Acidic Waste Research Articles

Separation and Extraction of Scandium from Titanium Dioxide Waste Acid

The solvent extraction method for extracting scandium from titanium dioxide waste acid is usually accompanied by co-extraction of titanium. In this paper, the scandium and titanium separation of the Sc(III) and Ti(IV)-loaded organic phase and the recovery of scandium were studied. A new scrubbing agent containing Na3Cit and H2O2 was used to selectively remove titanium from the Sc(III) and Ti(IV)-loaded organic phase. Results indicated that the removal ratio of titanium reached 100% with an nNa3Cit/nTi ratio of 1.5/1 and an nH2O2/nTi ratio of 3/1 at an O/A ratio of 1/1 and 25°C for 15 min through a three-stage cross-flow scrubbing. The co-removal ratio of scandium was less than 0.06%. The Fourier-transform infrared spectra results showed that titanium could be completely removed from the Sc(III) and Ti(IV)-loaded organic phase. Compared with the traditional scrubbing agent containing H2SO4 and H2O2, the new scrubbing agent has the characteristics of high efficiency and strong selectivity.

Produksi karkas, nilai gizi dan profil asam lemak daging serta produksi limbah kelinci New Zealand White akibat penyertaan rumput laut cokelat (Sargassum sp.) pada ransum

<p class="MDPI17abstract"><strong>Objective: </strong>The aim of this current paper was to evaluate effect of inclusion <em>Sargassum</em> sp. in the ration on meat nutrient content, meat fatty acid profile and waste production of New Zealand White (NZW) rabbit.</p><p class="MDPI17abstract"><strong>Methods: </strong>Twenty four NZW rabbit (70-80 d old) with initial body weight 1736 ± 50 g were randomly allocated in to three treatments. The treatments were: T1 basal feed, T2 inclusion of 4% <em>Sargassum</em> sp. in the basal feed and T3 inclusion of 8% <em>Sargassum</em> sp. in the basal feed.<strong></strong></p><p class="MDPI17abstract"><strong>Results: </strong>Results of this experiment showed that inclusion of <em>Sargassum</em> sp. in the ration gave no effect (P>0.05) on the moisture, ash, crude protein content of <em>Longisimus dorsi</em> (LD) muscle, carcass percentage, warm carcass weight, cold carcass weight and waste production. However, the treatment was significantly (P<0.05) decreasing fat content of LD muscle. Fatty acids profile of all treatments was relatively same.<strong></strong></p><p class="MDPI17abstract"><strong>Conclusions: </strong>Utilization of <em>Sargassum</em> sp. in the rabbit ration up to 8% has no impact on the carcass production, protein, ash, and meat water content, and the waste production. Even the inclusion of <em>Sargassum </em>sp. the ration at level of 4% can reduce the fat content of rabbit meat. Thus, based on the observed parameters <em>Sargassum</em> sp. can be used to substitute rabbit feed up to a level of 8%.</p>

Simple preparation of nano-anatase titanium dioxide from cold rolled titanic acid waste liquid

Anatase titanium dioxide has high photocatalytic activity and super hydrophilicity due to its special crystal structure. In this article, the anatase-type titanium dioxide has been simply prepared by cold-rolling titanic acid waste liquid for the first time, which effectively solves the problem that the valuable metal titanium in waste liquid is difficult to recover, and realizes the recycling of titanium resources. The effect of pH and EDTA on the impurity content of titanium dioxide is investigated in this study. It is found that nano-anatase-type titanium dioxide, with less impurities and uniform particle size, can be obtained at pH 2, EDTA, and iron molar ratio is 3. Meanwhile, the nitric acid pickling can effectively reduce the impurity content in the titanium dioxide, which provides a possibility for preparation of nanoscale anatase titanium dioxide from cold rolled titanic acid waste liquid.

