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Separation and Purification Technology
Elsevier Science B.V.
Separation and Purification Technology

Elsevier Science B.V.

1383-5866

Separation and Purification Technology/Journal Separation and Purification TechnologySCIEIISTP
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    Membrane aging effects on water recovery during full-scale potable reuse: Mathematical optimization of backwashing frequency for constant-flux microfiltration

    Cogan N.G.Ozturk D.Ishida K.Safarik J....
    10页
    查看更多>>摘要：? 2022 Elsevier B.V.One tool in efforts to tackle the ever growing problem of water scarcity is municipal wastewater reclamation to produce drinking water. Microfiltration (MF) is a central technology for potable reuse because it is highly effective in removing pathogenic protozoa, bacteria, and other colloids and for reverse osmosis pretreatment. However, as microfiltered materials accumulate at the membrane surface, its productivity is reduced requiring periodic removal of foulants. A mathematical model of MF is described in the context of hollow fiber filtration that focused on optimizing constant flux operation with backwashing. Design curves were also proposed for determining backwash timing. The model analysis is evaluated against real-world MF fouling for membranes that range in age from a few weeks to three years, observed at the world's largest water reuse facility operated by the Orange County Water District. The presented model compares well with the full-scale operational data, and model parameters accurately capture variations in fouling kinetics with membrane age, providing clues to changes in optimal regeneration timing and frequency as membrane performance declines over long time scales.
      原文链接:
    • NSTL
    • Elsevier

    Eutectic freeze crystallization for recovery of NiSO4 and CoSO4 hydrates from sulfate solutions

    Olsson R.T.Ashoka Sahadevan S.Gardner J.Ma Y....
    13页
    查看更多>>摘要：? 2022 The AuthorsIn this study, eutectic freeze crystallization (EFC) was investigated to recover NiSO4 and CoSO4 hydrates from aqueous and dilute sulfuric acid solutions of metal sulfates. Binary phase diagrams were established using a combination of thermodynamic modeling and experimental data. The mixed-solvent electrolyte (MSE) model was employed to model solid–liquid phase equilibria. The predicted binary phase diagrams from the model were in good agreement with the experimental results. Experimental eutectic temperatures and eutectic metal sulfate concentrations for the NiSO4-H2O and CoSO4-H2O systems are ?3.3 °C and 20.8 wt% and ?2.9 °C and 19.3 wt%, respectively. For NiSO4-H2SO4-H2O and CoSO4-H2SO4-H2O systems, the eutectic temperature and eutectic metal sulfate concentration decrease with increasing H2SO4 concentration. Batch experiments were performed to study the EFC of different sulfate solutions, including 25- wt% NiSO4 in H2O, 20- wt% NiSO4 in 0.5 mol/kg H2SO4, 25- wt% CoSO4 in H2O, and 20- wt% CoSO4 in 0.5 mol/kg H2SO4. The results show that controlling the supersaturation allows high-quality ice and salt crystals to be recovered as separate phases under eutectic conditions, with the crystalline salts in the form of heptahydrates. This study shows that EFC can be a promising alternative to evaporative crystallization for recovering NiSO4 and CoSO4 hydrates from sulfate solutions.
      原文链接:
    • NSTL
    • Elsevier

    A green synthesis of MOR zeolite membranes by wet gel conversion for dehydration of water-acetic acid mixtures

    Wang J.Wang L.raza W.Lu J....
    10页
    查看更多>>摘要：? 2021 Elsevier B.V.High performance mordenite (MOR) membranes were successfully synthesized by wet gel conversion (WGC) route using organic template-free and fluoride-free gels on seeded macroporous Al2O3 tubes. The seeded Al2O3 tubes were dipped into the gel solution with a composition of SiO2: 0.0045Al2O3: 0.19 Na2O: 27.76 H2O and then directly crystallized at 150 °C for 8 h without any extra solvent or solution in autoclave. The concentration of MOR seeds, crystallization time, composition of gels and crystallization way (hydrothermal growth or WGC) significantly influenced the membrane performance for dehydration of acetic acid (AA) mixtures by pervaporation. The prepared MOR membranes displayed a high water flux and good selectivity in long-term dehydration of 90 wt.% AA/H2O at 75 °C with the steay-state flux of 0.70 kg m?2 h?1 and separation factor increasing to 5000 after 200 h test. The WGC approach reduced the consumption of gel by about 96% with almost “zero” waste liquid. This WGC method is demonstrated as an efficient, green route to synthesze zeolite membranes and to possess potentiality for industrial dehydration applications.
      原文链接:
    • NSTL
    • Elsevier

