Development of Robust Fluorinated SiO₂/PVDF Composite Hollow Fiber Membrane for Bromine Resources Recovery from Brine via Membrane Distillation

Abstract

In this study, a superhydrophobic composite hollow fiber membrane consisting of a fluorinated silicification layer (fSiO 2 ) upon a poly(vinylidene fluoride) (PVDF) substrate was developed via in situ silicification integrated with surface hydrophobic modification for bromine resources recovery from brine via membrane distillation (MD). The re-entrant hierarchical structure was established via surface silicification, after which (1H,1H,2H,2H-heptadecafluorodecyl) silane was introduced to transfer the surface property to be hydrophobic by reducing the surface energy with long fluorinated chains. The resultant fSiO 2 / PVDF composite membrane exhibited a superhydrophobic property with a water contact angle of 147°, which effectively prevents wetting when conducting MD, and performed a high permeating flux of 0.62 kg•m −2 •h −1 . In a long-term stability test of 10-day operation duration, the fSiO 2 /PVDF composite membrane remained decent, with flux declines of 1.8% and 38.3% when treated by the aqueous bromine solution and real brine, respectively. This work sheds insight into the fabrication of novel inorganic/organic composite membranes for bromine resource extraction from brine.

Developmental Progress of Electrodialysis Technologies and Membrane Materials for Extraction of Lithium from Salt Lake Brines

“…Membrane technology is an advanced separation method with superior operation efficiency and low energy consumption, including microfiltration, ultrafiltration (UF), nanofiltration (NF), reverse osmosis (RO), and electrodialysis (ED). − NF membranes exhibit interception performance between RO and UF, intercepting low-molecular weight organic compounds and high-valent inorganic salts, and have been used to separate magnesium and lithium from brines. ED is an electrically driven membrane process, in which the anions and cations migrate through the membranes directionally under the action of an external electric field.…”

Selective Capture of Bromine over Iodine by a Nanometer-Sized Covalent Organic Framework Containing Imines and Hydrazones

“…The pollution due to these halogens stems from the commercial importance of these elements in the chemical industry. For example, the halogen group of elements is a constituent of various chemical intermediates in the multistep reactions that yield useful pharmaceutical products. , In particular, elemental bromine and its compounds are used for several industrial applications such as brominating butyl rubber (for use in the tire industry), treatment of printed circuit boards, industrial wastewater treatment, production of pesticides and biocides (bromomethane and 1,2-dibromoethane), flame retardants (such as TBBA, DECA, and HBCD), photographic emulsions, brominated drilling fluids, industrial coolants (lithium bromide solutions), and zinc–bromine batteries. − In addition, the use of the oxidizing ability of inorganic bromate salts in the explosives industry, hairdressing, food, and textile industries is also well documented . These applications indicate substantial commercial uses of bromine and also possible point sources of water pollution caused by bromides and other brominated compounds.…”