Understanding the extraction behaviour of UO22+ and Th4+ using novel picolinamide/N-oxo picolinamide in ionic liquid: A comparative evaluation with molecular diluent

The manuscript deals with efficient separation of hexavalent UO22+ and tetravalent Th4+ from aqueous acidic waste solution in ‘green way’ using ionic liquid with novel picolinamide (L I) and N-oxo picolinamide (L II) based ligands. A comparative evaluation was carried out to understand the extraction mechanism, kinetics, thermodynamics, speciation, radiolytic stability and stripping behaviour of UO22+ and Th4+ in ionic liquid vis-a-vis molecular diluent. The investigation demonstrates the predominance of ‘cation exchange’ mechanism in ionic liquid and ‘solvation' mechanism in n-dodecane based systems. The slower extraction kinetics in ionic liquid was attributed to the ‘viscosity effect’. The extractive mass transfer processes were found to be spontaneous, endothermic and entropically driven in nature. The picolinamide and N-oxo picolinamide ligands were found to form inner-sphere complexes in ionic liquid as well as n-dodecane. In molecular diluent, the species involved for separation of UO22+ were UO2(NO3)2. 2 LI and UO2(NO3)2. L II, respectively, whereas in ionic liquid thet were [UO2(NO3). 2 L]+ and [UO2(NO3). L]+. For Th4+, in molecular diluent, the most plaussible extracted species were Th(NO3)4. 2 L I and Th(NO3)4. L II, while in ionic liquid they were [Th(NO3)2. 2 L]2+ and [Th(NO3)2. L]2+, respectively. Ionic liquid based solvent systems exhibited more radiolytic stability compared to that in molecular diluent. The CO32− was more effective aqueous phase complexing agent to back extract UO22+, while C2O42− exhibited the same for Th4+.

Effects of roasting and NH4Cl catalysis on the direct electrotransformation products from an AlCl3 solution

Contemporary processes for extracting alumina from fly ash involve various disadvantages, including high-energy consumption, heavy slag discharge, and severe equipment corrosion, so a new method for extracting alumina via electrotransformation was developed in this work. This novel method reduced slag discharge, enabled recycling, and produced no acid or alkali waste. The theoretical solution pH associated with Al(OH)3 precipitation and the actual solution pH during electrotransformation were also compared herein. Differential thermogravimetric analysis was performed for the direct electrotransformation products generated with and without NH4Cl as a catalyst; the activation energy and reaction order of these reactions revealed large fluctuations. The effects of the roasting temperature on the phase, morphology, D(50), and D(90) of the roasting products were also studied. The results indicated that the solution reached the theoretical pH (4.7) of complete Al(OH)3 precipitation in a short time when NH4Cl was implemented as a catalyst. Additionally, the D(50) and D(90) of the roasting products were nearly ten times higher when NH4Cl was used, relative to when it was not, reaching 227.1 and 519.6 μm, respectively. The activation energies of each reaction in the electrotransformation and roasting process were also reduced in the presence of the NH4Cl catalyst. Between 100 °C–250 °C, the physical adsorption of water occurred, and some of the structural water of the electrotransformation products generated with NH4Cl were removed in an endothermic reaction (reaction order, n1 = 0.43; activation energy, E1 = 2.13J mol−1). At temperatures between 250 °C–500 °C, the nitrogen-containing substances were removed in another endothermic reaction (reaction order, n2 = 0.4697; activation energy, E2 = 5.316J mol−1). Increasing the roasting temperature was beneficial for improving the crystal form of the roasting products, and the reduced electrotransformation products appeared more compact after roasting.

Electrochemical Recovery of Phosphorus from Acidic Cheese Wastewater: Feasibility, Quality of Products, and Comparison with Chemical Precipitation.

The recovery of phosphorus (P) from high-strength acidic waste streams with high salinity and organic loads is challenging. Here, we addressed this challenge with a recently developed electrochemical approach and compared it with the chemical precipitation method via NaOH dosing. The electrochemical process recovers nearly 90% of P (∼820 mg/L) from cheese wastewater in 48 h at 300 mA with an energy consumption of 64.7 kWh/kg of P. With chemical precipitation, >86% of P was removed by NaOH dosing with a normalized cost of 1.34–1.80 euros/kg of P. The increase in wastewater pH caused by NaOH dosing triggered the formation of calcium phosphate sludge instead of condensed solids. However, by electrochemical precipitation, the formed calcium phosphate is attached to the electrode, allowing the subsequent collection of solids from the electrode after treatment. The collected solids are characterized as amorphous calcium phosphate (ACP) at 200 mA or a precipitation pH of ≥9. Otherwise, they are a mixture of ACP and hydroxyapatite. The products have sufficient P content (≤14%), of which up to 85% was released within 30 min in 2% citric acid and a tiny amount of heavy metals compared to phosphate rocks. This study paves the way for applying electrochemical removal and recovery of phosphorus from acidic P-rich wastewater and offers a sustainable substitute for mined phosphorus.

