Leaf chemistry of architecturally defended plants responds more strongly to soil phosphorus variation than non-architecturally defended ones.

Plants utilize a mixture of defence types in response to herbivores, including physical, chemical, and biological defences. Among chemical defences, phenolics are well-known to inhibit digestion and are highly variable across plant species and resource gradients. There are prominent hypotheses predicting the potential change of phenolics in response to soil nutrients, but most focus on nitrogen (N) and none consider their interaction with defence strategies. We proposed an updated theoretical model that incorporates defence types and predicts their relative advantages under herbivore attack. We studied intraspecific leaf chemistry of several architecturally defended and non-architecturally defended species growing together across four sites with varying soil chemistry. We measured individual-level leaf concentrations of carbon, nitrogen, phosphorus (P), potassium (K), and phenolics, and site-level soil N, P, and K. We found that architectural defenders had lower phenolics and higher P than non-architectural defenders across locations. Relationships between soil nutrients and leaf chemistry were steeper in architectural defenders. Most leaf nutrients and phenolics showed significant relationships with soil P, and only leaf P was related to its respective soil resource. Within leaves, phenolics were negatively related to leaf N in both groups but only negatively related to leaf P for architectural defenders. Our results suggest that architectural defenders are less able to accumulate phenolic defences in high P soils than non-architectural defender. One possible explanation is that phenolic production is limited in P-rich soils via active phloem loading, but only in architectural defenders that have defence options other than chemical ones.

Enhancing Nanofiltration Selectivity of Metal-Organic Framework Membranes via a Confined Interfacial Polymerization Strategy.

Development of well-constructed metal-organic framework (MOF) membranes can bring about breakthroughs in nanofiltration (NF) performance for water treatment applications, while the relatively loose structures and inevitable defects usually cause low rejection capacity of MOF membranes. Herein, a confined interfacial polymerization (CIP) method is showcased to synthesize polyamide (PA)-modified NF membranes with MOF nanosheets as the building blocks, yielding a stepwise transition from two-dimensional (2D) MOF membranes to polyamide NF membranes. The CIP process was regulated by adjusting the loading amount of piperazine (PIP)-grafted MOF nanosheets on substrates and the additional content of free PIP monomers distributed among the nanosheets, followed by the reaction with trimesoyl chloride in the organic phase. The prepared optimal membrane exhibited a high Na2SO4 rejection of 98.4% with a satisfactory water permeance of 37.4 L·m-2·h-1·bar-1, which could be achieved by neither the pristine 2D MOF membranes nor the PA membranes containing the MOF nanosheets as the conventional interlayer. The PA-modified MOF membrane also displayed superior stability and enhanced antifouling ability. This CIP strategy provides a novel avenue to develop efficient MOF-based NF membranes with high ion-sieving separation performance for water treatment.

Tailored design of nanofiltration membranes for water treatment based on synthesis-property-performance relationships.

Tailored design of high-performance nanofiltration (NF) membranes is desirable because the requirements for membrane performance, particularly ion/salt rejection and selectivity, differ among the various applications of NF technology ranging from drinking water production to resource mining. However, this customization greatly relies on a comprehensive understanding of the influence of membrane fabrication methods and conditions on membrane properties and the relationships between the membrane structural and physicochemical properties and membrane performance. Since the inception of NF, much progress has been made in forming the foundation of tailored design of NF membranes and the underlying governing principles. This progress includes theories regarding NF mass transfer and solute rejection, further exploitation of the classical interfacial polymerization technique, and development of novel materials and membrane fabrication methods. In this critical review, we first summarize the progress made in controllable design of NF membrane properties in recent years from the perspective of optimizing interfacial polymerization techniques and adopting new manufacturing processes and materials. We then discuss the property-performance relationships based on solvent/solute mass transfer theories and mathematical models, and draw conclusions on membrane structural and physicochemical parameter regulation by modifying the fabrication process to improve membrane separation performance. Next, existing and potential applications of these NF membranes in water treatment processes are systematically discussed according to the different separation requirements. Finally, we point out the prospects and challenges of tailored design of NF membranes for water treatment applications. This review bridges the long-existing gaps between the pressing demand for suitable NF membranes from the industrial community and the surge of publications by the scientific community in recent years.

