Salt Ions Research Articles

A new alcohol-soluble dye-tetraphenyl porphyrin functionalized copolymer: Inside the role as a third component/cathode interlayer in halogen-free OSCs

Development and step-by-step characterizations of a novel cationic thiophene based copolymer (P1buP), including ionic phosphonium salt and dye-tetraphenylporphyrin (TPP) moiety in side chains, with an iconic property of solubility in a wide range of polar solvents is reported. Synthesized by using simple, low-cost, and straightforward procedures, the material is used to fabricate completely halogen-free (i.e., from ethanol) ternary organic solar cells (OSCs), in the presence of an alcohol-soluble ionic 3,4-dialkoxythiophene based homopolymer (P2buP) and a serinol-fullerene derivative (C60-Ser). Indeed, thanks to co-sensitization techniques, where multiple dyes harvest different parts of the solar spectrum, the power conversion efficiency of the best final device dramatically increases up to nearly 5.0%, as the light absorption is usually optimized. Additionally, since the use of a cathode interlayer in OSCs also plays a pivotal role in electron extraction and device stability, a possible application of the ionic TPP material as the interfacial layer is also investigated. Furthermore, to improve and optimize the best performing device, a successful post-metalation with Zn of the porphyrin core is carried out, and a ternary OSC (P1buP:P2buP:C60-Ser = 0.33:0.67:1 w/w) is fabricated, resulting in a photoconversion efficiency (PCE) of ∼6.0%.

Characteristics of Microorganisms and Antibiotic Resistance Genes of the Riparian Soil in the Lanzhou Section of the Yellow River

Riparian soil is a critical area of watersheds. The characteristics of biological contaminants in riparian soil affect the pollution control of the watershed water environment. Thus, the microbial community structure, antibiotic resistance genes (ARGs), and mobile genetic elements (MGEs) in the riparian soil of the Lanzhou section of the Yellow River were investigated by analyzing the characteristics of soil samples collected from farmland, mountains, and industrial land. The results showed that the Proteobacteria, Bacteroidetes, and Actinobacteria were the dominant phyla in the riparian soil of Lanzhou section of the Yellow River. The microbial structure in the riparian soil was significantly correlated with the land use type (P < 0.05). The α diversity index of bacterial communities in land types was in the order of farmland > mountain > industry. Sulfonamide-typed ARGs were the most dominant genes in the soil of the Lanzhou section of the Yellow River Basin, among which the sul1 gene had the highest abundance, 20-36 000 times that of other detected ARGs. Moreover, the total absolute abundance of ARGs in industrial soil was the highest. Principal coordinate analysis (PCoA) displayed that the ARGs characteristics had a significant correlation with land types (P < 0.05), and intl1 and tnpA-04 drove the diffuseness of sulfonamide and tetracycline ARGs, respectively. Redundancy analysis (RDA) demonstrated that the content of inorganic salt ions and total phosphorus in the soil of the riparian zone of the Yellow River Lanzhou section were the main environmental factors, modifying the distribution of the microbial structure. Halobacterota and Acidobacteriota were the main microflora that drove the structural change in ARGs.

Efficient electro-Fenton degradation of organic pollutants via the synergistic effect of 1O2 and •OH generated on single Fe[sbnd]N4 sites

The electro-Fenton with in situ generated 1O2 and •OH is a promising method for the degradation of micropollutants. However, its application is hindered by the lack of catalysts that can efficiently generate 1O2 and •OH from electrochemical oxygen reduction. Herein, N-doped stacked carbon nanosheets supported Fe single atoms (Fe-NSC) with FeN4 sites were designed for simultaneous generation of 1O2 and •OH to enhance electro-Fenton degradation. Due to the synergistic effect of 1O2 and •OH, a variety of contaminants (phenol, 2,4-dichlorophenol, sulfamethoxazole, atrazine and bisphenol A) were efficiently degraded with high kinetic constants of 0.037–0.071 min−1 by the electro-Fenton with Fe-NSC as cathode (−0.6 V vs Ag/AgCl, pH 6). Moreover, the superior performance for electro-Fenton degradation was well maintained in a wide pH range from 3 to 10 even with interference of various inorganic salt ions. It was found that FeN4 sites with pyridinic N coordination were responsible for its good performance for electro-Fenton degradation. Its 1O2 yield was higher than •OH yield, and the contribution of 1O2 was more significant than •OH for pollutant degradation.

