Fractional Ion Research Articles

Development of a diafiltration-nanofiltration-reverse osmosis (DiaNF-RO) process for ion fractionation towards resource recovery in seawater desalination

A diafiltration-nanofiltration-reverse osmosis (DiaNF-RO) process is introduced to achieve solutes fractionation of divalent/monovalent ions, i.e., Mg/Na, to enable resource recovery in seawater desalination and brine management. The diafiltration process is applied at the NF stage (i.e., DiaNF) to enhance the Mg/Na fractionation performance of NF (i.e., SF1Mg-Na), while the RO is incorporated to produce desalinated water as well as diluent required by the DiaNF. By initiating the ion fractionation at the pre-treatment rather than post-treatment (i.e., RO-NF), the DiaNF-RO mitigates challenges of high concentration in RO brine management, which includes limitation of maximum allowable operating pressure and high energy requirement. The semi-empirical model, with at least 77.4 % accuracy, is first applied to simulate the performance of DiaNF-RO at different operating conditions and configurations (i.e., multi-stage and recycling). The sensitivity analysis then suggests that dilution should only occur in the last NF stage and without any retentate recycling, while NF pressure and element number should be optimized. Using NF membrane with SFMg-Na of 1.28 at 10 bar and feed seawater of 35 g/L TDS, the optimal 4-stage DiaNF-RO design achieves maximum SF1Mg-Na of 12.19 at 5.72 kWh/m3, or a minimum energy consumption of 5.41 kWh/m3 at SF1Mg-Na of 7.04.

A diafiltration-nanofiltration-reverse osmosis (DiaNF-RO) process for ion fractionation towards resource recovery in seawater desalination: Comparison with a RO-DiaNF process and effect of NF membrane performance

The diafiltration-nanofiltration-reverse osmosis (DiaNF-RO) is an innovative process that aims to achieve ion fractionation of divalent/monovalent ions, i.e., Mg/Na (SF1Mg-Na), an important step towards resource recovery, while producing clean water in seawater desalination at a reasonable specific energy consumption (SEC). Firstly, the novelty of DiaNF-RO process is compared with the RO-DiaNF process where ion fractionation is performed at the pretreatment stage (i.e., seawater) in the former and post-treatment stage (i.e., SWRO brine) in the latter. DiaNF-RO outperforms RO-DiaNF in many aspects, including higher Mg recovery, higher SF1Mg-Na, lower scaling risk, and more efficient cost utilization, which emphasizes the benefits of initiating ion fractionation at low salinity in brine management. Secondly, the process practicality is reiterated by showing how desirable performance is achievable at low number of stages with some modifications. One possible adjustment is to improve NF membrane performance in the priority order of higher water permeability, lower Na rejection, and higher Mg rejection, which enables the 2DiaNF-RO to achieve the desirable SF1Mg-Na of 13.7 at 5.71 kWh/m3. Another possible adjustment is to integrate the 2nd RO stage for more product water recovery to achieve a competitive net SEC (4.01 kWh/m3). These results further solidify the industrial implementation possibility of the DiaNF-RO process.

Integrated strategy facilitates rapid in-depth chemome characterization of traditional Chinese medicine prescriptions: Shengbai oral liquid as a case.

Chemome characterization is the prerequisite for either therapeutic mechanism clarification or quality control of traditional Chinese medicine prescriptions (TCMPs). Liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) currently serves as the most popular analytical tool; however, chemome characterization is still challenged by MS/MS spectral acquisition and post-acquisition data processing. Here, an integrated strategy was proposed for in-depth chemome clarification of Shengbai oral liquid (SBOL). Gas phase ion fractionation with staggered mass ranges was demonstrated to be the superior acquisition method regarding MS2 spectrum coverage in this study, and narrower mass range further advanced coverage. To facilitate information extraction, all ingredient materials were measured in parallel to form an in-house library, where each MS1 -MS2 item generated a square mass-to-charge ratio (m/z) frame to capture the tagged identity and each chemical family produced a pentagon frame for mass defect features to accomplish chemical analogs-targeted quasi-molecular ion extraction. Square m/z frame imprinting captured 355 identities, while mass defect frames extracted 275 compounds. Attributing to comprehensive MS2 spectrum acquisition and efficient data processing, 355 components were captured and tentatively identified, resulting in a clarified chemical composition for SBOL. Therefore, the proposed strategy should be meaningful for the chemome characterization of TCMPs.