The use of phosphoric acid waste product for calcium sulfide production

The article studies the technological features of calcium sulfide production from phosphogypsum. To ensure the environmental safety of industrial enterprises, closed production cycles creation is necessary. One of the criteria for “green” technologies is industrial waste recycling. Phosphogypsum formed during the orthophosphoric acid production from apatite raw materials by sulfuric acid method can be classified as large-tonnage waste. Phosphogypsum can be considered a mineral with zero mining costs and zero feedstock to produce valuable products. The synthesized materials are characterized using a complex of modern methods such as X-ray phase analysis, and electron microscopy. An environmentally friendly precursor, sucrose, is used as a reducing agent for calcium sulfate. The recovered material is a mixture of calcium sulfate and sulfide. When illuminated with ultraviolet light, it glows yellow-orange. The article presents an integrated approach to the problem of phosphoric acid production waste disposal by marketable products production.

Study on regeneration and desiliconization purification of pickling waste liquid of building steel

In this paper, Fe2O3 power was used to replace the scrap steel in the traditional process, as the medium for removing the free acid in the waste acid solution of the cold-rolled strip pickling. The removal effect of free acid and silicon of the system with Fe2O3 addition and crap steel were compared. The results indicated that the system with Fe2O3 addition obtained a better effect. Subsequently, the optimum dosage, optimum reaction temperature and time were determined by the orthogonal experiment. The effect of flocculants of polyacrylamide (PAM), PAC, PAM+PAC and MgCl2 with the desiliconization was explored.

Removal of arsenic from dusts produced during the pyrometallurgical refining of copper by vacuum carbothermal reduction

Removal of arsenic using the low-temperature vacuum carbothermal reduction method was investigated by taking dusts with high contents of arsenic and copper from furnaces for pyrometallurgical refining of Cu as raw materials. Based on TGA-DSC, differential thermal analysis was applied to the raw materials; by virtue of various methods including XRD, ICP, and SEM: the phases, chemical compositions and morphologies of dusts and evaporation residues were separately analysed; on the basis of thermodynamic analysis, the influences of the evaporating temperature, residual pressure, reductant dosage, and evaporation time on the removal rates of As and other valuable metals were explored. The results show that at an evaporating temperature of 350 °C, the residual pressure of 100 Pa, reductant dosage of 25%, and evaporation time for 50 min, the As removal rate can reach 93.48% while guaranteeing that the other metals are essentially not evaporated. This realises the selective separation of As from the other valuable metals. The evaporation products are higher-purity As2O3, which can be used as a primary As2O3 product. The valuable metals are concentrated in evaporation residues, being conducive to subsequent recovery by leaching with waste acids.

HAZOP Analysis and Research of Temporary Acid Adding System for High-Discharge Waste Liquid

To prevent the formation of salt from fission products of high-level radioactive liquid wastes (HLWs), a certain amount of acid is added to maintain the acidity of liquid waste. This study analyzes the accidents associated with the addition of acids in a factory by using the hazard and operability analysis (HAZOP), while elucidating the corresponding defects and risks of this approach. By improving the design of the system, the possibility of an accident is significantly reduced. This study can provide guidance for adding acids to treat other high-level waste liquids.

Graphene Oxide Membranes for Tunable Ion Sieving in Acidic Radioactive Waste.

Graphene oxide (GO) membranes with unique nanolayer structure have demonstrated excellent separation capability based on their size‐selective effect, but there are few reports on achieving ion–ion separation, because it is difficult to inhibit the swelling effect of GO nano sheets as well as to precisely control the interlayer spacing d to a specific value between the sizes of different metal ions. Here, selective separation of uranium from acidic radioactive waste containing multication is achieved through a precise dual‐adjustment strategy on d. It is found that GO swelling is greatly restricted in highly acidic solution due to protonation effect. Then the interlayer spacing is further precisely reduced to below the diameter of uranyl ion by increasing the oxidation degree of GO. Sieving uranyl ions from other nuclide ions is successfully realized in pH =3–3 mol L−1 nitric acid solutions.