Revisiting the Surface Energy Parameters of Standard Test Liquids with a Corrected Contact Angle Method over Rough Surfaces.

Interfacial free energy is a quantitative basis for explaining and predicting interfacial behavior that is ubiquitous in nature. The contact angle (CA) method can determine the surface free energy (γ) as well as Lifshitz-van der Waals (γLW) and Lewis acid/base (γ+/γ-) components of a solid material from its CAs with a set of known test liquids according to the extended Young-Dupré equation. However, the reliability of the "known" parameters of the test liquids is questioned due to the long-neglected surface roughness effect during calibration of the liquids. This study proposed a simple and practicable two-step approach to correct the energy parameters of several test liquids by incorporating Wenzel's surface roughness relationship into CA measurement. Step 1: water and two apolar liquids (diiodomethane and α-bromonaphthalene) were used as benchmarks to calibrate the surface roughness and energy parameters of two reference solids [apolar poly(tetrafluoroethylene) and monopolar poly(methyl methacrylate)], and step 2: the reference solids were used to calibrate any other test liquids by solving the energy parameters from their CAs in the extended Young-Dupré-Wenzel model. Monte Carlo simulation was used to evaluate error transmission and robustness of the model solutions. The obtained energy parameters (γLW/γ+/γ-) of four test liquids (dimethyl sulfoxide, formamide, ethylene glycol, and glycerol) are 28.01/13.68/4.67, 34.95/3.53/37.62, 26.26/7.51/15.74, and 32.99/9.24/26.02 mJ/m2, respectively, and different from the literature values. The liquids were applied to characterize an example solid surface with true γLW/γ+/γ- values of 28.00/1.00/8.00 mJ/m2 and a roughness index (r) of 1.60. Without correction of the liquid parameters, the calculated surface energy, hydration energy, and hydrophobic attraction energy of the solid sample can deviate by 50, 13, and 27%, respectively. This proves the necessity of correcting parameters of the test liquids before they can be used in CA and interfacial energy studies in the presence of surface roughness.

Exploitation of Amine Groups Cooped up in Polyamide Nanofiltration Membranes to Achieve High Rejection of Micropollutants and High Permeance of Divalent Cations.

To enhance the use of nanofiltration in the production of quality drinking water, particularly through the efficient removal of micropollutants yet still preserving essential minerals, the targeted nanofiltration membranes (NFMs) are required to have small pore dimensions coupled with a high, net-negative charge density. Herein, after the formation of a separation layer using piperazine interfacially polymerized with trimesoyl chloride, the exploitation of residual amine groups was systematically investigated by different diacyl chlorides in an organic milieu, which caused the upper part of the final separation layer to be denser and highly negatively charged. Hence, this protocol offers a novel means to fabricate NFMs simultaneously endowed with a low molecular cutoff (MWCO) of 145-238 Da and a reduced rejection of MgCl2 (48%-80%) as well as a competitive water permeance. Those features are ideally applicable to the goal of removing small micropollutants while preserving mineral ions, as needed for the energy-efficient production of safe, quality drinking water. Furthermore, an attempt was made to correlate MWCO with MgCl2 rejection, which provides some insights on the nexus of the electrostatic effects constrained by size exclusion. The significance of residual amine groups and the modification environment was unveiled, and this method paves a new avenue for designing functional NFMs.

Modulating the Asymmetry of the Active Layer in Pursuit of Nanofiltration Selectivity via Differentiating Interfacial Reactions of Piperazine.