    Green separation and recovery of cobalt and nickel from sulphuric acid achieved by complexation-assisted solvent extraction

    Yuan L.Yang H.Ning P.Wen J....
    12页
    查看更多>>摘要：? 2021Ternary cathodes account for more than half of the Lithium-Ion Batteries (LIBs) cathode market share and their recycling draws the most attention. Solvent extraction is the most efficient and common method to separate and recover Co and Ni from spent ternary cathode leachates. However, the traditional extraction process produces a large amount of saline wastewater, thus will seriously pollute the environment. In this work, an environmental approach is proposed by adding a water-soluble complexing agent into the aqueous phase, the separation factor is 2 times higher and the consumption of NaOH is 90% reduced compared to the Na-saponified counterpart, which was attributed to the differences of the complexation between metal ions and complexing agent in aqueous phase. The differences in the complexing ability are enhanced with an increased local nucleophilicity index of the active sites along with a reduced molecular volume in complexing agent, thus leading to superior cobalt extraction efficiency (～98.9%) and separation factor (～345). In addition, because of the fact that the whole-process pollution control is needed for cleaner chemical production, a green process is developed by recovering additives through Tri-n-butyphosphate. This excellent separation performance suggests that adding complexing agent in solvometallurgical recovery process may aid in the future development of high-purity raw metals for advanced fields.
      原文链接:
    • NSTL
    • Elsevier

    Inherent safer, eco-friendly and energy saving vapor recompression assisted extractive dividing-wall column process for the separation of minimum-boiling azeotrope

    Zhu J.Jing C.Hao L.Wei H....
    12页
    查看更多>>摘要：? 2022 Elsevier B.V.The vapor recompression (VRC) also called heat pump is widely used in the distillation to achieve energy saving. However, considering economic performance, high compression ratio impedes the application of VRC in the wide-boiling mixtures system such as extractive dividing-wall column (EDWC). In addition, the flammability of hydrocarbons as working fluids in VRC causes serious potential hazard especially for wide-boiling mixtures system. Hence, in this article, a systematic method is proposed to investigate vapor recompression assisted extractive dividing-wall column (EDWC-VRC) with multi-criteria assessment for the separation of dimethyl carbonate-methanol with heavy entrainer aniline as a case. Process preliminary analysis shows feed heater/vaporizer (feed preheating strategy) and intermediate reboiler can improve economic and inherent safety performance of VRC simultaneously. Especially for feed heater/vaporizer, the definition of minimum boiling azeotrope demonstrates that the application of vapor recompression between feed heater/vaporizer and condenser in EDWC is inherently attractive. Then, two novel configurations called EDWC-VRC integrating all feed preheating and heat integration (EDWC-VRC-AFPH-HI) and EDWC-VRC integrating two-feed preheating and intermediate reboiler (EDWC-VRC-TFPH-IR) are proposed and optimized to get optimal flowsheet. The economic and environmental results show that EDWC-VRC-AFPH-HI and EDWC-VRC-TFPH-IR are superior to original EDWC process in the open literature and EDWC-VRC with high compression ratio. Especially for EDWC-VRC-AFPH-HI with best performance, there are 12.42% TAC (five-year payback period) and 18.71% CO2 emission reduction and 20.78% energy saving than original EDWC process, respectively. Quantitative consequence assessment shows that EDWC-VRC-AFPH-HI and EDWC-VRC-TFPH-IR is inherent safer than EDWC-VRC with high compression ratio. We believe that integration of feed preheating strategy/intermediate reboiler with VRC can promote the application of VRC in the wide-boiling mixtures system.
      原文链接:
    • NSTL
    • Elsevier

    Individual effects of different co-existing ions and polystyrene (PS) microplastics on the reactivity of sulfidated nanoscale zero-valent iron (S-nZVI) toward EDTA-chelated CdII removal

