Search

In this work, a new strategy by in situ combining slag-based geopolymer microsphere (SGS) with dithiocarbamate (DTC) was employed to synthesize in situ the composite adsorbent of the SGS and DTC (SGS-DTC). The differences of material properties, performance, and mechanisms in adsorption and immobilization of toxic Cd(II) in water between the SGS and SGS-DTC were investigated. For the static adsorption, the adsorption rate of SGS-DTC(1.5h) was faster than that of SGS(6h); the Cd(II) adsorption capacity of the SGS-DTC (211.2 mg/g) was almost twice that of the SGS (116.7 mg/g), corresponding to the removal rate of the SGS-DTC (99.75%) was nearly twice that of the SGS (53.2%). For the dynamic adsorption, the adsorption capacity of the SGS-DTC is higher than that of the SGS in the Cd(II) solution prepared by the deionized water or the river water from Yongjiang, Nanning, Guangxi, China. The mechanism of the difference of the Cd(II) adsorption between SGS and SGS-DTC was analyzed in dept. [Display omitted] In this study, slag-based geopolymer microspheres (SGS) were combined with dithiocarbamate (DTC) to synthesize the composite adsorbent of SGS and DTC in situ (SGS-DTC). Synthesis was carried out with optimal dosages of 10 mL of EDA, 1.0 g of SGS, and 20 mL of CS 2. The differences in material properties, performance, and mechanisms in the adsorption and immobilization of toxic Cd(II) in water between SGS and SGS-DTC were investigated. SGS-DTC showed better adsorption performance than SGS, irrespective of adsorbent dosage, pH, original content, and contact duration. Although after the Cd(II) adsorption, the immobilization performance at a different pH was better in the SGS-DTC than in the SGS, the immobilization performance was unaffected by changes in the other factors. For static adsorption, the adsorption rate of SGS-DTC (1.5 h) was faster than that of SGS (6 h); the Cd(II) adsorption capacity of SGS-DTC (211.2 mg/g) was almost twice that of SGS (116.7 mg/g), and correspondingly, the removal rate of SGS-DTC (99.75%) was nearly twice that of SGS (53.2%). For dynamic adsorption, the adsorption capacity of SGS-DTC was 389.78 mg/g, which is considerably higher than that of SGS (293.38 mg/g) in the Cd(II) solution prepared with deionized water. Furthermore, the adsorption capacity of the SGS-DTC was 299.26 mg/g, which is significantly higher than that of SGS (150.03 mg/g) in the Cd(II) solution prepared by the river water from Yongjiang, Nanning, Guangxi, China. One reason is that DTC was able to activate Si-O-Si without adsorption performance within SGS, thereby improving its adsorption and purification properties significantly. The other reason is that, after anchoring DTC on SGS, the specific surface area varied from 34.05–146.47 m2/g, the morphology was smooth-leaf-like, the pore volume was 0.13–0.20 cm3/g, and the pore size in SGS, was 14.75–5.60 nm. The high potential of SGS-DTC in removing and immobilizing heavy metal materials in wastewater is demonstrated in the results. [ABSTRACT FROM AUTHOR]

The fluorine content of groundwater exceeds the standard in most areas of China. In this study, the self-made mesoporous carbon electrode combined with the ion exchange membrane was used to form a membrane capacitive deionization (MCDI) device. In this article, a single factor test was conducted with the removal efficiency of the configured simulated fluorine-containing water as the evaluation index. The results showed that, under the conditions of 3.6 mg/L of influent water and 18 mL/min of flow rate, the optimal process conditions were voltage 1.2 V and the spacing was 1 mm. The adsorption of the electrode was saturated by a cycle test, and the maximum removal rate of fluoride ions reached 77.3%. Using F− excess groundwater as raw water, the application test showed that the fluorine content dropped sharply within 2 min, and the instantaneous removal rate was 95.8%. By monitoring the adsorption-desorption process of the electrode, the fluorine removal rate was 85.1% and the water production was 79.2%. The fluorine content in the effluent reaches lower than the drinking water standard. Different kinetic and equilibrium models were applied to the experimental data of F− electrosorption. The first-order dynamics model and Freundlich adsorption isotherm model showed better fitness to the experimental data. The adsorption process of F− by mesoporous carbon electrode belongs to multilayer physical adsorption. The results of this study can be used to develop a new type of MCDI groundwater removal F− electrode material. [ABSTRACT FROM AUTHOR]

