Gutierrez, AlvaroRodriguez, Juan F.Castaneda, Locksley F.Nava, Jose L....
8页
查看更多>>摘要：This paper shows the elimination of arsenic (As) and hydrated silica from natural groundwater (48.63 mu g L-1 arsenic, 77.5 mg L-1 hydrated silica, 0.33 mg L-1 phosphate, 5 mg L-1 sulfate, 240 mg L-1 alkalinity, 89.5 mg L-1 hardness, pH 8.44 and 450 mu S cm(-1) conductivity) by electrocoagulation (EC). The flow plant employed a parallel plates EC reactor in series with a flocculator-settler. Aluminum was used as the sacrificial electrode. Before the electrolysis in the flow plant, a systematic study of the aluminum dose was carried using the EC reactor adapted to a jar test. The influence of the mean linear flow velocity (1.2-4.8 cm s(-1)) and current density (6-9 mA cm(-2)) on the removal of As and hydrated silica was addressed. The residual concentration of As and hydrated silica in the flow plant was C-As = 4.2 mu g L-1 and C-hs = 4.5 mg L-1, respectively, at 9 mA cm(-2) and 1.2 cm s(-1), which agree well with that obtained in the jar test array. The residual As concentration fulfills the World Health Organization (WHO) recommendation (<10 mu g L-1). The total operating cost of EC was 0.48 USD m(-3), considering electrolytic energy consumption, aluminum price, pumping costs, and sludge confinement. Flocs analyses performed by SEM-EDS, XRF-EDS, XRD, and FTIR showed the existence of aluminosilicates formed by the reaction of aluminum and hydrated silica. At the same time, As, phosphates and sulfates were separated by adsorption on flocs.
查看更多>>摘要：To improve the process of ethanol dehydration, asymmetric chitosan membranes were prepared and applied in the pervaporation process. A porous structure was obtained by adding absolute ethanol into chitosan solution. Fabricated membranes were comprehensively characterized by means of contact angle measurements, degree of swelling analysis, scanning electron microscopy, positron annihilation lifetime spectroscopy and wide angle X-rays scattering, to provide an extensive analysis of their physicochemical properties. The results showed a strong correlation between structure, amount and size of pores, and separation effectiveness of investigated membranes. Additionally, an interesting phenomenon of changing in membrane structure during pervaporation process was observed and was found to cause a nonlinear time dependence of transport and separation parameters. Consequently, the best performance of PV separation of 96 vol% ethanol (feed) was obtained for a membrane prepared from casting solution containing 0.1 ml of absolute ethanol, for which the values of separation factor and permeate flux reached 599.7 and 3.534 kg.m(-2).h(-1), respectively.
Hanada, TakafumiSeo, KosukeFajar, Adroit T. N.Goto, Masahiro...
8页
查看更多>>摘要：To establish more efficient and environmentally friendly lithium-ion battery (LiB) recycling processes, novel extractants derived from amino acids that enable better separation of Ni and Co were explored using density functional theory (DFT) calculations. DFT calculations and experimental validation indicated that of the three coordination sites-namely amine, amide, and carboxyl groups in the amic-acid ligands-the bond strength of the central amine group to the metal determines the Ni and Co separation performance. Based on the findings, the glycine-derived amic-acid extractant N-[N,N-di(2-ethylhexyl)aminocarbonylmethyl]glycine (D2EHAG) was applied for the recovery of Ni and Co from a spent automotive LiB leachate. Preferential and mutual recovery of Ni and Co from manganese by the D2EHAG-based recycling process was demonstrated. This study provides insights into the design of extractants that enable the mutual separation of Ni, Co, and Mn, and indicates the suitability of amic-acid extractants for LiB recycling processes.
