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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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    Ammonia removal from municipal wastewater via membrane capacitive deionization (MCDI) in pilot-scale

    Wang Q.Fang K.He C.Wang K....
    12页
    查看更多>>摘要：? 2022 Elsevier B.V.With the depletion of energy, renovation of wastewater has attracted wide attention around the world, among which the recovery of ammonia has also been an ongoing topic. Membrane capacitive deionization (MCDI) has emerged as a promising technology for nutrient removal and recovery. However, limitations of both scale-up and treatment of practical wastewater still restrict its real application. This study aims to investigate the feasibility of ammonia removal from real wastewater by MCDI on a pilot scale. The MCDI module used in this study was expanded to a 2-unit facility (15 pairs of electrodes per unit). Firstly, synthetic wastewater was used as feed water to optimize different kinds of operating parameters, including applied voltage (0–2.5 V), flow rate (7–30 L/h), and initial concentration (20–100 mg/L). Further experiments investigated the competitive adsorption performance under complex inflow conditions. Results indicated that the presence of co-existing cations significantly reduced the removal efficiency and adsorption capacity of ammonia. With the same inflow concentration, the removal efficiency of NH4+, Mg2+, and Ca2+ was 39.12 ± 5.31%, 47.56 ± 2.68%, and 33.33 ± 1.90% respectively. The interplay of initial ion concentration, charge valence, and hydrated radii led to the different electro-sorption performances. Subsequently, practical municipal wastewater after the up-concentration of organics was used as feed water to evaluate the feasibility of the pilot-scale MCDI. Under the optimized condition, a long-term experiment was carried out for 15-day to deal with actual wastewater. Besides, ion removal performance, the energy consumption, and desorption efficiency were also analyzed. The system maintains a stable removal efficiency for all cations, with low energy consumption (1.16 kWh/m3) and high desorption efficiency (around 90%). Overall, the results of this study posed the MCDI process as a potential approach to ammonia removal and recovery from municipal wastewater.
      原文链接:
    • NSTL
    • Elsevier

    Synthesis of ZIF-67 derived honeycomb porous Co/NC catalyst for AO7 degradation via activation of peroxymonosulfate

    Long Y.Li S.Yang P.Chen X....
    14页
    查看更多>>摘要：? 2022 Elsevier B.V.MOF-derived metal-carbon composite catalyst was an alternative high-efficient catalyst for activating peroxymonosulfate (PMS). In this study, a novel cobalt-carbon-nitrogen doped composite catalyst with honeycomb porous structure (Co-HPNC) was obtained through a simple strategy consisting of three steps: self-growth of ZIF-67 on the SiO2 core, pyrolysis, and NaOH etching away SiO2 core. The Co-HPNC exhibited an outstanding catalytic performance (98.1% in 10 min) to activate PMS for acid orange 7 (AO7) degradation. The observed reaction kinetic constant (0.4319 min?1) was 2.64 times superior to that of the unmodified Co/NC catalysis system (0.1636 min?1). In the meantime, the catalyst demonstrated a high PMS activation capacity over a wide pH range of 3–11 and strong adaptability to the high concentration of inorganic anions (Cl-, SO42-, and CO32–). After being recycled three times, the removal efficiency could still reach 92.7% in 25 min. The quenching tests and EPR spectrum illustrated the existence of radical and non-radical pathways, in which singlet oxygen was dominant during the degradation process. It was hypothesized that Co(0)/Co(Ⅱ)/Co(Ⅲ), pyridinic-N and pyrrolic-N contributed to the generation of hydroxyl and sulfate radicals, while C=O functional group and graphitic-N were catalytic sites for singlet oxygen. Finally, the radical electrophilic attacking sites of AO7 were calculated by the density functional theory (DFT), and the degradation routes of AO7 were speculated by GC–MS. The toxicity test illustrated that the Co-HPNC/PMS system was an environmental-friendly technology for AO7 degradation. The prepared Co-HPNC with a unique honeycomb porous structure presents a novel synthesis route for MOF-derived catalyst applied in the PMS activation system for wastewater treatment.
      原文链接:
    • NSTL
    • Elsevier

    New insight into the mechanism of peroxymonosulfate activation by Fe3S4: Radical and non-radical oxidation