• 3D titanium mesh (3D-TM) was used as current collector in FCDI for salt separation and enrichment. • A comprehensive enhancement of the charge transfer process was revealed in 3D-TM FCDI device. • The 3D-TM FCDI device exhibited exceptional cyclic stability over 100 desalination cycles. • The east China seawater sample was successfully desalted with a salt removal efficiency of 97.5 %. • The Li+ ion was enriched to 17.3 g L−1 from 1.30 g L−1 for lithium-ion enrichment by the 3D-TM FCDI device. Flow electrode capacitive deionization (FCDI) is a highly promising desalination technique known for its exceptional electrosorption capacity, making it suitable for efficient salt separation in high salinity water. However, the unsatisfactory charge transfer process between the flow electrode and current collector severely curtails the salt separation and enrichment performance of the FCDI device. To address this issue, three-dimensional titanium mesh (3D-TM) was proposed as a novel current collector for FCDI device, which significantly amplifies the charge transfer area and exhibits excellent salt separation performance. The 3D-TM current collector promotes the electron transfer, charge percolation, and ion migration processes through the electroconvection generated by the turbulence effect on the flow electrode. In the specific case of the 20-mesh 3D-TM, which is composed of 12 stacking layers of titanium mesh, the remarkable average salt removal rate and charge efficiency were achieved 5.06 μmol cm−2 min−1 and 92.9 % under an appropriate applied voltage of 2.0 V, respectively. Dramatically, the desalination performance maintained above 76.4 % over 100 desalination cycles at 2.0 V, demonstrating the exceptional cyclic stability of the 3D-TM FCDI cell. In the seawater desalination, the 3D-TM FCDI cell exhibited an impressive salt removal efficiency of 97.5 % (from 34.2 g L−1 to 0.84 g L−1) for 1 L East China seawater at 2.0 V for 24 h. For lithium-ion enrichment, the FCDI continuous desalting system achieved an astonishing concentration of 17.3 g L−1 for Li+ ions enrichment from an initial concentration of 1.30 g L−1, obtaining the average salt treating rate of 23.6 g m −2 h −1 and charge efficiency of 80.0 %. Moreover, the lithium-sodium ions and lithium-magnesium ions enrichments were both conducted, yielding an enriched concentration of 10.4 g L−1 and 7.30 g L−1 for Li+ ions, respectively. These findings highlight the enormous potential of FCDI technology in industrial engineering applications, further establishing it as a highly viable solution. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel edge-N doped hierarchical carbons were firstly reported for P electrosorption. • The edge-N strategy endowed more accessible active centers and conductive efficiency. • The LNPC900 electrode showed a superior phosphate removal capacity of 533.06 mg g−1. • The system performed well in natural water purification with low P concentration. • The coupling of electrical capacitance and chemical interactions were achieved. Achieving high-efficiency removal of phosphate has been an urgent issue to combat eutrophication and meet ever-stricter emission standards. Electro-assisted adsorption, a mild electrochemical technology, demonstrated great potential for wastewater treatment owing to the merits of considerable removal performance, facile operation, and energy efficiency. Exploring and boosting the properties of electrode materials is exceedingly vital for technological advancement. In this study, the novel edge-N decorated La-doped hierarchical carbon composites (LNPCs) were developed via in-situ nucleation and one-pot pyrolysis strategy as phosphate capture electrodes. The LNPC900 electrode exhibited an ultrahigh phosphate removal capability of 533.06 mg PO 4 3- g−1 at 1.2 V, surpassing most of the reported electrode materials. Furthermore, this electrochemical system also performed well in the purification of natural river water with low phosphate concentration, where the treated concentration was below the first-class emission standard in China (0.5 mg P L−1). Comprehensive analysis and theoretical calculations indicate that the synergistic property of edge-N and small graphitic carbon nanodomains ensured more accessible active centers and conductive efficiency. The superb phosphate removal capability mainly originated from the coupling contribution of the electrical double layer capacitance, ligand exchange, and electrostatic attraction. This study possesses insight into the theoretical basis for the practical application of phosphate electrosorption and provides a new level of the technology. [ABSTRACT FROM AUTHOR]