查看更多>>摘要：In this work, novel nitrogen and sulfur co-doped porous carbons were synthesized by thiourea modification of carbonized hazelnut shell, then followed by KOH activation. In current preparation protocol, thiourea acted as both N and S agent, thereby, nitrogen and sulfur were simultaneously doped into the carbon skeleton by a single-step reaction. After KOH activation, the resultant sorbents hold advanced porosity and a certain amount of N and S contents. This series of sorbents possess the highest CO2 uptake of 4.30 and 6.44 mmol g(-1) at 1 bar, 25 degrees C and 0 degrees C, respectively. Comprehensive investigations found that the joint effects of narrow microporostiy, N and S content govern the CO2 uptake of these adsorbents. Moreover, these adsorbents display various exceptional CO2 adsorption performances such as excellent reversibility, fast CO2 adsorption kinetics, moderate heat of adsorp-tion, good CO2/N-2 selectivity and high dynamic CO2 capture capacity. Therefore, these hazelnut shell derived N, S co-doped carbons are promising in actual CO2 capture.
查看更多>>摘要：In this study, a 3D porous Ag+ decorated PCN-222 @ graphene oxide-chitosan foam adsorbent (APGC foam), which is grounded upon the growth of Ag+ decorated zirconium-metalloporphyrin metal-organic framework (PCN-222) on an EDTA-silane modified graphene oxide-chitosan foam substrate (EGC foam) for recovering U(VI) ions out of the seawater, was designed and synthesized with the in-situ growth and solvothermal method. The successfully synthesized APGC foam with excellent antibacterial property not only overcame the difficulty of powder adsorbents in practical application, but also reduced the negative impact of bacteria on the adsorption performance of porous material. The APGC foam showed excellent adsorption capacity (348.8 mg/g), selectivity and reusability of U(VI) adsorption at nearly seawater pH, and this also exhibited excellent adsorption performances in the seawater. The influence factors in the adsorption process were investigated by static and dynamic adsorption in different conditions. Moreover, the U(VI) adsorption mechanism of APGC foam was determined as the comprehensive effect of coordination, electrostatic interaction and intraparticle diffusion. All results indicated that APGC foam was an encouraging adsorbent to recover U(VI) out of the seawater.
查看更多>>摘要：Efficient activation of peroxymonosulfate using cobalt-based heterogeneous catalytic composites to produce highly reactive oxygen species for the degradation of toxic organic pollutants has been paid increased attention nowadays; however, the concept of transforming bio-waste into valuable cobalt-based catalysts remains much room to undertake. Herein, the natural marine bio-waste shrimp shell with a high total silicon content was firstly utilized as functional matrix for cobalt species to activate peroxymonosulfate for environmental remediation is reported. Remarkably, benefiting from the cooperative synergistic effect between in-situ formed CoSiOx and biochar, onto which is enriched in abundant surface functional groups, the resultant Co-SSP-700 with high specific surface area and outstanding stability exhibited prominent activity for ciprofloxacin degradation, namely nearly 90% of ciprofloxacin could be achieved within 40 min. EPR spectroscopy and scavenger tests were conducted out to investigate oxygen species, illustrating that the possible activation mechanism of PMS mainly ran through the multi-reaction pathways, whereas the radical mechanism induced by SO4 center dot- and O(2)(center dot-)was a determining factor. More importantly, the intermediates of cipmfloxacin degradation were identified by LC-MS analyses to propose the possible degradation pathways and the aquatic toxicity of intermediates was explored by constructing a QSAR model.
查看更多>>摘要：Electro-Fenton (EF) generally relies on the addition of iron in acidic conditions, which caused an increase in cost and secondary pollution. In this paper, Fe3O4 was in-situ loaded on the surface of the graphite felt (GF) electrode by a moderate solvothermal synthesis method. The modified electrode (Fe3O4/GF) could be used in a wide pH range (acid, and even neutral conditions), and Fe dissolution was not detected under neutral conditions. Compared with the pre-activated graphite felt electrode (aGF), the Fe3O4/GF electrode could directly utilize the generated hydrogen peroxide (H2O2) to obtain more hydroxyl radicals (center dot OH). The influence of electrolyte types was also investigated, and the results showed unstable or reductive electrolytes were not conducive to the degradation of levofloxacin (LEV). The Fe3O4/GF electrode had good reusability, and could maintain a LEV degradation ratio of over 70% during 6 cycles. The degradation effect of EF with unmodified GF is poor under neutral conditions, but the degradation with the Fe3O4/GF cathode is continuous and has a high total organic carbon (TOC) removal ratio of 81.4% at 6 h. The Fe3O4/GF cathode is conducive to promote the application of EF technology in the field of wastewater treatment, especially under neutral conditions.