Nanofiltration (NF), highly prospective for drinking water treatment, faces a challenge in simultaneously removing emerging contaminants while maintaining mineral salts, particularly divalent cations. To overcome this challenge, NF membranes possessing small pores concomitant with highly negatively charged surfaces were synthesized via a two-step fabrication strategy. The key is to generate a polyamide active layer having a loose and carboxyl group-abundant segment on top and a dense barrier segment underneath. This was achieved by restrained interfacial polymerization between trimesoyl chloride and partly protonated piperazine to form a highly depth-heterogeneous polyamide network, followed by second amidation in an organic environment to remove untethered polyamide fragments and associate malonyl chlorides with reserved amine groups to introduce more negative charges. Most importantly, on first-principle engineering the spatial architecture of the polyamide layer, amplifying asymmetric charge distribution was paired with the thinning of the vertical structure. The optimized membrane exhibits high salt/organic rejection selectivity and water permeance superior to most NF membranes reported previously. The rejections of eight emerging contaminants were in the range of 66.0-94.4%, much higher than the MgCl2 rejection of 41.1%. This new fabrication strategy, suitable for various diacyl chlorides, along with the new membranes so produced, offers a novel option for NF in potable water systems.

Molecular Design of the Polyamide Layer Structure of Nanofiltration Membranes by Sacrificing Hydrolyzable Groups toward Enhanced Separation Performance.

Nanofiltration (NF) is an effective technology for removing trace organic contaminants (TrOCs), while the inherent trade-off effect between water permeance and solute rejections hinders its widespread application in water treatment. Herein, we propose a novel scheme of "monomers with sacrificial groups" to regulate the microstructure of the polyamide active layer via introducing a hydrolyzable ester group onto piperazine to control the diffusion and interfacial polymerization process. The achieved benefits include narrowing the pore size, improving the interpore connectivity, enhancing the microporosity, and reducing the active layer thickness, which collectively realized the simultaneous improvement of water permeance and enhancement of TrOCs rejection performance. The resulting membranes were superior to both the control and commercial membranes, especially in water-TrOCs selectivity. The effects of using the new monomers on the membrane physicochemical properties were systematically studied, and underlying mechanisms for the enhanced separation performance were further revealed by simulating the polymerization process through density functional theory calculation and measuring the trans-interface diffusion rate of monomers. This study demonstrates a novel promising NF membrane synthesis strategy by designing the structure of reaction monomers for achieving excellent rejection of TrOCs with a low energy input in water treatment.

Boosting the Performance of Nanofiltration Membranes in Removing Organic Micropollutants: Trade-Off Effect, Strategy Evaluation, and Prospective Development.

In view of the high risks brought about by organic micropollutants (OMPs), nanofiltration (NF) processes have been playing a vital role in advanced water and wastewater treatment, owing to the high membrane performance in rejection of OMPs, permeation of water, and passage of mineral salts. Though numerous studies have been devoted to evaluating and technically enhancing membrane performance in removing various OMPs, the trade-off effect between water permeance and water/OMP selectivity for state-of-the-art membranes remains far from being understood. Knowledge of this effect is significant for comparing and guiding membrane development works toward cost-efficient OMP removal. In this work, we comprehensively assessed the performance of 88 NF membranes, commercialized or newly developed, based on their water permeance and OMP rejection data published in the literature. The effectiveness and underlying mechanisms of various modification methods in tailoring properties and in turn performance of the mainstream polyamide (PA) thin-film composite (TFC) membranes were quantitatively analyzed. The trade-off effect was demonstrated by the abundant data from both experimental measurements and machine learning-based prediction. On this basis, the advancement of novel membranes was benchmarked by the performance upper-bound revealed by commercial membranes and lab-made PA membranes. We also assessed the potentials of current NF membranes in selectively separating OMPs from inorganic salts and identified the future research perspectives to achieve further enhancement in OMP removal and salt/OMP selectivity of NF membranes.

Application of interdisciplinary collaborative hospice care for terminal geriatric cancer patients: a prospective randomized controlled study.