Faradaic deionization (FDI) is an emerging water treatment technology based on electrodes able to remove ionic species from water by charge transfer reactions. It is a young and promising technology that has attracted much attention due to its large capacity to store ions and the high selectivity of the faradaic electrode materials. This study reviews published papers on FDI from different angles: data mining, bibliometric and machine learning. Metrics such as annual growth rate, most important journals, relevant authors, collaborations maps, sentiment and subjectivity analysis, similarity and clustering analysis were performed. The results indicated that the strong interest in FDI really started in 2016, China is the most active country in FDI, and Desalination is the most important journal publishing FDI articles. The word cloud method showed that the most preferred adopted words are deionization, capacitive, electrode, material. Sentiment analysis results indicated that most of the researchers are optimistic about FDI technology. The title similarity method revealed that FDI researchers were successful in proposing unique and appropriate titles. The clustering approach stressed that FDI literature is concentrated on electrode material production, desalination application, lithium recovery and comparison with CDI. [Display omitted] • Faradaic Deionization (FDI) dataset includes 170 papers downloaded from Scopus. • Annual growth rate of FDI research based on published articles is 55.12 %. • Desalination , J. Mat. Chem. and ACS Appl. Mater. Inter. are the core sources of FDI. • China and the USA are the most active countries on FDI research. • Deionization , capacitive and desalination are frequent words in FDI articles titles. [ABSTRACT FROM AUTHOR]

Water and fertilizer are indispensable inputs to crop production in modern agriculture. Drought, water shortage and low efficient utilization of water have posed a great challenge on agricultural production and food security in China. New fertilizers with dual functions of water retention and slow release become significant to enhance the utilization efficiency of water, and thereby to ensure the sustainable development of agriculture. Therefore, previous studies on the new fertilizers have drawn much attention in water and fertilizer technology in recent years. This paper explores the preparation method of a novel water-retaining material that incorporated with nano-SiO2 for the slow-release fertilizer with water retention properties. A P(AA-AM)/SiO2 water-retaining composite was fabricated by in-situ polymerization in aqueous solution using acrylic acid (AA) and acrylamide (AM) as raw materials. A water-retaining slow-release fertilizer was then produced by the double-layer coating process. The mass ratio of acrylic acid (AA) and acrylamide (AM) was set as 3.5:1 to synthesize water-retaining materials. The initiator (potassium persulfate and sodium sulfite), crosslinking agent (N, N-methylenebisacrylamide), plasticizer (glycerol), and nano-SiO2 were added by 1%, 0.04%, 15%, and 2% in monomer mass, respectively. A drum coating process was selected to prepare the water-retaining slow-releasing fertilizer, where the inner coating layer was made of polyurethane, with the mass ratio of coating materials to the inner core of 3%, whereas the outer coating layer was P(AA-AM)/SiO2 water-retaining composite material, with a mass ratio to the core of 27%. Fourier Infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and thermogravimetry (TG) were used to characterize the microstructure, morphology and thermal stability of water-retaining materials. A filtration was selected to determine the water absorption of water-retaining material. Soil culture experiment was used to investigate the capacity of water-retaining and water-holding in the fabricated fertilizer. A water immersion method was utilized to explore nitrogen release properties of fertilizer at the temperature of 25℃. The results showed that the water absorption rates of composite materials with nano-SiO2 in deionized water and 0.9% NaCl aqueous solution were 152% and 87% higher than those of only P(AA-AM) materials, while the thermal stability was also significantly improved. SEM images and FTIR analysis indicated that nanoparticles of SiO2 were evenly dispersed into the P(AA-AM) composites, while the silicon hydroxyl groups on the surface of SiO2 increased the cross-linking density of water-retaining materials. Compared with the slow-release fertilizer without water-retaining layer, the water absorption rate and retention rate of slow-release fertilizer with water-retaining layer (after 25 days of incubation) increased by 25.5% and 47.2%, respectively, indicating the releasing duration of fertilizer was extended from 60 days to 72 days. The preparation method of water-retaining composite material that incorporated with nano-SiO2 and water-retaining slow-release fertilizers can provide excellent properties of water absorption and retaining, as well a high performance of slow release in soil. A mechanism of water-retaining was proposed to clarify the slow release of nutrients in the water-retaining material and water-retaining slow-release fertilizers. The findings can offer new insights into high efficiency fertilizers to enhance the utilization efficiency of water and fertilizers. [ABSTRACT FROM AUTHOR]