Synergistic effects of nonionic surfactants ethoxylated alkylamines and sodium dodecyl sulfate in mixed systems

HypothesisIn general, the performance of surfactant hybrid systems is better than that of single surfactants, so surfactant hybrid systems are widely used in various industries. As a very important class of nonionic surfactants, ethoxylated alkylamines have been widely used in industries such as washing, coating, and pesticide, but little research has been conducted on their mixed systems. In order to improve the utilization efficiency of surfactants and reduce wastage, the surface properties and aggregation behavior of ethoxylated alkylamine mixed systems should be further explored. ExperimentIn this study, the nonionic surfactant ethoxylated dodecylamine (AC-1202) and the anionic surfactant sodium dodecyl sulfate (SDS) were used to form a mixed system. The static surface tension and interaction parameters of the mixed system under the influence of inorganic salt ions were investigated using a KRÜSS K12 surface tensiometer. The diffusion process of the mixed system was investigated using a KRÜSS bubble pressure tensiometer. At the same time, the aggregate behavior of the mixed system was studied by particle size analyzer. In addition, the contact angle and rheological properties of the mixed solution were also investigated. FindingsThe SDS/AC-1202 mixture system formed a synergistic effect that could reduce the CMC value to 24.20 mN/m and the CMC value was as low as 22.89 mN/m after the addition of inorganic salts. The mixed system conforms to the kinetic mechanism of mixing and diffusion and the Ostwald de model for non-Newtonian fluids. Finally, there is a good aggregation pattern in the mixed system, and the stronger synergistic effect will lead to the reduction of the average particle size of the mixture to 45.41 nm.

Phytoremediation ability of Panicum maximum and Salicornia europaea irrigated with treated wastewater for salt elements in the soil

Soil salinity is one of the major problems that threaten the soils in Jordan, which led to a decrease in the percentage of arable land in Jordan. The phytoremediation process is concerned with the restoration of contaminated soils using tolerant plants, such as halophyte plants. In this context, the potential short-term phytoremediation ability of Panicum Mombasa and Salicornia Europaea was evaluated and measured. A field experiment was conducted over two consecutive years to study the ability of these previous two crops for the phytoremediation of saline soils induced by treated wastewater irrigation. Both crops with bare soil as a control were irrigated together from the effluent of the Ramtha Wastewater Treatment Plant at the same time. Soil electrical conductivity was identified as the main parameter for measuring the plant’s ability for salt absorption. The results for both seasons show a higher accumulation of salts in bare soil significantly as expected since no plants were present to absorb these salts and no leaching requirements were added with irrigation water. The absorption rate for each crop was measured at the 1st season for comparison. It is measured for each crop depending on the length of the growing season. Salicornia’s absorption rate was greater than Panicum, and it reached 36 ppm/day for salicornia, whereas it reached 33 ppm/day for panicum. In the 2nd season, both crops are planted and harvested together. Salt absorbed percentage from the soil under Salicornia was greater than Panicum and it reached 73 % as compared to bare soil. However, in the soils under Panicum, the amount of salts absorbed reached 37 % as compared to bare soil. Plant analysis for both crops shows higher salt ions accumulation in Salicornia tissues than Panicum, and this explains the higher absorption rate for Salicornia than Panicum. Microbiological analysis for Panicum shows some contamination, whereas no contamination occurs in Salicornia. This is explained by the high salinity environment in Salicornia which is not favorable for e-coil, total, and fecal coliform to grow. The obtained Results from this research state that both crops have the ability for phytoremediation, with greater ability for Salicornia.