Simultaneous ion fractionation and concentration by selectrodialysis for saline wastewater valorization

In order to desalinate saline wastewater and achieve energy-efficient recovery of mixed salt (Na2SO4 and NaCl), selectrodialysis (SED) stack with commercial monovalent selective anion exchange membranes (MVA) was utilized in this work. The experiments proved that the final concentration and purity of Na2SO4 in Product could reach 0.84 mol·L−1 and 94.9%, respectively, under the optimal testing conditions (initial concentration of Product solution was 15 wt.% NaCl and the current density of 200 A·m−2). Simultaneously, the concentration and purity of NaCl in Brine achieved 1.90 mol·L−1 and 97.1%, respectively. In order to guide the engineering application, a formula was established to predict the termination time of SED process according to the applied current density. Furthermore, glycerol retention rate of the SED stack in Feed solution could reach more than 95%. And low energy consumption on Na2SO4 and NaCl fractionation/concentration by 0.13–0.15 kWh·kg−1 at 200 A·m−2. Hence, this work illustrated the techno-economic feasibility of using SED for saline wastewater valorization.

Enhancement of metal ion fractionation by adding alginate in batch foam separation

The influence of the addition of alginate on the separation rate, the recovery efficiency, and the fractionation of metal ions (Pb2+, Cu2+, and Cd2+) in a batch foam separation was investigated in the coexisting system. Sodium dodecyl sulfate (SDS) was employed as an ion collector and a foaming agent. The separation rate was evaluated by the rate constant, k, which was obtained by fitting of the data to a first-order kinetic equation. By adding alginate, the fractionation effect relatively affected up to 0.05 g/L of alginate. In particular, the separation of Pb2+ was significantly affected by adding alginate in terms of the separation rate and the recovery efficiency. Pb2+ remained more in the liquid phase within the column with increasing the amount added of alginate. The optimum experimental condition was found in the range of the initial concentration of metal ion over 3.0 × 10-5 mol/L and concentration of alginate over 0.199 g/L for the effective fractionation of Pb2+ and Cd2+. This fractionation could be considered to be caused by the difference between the binding strength of Pb2+ and Cd2+ to the carboxyl and the sulfate functional groups included in alginate and SDS, respectively.

Proteogenomics and Differential Ion Mobility Enable the Exploration of the Mutational Landscape in Colon Cancer Cells.

The sensitivity and depth of proteomic analyses are limited by isobaric ions and interferences that preclude the identification of low abundance peptides. Extensive sample fractionation is often required to extend proteome coverage when sample amount is not a limitation. Ion mobility devices provide a viable alternate approach to resolve confounding ions and improve peak capacity and mass spectrometry (MS) sensitivity. Here, we report the integration of differential ion mobility with segmented ion fractionation (SIFT) to enhance the comprehensiveness of proteomic analyses. The combination of differential ion mobility and SIFT, where narrow windows of ∼m/z 100 are acquired in turn, is found particularly advantageous in the analysis of protein digests and typically provided more than 60% gain in identification compared to conventional single-shot LC-MS/MS. The application of this approach is further demonstrated for the analysis of tryptic digests from different colorectal cancer cell lines where the enhanced sensitivity enabled the identification of single amino acid variants that were correlated with the corresponding transcriptomic data sets.

Ion‐“distillation” for isolating lithium from lake brine

AbstractLithium demands increase dramatically and make it highly attractive to develop advanced ion separation technology/material. However, high Mg2+/Li+ ratio impedes the extraction due to the difficulties in separation of the two ions. Here, we propose an ion‐“distillation” technology based on electro‐membrane stacking for the extraction of Li+ from lake brine (Mg2+/Li+ ratio: 31.58). This technology employs commercially available monovalent ion‐selective membranes, and ions are driven by electric. Using the four‐stage ion‐“distillation” technology, selectivity values of 26,177 and 27,000 are achieved between Li+ and Mg2+ and between Cl− and SO42−, respectively. The electro‐stripping mechanism when monovalent ion migrating across the membranes probably magnitude the Li+ selectivity, which is higher than the other reported values in the literature for membrane processes, and the purity of the final LiCl product is greater than battery grade (99.95%). The proposed process can potentially be applied in efficient ion fractionation and special separations.

Rapid tryptic peptide mapping of human serum albumin using DI-MS/MSALL.