[Display omitted] • Scaling up preparation of modified catalysts by direct calcination in air. • Both defects and oxygen-containing groups contribute to performance enhancement. • Electro-Fenton for high pollutant removal kinetics in a wide pH range. • Industrializable case of 30 g catalyst synthesis theoretically for 5.4 m2 electrode. • Lab-scale demonstration for wastewater treatment with capacity of 7.2 L/h. Electro-Fenton (EF) regarded as a green substitution to traditional homogeneous Fenton, produces highly oxidizing OH through in-situ H 2 O 2 electrosynthesis and electrochemical Fe2+ regeneration. One of obstacles that hinders translation of bench-scale EF performance to water treatment practices is the difficulty of scaling up catalyst/electrode preparation in low cost while producing high performance. Here we report scalable preparation of modified carbon catalysts for high-efficiency EF by directly calcinating commercial carbonaceous materials in air. The EF with modified carbon cathode shows high kinetics of 0.296–0.569 min−1 for levofloxacin removal in much wider pH range of 3.0–6.6 using less Fe dosage compared with homogeneous Fenton. This EF system can reduce chemical oxygen demand (COD) of coking wastewater from 312.0 to 99.5 mg L−1 to satisfy wastewater discharge standard in China while consuming low electricity of 1.8–4.9 kWh kg−1 COD−1. We demonstrated the scalability of this EF process by scaling up preparative throughput of catalyst (30 g that can be processed into electrodes with total working areas of 54000 cm2), enlarging electrode size (230 cm−2) and reactor volume with wastewater treatment capacity of 7.2 L/h. This scalability demonstration of EF technology shows the promising potential of achieving low-cost advanced wastewater treatment. [ABSTRACT FROM AUTHOR]

Sinopodophyllum hexandrum is an important traditional Tibetan medicinal plant with great development potential in pharmaceutical industry because of the presence of major bioactive lignans such as podophyllotoxin (PT) that are widely used in combination therapy of cancer. In this study, a green and efficient method for the extraction of PT from S. hexandrum was established by optimized subcritical water extraction (SWE) combined with macroporous resin enrichment. Response surface methodology was introduced for SWE optimization to obtain the maximum yield of PT. The maximum extraction efficiency was achieved under the following conditions: extraction pressure 4 MPa, extraction solvent to feed ratio 18 mL/g, extraction temperature 180 °C, and SW flow rate 2.5 mL/min. Subsequently, an efficient macroporous resin enrichment method was developed to further purify PT in the crude extract obtained from SWE. D101 resin was selected as a proper adsorbent owing to its adsorption and desorption properties, whereas its adsorption process was found to be consistent with a pseudo-second-order model. The optimized loading amount was 3 BV of extract solution, and the desorption conditions were as follows: First, the product was eluted with deionized water until no sugar was detected in the effluent, followed by 6 BV of 20% aqueous ethanol elution and then by 15 BV of 60% aqueous ethanol elution. After the treatment with D101 resin, the concentration of PT increased from 8.3% in the crude extract to 61.5% in the final product. Moreover, the recovery yield of PT extracted with SW combined with D101 resin enrichment was 74.6%. The results show that SWE combined with macroporous resin enrichment is a green, effective, and low-cost technique for the extraction of PT from S. hexandrum. [ABSTRACT FROM AUTHOR]

[Display omitted] • GMZ bentonite in China was modified and purified by adopting a simple method. • Different inorganic salts have different modification effects. • The content of montmorillonite increased after modification and purification. • The yield of bentonite was improved by modifying first and then purifying. Na-bentonite of high purity has numerous applications in many industries. The raw bentonite ore contains many impurities and consists mainly of Ca-bentonite. In this study, sodium chloride (NaCl), sodium carbonate (Na 2 CO 3), sodium pyrophosphate (Na 4 P 2 O 7), and sodium hexametaphosphate (NaPO 3) 6 were used to modify GMZ bentonite, followed by purification. The optimal modification and purification conditions (such as inorganic salt, temperature, time, dosage, and particle size) were determined by testing the montmorillonite content, adsorption and expansion properties of modified bentonite. The results showed that the modification effect was the best when NaCl was added at t = 3 h and T = 60 °C. During the modification process, Na+ replaced Ca2+ and Mg2+ through ion exchange; the impurity minerals, quartz and feldspar, were removed from the bentonite by purification; and the montmorillonite content increases from 46.6 % to around 90 %. The modification effects of NaCl, Na 4 P 2 O 7, and (NaPO 3) 6 were improved with the dosage increasing, and Na 2 CO 3 can complete the modification of GMZ bentonite when the dosage was 2 %. Compared with the bentonite purified by tap water (TW) and deionized water (DW), the yield of bentonite can be greatly improved by adopting the technique of modifying first and then purifying. [ABSTRACT FROM AUTHOR]