Comparison of epoxidation methods for biobased oils: dioxirane intermediates generated from Oxone versus peracid derived from hydrogen peroxide

AbstractA study was carried out to compare the epoxidation of unsaturated vegetable oils using dioxirane intermediates generated in situ using Oxone to that by the peracid/hydrogen peroxide method. Epoxidized oils are typically synthesized using hydrogen peroxide, as well as acetic or formic acid. This synthesis requires heating and catalysts and generates acidic waste. Recently, advances have been made in the process of using Oxone (potassium peroxymonosulfate) and ketones to generate in situ dioxiranes to epoxidize alkenes. The dioxirane method allows for room temperature reactions and eliminates the use of peroxides and acids. Epoxidation of soybean oil, hempseed oil and sucrose soyate using in situ generated dioxiranes was carried out and parameters such as molar ratios and addition rates were studied. The data show that optimum reaction conditions are reached when molar ratios of Oxone and unsaturation are 1.6:1 and the Oxone addition rate is 1 mL min–1. As a comparison, epoxidations using the acetic acid/hydrogen peroxide method were carried out and cured materials were prepared from the epoxidized compounds. Negligible differences were identified in the materials prepared from both synthetic pathways. An environmental sustainability assessment using green chemistry principles was also conducted for both methods to evaluate their safety and efficiency with respect to multiple criteria including minimizing waste generation and energy consumption. The analysis shows that, although the peracid method is atom economic and generates less waste, the dioxirane method offers better occupational safety and requires less energy, demonstrating the tradeoffs involved with either pathway if one is to be selected. © 2021 Society of Chemical Industry

Feeding preparation strategy for the supercritical water oxidation (SCWO) system for disposing of liquid hazardous waste

Abstract Supercritical water oxidation (SCWO) technology has a great potential application for the disposal of liquid hazardous wastes. The feeding process is vital for the safety and normal operation of SCWO. This paper describes the feeding preparation strategy of SCWO with multilevel grouping and programming. Based on the physicochemical properties, the liquid hazardous wastes from various industrial manufacturers were first grouped into acid, neutral and alkaline groups. By mixing between samples, the primary grouping tanks were determined to be acid, alkali, amphoteric reacting, organic and organic high-chlorine liquid wastes. By distributing acid, alkali, amphoteric reacting liquid wastes into organic wastes, three parallel feeding routes are regulated for the homogenizing tank phase, which avoids the reaction between wastes. By calculating with the linear programming optimization model of MATLAB, the waste compatibility ratio of each feeding route was determined to meet the feeding requirements of SCWO. The feeding preparation strategy of this paper provides a practical instruction for the SCWO design and operation.

Influences on Subsurface Plutonium and Americium Migration

Plutonium (Pu) has been released to the environment worldwide, including approximately 1.85 × 1015 Bq (200 kg) of Pu from process waste solutions to unconfined soil structures at the Hanford Site in Washington State. The subsurface mobility of Pu is influenced by complex interactions with sediments, groundwater, and any co-contaminants within the waste stream. Previous investigations at Hanford have shown that Pu exists as discrete PuO2 particles forming before or after disposal, as secondary solid phases formed from waste interactions with sediments as adsorbed/incorporated species, and/or as dissolved species. In this research, new evidence is presented for the existence of PuO2, PuO2-Bi2O3 composites, and particles from burnt Pu metal in near-surface sediments where Pu-laden acidic process waste was disposed to sediments. Pu and americium (Am) L3 X-ray absorption spectroscopy and density functional theory suggest that, in larger, more crystalline PuO2 particles, Am formed from radioactive decay is retained in the PuIVO2 structure as AmIV. The Pu and Am that were disposed of in an acidic waste stream have since migrated deeper into the subsurface with detection to at least 37 meters below ground surface. In contrast, Pu deposited near the ground surface from neutral pH waste is found to be homogeneously distributed and relatively immobile. Groundwater extractions performed on contaminated sediments indicate that both Pu and Am are recalcitrant, with Am being fractionally less extractable than Pu on a molar basis. These results suggest that the more mobile fraction of Am has migrated from the near-surface and may be present in the deeper sediments as a different phase than Pu. From these results, it is suggested that Pu and Am deposited from acidic wastes were initially mobile and became significantly less mobile as wastes were neutralized within the soil profile.