Drag reducing performance and its influencing on natural yam mucilage

Yam mucilage is a novel environmentally friendly drag reducer. This study investigates drag reduction and degradation characteristics of Chinese yam mucilage, using an in-house rotor device. The effects of temperature, aging, and salts on the drag reduction rate (DR) of yam mucilage were also explored. Furthermore, the synergistic drag reduction properties of Chinese yam-polyethylene oxide (PEO) solution were investigated by blending Chinese yam mucilage with PEO. The rotational speed range of the rotor device was set at 200–700 r/min, corresponding to Reynolds numbers (Re) ranging from 30 396 to 106 385. The results demonstrated that the DR of yam mucilage initially increased, and then decreased at low concentrations, with increasing Re. Conversely, the DR of yam mucilage at high concentrations increased with increasing Re, albeit at a gradually slowing rate as concentration increased; however, the shear stability was gradually enhanced. Degradation testing revealed that yam slime exhibited semi-rigid, or rigid polymer characteristics, with notable shear stability. At a concentration of 2000 ppm and Re = 106 385, the maximum DR reached 44.1%. Prolonged heating and standing resulted in the reduced DR of yam mucilage. However, salt ions exerted dual effects on the DR of yam mucilage: Low concentrations of NaCl improved its effectiveness while Na2SO4 and high concentrations of NaCl diminished its efficacy. The addition of a small quantity of PEO was found to significantly enhance the drag reduction efficacy of yam mucilage, but no significant improvement in the shear stability of yam mucilage was observed. Yam mucilage exhibits promising potential as an environmentally friendly drag reducer with remarkable drag reduction capabilities.

Simulations of novel mixed-patterned membrane surfaces: Enhanced hydrodynamics and concentration polarization to mitigate fouling in water treatment

The accumulation of particles and salt ions on the membrane surface is the main challenge in different water treatment applications, such as microfiltration (MF), ultrafiltration (UF), reverse osmosis (RO), and nanofiltration (NF), undesirably affecting the membrane's water permeance and salt rejection. This study used computational fluid dynamics (CFD) simulations to investigate novel mixed triangular-rectangular (mixed tri-rec) shaped patterned membrane surfaces toward reducing membrane fouling and increasing water flux. These outcomes were compared with previously reported flat, triangular (tri), and rectangular (rec) patterned surfaces. The fluid flow behavior and transport of diluted species under laminar flow conditions were investigated in the vicinity of different patterned membrane surfaces. Parameters such as diffusion coefficient, pressure difference across the membrane, and feed solute concentration remained fixed during the investigation. The key parameters evaluated were the velocity streamline profile, shear stress, concentration polarization (CP), and permeate flux (PF). The overall wall shear stress (OWSS) and local wall shear stress (LWSS) were also evaluated, and unobvious behavior was observed in both cases. Also, interesting behavior emerged when the averaged CP and PF were analyzed as a function of varying crossflow velocities. Further, the results indicate that pattern geometry significantly affects the PF. Additional simulations varying pattern sizes parametrically were performed, and the influence of pattern size ratio on CP, PF, and consequently, boundary layer thickness was investigated. Overall, this study presents a new understanding of fouling mitigation and enhanced permeate flux while comparing a novel mixed tri-rec-shaped membrane surface with previously reported homogeneous patterned surfaces.

Interfacial and aggregation behavior of ionic liquid-bile salt conjugates

Bile salt derived nontoxic surface-active ionic liquids (SAILs), 1-butyl-3-methylimidazolium cholate ([bmim]C) and deoxycholate ([bmim]DC) were synthesized by reacting [bmim] tetrafluoroborate separately with sodium cholate (NaC) and sodium deoxycholate (NaDC) which were subsequently characterized by FTIR, 1H-NMR, 13C-NMR, HRMS, PXRD, and TGA-DTA studies. Interfacial and aggregation behavior of the SAILs were assessed by surface tension, conductance, pyrene fluorescence, dynamic light scattering, and isothermal titration calorimetric studies. Critical micelle concentration values were substantially lower than their precursor sodium salts. SAILs were less surface active than their corresponding sodium salts due to enhanced aqueous solubility induced by the ionic liquid cation. Both the aggregation number and size of the SAIL micelles were higher/larger where the SAIL micelles were more compact than NaC/NaDC. Exothermic changes in the enthalpy of micellization were higher for SAILs, where the micellization processes were found to be entropy driven. Such comprehensive studies can shed further light on the microstructure, besides the fundamental understanding on SAIL aggregation. The combined advantages of surfactant and ionic liquid in the SAILs can result in superior amphiphilic characteristics. Such nontoxic aggregates are capable to enhance the limited solubility of organic compounds in water besides their possible uses in catalysis, drug delivery, and energy storage, etc.

