Nanofiltration Mixed Matrix Membranes from Cellulose Modified with Zn-Based Metal–Organic Frameworks for the Enhanced Water Treatment from Heavy Metal Ions

Abstract

Nowadays, nanofiltration is actively used for water softening and disinfection, pre-treatment, nitrate, and color removal, in particular, for heavy metal ions removal from wastewater. In this regard, new, effective materials are required. In the present work, novel sustainable porous membranes from cellulose acetate (CA) and supported membranes consisting of CA porous substrate with a thin dense selective layer from carboxymethyl cellulose (CMC) modified with first-time synthesized Zn-based metal–organic frameworks (Zn(SEB), Zn(BDC)Si, Zn(BIM)) were developed to increase the efficiency of nanofiltration for the removal of heavy metal ions. Zn-based MOFs were characterized by sorption measurements, X-ray diffraction (XRD), and scanning electron microscopy (SEM). The obtained membranes were studied by the spectroscopic (FTIR), standard porosimetry and microscopic (SEM and AFM) methods, and contact angle measurement. The CA porous support was compared with other, prepared in the present work, porous substrates from poly(m-phenylene isophthalamide) and polyacrylonitrile. Membrane performance was tested in the nanofiltration of the model and real mixtures containing heavy metal ions. The improvement of the transport properties of the developed membranes was achieved through Zn-based MOF modification due to their porous structure, hydrophilic properties, and different particle shapes.

Pervaporation Membranes Based on Polyelectrolyte Complex of Sodium Alginate/Polyethyleneimine Modified with Graphene Oxide for Ethanol Dehydration

“…The creation of a thin dense selective layer on a substrate may cause some defects, such as non-uniform thickness of the layer and some clogging of the substrate pores [49]. The influence of the choice of the nature and structure of substrates on transport properties was also previously confirmed for supported membranes with a thin dense selective layer based on carboxymethylcellulose, polyvinyl alcohol, CS, and SA [51][52][53][54].…”

Holmium-Containing Metal-Organic Frameworks as Modifiers for PEBA-Based Membranes

“…For gas separation, a large specific surface plays a major role, but for processes of liquid mixture separation, it is not so significant, especially taking into account the fact that MOFs are introduced inside the PEBA polymer film in this study. The habit and size of crystals, as well as the porosity of MOFs, will largely determine the transport properties of MMMs [ 42 , 46 , 98 ]. It should be noted that in order to obtain highly porous materials, many factors must be taken into account, in particular, the used solvent during synthesis.…”

“…Most modern research into the use of membrane technologies for the separation of components is based on the use of mixed matrix membranes (MMMs) containing various additives, such as metal oxides, fullerene and its derivatives, MOFs, etc. [ 38 , 39 , 40 , 41 , 42 , 43 , 44 ]. MOFs are one of the promising modifiers of membranes due to their surface area and functionality, controlled size and form of pores and particles [ 45 ].…”

“…MOFs are one of the promising modifiers of membranes due to their surface area and functionality, controlled size and form of pores and particles [ 45 ]. MMMs based on polymer/MOFs are actively used for different membrane processes—pervaporation, ultrafiltration, gas separation and nanofiltration [ 41 , 42 , 46 , 47 , 48 ]. In recent years, nanofiltration MMMs based on polymer/MOFs were investigated for metal ion [ 42 , 46 , 49 ] and dye [ 49 , 50 , 51 , 52 ] removal from water.…”

“…MMMs based on polymer/MOFs are actively used for different membrane processes—pervaporation, ultrafiltration, gas separation and nanofiltration [ 41 , 42 , 46 , 47 , 48 ]. In recent years, nanofiltration MMMs based on polymer/MOFs were investigated for metal ion [ 42 , 46 , 49 ] and dye [ 49 , 50 , 51 , 52 ] removal from water. In the study [ 49 ], polyethersulfone (PES) membranes modified with various UiO-66-NH 2 content were tested in the nanofiltration of three dyes (Methylene Blue, Rhodamine B and Reactive Blue 21).…”