Potensi Bakteri Pereduksi Sulfat dan Jenis Bahan Organik dalam Pengolahan Air Asam Tambang menggunakan System Constructed Wetland Tanaman akar Wangi (Vetiveria zizanioides L)

Acid mine drainage (AMD) is a waste product from coal mining process. Acidic waste will impose a serious environmental issue such as organism annihilation and destruction of environmental ecosystem. Proper AMD management is required in order to restore polluted water to the proper standard condition. The Constructed Wetland system with Akar Wangi (Vetiveria zizanioides L.) and various organic growth medium compositions and sulphate-reducing bacteria and the composition of the media for several types of organic matter with sulfate-reducing bacteria (SRB) inoculation as stimulant was deemed a promising solution. This study was designed in randomized block design (RBD) consisted of nine treatments with three replicates. The treatments were: (A) = without organic matter and without SRB inoculation (control), (B) = 100% compost, (C) = 100% sawdust, (D) = 50% compost + 50% sawdust, (E ) = no organic matter + SRB inoculation (105 MPN ml-1), (F) = 100% compost + SRB inoculation, (G) = 100% sawdust + SRB inoculation, H = 50% compost + 50% sawdust + SRB inoculation, I = 75% compost + 25% sawdust + SRB inoculation. Results showed that 100% compost and SRB application increased polluted water pH. Application of 100% sawdust with or without SRB inoculation gave the highest reduction in sulfate content. SRB also has the potential to increase the height of Akar Wangi plant.

Internally cross-linked poly (2,6-dimethyl-1,4-phenylene ether) based anion exchange membrane for recovery of different acids by diffusion dialysis

Acid recovery from acidic waste is a critical issue to be focused on nowadays. Chemical approaches for recovery are not commercially viable and energy intensive to save the environment. Here, we report internally cross-linked poly (2,6-dimethyl-1,4-phenylene ether) (PPE) based anion exchange membranes (AEMs) for acid recovery by diffusion dialysis, prepared via quick grafting of N-methyl-4-piperidone using ultrasonication. The prepared AEMs are assessed for their physicochemical parameters and depicted water uptake (WU) and ion-exchange capacity (IEC) in the range 22.00%–31.00% and 0.64 meq/g–2.18 meq/g respectively for Cl−1, NO3− and SO42− ions. AEMs were investigated for recovery of hydrochloric acid (HCl), nitric acid (HNO3) and sulphuric acid (H2SO4) from simulated effluent based on their proton diffusion coefficient (UH+), separation factor (S) and recovery efficiency (Ƞ). These membranes illustrated the proton diffusion coefficient as high as 0.065 m h−1 and enhanced separation factor values up to 132 at 27 °C. Recovery performance for different acids is corroborated based on unique self-organized membrane structure, studied using AFM phase imaging and cumulative influence of bulk diffusion coefficient, ion-exchange capacity, and hydration radii of Cl−1, NO3− and SO42− ions. The acid recovery efficiency illustrated the trend HCl > HNO3 > H2SO4. The hydrate (–OH) functionality with a non-overlapping set of lone pairs on oxygen enhances the proton mobility via Grotthuss mechanism inside the membrane matrix and provides a cradle-like pathway for high proton mobility. The results are pronounced for fabricated membranes compared to commercially available standards for acid recovery via diffusion dialysis.

Char Products From Bamboo Waste Pyrolysis and Acid Activation

Bamboo is found worldwide but is especially concentrated in tropical and subtropical areas with the major producing nations being China, Indonesia and Thailand with an annual production of 12 million tonnes. It has found uses in many applications such as: furniture, flooring, roofing, fencing, interior design and scaffolding in the construction industry. In this study, discarded waste bamboo furniture was used in the ground form as the raw material feedstock for the production of a series of biochars and activated carbons. The biochars were produced at different temperatures, namely, 723, 823, 923, 1,023, 1,123 and 1223 K, in a muffle furnace inerted with nitrogen and for different pyrolysis times. The product chars yields were 20–30% by weight of the raw material, surface areas were 100–350 m2/g. Other tests include elemental analysis, helium displacement density, pH, ICP-AES on a leachate sample. Four of the different temperature samples of biochar were used to adsorb the basic dye methylene blue and were shown to possess high adsorption capacities. Then, the same bamboo raw material powder was treated with acid and pyrolysed/activated in a nitrogen atmosphere at the same range of temperatures to produce activated carbons; these were characterized using similar test methods to the biochars. The yields are in the range 20–40% by weight of the raw material feedstock and the BET surface areas are in the range 200–600 m2/g. Three of the different temperature activated carbons were used to adsorb methylene blue and the results were compared with the biochar results. All the adsorption experimental isotherm results were analyzed using conventional isotherm equations. The benefits and cost implications of both biochar and activated carbon routes are discussed. The methylene blue adsorption capacities are extremely attractive in the range 0.42–1.12 mmol/g (150–300 mg/g char product) and extend to over 2.35 mmol/g (700 mg/g) for the bamboo derived activated carbons. The micropore and mesopore volumes have been determined under the various char and activated carbon experimental conditions and coupled with the surface areas; these results have been used to explain the trends in the methylene blue adsorption capacities.