BACKGROUND: Hospice care (HC) is specialized medical care for terminal patients who are nearing the end of life. Interdisciplinary collaborative hospice care (ICHC) is where experts from different disciplines and patients/caregivers form a treatment team to establish shared patient care goals. However, the ICHC efficacy has not been frequently studied in the terminal geriatric cancer patient (TGCP) population. This study aimed to gain insight into ICHC provided to TGCPs by an ICHC team and identify factors to ameliorate multidimensional HC. METHODS: 166 TGCPs were randomized by a computer-generated random number table using an allocation ratio of 1:1. The patients were divided into the ICHC group and life-sustaining treatment (LST) group. The scores of these questionnaires, such as EORTC, QLQ-C30, Hamilton anxiety scale, the median survival time (MST), symptoms improvement, the median average daily cost of drugs (MADDC), the median total cost of drugs (MTDC) in the last 2 days, and medical care satisfaction were observed in both groups. RESULTS: After treatment, the improvement of emotional function and symptoms in the ICHC group were statistically higher than those in the LST group (P < 0.05). The MADDC and the MTDC in the last 2 days were statistically lower in the ICHC group than those in the LSTs group (P < 0.01). In addition, the overall satisfaction situation and the cooperation ability in the ICHC group were statistically higher than those in the LST group (P < 0.01). CONCLUSION: The ICHC could provide TGCPs with coordinated, comfortable, high-quality, and humanistic care.

The effect of different carbon sources on biofouling in membrane fouling simulators: microbial community and implications.

Biofouling is a problem affecting the operation of nanofiltration systems due to the complexity of the carbon matrix affecting bacteria and biofilm growth. This study used membrane fouling simulators to investigate the effects of five different carbon sources on the biofouling of nanofiltration membranes. For all the carbon sources analyzed, the increase in pressure drop was most accelerated for acetate. The use of acetate as the single carbon source produced less adenosine triphosphate but more extracellular polymers than glucose. The microbial community was analyzed using 16 s rRNA. The use of more than a single carbon source produced an increase in bacteria diversity even at similar concentrations. The relative abundance of proteobacteria was the highest at the phylum level (95%) when a single carbon source was added. Additionally, it was found that the use of different carbon sources produced a shift in the microbial community, affecting the biofouling and pressure drop on membranes.

Differentiating Solutes with Precise Nanofiltration for Next Generation Environmental Separations: A Review.

Selective removal or enrichment of targeted solutes including micropollutants, valuable elements, and mineral scalants from complex aqueous matrices is both challenging and pivotal to the success of water purification and resource recovery from unconventional water resources. Membrane separation with precision at the subnanometer or even subangstrom scale is of paramount importance to address those challenges via enabling "fit-for-purpose" water and wastewater treatment. So far, researchers have attempted to develop novel membrane materials with precise and tailored selectivity by tuning membrane structure and chemistry. In this critical review, we first present the environmental challenges and opportunities that necessitate improved solute-solute selectivity in membrane separation. We then discuss the mechanisms and desired membrane properties required for better membrane selectivity. On the basis of the most recent progress reported in the literature, we examine the key principles of material design and fabrication, which create membranes with enhanced and more targeted selectivity. We highlight the important roles of surface engineering, nanotechnology, and molecular-level design in improving membrane selectivity. Finally, we discuss the challenges and prospects of highly selective NF membranes for practical environmental applications, identifying knowledge gaps that will guide future research to promote environmental sustainability through more precise and tunable membrane separation.

Electrically Tuning Ultrafiltration Behavior for Efficient Water Purification.