    Li W.Liang L.Li Y.Tian Y....
    9页
    查看更多>>摘要：? 2022 Elsevier B.V.Recently, EDTA-chelated CdII (CdII-EDTA) was effectively removed by sulfidated nanoscale zero-valent iron (S-nZVI). However, few studies have been performed to investigate the influence of co-existing ions and emerging contaminants (such as microplastics) on the performance of S-nZVI toward CdII-EDTA, which is vital for the application of S-nZVI in practical wastewater treatment. In this study, the individual effects of different co-existing ions (NO3?, SO42?, PO43?, Mg2+, Cu2+, and Zn2+) and polystyrene (PS) microplastics with different concentrations on the removal of CdII-EDTA by S-nZVI were systematically investigated. The removal capacity of S-nZVI toward CdII-EDTA fell in the range of 579.3–644.7, 612.3–670.2, 607.4–691.3, 533.3–623.6, 79.9–545.3, 544.3–631.7, and 568.6–663.8 mg/g for the presence of NO3?, SO42?, PO43?, Mg2+, Cu2+, Zn2+, and PS microplastics over the concentration range of 10.0–150.0 mg/L, respectively, which were all smaller than that of the system of CdII-EDTA alone (746.6 mg/g), indicating that all of the investigated co-existing substances showed inhibitory effects on CdII-EDTA removal. As for NO3?, SO42?, or Mg2+-containing system, the inhibitory effect was ascribed to the influence of S-nZVI corrosion rate; As for PO43?, Mg2+, Cu2+, Zn2+, or PS microplastics-containing system, the negative effect was caused by changing the corrosion of S-nZVI and occupying the reactive sites at the surface of S-nZVI. The final corrosion products of S-nZVI under different reaction conditions were strongly dependent on the species and concentration of co-existing substance with the combinations of γ-FeOOH, α-Fe2O3, FeO, or β-FeOOH as the dominant corrosion products.
      原文链接:
    • NSTL
    • Elsevier

    In-situ synthesis of metal oxide and polymer decorated activated carbon-based photocatalyst for organic pollutants degradation

    Singh A.R.Dhumal P.S.Bhakare M.A.Lokhande K.D....
    9页
    查看更多>>摘要：? 2022 Elsevier B.V.The development of eco-friendly, outstanding, cost-effective, and efficient material for wastewater treatment remains a challenge towards the sustainable approach. Herein, we synthesized zinc oxide (ZnO) and polypyrrole (PPy) fabricated activated carbon (AC) based trinary-nanocomposite (ZCP) for dye degradation application. The carbonization of biowaste and polymerization were achieved in acidic condition. The reaction mass pH was converted to a basic medium, as necessary for the in-situ formation of zinc oxide nanoparticles. This trinary-nanocomposite (ZCP) was used to degrade organic dyes such as methylene blue (MB). The influence of several factors such as pH, temperature study, electrolyte, photocatalyst dose, and contact duration on photodegradation were investigated. The ZCP composite was able to degrade 98.12% of MB dye solution within 20 min under visible light at room temperature. The degradation efficiency of ZCP was further increased (99.05%) at high temperatures. The above result indicates that the as-prepared ZCP nanocomposite is exhibiting excellent photocatalytic activity as compared to only low recombination of photogenerated electrons and holes. Compared to the control samples, ZCP has better dye degradation ability and a significant efficiency even after 10 consecutive cycles. Chemical oxygen demand (COD) analysis confirmed the photocatalytic degradation of MB. This study mainly focused on the facile in-situ synthesis of ZCP nanocomposite for cost-effective mass production for various applications, including organic pollutants degradation.
      原文链接:
    • NSTL
    • Elsevier

    Synthesis of N-(2-ethylhexyl)-pyridine-4-carboxamide and its synergistic behaviors with dinonylnaphthalene sulfonic acid for the selective extraction of nickel and cobalt