Temperature-responsive salt-resistant poly(sulfobetaine methacrylate)-based emulsifiers for heavy oils

The emulsions prepared with most currently reported emulsifiers are stable only at room temperature and are susceptible to demulsification at higher temperatures. This thermal instability prevents their use in high-temperature and high-salt environments encountered oilfield extraction. To address this issue, in this study, two temperature-responsive emulsifiers, PSBMA and CS-PSBMA, were synthesized. Both emulsifiers exhibited the ability to form stable emulsions within the temperature range of 60–80 °C and undergo demulsification at 20–40 °C. A comprehensive investigation was conducted to assess the impact of emulsifier concentration, water-to-oil ratio, and salt ion concentration on the stability of emulsions formed by these two emulsifiers. The results demonstrated their remarkable emulsification capabilities across diverse oil phases. Notably, the novel emulsifier CS-PSBMA, synthesized through the grafting chitosan (CS) onto PSBMA, not only exhibits superior emulsion stability and UCST temperature responsiveness but also significantly enhanced the salt resistance of the emulsion. Remarkably, the emulsion maintained its stability even in the presence of monovalent salt ions at concentrations up to 2 mol/L (equivalent to a mineralization level of 1.33 × 105 mg/L in water) and divalent salt ions at concentrations up to 3 mol/L (equivalent to a mineralization level of 2.7 × 105 mg/L in water). The emulsions stabilized by both emulsifiers are resilient to harsh reservoir conditions and effectively emulsify heavy oils, enabling high-temperature emulsification and low-temperature demulsification. These attributes indicate their promising potential for industrial applications, particularly in the field of enhanced oil recovery.

Short Zwitterionic Sulfobetaine-Modified Silica Nanoparticles: Is Neutrality Possible?

Zwitterionic coatings are an efficient strategy for preventing biomolecule adsorption and enhancing nanoparticle stability in solution. The properties of zwitterions and other antifouling materials, including suppression of nonspecific adsorption and improved colloidal stability of nanoparticles, are believed to derive from their electroneutral and highly hydrophilic nature. Among different zwitterions, short sulfobetaines have been demonstrated to be effective in preventing protein adsorption onto several nanoparticles and providing enhanced colloidal stability. Although zwitterionic sulfobetaine silane (ZS) is electrically neutral, the negatively charged zwitterionic sulfobetaine-functionalized silica nanoparticles (ZS@SiO2NPs) exhibit a similar ζ-potential to nonfunctionalized silica nanoparticles (SiO2NPs). In this work, we present a thorough comprehension of the surface properties of ZS@SiO2NPs, which encompasses the development of meticulous functionalization procedures, detailed characterization approaches, and cutting-edge modeling to address the questions that persist regarding the surface features of ZS@SiO2NPs. The negative charge of ZS@SiO2NPs is due to the stabilization of siloxide from residual surface silanols by the quaternary amine in the sulfobetaine structure. Consequently, we infer that zero-charge ZS@SiO2NPs are unlikely to be obtained since this stabilization increases the dissociation degree of surface silanols, increasing the overall structure negative charge. Additionally, colloidal stability was evaluated in different pH and ionic strength conditions, and it was found that ZS@SiO2NPs are more stable at higher ionic strengths. This suggests that the interaction between ZS and salt ions prevents the aggregation of ZS@SiO2NPs. Together, these results shed light on the nature of the ZS@SiO2NP negative charge and possible sources for the remarkable colloidal stability of zwitterionic nanoparticles in complex media.