Conventional ultrafiltration (UF) technology suffers from membrane fouling and limited separation performance. This work demonstrates a novel electrical tuning strategy to improve the separation efficiency of the UF process. An electrically enhanced UF (EUF) system with two sets of oppositely placed membrane-electrode modules was set up. A series of multicycle treatment experiments were conducted to reveal the performance and tuning mechanism of the EUF system. The applied electrical tuning operation brought about an up to 68% reduction of average transmembrane pressure increasing rate (Rp), indicating a strong capability in inhibiting membrane fouling. This fouling reduction can be mainly ascribed to the applied electrophoretic force, changes in solution chemistry, and generation of peroxide, which repulses foulants away from the membrane, hampers foulant adsorption owing to enhanced electrostatic repulsion, and degrades foulants, respectively. The 1.2 V voltage was identified as an effective voltage for stably inhibiting membrane fouling. Besides, the electrical tuning operation led to an up to ∼32% increase in foulant retention rate (φ) owing to both non-Faradaic effects (including electrosorption and electrophoretic repulsion) and Faradaic oxidative degradation. Moreover, the electrical tuning operation allowed a remarkable desalination capability with a significantly higher desalination rate and an up to ∼43% greater salt adsorption capacity as compared with a conventional capacitive deionization process. Additionally, the EUF system achieved a good performance in removing heavy metals (Ag, Cu, Pb, Se, and Sb). The overall enhanced EUF performance suggests promising prospects for practical applications.

A Facile and Scalable Fabrication Procedure for Thin-Film Composite Membranes: Integration of Phase Inversion and Interfacial Polymerization.

Conventional dense thin-film composite (TFC) membranes evince a universally low water permeability, the increase of which typically relies on introducing additional transport channels based on intricate steps within a membrane preparation process. In this study, we reported a novel and simplified procedure for the fabrication of high-performance TFC membranes. Specifically, the dissolution of aqueous monomers in the casting solution was utilized for the following interfacial polymerization (IP). Since the monomers diffused to the water bath during phase inversion, the control of precipitation time enabled an effective regulation of the monomer concentration in the formed polymeric substrates, where the IP reaction was initiated by the addition of the organic phase. The entire and uniform embedment of aqueous monomers inside the substrates contributed to the formation of ultrathin and smooth selective layers. An excellent separation performance (i.e., water permeability: 34.7 L m-2 h-1 bar-1; Na2SO4 rejection: ∼96%) could be attained using two types of aqueous monomers (i.e., piperazine and ß-cyclodextrin), demonstrating the effectiveness and universality of this method. Compared to the conventional immersion-based process, this novel procedure shows distinct advantages in reducing monomer usage, shortening the production cycle, and achieving a more superior membrane performance, which is highly promising for large-scale membrane manufacture.

Determination of Surface Energy Parameters of Hydrophilic Porous Membranes via a Corrected Contact Angle Approach.

While the contact angle is a well-applied indicator of membrane hydrophobicity and surface energy, the interference of surface roughness and porosity in contact angle measurement and surface energy calculation has been long neglected in the field of porous membrane study. We propose an improved method to straightforwardly derive the surface energy of the porous membrane from contact angles with the interference effect corrected. A linearized model was established combining the Young-Dupré and Cassie-Baxter equations, from which the surface energy (Lifshitz-van der Waals and Lewis acid/base components) and roughness index (surface area difference) can be solved simultaneously at a given porosity using contact angles measured with a set of standard polar/nonpolar test liquids. The model solution was examined using hydrophilic microfiltration membranes with different pore morphologies (including perforated plate-like PCTE, irregular particulate bed-like PVDF, and fibrous mesh-like PTFE membranes), with the robustness of the results evaluated via Monte Carlo simulation. In comparison with the verified results of the model solution, it was found that the Lifshitz-van der Waals Lewis acid/base energy values for the tested membranes would deviate by 50-87, 30-160, and 52-97%, respectively, if surface roughness and porosity were neglected in the calculation. The profound effect of roughness and porosity on surface energy determination was further confirmed via theoretical analysis of the Young-Dupré and Cassie-Baxter relationships. This improved approach may apply to the surface energy characterization of hydrophilic rough porous membranes (e.g., hydrophilic microfiltration membranes).

Occurrence and fate of PPCPs in typical drinking water treatment plants in China.

