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Membrane separation technology is one of the most promising strategies for post-combustion CO 2 capture. The high-performance membrane module is one of the most critical components in the CO 2 capture membrane system. The spiral-wound module is a promising type for industrial application; however, most of the research remains in the laboratory. In this work, industrial-scale spiral-wound membrane modules containing facilitated transport membranes have been developed and investigated. Under given practical operating conditions, an apparent gas separation performance was defined as an indicator to study the effects of various feed conditions on membrane performance within the module. As a crucial process parameter, the operating pressure was considered a variable to investigate the module performance at a fixed feed-to-permeate pressure ratio, and techno-economic indicators were also studied. Furthermore, a multi-core module containing up to 14 membrane elements was designed based on the experimental results of the arrangement mode cases. This work could bridge the research gap between membrane development and membrane system engineering. It could also provide essential data for the industrial application of post-combustion CO 2 capture. [Display omitted] • The industrial-scale spiral-wound membrane module was developed. • An apparent gas separation performance was defined to investigate feed conditions. • The effects of operating pressure and arrangement mode were discussed. • A multi-core membrane module containing up to 14 elements was designed. [ABSTRACT FROM AUTHOR]

Extraction of lithium from salt lakes is an important route for lithium sources. Due to the unique structure and separation mechanism, i.e., size exclusion and Donnan effect, nanofiltration (NF) is considered as a promising way to separate magnesium (Mg2+) and lithium (Li+) ions. However, the Mg2+/Li+ separation factor of NF membrane fabricated by traditional interfacial polymerization (IP) is usually dissatisfactory. Here, a swelling-embedding-shrinking strategy was proposed to modify polyethyleneimine (PEI)/trimesoyl chloride (TMC) NF membranes using diethylenetriamine (DETA) to improve the performance in Mg2+/Li+ separation. The pristine PEI/TMC NF membrane was swollen with methanol to increase the polyamide chain spacing followed by embedding electropositive DETA as a modifier. The charge properties and pore structure of the active layer could be regulated by optimizing the modification conditions. Within comparison to the pristine membrane (TFC-0), the pure water flux of modified NF membrane (TFC-3) increased by 63.6% because of the rougher surface and the larger pore size. Meanwhile, the embedding of electropositive DETA reduced the electronegative property of membrane surface. In consequence, TFC-3 membrane exhibited higher rejection of MgCl 2 (93.9% against 88.4%) and lower rejection of LiCl (31.0% against 32.1%), thus showing a twofold improvement in Mg2+/Li+ separation factor (S Li, Mg = 11.38 against 5.87). The swelling-embedding-shrinking strategy in this article provided a good reference for the modification of NF membranes in the separation of multivalent and monovalent ions. [Display omitted] • A swelling-embedding-shrinking strategy was proposed to enhance membrane performance. • Surface property and pore size could be regulated by embedding diethylenetriamine (DETA). • Modified PEI/TMC NF membrane had higher rejection of Mg2+ but lower rejection of Li+. • Mg2+/Li+ separation factor reached up to 11.38 compared to 5.87 of pristine membrane. [ABSTRACT FROM AUTHOR]

Nanofiltration is considered a promising technology for separation of multivalent/monovalent ions such as extracting lithium from Salt Lake brine with high Mg2+/Li+ ratio. However, the nanofiltration membranes fabricated via conventional interfacial polymerization process generally possess negatively charged surface and have low Mg2+/Li+ selectivity. Herein, we proposed a new and facile method, i.e., reversed interfacial polymerization (RIP), to prepare nanofiltration membranes with positively charged surface and uniform charge distribution. The sequence of amine (polyethyleneimine, PEI) and acyl chloride (trimesoyl chloride, TMC) monomers on polysulfone support was reversed compared to the conventional interfacial polymerization (IP) process. Moreover, the solvent of amine monomer was acetone instead of water. The nanofiltration membranes fabricated by this method exhibited higher water flux (from 4.88 to 22.25 Lm−2h−1) and MgCl 2 rejection (from 84.36% to 97.71%). Meanwhile, LiCl/MgCl 2 separation factor in single salt solution reached up to 13.93, which was almost quadruple compared to the conventional control membrane. In addition, the developed nanofiltration membrane also exhibited an excellent separation selectivity (S Li, Mg = 9.22) in mixture system (Mg2+/Li+ mass ratio of 20), which had good application potential in extracting lithium resources from Salt Lake brine. [Display omitted] • A facile reversed interfacial polymerization (RIP) method was proposed. • Positively charged nanofiltration membranes with uniform charge distribution. • Acetone was selected as solvent of polyethyleneimine monomer instead of water. • Mg2+/Li+ selectivity reached 13.93 and 9.22 in single and mixed salt system, respectively. [ABSTRACT FROM AUTHOR]

The enhancement in selectivity of nanofiltration (NF) membranes is of great significance for extending the application areas and improving the process economy, especially for the separation of monovalent/divalent ions. The characteristics of moderately increased pore size, fewer nonselective defects and a more uniform structure are conducive to NF membrane exhibiting higher rejection of divalent ions but lower rejection of monovalent ions. Nonylphenol polyoxyethylene ether (NP-10) was introduced in interfacial polymerization process in this study to optimize the microstructure and surface properties of polyamide (PA) layer to manufacture highly selective NF membranes. The hydrophobic benzene ring and aliphatic chain in NP-10 could form a local space that restricted the interfacial polymerization reaction on the side of the oil phase, thereby appropriately increasing the pore size of the PA layer. It was advantageous to the permeation of water molecules and monovalent ions with a smaller radius. The long hydrophilic oxyethylene group as a guide could facilitate the uniform diffusion of the monomer to the water/hexane interface. NP-10 as an amphiphilic substance would form a self-assembled network at the water/hexane interface, which was expected to optimize the distribution of aqueous amine monomers at the phase interface. Meanwhile, introducing NP-10 can form a stable interface and reduce the interface disturbance, thus inhibiting the formation of non-selective macropores (or "defects") in PA layer, which could improve the separation selectivity of monovalent/divalent ions. In addition, the hydrophilicity and electronegativity were also enhanced. The results showed that the MWCO of NF membrane increased from 210.1 Da (TFC-0) to 269.6 Da (TFC-0.25), and the average pore radius increased from 0.248 nm to 0.276 nm. The water flux of optimized membrane was doubled compared to the control membrane. Most important, the optimized exhibited higher rejection of divalent Na 2 SO 4 (from 98.07% to 99.43%), and meanwhile lower rejection of monovalent NaCl (from 54.07% to 27.52%). NaCl/Na 2 SO 4 separation factor reached up to 130.53, which was about four times of TFC-0 membrane. [Display omitted] • Separation factor (NaCl/Na 2 SO 4) reached up to 130.53. • Higher rejection of divalent ions but lower rejection of monovalent ions. • Moderately increased pore size, fewer defects, and uniform structure. • Restricted IP reaction to appropriately increase the pore size of PA layer. • A stable interface and reduce the interface disturbance. [ABSTRACT FROM AUTHOR]