A Review on the Improvement of Saline-alkali Soil by Organic Fertilizer

In recent years, soil salinization has become a serious problem in the global environment. The application of organic fertilizer to improve saline-alkali soil has been widely concerned because of its advantages of improving soil fertility, improving soil structure and improving soil salt ion composition. This paper reviews the mechanism of saline-alkali soil improvement, and expounds the improvement prospect of organic fertilizer on saline-alkali soil from the influence of organic fertilizer on soil physical and chemical properties, water and salt transport law, crop yield and quality, in order to provide theoretical guidance for saline-alkali soil restoration.

GhCLCc-1, a Chloride Channel Gene from Upland Cotton, Positively Regulates Salt Tolerance by Modulating the Accumulation of Chloride Ions.

The ionic toxicity induced by salinization has adverse effects on the growth and development of crops. However, researches on ionic toxicity and salt tolerance in plants have focused primarily on cations such as sodium ions (Na+), with very limited studies on chloride ions (Cl-). Here, we cloned the homologous genes of Arabidopsis thaliana AtCLCc, GhCLCc-1A/D, from upland cotton (Gossypium hirsutum), which were significantly induced by NaCl or KCl treatments. Subcellular localization showed that GhCLCc-1A/D were both localized to the tonoplast. Complementation of Arabidopsis atclcc mutant with GhCLCc-1 rescued its salt-sensitive phenotype. In addition, the silencing of the GhCLCc-1 gene led to an increased accumulation of Cl- in the roots, stems, and leaves of cotton seedlings under salt treatments, resulting in compromised salt tolerance. And ectopic expression of the GhCLCc-1 gene in Arabidopsis reduced the accumulation of Cl- in transgenic lines under salt treatments, thereby enhancing salt tolerance. These findings elucidate that GhCLCc-1 positively regulates salt tolerance by modulating Cl- accumulation and could be a potential target gene for improving salt tolerance in plants.

Interfacial Growth of Large Area Single-Crystalline Silver Sheets Through Ambient Microdroplets.

The creation of micrometer-sized sheets of silver at the air-water interface by direct deposition of electrospray-generated silver ions (Ag+) on an aqueous dispersion of reduced graphene oxide (RGO), in ambient conditions, is reported. In the process of electrospray deposition (ESD), an electrohydrodynamic flow is created in the aqueous dispersion, and the graphene sheets assemble, forming a thin film at the air-water interface. The deposited Ag+ coalesce to make single-crystalline Ag sheets on top of this assembled graphene layer. Fast neutralization of Ag+ forming atomic Ag, combined with their enhanced mobility on graphene surfaces, presumably facilitates the growth of larger Ag clusters. Moreover, restrictions imposed by the interface drive the crystal growth in 2D. By controlling the precursor salt concentration, RGO concentration, deposition time, and ion current, the dimensionality of the Ag sheets can be tuned. These Ag sheets are effective substrates for surface-enhanced Raman spectroscopy (SERS), as demonstrated by the successful detection of methylene blue at nanomolar concentrations.

Subsidy-stress responses of ecosystem functions along experimental freshwater salinity gradients

Human activity is increasing salt concentrations in freshwaters worldwide, but effects of freshwater salinity gradients on biogeochemical cycling are less understood than in saline, brackish, or marine environments. Using controlled microcosm experiments, we characterized (1) short-term (one to five days) biogeochemical responses and (2) water column metabolism along a freshwater salinity gradient of multiple salt types. After one day, microcosms were oxic (4.48–7.40 mg O2 L−1) but became hypoxic (1.20–3.31 mg L−1) by day five. After one day in oxic conditions, microbial respiration in magnesium-, sodium-, and sea salt-based salinity treatments showed a subsidy-stress response, with respiration increasing by over 100% as salinity increased from 30 to 350–800 µS cm−1. Conversely, respiration consistently increased along a calcium-based salinity gradient, peaking at 1500 µS cm−1. By day five, an inverse subsidy-stress response was observed with elevated respiration at upper or lower ends of the gradient except for the magnesium treatment, which had the lowest respiration at the highest salinity. Calcium- and magnesium-based salinity treatments also caused considerable changes in phosphorus concentrations and C:P and N:P. In a separate experiment, microbial respiration and water column primary production also displayed subsidy-stress responses, but imbalances in effect sizes caused consistently declining net community production with increasing salinity. Collectively, our results establish that short-term exposure to different salt ion concentrations can enhance freshwater biogeochemical cycling at relatively low concentrations and alter resource stoichiometry. Furthermore, the nature of effects of freshwater salinization may also change with oxygen availability.