In this study, the occurrence and removal of twenty-nine pharmaceuticals and personal care products (PPCPs) in two water treatment plants (WTPs) in China were investigated. WTP1 employed ozonation and granular active carbon (GAC) filtration after coagulation and sedimentation, while WTP2 applied anthracite and GAC filtration instead. In the influent, six and four selected PPCPs with total concentrations of 554.97 and 12.94 ng/L were detected in WTP1 and WTP2, respectively (in October), among which, sulfamethoxazole and erythromycin were detected with highest concentrations due to their widely used as both human and veterinary medicines. PPCPs removal varied significantly among compounds and treatment units. In general, coagulation, filtration and single GAC units worked inefficiently and removed the detected PPCPs by less than 50%, as they were not hydrophobic. Ozonation was capable to eliminate a majority of PPCPs by more than 90%, which, however, presented limited mineralization and generated a certain amount of degradation by-products. To seek the improvement of PPCPs removal by coagulation and flocculation, the feasibility of adding hydrogen peroxide (H2O2) into the coagulation process (Fe2+ or Fe3+) to trigger the Fenton reaction was investigated. Results indicated that only under acidic condition, Fe2+ combined H2O2 efficiently removed PPCPs, while Fe3+/H2O2 also showed some removal capacity compared to coagulation process only. It will be impractical to employ this process under neutral pH. But when acidic wastewater is involved, this process may have its potential application.

Characteristic Regions of the Fluorescence Excitation-Emission Matrix (EEM) To Identify Hydrophobic/Hydrophilic Contents of Organic Matter in Membrane Bioreactors.

This study systematically investigated the correlations between fluorescence distributions characterized by the excitation-emission matrix (EEM) and hydrophobic/hydrophilic composition of dissolved organic matter (DOM) in membrane bioreactors (MBRs). On the basis of samples from 10 full-scale MBRs, we performed point-to-point comparisons among different components using an EEM fluorescence quotient (FQ) method and obtained a hydrophobic/hydrophilic fluorophore distribution map via Wilcoxon signed rank test. Hydrophobic acids/bases (HOA/HOB) concentrated in the low-wavelength region [excitation wavelength (Ex) < 235 nm], while hydrophilic substances (HIS) were enriched in the region of Ex > 235 nm [especially with emission wavelength (Em) = 300-360 nm]. Quantitatively, EEM regional contribution to whole wavelength fluorescence was found to significantly correlate with the hydrophobic/hydrophilic proportions of DOM, with Pearson's coefficients of 0.94 and 0.78 ( p < 0.01) for HOA and HIS, respectively. We established a linear regression model showing the HOA proportion as a function of the EEM regional contribution at (Ex, Em) = (200-285, 340-465 nm), with R2 = 0.876, which was validated via leave-one-out cross-validation and Monte Carlo simulation. This study shows a statistically hydrophobicity-dependent fluorescence property across different MBRs, and it might be applied to provide a quick estimation of hydrophobic/hydrophilic composition of DOM in wastewater treatment systems based on EEM monitoring.

Membrane fouling in ultrafiltration of natural water after pretreatment to different extents.

The combined fouling during ultrafiltration (UF) of surface water pretreated to different extents was investigated to disclose the roles of polysaccharides, proteins, and inorganic particles in UF membrane fouling. Both reversible and irreversible fouling decreased with enhanced pretreatment (biologically active carbon (BAC) treatment and sand filtration). The sand filter effluent fouled the membrane very slowly. The UF membrane removed turbidity to less than 0.1 nephelometric turbidity unit (NTU), reduced polysaccharides by 25.4%-29.9%, but rejected few proteins. Both polysaccharides and inorganic particles were detected on the fouled membranes, but inorganic particles could be effectively removed by backwashing. The increase of turbidity in the sand filter effluent to 3.05 NTU did not significantly increase the fouling rate, but an increase in the turbidity in the BAC effluent to 6.11 NTU increased the fouling rate by more than 100%. The results demonstrated that the polysaccharide, not the protein, constituents of biopolymers were responsible for membrane fouling. Membrane fouling was closely associated with a small fraction of polysaccharides in the feed water. Inorganic particles exacerbated membrane fouling only when the concentration of fouling-inducing polysaccharides in the feed water was relatively high. The combined fouling was largely reversible, and polysaccharides were the predominant substances responsible for irreversible fouling.