In recent decades, proteinic drugs, in particular monoclonal antibodies, are taking the leading role of small molecule drugs, and peptide mapping relying on liquid chromatography-tandem mass spectrometry (LC-MS/MS) is an emerging approach to substitute the role of a ligand-binding assay for the quality control of the proteinic drugs. However, such LC-MS/MS approaches extensively suffer from time-intensive measurements, leading to a limited throughput. To achieve accelerated measurements, here, the potential of DI-MS/MSALL towards tryptic peptide mapping was evaluated through comparing with well-defined LC-MS/MS means, and human serum albumin (HSA) was employed as the representative protein for applicability illustration. Among the 55 tryptic peptides theoretically suggested by Skyline software, 47 were successfully captured by DI-MS/MSALL through acquiring the desired MS2 spectra, in comparison to 51 detected by LC-MS/MS. DI-MS/MSALL measurements merely took 5 min, which was dramatically superior to the LC-MS/MS assay. Noteworthily, different from fruitful multi-charged MS1 signals for LC-MS/MS, most quasi-molecular ions received lower charged states. DI-MS/MSALL also possessed advantages such as lower solvent consumption and facile instrumentation; however, more sample was consumed. In conclusion, DI-MS/MSALL is eligible to act as an alternative analytical tool for LC-MS/MS towards the peptide mapping of proteinic drugs, particularly when a heavy measurement workload.

Simultaneous Ion Fractionation and Concentration by Selectrodialysis for Industrial Saline Wastewater Valorization

Simultaneous Ion Fractionation and Concentration by Selectrodialysis for Industrial Saline Wastewater Valorization

Rapid chemome profiling of Artemisia capillaris Thunb. using direct infusion-mass spectrometry

As one of the most popular traditional Chinese medicines (TCMs) for the treatment of various liver diseases, virgate wormwood herb ( Artemisia capillaris Thunb.) has a long application history in TCM practices. It has been well established that the chemical composition is responsible for the pronounced therapeutic spectrum of A. capillaris . Although they are comprehensive, the time-intensive liquid chromatography coupled to tandem mass spectrometry (LC–MS/MS) assays cannot fully satisfy the analytical measurement workload from many test samples. Direct infusion-MS/MS (DI–MS/MS) may be the optimal choice to achieve high-throughput analysis if the mass spectrometer can universally record MS 2 spectra. According to the application of gas phase ion fractionation concept, the MS/MS ALL program enables to gain MS 2 spectrum for each nominal m/z value with a data-independent acquisition algorithm via segmenting the entire MS 1 ion cohort into sequential ion pieces with 1 Da width, when sufficient measurement time is allowed by DI approach. Here, rapid clarification of the chemical composition was attempted for A. capillaris using DI–MS/MS ALL . A. capillaris extract was imported directly into the electrospray ionization interface to obtain the MS/MS ALL measurement. After the MS 1 -MS 2 dataset was well organized, we focused on structural characterization through retrieving information from the available databases and literature. Twenty-six compounds were found, including 12 caffeoyl quinic acid derivatives, 7 flavonoids, and 7 compounds belonging to other chemical families. Among them, 24 ones were structurally identified. Compared with the LC–MS/MS technique, DI–MS/MS ALL has the advantages of low-costing, solvent-saving, and time-saving. Chemical profiling of A. capillaris extract was accomplished within 5 min by DI–MS/MS ALL , and this technique can be an alternative choice for chemical profile characterization of TCMs due to its extraordinary high-throughput advantage.

Integration of Segmented Ion Fractionation and Differential Ion Mobility on a Q-Exactive Hybrid Quadrupole Orbitrap Mass Spectrometer.

High-field asymmetric waveform ion mobility spectrometry (FAIMS) has gained popularity in the proteomics field for its capability to improve mass spectrometry sensitivity and to decrease peptide co-fragmentation. The recent implementation of FAIMS on Tribrid Orbitrap instruments enhanced proteome coverage and increased the precision of quantitative measurements. However, the FAIMS interface has not been available on older generation Orbitrap mass spectrometers such as the Q-Exactive. Here, we report the integration of the FAIMS Pro device with embedded electrical and gas connections to a Q-Exactive HF mass spectrometer. Proteomic experiments performed on HeLa tryptic digests with the modified mass spectrometer improved signal to noise and reduced interfering ions, resulting in an increase of 42% in peptide identification. FAIMS was also combined with segmented ion fractionation where 100 m/z windows were obtained in turn to further increase the depth of proteome analysis by reducing the proportion of chimeric MS/MS spectra from 50 to 27%. We also demonstrate the application of FAIMS to improve quantitative measurements when using isobaric peptide labeling. FAIMS experiments performed on a two-proteome model revealed that FAIMS Pro provided a 65% improvement in quantification accuracy compared to conventional LC-MS/MS experiments.

Nitrate-Selective Anion Exchange Membranes Prepared using Discarded Reverse Osmosis Membranes as Support.