    Li J.Gou G.Kang S.Tan X....
    12页
    查看更多>>摘要：? 2022Sulfamethoxazole (SMX) degradation was investigated through peroxymonosulfate (PMS) activation by the synthesized flower-like Fe3S4, which showed the best performance with the highest reaction stoichiometric efficiency (7.9%). 99% of SMX (2 mg/L) was eliminated from reaction solution during 30 min with 20 mg/L Fe3S4 and 0.1 mM PMS. The main reactive oxygen species (ROS) involved in the contaminant decomposition were investigated through quenching experiments, electron paramagnetic resonance, and X-ray photoelectron spectroscopy characterization. In addition to the typical sulfate radical (SO4?-) and hydroxyl radical (HO?), it should be noted that non-radical singlet oxygen (1O2) was generated and participated in the catalytic oxidation of compounds. The degradation of SMX in the PMS alone system through non-radical pathway and in the Fe3S4/PMS system by both radical and non-radical pathways were proposed according to the detected intermediates. The ecotoxicity of SMX and its by-products were evaluated through the quantitative structure–activity relationship (QSAR) analysis. The present study provided new insight into the mechanism of organic compound removal by ROS including radical and non-radical in Fe3S4/PMS system.
      原文链接:
    • NSTL
    • Elsevier

    Antisolvent crystallization of battery grade nickel sulphate hydrate in the processing of lateritic ores

    Demirel H.S.Uysal D.Dogan O.M.Uysal B.Z....
    16页
    查看更多>>摘要：? 2022 The AuthorsLithium-ion batteries are a crucial part in the rapid, on-going electrification of the global vehicle fleet, which is essential in enabling a transition to a society based on renewable energy. By combining metals including lithium, nickel, cobalt, and manganese in different proportions, cathode active materials with different properties can be obtained. Nickel sulphate hexahydrate, which is of great importance to the battery industry, can be produced by hydrometallurgical processing of lateritic and sulphide ores. Antisolvent crystallization is examined as an alternative to conventional crystallization methods for the production of high-grade nickel sulphate hexahydrate in the processing of lateritic nickel ores from Turkey. The ore has been leached under atmospheric pressure followed by purification by ion exchange resulting in a solution enriched with respect to nickel together with a range of impurity metals from which NiSO4·6H2O can be obtained by antisolvent crystallization. Separate antisolvent crystallization experiments have been carried out for nickel, cobalt and iron sulphate systems, which are the main metals present in the solution, and solubility data has been determined for key conditions. Acetone and isopropanol have been evaluated as antisolvents. Antisolvent crystallization experiments have also been carried out using synthetic solutions and the effect of addition rate of antisolvent, addition of diluted antisolvent and seeding on the purity of the crystals has been investigated. Acetone gives the best product quality in terms of purity and shape. Seeding and a slow rate of addition of dilute antisolvent gives the highest purity of the NiSO4·6H2O crystals. Under optimised conditions, crystals containing 22.3% Ni with a purity of 99.8% by mass have been obtained with a crystallization yield of 63.5%.
      原文链接:
    • NSTL
    • Elsevier

    Hydrometallurgical recovery of platinum-group metals from spent auto-catalysts – Focus on leaching and solvent extraction

    Paiva A.P.Rodrigues P.G.Piedras F.V.Nogueira C.A....
    14页
    查看更多>>摘要：? 2022 The AuthorsTo ensure the supply of raw materials for products of extreme importance in strategic sectors, the recovery of critical metals from secondary sources becomes increasingly urgent. Platinum group metals (PGMs), being rare and very valuable, fall into this demand, and the catalytic converters that contain them are recognized as one of the main sources. Hydrometallurgical processes have been proposed as an alternative to pyrometallurgical ones, with leaching and separation by solvent extraction being core operations in this type of processing. This article investigates these two operations, seeking to optimize conditions and propose new arrangements to improve them. Two different catalyst samples were considered in the experimental work. Leaching was carried out involving concentrated HCl solutions (with H2O2 as oxidant) and low liquid/solid ratios, seeking to maximize PGMs recovery, guaranteeing their high concentration in leachates and minimizing aluminum co-dissolution. Cerium leaching was also followed since this is a rare-earth metal with potential interest. Temperature, HCl concentration, liquid/solid ratio (L/S), time and particle size factors were evaluated, and the optimized conditions found were 11.6 mol L?1 HCl, 1%vol H2O2, 60 °C, L/S = 2 L kg?1 and 3 h, leading to PGM yields of 90–98% Pt, 99% Pd and 70–96% Rh, and leachate compositions of 0.41–0.78 g L?1 Pt, 1.6 g L?1 Pd, 0.062–0.066 g L?1 Rh, depending on the catalyst sample. For solvent extraction (SX), several commercial extractants dissolved/diluted in toluene were checked, firstly with a model solution, and then applied to the real spent auto-catalyst (SAC) leachates produced in-situ. The overall results showed that the most promising SX systems among those tested were Cyanex? 471X and Cyphos? IL 101. Cyanex? 471X allowed the quantitative extraction of Pd(II) and Fe(III), but the latter was conveniently scrubbed by water prior to Pd(II) stripping by an acidic thiourea solution. Pt(IV) and Pd(II) extraction values by Cyphos? IL 101 were very encouraging, as only Fe(III) and Zn(II) were appreciably co-extracted, however, scrubbing of the contaminating metals, and Pd(II) and Pt(IV) stripping, did not work. Hence, investigation to find proper scrubbing/stripping agents for Cyphos? IL 101 SX system, to recover PGMs from recycled SACs, is further needed.
      原文链接:
    • NSTL
    • Elsevier