    Liu W.Liang J.Su H.Zhang J....
    11页
    查看更多>>摘要：? 2022 Elsevier B.V.The hydrometallurgical process for the recovery of nickel and cobalt requires a complex and expensive impurity removal process. Solvent extraction is widely used in industry for the separation, purification, and concentration of metals. However, current commercial extractants encounter some difficulties when cobalt and nickel are extracted from solutions containing a large amount of impurities such as manganese and calcium. There is an urgent need to develop new reagents for the selective extraction of Ni and Co. In this study, N-(2-ethylhexyl)-pyridine-4-carboxamide (NEHPCA) was synthesized, and the metal extraction capacity of its synergistic solvent extraction (SSX) system with dinonylnaphthalene sulfonic acid (DNNSA) and tributyl phosphate (TBP) modifier was examined. The experimental results show that the selectivity of the new SSX system has the order Cu > Ni > Co > Zn > Mn > Ca > Al ≈ Cr (III) ≈ Mg ≈ Fe (III), with excellent selectivity for nickel and cobalt. Using an organic phase composed of 0.7 M NEHPCA, 0.35 M DNNSA, and 0.2 M TBP under 1:1O/A operation, after three-stage theoretical extraction, more than 99% of nickel and cobalt can be recovered from a synthetic leaching solution of nickel laterite ore. Mechanistic studies showed that NEHPCA and water molecules participate in the internal coordination of metals, and DNNSA provided coordination anions to achieve charge balance, forming the Ni complex in this SSX system which existed most likely in the form of [Ni(NEHPCA)2(H2O)4](DNNS)2 in the organic phase.
      原文链接:
    • NSTL
    • Elsevier

    Aqueous phase of thermo-catalytic reforming of sewage sludge – quantity, quality, and its electrooxidative treatment by a boron-doped diamond electrode

    Kick C.Uchaikina A.Apfelbacher A.Daschner R....
    11页
    查看更多>>摘要：? 2022 Elsevier B.V.Pyrolysis is a promising conversion technology to produce biofuels from residues such as sewage sludge. In this study, the chemical composition and the amount of the resulting aqueous phase from the thermo-catalytic reforming process of sewage sludge at different process parameters are compared to those of non-catalytic fast pyrolysis processes from literature. Furthermore, electrooxidation using a boron-doped diamond (BDD) electrode was investigated as purification technology for the resulting aqueous phase. The results of this study show that the quantity of the aqueous phase strongly depends on the temperature of the thermo-catalytic reforming process and is presumably governed by the influence of secondary gas-carbonisate reactions like the water gas shift reaction. Higher reaction temperatures result in a reduced amount of the aqueous phase. The chemical composition of the aqueous phase of fast pyrolysis processes was comparable to that obtained at the thermo-catalytic reforming process. To reduce the chemical oxygen demand (COD) and the number of refractory substances to a level at which the aqueous phase can be discharged into a conventional wastewater treatment plant, electrooxidation experiments with the aqueous phase of the thermo-catalytic process were carried out using a BDD electrode. The treatment efficiency was investigated in galvanostatic operation varying the applied current density and the flow rate of the aqueous phase. A COD removal of 94.6 % was achieved after 0.54 kWh at an instantaneous current efficiency of 0.47 at a current density of 50 mA/cm2 and a flow rate of 3.7 L/min. This indicates that electrooxidation by a BDD electrode can be a promising purification technology for the aqueous phase from pyrolysis of sewage sludge. However, the high energy consumption of the process will need to be addressed in future studies to make the process economically feasible.
      原文链接:
    • NSTL
    • Elsevier

    Statistical capillary tube model for porous filter media

    Liu X.Matti Maricq M.Dobson D.A.
    11页
    查看更多>>摘要：? 2021A new statistical capillary tube model is presented to predict both filtration efficiency and permeability of particulate filters. The model considers the porous structure of the filter media as an assembly of curved capillary tubes with a statistical size distribution. The key model descriptors of pore microstructure are porosity, pore size, pore size distribution, and tortuosity. The model was validated by permeability and size dependent filtration efficiency measurements of bare and washcoated gasoline particulate filters (GPFs), using porosimetry data of the filter media as model inputs. Comparing with a more widely used spherical model for particulate filters with typical porosity range of 30–60%, the capillary tube model has similar input parameters but provides additional permeability prediction as well as better filtration predictions over a wider porosity range including the lower porosity of washcoated filters. Furthermore, it offers a more visually straightforward and intuitive correlation between filtration paths and filter performance. This allows convenient adoption of the capillary tube model in numerous applications that are currently based on spherical model assumption and provides improved guidance for filter optimization. Beyond ceramic automotive exhaust filters, this geometric model offers a new framework for examining porous filter media in general.
      原文链接:
    • NSTL
    • Elsevier