The present work shows a methodology for the preparation of membranes with a high affinity for nitrates. For this purpose, a polymeric mixture containing an anion exchange resin was extended on a recycled pressure filtration membrane used as mechanical support. Different ion exchange resins were tested. The influence in ion fractionation of (i) the type of ion exchange resin, (ii) the use of a recycled membrane as support and (iii) the operating current density during the separation process were studied. Results revealed that the employed anion exchange resin could tune up the transport numbers of the anions in the membrane and enhance the transport of nitrates over sulfates. The use of the recycled filtration membrane as support further increased the transport of nitrates in detriment of sulfates in nitrate-selective membranes. Moreover, it considerably improved the mechanical stability of the membranes. Lowering the operational current density also boosted ion fractionation. In addition, the use of recycled membranes as support in membrane preparation is presented as an alternative management route of discarded reverse osmosis membranes, coupling with the challenging management of waste generated by the desalination industry. These membranes could be used for nitrate recovery from wastewater or for nitrate separation from groundwater.

Dynamic Range Expansion by Gas-Phase Ion Fractionation and Enrichment for Imaging Mass Spectrometry.

In the analysis of biological tissue by imaging mass spectrometry (IMS), the limit of detection and dynamic range are of paramount importance in obtaining experimental results that provide insight into underlying biological processes. Many important biomolecules are present in the tissue milieu in low concentrations and in complex mixtures with other compounds of widely ranging abundances, challenging the limits of analytical technologies. In many IMS experiments, the ion signal can be dominated by a few highly abundant ion species. On trap-based instrument platforms that accumulate ions prior to mass analysis, these high abundance ions can diminish the detection and dynamic range of lower abundance ions. Herein, we describe two strategies for combating these challenges during IMS experiments on a hybrid QhFT-ICR MS. In one iteration, the mass resolving capabilities of a quadrupole mass filter are used to selectively enrich ions of interest via a technique previously termed continuous accumulation of selected ions. Second, we have introduced a supplemental dipolar AC waveform to the quadrupole mass filter of a commercial QhFT-ICR mass spectrometer to perform selected ion ejection prior to the ion accumulation region. This setup allows the selective ejection of the most abundant ion species prior to ion accumulation, thereby greatly improving the molecular depth with which IMS can probe tissue samples. The gain in sensitivity of both of these approaches roughly scales with the number of accumulated laser shots up to the charge capacity of the ion accumulation cell. The efficiencies of these two strategies are described here by performing lipid imaging mass spectrometry analyses of a rat brain.

Separating and recovering lithium from brines using selective-electrodialysis: Sensitivity to temperature

This work was to investigate the lithium ion fractionation from various binary cation systems at various operating temperatures by electrodialysis (ED) with monovalent selective ion exchange membranes (usually called selective-electrodialysis, S-ED). Then a ternary cation system was selected to verify the results obtained from the binary cation systems. In Li+–Mn+ (Mn+: Na+, K+, Mg2+, Ca2+) brines containing only one kind of anion-Cl−, higher efficient recovery of lithium was obtained at higher temperature than at lower one, and the separation coefficients (FM–Li) at the same lithium recovery ratio were found to be changed slightly with temperature ranging from 10°C to 30°C. The results indicate the relationship between transport enhancement/interionic separation effects and temperature could be preliminarily expressed by Arrhenius-type equation. Moreover, the pore size of membrane and the cationic hydration number were analyzed with temperature increase, and then that FM–Li had little variation caused by temperature was explained. It should attribute to the swelling of membrane and a small reduction of cationic hydration numbers. Further verification was done in Li+–Na+–Mg2+ cation system, and the same results were obtained. The investigation experimentally demonstrates that S-ED technology is feasible for separating and recovering lithium from brines in different regions with different environment temperatures.

Effect of coexisting ions on recovering lithium from high Mg2+/Li+ ratio brines by selective-electrodialysis

Abstract Selective-electrodialysis (S-ED) is a booming technology for recovering lithium from salt lake brine and (concentrated) seawater, especially from high Mg2+/Li+ ratio brines. The coexisting ions in the solutions containing lithium can make some impact on the ion fractionation of lithium and magnesium in high Mg2+/Li+ brines. The effect of the concentration of coexisting cations (Na+, K+) and anions (SO42−, HCO3−) on the separation coefficient of magnesium and lithium (FMg-Li), recovery ratio of Li+ (RLi), current efficiency (η) and specific energy consumption (ESEC) was evaluated. The results show that an applied voltage of 6 V is more preferable for lithium ions recovery from high Mg2+/Li+ brines by S-ED. The separation of Mg2+/Li+ tends to unsatisfactory with increasing cation concentration (Na+, K+), and FMg-Li drops from 8.73 to 1.83 with the increase of Na+/Li+ from 1 to 5 and from 8.33 to 2.13 with the rise of K+/Li+ from 1 to 5. The strength of influence on the separation of Mg2+/Li+ is K+ > Na+, correlating with the order of their hydrated ion radiuses. However, FMg-Li rises from 7.99 to 14.66 with the increase of SO42−, reversing with the influence of cations concentration. As for HCO3−, the variation tendency of FMg-Li is opposite to RLi, probably ascribing to the appearance of MgHCO3+. These observations showed that S-ED has a wide adaptability for the ion fractionation of magnesium and lithium from brines.