    Dynamic controllability comparison of different side-stream extractive distillation processes with intermediate boiling entrainer

    Wang C.Zhuang Y.Dong Y.Liu L....
    17页
    查看更多>>摘要：? 2022It is of great significance to simultaneously consider the economy and controllability for promoting the sustainability of the process industry. In the paper, the controllability of different energy-efficient side-stream extractive distillation (SSED) processes using intermediate boiling entrainer including two double column side-stream extractive distillation (DC-SSED) processes and one single column side-stream extractive distillation (SC-SSED) process are explored for separating the methanol/toluene azeotrope with triethylamine as entrainer. The side stream withdrawal locations of the DC-SSED processes are located in the rectifying section (DC-SSED (a)) and extraction section (DC-SSED (b)), respectively. The recycled intermediate boiling entrainer concentration is 45 mol% for the SC-SSED process. The two robust control strategies constructed for the DC-SSED (b) process are also suitable for the DC-SSED (a) process in resisting the same feed disturbances, which do not adopt the construction concept of the feasible control strategy for the SSED separation process with heavy entrainer. The difference between the two novel control strategies exists in how to control the methanol product purities via reflux ratios. Simultaneously, the two robust control strategies are constructed to resist the same feed disturbances for the SC-SSED process and compared to the two DC-SSED processes in terms of dynamic performances. The dynamic performances demonstrates that the DC-SSED (a) process with worst energy and economic performances is superior to the SC-SSED process and the DC-SSED (b) process from the perspective of the total integral squared error. However, the number of control loops used in the control strategies constructed for the SC-SSED process with optimal energy and economic performances is much smaller than that used in the control strategies constructed for the DC-SSED process, especially the number of composition control loops. Overall, the dynamic performances and economic performances of different processes may not be consistent, and the paper provides some advice for the construction of the robust control strategies for the SSED separation processes with intermediate boiling entrainer.
      原文链接:
    • NSTL
    • Elsevier

    Research on methylene blue degradation based on multineedle-to-plane liquid dielectric barrier discharge mode

    Zhang X.Shi P.Zhao W.Lu W....
    10页
    查看更多>>摘要：? 2022 Elsevier B.V.Advanced oxidation processes (AOPs) focusing on non-thermal plasma induced by dielectric barrier discharge (DBD) are adequate sources of diverse reactive oxygen species beneficial for water and wastewater treatment. The degradation of methylene blue (MB) was investigated using plasma liquid dielectric barrier discharge with a multineedle-to-plane reactor. MB at 20 mg/L concentration was almost completely degraded after 40 min of treatment. In this study, several important parameters, such as input voltage, initial concentration, initial pH, discharge gap, tip radius of curvature, and presence of radical, were evaluated, and their effects on MB degradation rate were investigated. The degradation rate of MB increased with initial pH. By contrast, the degradation rate showed a downward trend with increasing initial concentration, discharge distance, and tip curvature radius. O3 and H2O2 produced during the degradation process considerably influenced the entire degradation process, especially when the quenching agents of HO?, O2·- and e? were added, and the degradation efficiency was obviously reduced. According to the measured spectrum, the possible process of the discharge process was analyzed, and the COMSOL finite element simulation is performed to obtain the visualization of the discharge model. This work can provide exploratory platforms for comprehensively understanding and enhancing MB degradation in DBD plasma technology.
      原文链接:
    • NSTL
    • Elsevier

    A novel composite of monosodiumtitanate-amidoximatedpolyacrylonitrilefor the sequestration of uranium from contaminated water: An experimental and simulation study