Chernyaev, AlexanderZou, YuanminWilson, Benjamin P.Lundstrom, Mari...
11页
查看更多>>摘要：Copper and iron are known to be effective alternative reducing agents to H2O2 in Li-ion battery leaching. The aim of this work is to study the effect of added H2O2 on its overconsumption to the side reactions such as oxidation of copper, iron, and aluminum in leaching of NMC 111 active material. The interactions between the reducing agents separately were first investigated (T = 30 degrees C, [H2SO4] = 2 M, t = 120 min). Elemental copper was found to be a less efficient reducing agent (78%) compared to aluminum (100%) in terms of Fe3+ reduced to Fe2+. Nevertheless, copper exhibited much higher rate of iron reduction than aluminum. Additionally, aqueous copper ions were found to cement on aluminum surface and redissolve in the presence of iron, thus acting as the metallic reducing agent. In contrast, in the presence of H2O2 ferrous iron and copper were rapidly oxidized resulting in the consumption of all reducing agents. These effects were confirmed also during the leaching of NMC (T = 30 degrees C, [H2SO4] = 1.5 M, t = 120 min), which demonstrated that the leaching efficiency markedly decreased (similar to 63%) in the presence of H2O2 and Cu when compared to H2O2 alone (similar to 78%). Furthermore, results from NMC leaching showed that when copper-iron reductant or H2O2 were added separately, a much higher leaching efficiency was achieved (similar to 66% and similar to 78%, respectively) in contrast to being added together (similar to 58%).
查看更多>>摘要：Nanofiltration can be used to separate succinic acid (SA) from other organic acids in a fermentation broth. However, commercial nanofiltration membranes can be insufficiently selective since some produced organic acids have similar molecular weights. SA production from biomass fermentation entails separation of succinic acid from the other concomitantly produced organic acids such as acetic acid, formic acid, pyruvic acid etc. In this study, five commercial nanofiltration membranes were tested for SA rejection and selectivity under dead-end and crossflow modes of SA recovery from selected synthetic solutions and a real fermentation broth. SA rejections up to 94.1 +/- 1.5% and 95.5 +/- 3.5% were observed for the synthetic broth and the fermentation broth, respectively. The SA fractions obtained in the retentate were nearly 70% and 60% for synthetic and fermentation broth, respectively. The highest rejections and SA fraction values were achieved with DK and NF270 membranes, which also showed the highest permeate flux. Model evaluation using the Donnan-steric pore model with dielectric exclusion (DSPM-DE) showed that 99% of the SA rejection occurs at the membrane interface and not inside the membrane. Based on the modelling, the most important mechanism affecting separation was dielectric exclusion at both sides of the membrane surfaces. Moreover, identified sensitive model parameters, i.e. pore dielectric constant (epsilon pore), charge density (Xd) and pore radius (rp), were estimated through model fitting and were found to be highly correlated with significant variations. Finally, for the first time, a calibrated model with synthetic broth was successfully used to predict organic acids rejection for a real fermentation broth (with 12% and 3% prediction error for succinate rejection by NF270 and DK, respectively). Such prediction was achieved only by measuring organic acid concentrations in the fermentation broth and using the three sensitive parameters. Furthermore, the potential contribution of different transport mechanisms of SA was quantified for the first time.
Maidel, MichelePonte, Maria Jose Jeronimo de SantanaPonte, Haroldo de AraujoValt, Renata Bachmann Guimaraes...
8页
查看更多>>摘要：The electrokinetic remediation assistance on the leaching of spent FCC catalysts demonstrated satisfactory performance as an alternative method to the traditional leaching method, aiming to recycle rare earth elements from this solid waste, by former studies. The present work identified the process conditions that improved the mass transfer performance of lanthanum by electrokinetic phenomena, by means of a central composite design and variance analysis. Thereby, the system that operated with the sulfuric acid concentration in the electrolyte of 1 mol/l and the applied electric field of 0.15 V/m, for 8 h of the experiment, was the best in terms of energy and acid consumption per mass of lanthanum recovered, amid the tested conditions.
NSTL
Elsevier