Collapse and expansion kinetics of a single polyelectrolyte chain with hydrodynamic interactions.

We investigate the collapse and expansion dynamics of a linear polyelectrolyte (PE) with hydrodynamic interactions. Using dissipative particle dynamics with a bead-spring PE model, long-range electrostatics, and explicit ions, we examine how the timescales of collapse tcol and expansion texp depend on the chain length N and obtain scaling relationships tcol ∼ Nα and texp ∼ Nβ. For neutral polymers, we derive values of α = 0.94 ± 0.01 and β = 1.97 ± 0.10. Interestingly, the introduction of electrostatic interaction markedly shifts α to α ≈ 1.4 ± 0.1 for salt concentrations within c = 10-4 to 10-2M. A reduction in the ion-to-monomer size ratio noticeably reduces α. On the other hand, the expansion scaling remains approximately constant, β ≈ 2, regardless of the salt concentration or ion size considered. We find β > α for all conditions considered, implying that expansion is always slower than collapse in the limit of long polymers. This asymmetry is explained by distinct kinetic pathways of collapse and expansion processes.

Nanocellulose membrane with double-salt deep eutectic solvent for efficient carbon capture

Membrane-based gas separation technology is becoming increasingly attractive as a feasible alternative for carbon capture to alleviate global warming. Here, a double-salt deep eutectic solvent (DES) composed of organic salt (choline chloride) and inorganic salt (ZnCl2) is designed. The as-prepared DES exhibits a superb affinity and compatibility with nanocellulose because of the interactions between salt ions and cellulose carboxyl/hydroxyl groups. Through a solvent impregnation process, the DES was integrated into the nanocellulose gel precursor and used as a facilitated transport agent to form the functionalized nanocellulose membrane. The DES is tightly attached to the cellulose fibers with a high uniformity in the membrane matrix. Gas separation tests demonstrated that the DES@nanocellulose membranes presented a maximum CO2 permeability of 155.8 Barrer, with CO2/N2 and CO2/CH4 ideal selectivities of 43.6 and 48.4, respectively. Mixed gas separation tests were performed and the optimal membrane exhibited separation factors of 48.1 and 52.3 for CO2/N2 and CO2/CH4, respectively. The membranes provide a high solubility for CO2 due to the presence of abundant zinc ions, choline cations and carboxyl groups in the network, which can establish reversible coordination with CO2 and promote CO2 transport.

Molecular and electrostatic origins of mixed salt partitioning phenomena in uncharged poly(ethylene oxide)-based membranes

Despite the increasing interest in membranes for water purification and resource recovery from aqueous electrolyte mixtures, few studies rigorously investigate the influence of salt solution composition (e.g., mole fraction and total salt concentration) on membrane material properties such as partition coefficients. Here, we systematically investigate the influence of solution composition on the partitioning of ionic species from binary aqueous salt solutions into crosslinked poly(ethylene glycol) diacrylate membranes at fixed ionic strength. These results are compared to partition coefficients observed for pure salt solutions. We observe large systematic deviations between the pure salt and mixed salt ion partition coefficients, indicating that the single salt partition coefficients that are often reported do not describe the more complex and realistic mixed salt scenario. Free energy calculations from molecular dynamics simulations, coupled with equilibrium thermodynamic modeling, indicate that mixed salt partitioning trends result from (i) different ions exhibiting different affinities for the membrane and (ii) the constraint of global electrical neutrality within the membrane. With this physical insight, we develop a simple approach to predicting the concentration of various ions in a membrane equilibrated with a mixed salt solution which requires no adjustable parameters.