    Kamble P.Banerjee D.Sugilal G.Kaushik C.P....
    14页
    查看更多>>摘要：? 2022 Elsevier B.V.A new inorganic–organic hybrid composite, comprising Monosodiumtitanate(MST) and AmidoximatedPolyacrylonitrile (MPA), has been developed in bead form for the separation of uranium from contaminated water.Inline with the design objectives, asynergistic effect on uranium uptake by MST and Amidoximewas obtained.The measured U uptake capacity is 280 mg/g, the highest ever reported U uptake by any composite in column useable form. U uptake by the composite follows the Langmuir isotherm mechanism. The uptake performance remains unaltered even in the presence of sulphate, nitrate, chloride ion, and carbonate ions. The column performance of the composite was demonstrated by removing U over 12,000-bed volumes of waste effluent from 1000 ppb to down below < 60 ppb level. A mathematicalmodel is developed and used to predict process performance under various operating conditions mimicking scale-up operations with an eye in generating potable water from groundwater.
      原文链接:
    • NSTL
    • Elsevier

    Effective adsorption of crystal violet dye on sugarcane bagasse–bentonite/sodium alginate composite aerogel: Characterisation, experiments, and advanced modelling

    Gong X.-L.Lu H.-Q.Li K.Li W....
    12页
    查看更多>>摘要：? 2022 Elsevier B.V.A novel sugarcane bagasse–bentonite/sodium alginate (SCB–Ben/SA) composite aerogel was prepared as an effective green adsorbent via blending–cross-linking for the removal of crystal violet (CV) dye from aqueous solution. The equilibrium adsorption capacity of SCB–Ben/SA for CV was 839.9 mg/g at 0.8 mg/mL adsorbent dosage, temperature 303 K, pH 4, and 800 mg/L initial CV concentration, and presented a removal rate of 85%. Adsorption kinetics studied using the novel pseudo-first-order and pseudo-second-order (PFO–PSO) combined model showed that CV adsorption by SCB–Ben/SA was a complex process and did not include a single mechanism, but involved both chemical and physical adsorption reactions; however, chemisorption was the dominant kinetic mechanism. The dynamic characteristics of CV adsorption process achieved through the liquid film around SCB–Ben/SA and the pores inside SCB–Ben/SA was described satisfactorily and conveniently using the novel film–pore mass transfer (FPMT) model. A multilayer adsorption model was applied to further understand the CV adsorption behaviour of SCB–Ben/SA. The number of linked CV molecules per functional group varied from 0.53 to 0.63 for SCB–Ben/SA. The CV molecules were adsorbed on SCB–Ben/SA via mixed orientation. The adsorption isotherms and thermodynamics revealed that the multilayer adsorption process was endothermic and spontaneous. Overall, SCB–Ben/SA was found to be an efficient, low-cost, green, and recyclable adsorbent for organic dye removal.
      原文链接:
    • NSTL
    • Elsevier

    Synthesis of formaldehyde from CO2 catalyzed by the coupled photo-enzyme system

    Guo M.Gu F.Meng L.Liao Q....
    9页
    查看更多>>摘要：? 2022 Elsevier B.V.Using the reduced nicotinamide adenine dinucleotide (NADH) as coenzyme, formate dehydrogenase (FDH) and formaldehyde dehydrogenase (FADH) can catalyze the reduction of CO2 to formaldehyde. In this study, a hollow fiber membrane module was used as the enzyme-bearing reactor and gas distributor, and then coupled with a UV/TiO2 photocatalytic NADH regeneration system. First, photocatalytic CO2 reduction with varied pH value and electron donor was studied as a control. Then, CO2 reduction catalyzed by the photo-enzyme coupled system was investigated and the limiting step of the reactions was analyzed. At last, the ratio of FDH and FADH, and cofactor concentration were optimized, and the operation stability was examined as well. The results show that the optimal pH value for the production of formaldehyde by photocatalysis and photo-enzyme coupling catalysis is respectively 6.5 and 7.0 with H2O as electron donor. At pH 7.0, the initial reaction rate is 0.035 and 0.104 mmol/(L·h), and the formaldehyde production after 5 h is 0.117 and 0.393 mmol/L, proving the enzymatic reduction of CO2 is predominant in the coupled system. With EDTA as electron donor, the optimal pH value is 5.5 for the coupled system, and the formaldehyde production is much higher than that with H2O at all pH values, however, part of them might come from EDTA. For the sequence reactions, the second step is a rate-limiting step, and cofactor regeneration is vital for enzyme catalysis. The optimal loading ratio of FDH and FADH is 1:0.3, and with the addition of 1 mmol/L NAD+ or NADH, the yield of formaldehyde can reach 3.83% and 6.47% after 4 h. The photo-enzyme coupled system shows a good manipulation stability during 48 h.
      原文链接:
    • NSTL
    • Elsevier