• The ash content and B/A of coal treated by [Bmim]HSO 4 decreased significantly. • The removal rate of AAEMs and Fe increased with the [Bmim]HSO 4 concentration. • NH 4 Ac-soluble and HCl-soluble metal elements can be removed by [Bmim]HSO 4 solution. • The removal mechanism of AAEMs and Fe from Zhundong coal was expounded. China's Zhundong region is rich in coal resources. However, the high content of AAEMs and Fe (Na, Mg, Ca and Fe) in the coal leads to serious equipment fouling and slagging problems during combustion. In this paper, eco-friendly acidic ionic liquid [Bmim]HSO 4 was used as a pretreatment solvent for the removal of AAEMs and Fe from Zhundong coal. The effects of [Bmim]HSO 4 concentration on the removal of Na, Mg, Ca and Fe were comprehensively investigated. The changes of occurrence modes of four metal elements were systematically analyzed. The removal mechanism of AAEMs and Fe from Zhundong coal was expounded. The results showed that the ash content and B/A of coal treated by [Bmim]HSO 4 were significantly lower than those of water leached coal and raw coal. The content of Na 2 O in coal ash treated by [Bmim]HSO 4 was as low as 0.939%, which met the standard of power coal. The removal rate of AAEMs and Fe increased with the increment of [Bmim]HSO 4 solution concentration. At the optimum concentration of 5%, the removal rate of Na, Mg, Ca and Fe were 92.89%, 81.11%, 79.31% and 48.27%, respectively. Compared with deionized water, [Bmim]HSO 4 solution showed an excellent removal effect on NH 4 Ac-soluble and HCl-soluble metal elements. It was mainly attributed to the following two points: Firstly, [Bmim]HSO 4 destroyed the ionic force and coordination interaction between metal ions and organic oxygen-containing functional groups in coal, carboxylates and phenates were protonated and H+ replaced metal ions. Secondly, the swelling effect of [Bmim]HSO 4 on coal was beneficial to the removal of tiny acid soluble minerals embedded in the coal matrix, which further enhanced the removal of AAEMs and Fe in Zhongdong coal by [Bmim]HSO 4. [ABSTRACT FROM AUTHOR]

Highlights: [•] Levels and distribution of atmospheric and water PAHs were studied in Lake Chaohu. [•] The monthly diffusive air–water exchange flux were estimated by a two-film model. [•] PAH16 levels in atmosphere and water were significantly correlated with temperature. [•] Significant correlations between gas-particle partition and and Log K oa. [•] PAH levels in water and gas were the most important factors for air–water exchange. [ABSTRACT FROM AUTHOR]

An evaluation of shale pore connectivity is essential for predicting the production behavior and optimizing the development plan of shale gas. To systematically investigate the multiscale connectivity characteristics and controlling factors, complementary tests were conducted on four overmature marine shale samples from southern China (one each from Longmaxi Formation and Wufeng Formation, and two from Niutitang Formation) with different maturity and composition. The methods included mercury intrusion capillary pressure (MICP), spontaneous imbibition with deionized water and n-decane, saturated diffusion distribution with seven nano-sized tracers, N 2 physisorption, small-angle neutron scattering (SANS), and focused ion beam-scanning electron microscopy (FIB-SEM) tomography. Moreover, a novel repeated MICP measurement technique was developed and used to evaluate the pore connectivity from the distribution behavior of residual mercury. Results indicate that the connectivity loss of hydrophilic pore networks owing to an increased maturity and the compaction causes pore shrinkage and bond breakage between pore networks. According to the three-dimensional reconstruction and pore network extraction of FIB-SEM images, pores in organic matter (OM) have a good pore connectivity, but the minerals surrounding the OM reduce the overall pore connectivity of the shale matrix. By evaluating the pore connectivity using different methods, the hydrocarbon migration pattern in overmature marine shales was established. Our results imply that in addition to creating induced fracture networks, effectively connecting induced fractures with preexisting microcracks or joint sets between OM pore networks and transport pores can also be used to enhance overall pore connectivity. Microwave heating in shale reservoirs may be an effective way of further improving the production and recovery of hydrocarbons. • Pore connectivity for shale samples from marine formations was studied with complementary methods at multiple scales. • A novel repeated MICP measurement was developed to evaluate the pore connectivity. • Shale pore connectivity was indicated from diffusion distribution of seven nanotracers. • Controlling factors of pore connectivity were discussed by visual and quantitative techniques. • Hydrocarbon migration pattern was established based on pore connectivity of shale. [ABSTRACT FROM AUTHOR]