Photothermal graphite phase carbon nitride membrane intercalated with polyoxovanadate for efficient solar steam generation

Graphite phase carbon nitride (GCN) has shown promising prospects in diverse fields due to its exfoliating two-dimensional (2D) layered structure, adjustable electronic properties, wide absorption of visible light, and excellent chemical stability. It is crucial to accurately regulate and functionalize the intercalation space of 2D membrane materials for specific functions. Herein, we demonstrate the first GCN-based photothermal membrane for efficient solar steam generation. The polyoxovanadate anion was intercalated in between protonated GCN layers via an electrostatic interaction strategy, which enlarged the layer spacing up to ∼12.4 Å and increased the water and salt ions transport capability. Owing to the excellent photothermal conversion efficiency of polyoxovanadate, the polyoxovanadate-intercalated GCN membrane fabricated by suction filtration exhibited effective absorbance in full solar spectrum (>95.5 %) and achieved efficient solar steam generation (2.62 kg m−2 h−1 under 1 sun) when floating on water. The long-term durability test showed that the evaporation performance is stable and no salt precipitation observed. These findings not only expand the functional applications of carbon nitride materials, but also provide a new strategy for solar desalination.

Carbon nanotube incorporated quaternized lignin-based loose nanofiltration membrane toward dye/salt separation

Lignin is a promising raw material for membrane fabrication due to its abundant oxygen-containing functional groups, branched molecular structure, and high abundance in the botanic field. In this report, polydopamine (PDA) coated carbon nanotubes (PCNTs) are synthesized. Then, a PCNT-incorporated lignin-based loose nanofiltration membrane is fabricated using quaternized lignin (QL) as a raw material, triphosgene (TP) as a crosslinker, and PCNTs as nanoadditive by interfacial polymerization. The results show that the PCNTs uniformly distribute in the QL-based separation layer providing quick diffusion paths for water molecules and salt ions. The coated PDA layer improves the chemical compatibility between the PCNTs and the separation layer. The incorporated PCNTs optimize the membrane microstructure and elevate the pure water permeance to 45.5 LMH bar−1. The membrane exhibits high rejections to various dyes (> 90%) and high salt permeation (> 90%), demonstrating an excellent dye/salt separation performance. Moreover, it has satisfactory capabilities for resisting dye adsorption and fouling, and its separation capability also has good tolerances to the acid, alkali, and active chlorine treatments. The quaternary ammonium ions and hydrophilic surface endow the membrane with favorable bactericidal property (99.3%) and bacteria-adhesion resistance. Besides, TP is a better crosslinker than trimesoyl chloride for optimizing the membrane microstructure and crosslinking degree in terms of dye/salt separation.

Quantitative evaluation and mechanism analysis of soil chemical factors affecting rice yield in saline-sodic paddy fields

Salinization and sodication have become an important abiotic stress affecting soil fertility and crop production in the western of the Songnen Plain in Northeast China. And rice cultivation is considered as one of the most effective biological methods to reclaim saline-sodic soils and ensure food security. However, it is difficult to select the optimal measures to regulate rice growth for increasing yield, because the independent and comprehensive influences of the soil limitation factors on rice yield are not quantitatively evaluated. In this study, the hierarchical partitioning (HP) and the structural equation model (SEM) were used to quantitatively evaluate the influences of salinization parameters, salt ion concentrations and soil nutrients to identify the dominant limitation factors and obstacle mechanism for rice yield. The results showed that soil pH was the key index in salinization parameters, [CO32− + HCO3−] was the key index in salt ion concentrations and available nitrogen (AN) was the key index in soil nutrients to impact rice yield, which independent influences reached 53.7 %, 45.4 % (negative) and 53.2 % (positive), respectively. Soil pH was determined by [CO32− + HCO3−], and the negative effect of alkali stress on rice yield mainly caused by [CO32− + HCO3−] was greater than that of salt stress mainly caused by [Na+] in saline-sodic paddy fields. Among the soil chemical factors, soil pH and AN were the most important explanatory variables of rice yield in saline-sodic paddy fields, which standardized total effects were − 0.32 and 0.40, respectively. Furthermore, the AN showed a more significant negative correlation with soil pH and a higher yield-increasing potential in severe saline-sodic soils (9 ≤ pH < 10) than that in moderate saline-sodic soils (8 ≤ pH < 9). Therefore, decreasing [CO32− + HCO3−] and increasing the content of AN are key to improve rice yield in saline-sodic paddy fields.