Pollution Source Localization in Wastewater Networks.

In December 2016, the wastewater treatment plant of Baarle-Nassau, Netherlands, failed. The failure was caused by the illegal disposal of high volumes of acidic waste into the sewer network. Repairs cost between 80,000 and 100,000 EUR. A continuous monitoring system of a utility network such as this one would help to determine the causes of such pollution and could mitigate or reduce the impact of these kinds of events in the future. We have designed and tested a data fusion system that transforms the time-series of sensor measurements into an array of source-localized discharge events. The data fusion system performs this transformation as follows. First, the time-series of sensor measurements are resampled and converted to sensor observations in a unified discrete time domain. Second, sensor observations are mapped to pollutant detections that indicate the amount of specific pollutants according to a priori knowledge. Third, pollutant detections are used for inferring the propagation of the discharged pollutant downstream of the sewage network to account for missing sensor observations. Fourth, pollutant detections and inferred sensor observations are clustered to form tracks. Finally, tracks are processed and propagated upstream to form the final list of probable events. A set of experiments was performed using a modified variant of the EPANET Example Network 2. Results of our experiments show that the proposed system can narrow down the source of pollution to seven or fewer nodes, depending on the number of sensors, while processing approximately 100 sensor observations per second. Having considered the results, such a system could provide meaningful information about pollution events in utility networks.

Assessment and source identification of toxic metals in an abandoned synthetic diamond production plant from Anhui Province, China

In this study, soil and sediment samples along with groundwater samples were collected and analyzed from an abandoned synthetic diamond production plant in Anhui Province, South China. Chemical analysis, pollution characteristics analysis, and correlation analysis were conducted to assess and to determine the source(s) of the toxic metal and organic pollutions in the study sites. The Co and Ni concentrations of soil samples collected from the production area exceed the risk screening value for contaminated development land in Soil Environment Quality Standards for soil pollution risk control on construction land (Trial) of China, while the concentrations of other toxic elements such as Cr, Cu, and Zn are lower than the screening value. The PCA and HCA results are consistent with the correlation coefficient analysis and indicate that industrial activities are the main sources of Co and Ni. The chemical composition and source analysis results of soil and groundwater show that toxic metals originating from catalyst and low pH value from acid waste water should be the main point of concern in the synthetic diamond production plant.

Extraction of tetra- and hexavalent actinide ions from nitric acid solutions using some diglycolamide functionalized calix[4]arenes

Abstract Neptunium is one of the most important minor actinide elements with some of its isotopes having very long half-lives, therefore necessitating its separation from acidic radioactive wastes. Solvent extraction of Np4+ and NpO2 2+ was studied using three multiple diglycolamide (DGA) extractants with n-propyl, n-octyl and 3-pentyl substituents termed as L I , L II and L III , respectively, in a mixed diluent of 5% isodecanol and 95% n-dodecane. For comparison purpose, the extraction of Pu4+ and UO2 2+ was carried out under identical conditions. The extraction efficiency of the ligands for the tetravalent ions followed the trend: L II > L I > L III , which changed to L III > L II > L I for the hexavalent ions. While the extraction of the tetravalent ions was reasonably good (ca. 90–98%) with an extremely low (5.0 × 10−5 M) ligand concentration, poor extraction (ca. 5–16%) of the hexavalent ions was seen even with a 20 times higher concentration of the ligand. In general, Pu4+ was better extracted than Np4+, while NpO2 2+ was marginally better extracted then UO2 2+. A ‘solvation’ type extraction mechanism was proposed based on the extraction profiles obtained as a function of the concentrations of the feed nitric acid, extractant as well as nitrate ion. The extracted species were found out to be M(NO3)4·mL and MO2(NO3)2·nL (M = Np or Pu, 1 < m < 2, n ≃ 1).