Tailoring properties and performance of thin-film composite membranes by salt additives for water treatment: A critical review.

During the fabrication of thin film composite (TFC) membranes by interfacial polymerization (IP), the utilization of salt additives is one of the effective methods to regulate membrane properties and performance. Despite gradually receiving widespread attention for membrane preparation, the strategies, effects and underlying mechanisms of using salt additives have not yet been systematically summarized. This review for the first time provides an overview of various salt additives used to tailor properties and performance of TFC membranes for water treatment. By classifying salt additives into organic and inorganic salts, the roles of added salt additives in the IP process and the induced changes in membrane structure and properties are discussed in detail, and the different mechanisms of salt additives affecting membrane formation are summarized. Based on these mechanisms, the salt-based regulation strategies have shown great potential for improving the performance and application competitiveness of TFC membranes, including overcoming the trade-off relationship between water permeability and salt selectivity, tailoring membrane pore size distribution for precise solute-solute separation, and enhancing membrane antifouling performance. Finally, future research directions are suggested to focus on the long-term stability assessment of salt-modified membranes, the combined use of different salt additives, and the integration of salt regulation with other membrane design or modification strategies.

Fabrication of Loose Nanofiltration Membranes with High Rejection Selectivity between Natural Organic Matter and Salts for Drinking Water Treatment.

Loose nanofiltration (LNF) membranes with a molecular weight cut-off (MWCO) of about 1000 Da and high surface negative charge density have great application potential for drinking water treatment pursuing high rejection selectivity between natural organic matter (NOM) and mineral salts. This study was conducted to exploit the novel method coupling non-solvent induced phase separation (NIPS) and interfacial polymerization (IP) for the preparation of high-performance LNF membranes. A number of LNF membranes were synthesized by varying the polyethersulfone (PES) and piperazine (PIP) concentrations in the cast solution for the PES support layer preparation. Results showed that these two conditions could greatly affect the membrane water permeance, MWCO and surface charge. One LNF membrane, with a water permeance as high as 23.0 ± 1.8 L/m2/h/bar, when used for the filtration of conventional process-treated natural water, demonstrated a rejection of NOM higher than 70% and a low rejection of mineral salts at about 20%. Both the mineral salts/NOM selectivity and permselectivity were superior to the currently available LNF membranes as far as the authors know. This study demonstrated the great advantage of the NIPS-IP method for the fabrication of LNF membranes, particularly for the advanced treatment of drinking water.

Fluorescence-based method for fast quantification of active aluminums in natural and treated water.

Fast quantitative determination of active aluminum (Ala) in natural and treated water is extremely desirable. The fluorescence method based on complexation by 8-hydroxyquinoline (8-HQ) is highly promising, but the measurement could be severely interfered by hardness ions and natural organic matter (NOM). This study was devoted to refining the 8-HQ complexation-fluorescence method for measurement of Ala by eliminating the interferences. Results showed that magnesium ions at a typical concentration in natural water could have a substantial positive interference, due to the formation of Mg-8-HQ complexes which have fluorescence regions similar to Al-8-HQ. NOM, represented by fulvic acid (FA), could not interfere the aluminum measurement considerably. It was primarily because 8-HQ has much stronger complexing ability than NOM with aluminum. Theoretical calculations showed that reducing the buffering pH (from 7.5) to 6.5 or using a masking ligand such as edetate (EDTA) could effectively alleviate the interference mainly caused by magnesium. Experimental results confirmed the theoretical predictions. Refined procedures were suggested for more accurate while fast determination of Ala in natural or treated water. The refined method has a quantification limit of ~4 µg/L, a linear range of measurement up to 700 µg/L, and a relative standard deviation of ~0.8%.