramic membrane. Although the pure water permeability of the ceramic membrane (14.4-58.6 L/m h/bar) was slightly lower than that of the pristine membrane (25.1-62.7 L/m h/bar), the removal efficiencies associated with hydrophobic attraction and charge effects were improved significantly after GO coating. Additionally, solute transport in the GO nanosheets of the ceramic membrane played a vital role in the retention of target compounds: natural organic matter (NOM; humic acid and tannic acid), pharmaceuticals (ibuprofen and sulfamethoxazole), and inorganic salts (NaCl, NaSO, CaCl, and CaSO). While the retention efficiencies of NOM, pharmaceuticals, and inorganic salts in the pristine membrane were 74.6%, 15.3%, and 2.9%, respectively, these increased to 93.5%, 51.0%, and 31.4% for the ceramic membrane. Consequently, the improved removal mechanisms of the membrane modified with functionalized GO nanosheets can provide efficient retention for water treatment under suboptimal environmental conditions of pH and ionic strength.

Nano-based adsorbent and photocatalyst use for pharmaceutical contaminant removal during indirect potable water reuse

“…The oxygen rich structure of GO has been shown to increase hydrophilicity, decrease pore size, as well as increase electrostatic repulsion, thereby, improving its removal mechanism of contaminants for water treatment. 88 In particular, GO coated membranes were shown to retain approximately 20% more of the pharmaceuticals (ibuprofen and sulfamethoxazole) than the uncoated ultrafiltration membrane. 88 Furthermore, 0.22 μm membranes coated with GO and AC have shown 98.9% removal of tetracycline hydrochloride via vacuum filtration.…”

“…88 In particular, GO coated membranes were shown to retain approximately 20% more of the pharmaceuticals (ibuprofen and sulfamethoxazole) than the uncoated ultrafiltration membrane. 88 Furthermore, 0.22 μm membranes coated with GO and AC have shown 98.9% removal of tetracycline hydrochloride via vacuum filtration. 104 Since very little information about pharmaceutical removal is out there, assumptions about the behavior towards pharmaceutical removal are complicated, however, the inclusion of graphene and graphene oxide have been a probe to exhibit good antimicrobial and durability properties.…”

“…While nanofiltration and reverse osmosis membranes are highly effective, they require more energy than microfiltration and ultrafiltration membranes. As such, different membrane technologies are continuously being investigated, such as ceramic membranes, 87,88 polymer membranes, 89,90 metal-organic frameworks, 67 or other advanced membranes. 91 While a vast variety of membranes exist, polyamide-based membranes are one of the most commonly used membranes for EPC removal.…”

“…87 However, when the coating was with GO, the membrane was only able to remove approximately 50% of the EPC. 88 Furthermore, polymer membranes such as polyamide membranes 89 were able to remove 50 to 95% of the pharmaceutical compound studied. 97 The modification of polysulfone with graphene oxide showed efficiencies in removal higher than 90%.…”

Review of MXenes as new nanomaterials for energy storage/delivery and selected environmental applications

“…Many waterborne inorganic and organic contaminants occur worldwide [131][132][133][134][135][136]; effective water and wastewater treatments are essential. Existing methods include coagulation-flocculationsedimentation, softening, addition of granular/powdered activated carbon or carbon nanomaterials, oxidation (e.g., chlorination, ozonation, ultraviolet (UV) light oxidation, and sonodegradation), biological degradation, and membrane filtration [16,17,[137][138][139][140][141][142][143][144][145][146][147][148]. Adsorption is favored, being feasible, extensively applicable, and relatively low-cost [149].…”