Sorption and fractionation of rare earth element ions onto nanoscale zerovalent iron particles

The removal behaviour of rare earth element (REE), (Sc, Y, La-Lu), ions onto nanoscale zerovalent iron (nZVI) particles has been investigated. Batch sorption isotherms were conducted using REE-bearing acid mine drainage (AMD) and a range of different synthetic REE solutions, which were exposed to nZVI at 0.1–4.0 g/L. Maximum adsorption capacity of Yb and La was 410 and 61 mg/g respectively (1000 mg/L LaCl3 and YbCl3 starting concentration, initial pH = 4.5, T = 294 K), the highest currently reported in the literature. Aqueous REE removal to ultratrace concentrations (<1 µg/L, >99.9% removal) was also recorded after 30 min (the first sampling interval) exposure of ≥0.5 g/L nZVI to 10 mg/L aqueous REE solutions (nitrate counterion). Similar rapidity and near-total removal ability was recorded for the exposure of nZVI to the AMD, however, a greater nZVI concentration was required, with the removal of all REEs (with the exception of La, Ce, Nd and Gd) to <1 µg/L when exposed to nZVI at 4.0 g/L for 30 min. In all systems nZVI was selective for the removal of HREE ions in preference to LREE ions, with the mechanism determined using HRTEM-EDS and XPS analysis as via surface mediated precipitation. Overall the results demonstrate nZVI as exhibiting great promise as an effective and versatile agent for simultaneous REE ion recovery and fractionation.

Gallium recovery from aluminum smelting slag via a novel combined process of bioleaching and chemical methods

Smelting slag generally contains a large number of heavy metals. In this study, the separation and selective recovery of gallium from aluminum smelting slag was studied deeply. Processes for bioleaching and recovering gallium from aluminum smelting slag have been executed. Under the condition of 2% pulp density, the Ga dissolution reached 505 mg/L, with a Ga bioleaching efficiency close to 100%. Ion exchange resin, fractionation precipitation, and milk of lime were assessed to test their efficiency in the separation and selective recovery of Ga from bioleachate. The results show ion exchange resin does not have selectivity to separate Ga from metals-based pregnant bioleachate. In addition, due to the similar properties between Ga and Al elements, copercipitation reaction occurred, consequently resulting in the failure of chemical fractionation precipitation to separate and recover Ga. However, under the optimized experimental conditions, the milk of lime technique yielded the maximum recovery of 60.6%, proving that the method is superior to the first two methods. Therefore, a combined process development of bioleaching and milk of lime can be considered high-efficiency, economically and environmentally friendly for separating and selective recovery of Ga from aluminum smelting slag.

Tumour control in ion beam radiotherapy with different ions in the presence of hypoxia: an oxygen enhancement ratio model based on the microdosimetric kinetic model

Few attempts have been made to include the oxygen enhancement ratio (OER) in treatment planning for ion beam therapy, and systematic studies to evaluate the impact of hypoxia in treatment with the beam of different ion species are sorely needed. The radiobiological models used to quantify the OER in such studies are mainly based on the dose-averaged LET estimates, and do not explicitly distinguish between the ion species and fractionation schemes. In this study, a new type of OER modelling, based on the microdosimetric kinetic model, taking into account the specificity of the different ions, LET spectra, tissues and fractionation schemes, has been developed. The model has been benchmarked with published in vitro data, HSG, V79 and CHO cells in aerobic and hypoxic conditions, for different ion irradiation. The model has been included in the simulation of treatments for a clinical case (brain tumour) using proton, lithium, helium, carbon and oxygen ion beams. A study of the tumour control probability (TCP) as a function of oxygen partial pressure, dose per fraction and primary ion type has been performed. The modelled OER depends on both the LET and ion type, also showing a decrease for an increased dose per fraction with a slope that depends on the LET and ion type, in good agreement with the experimental data. In the investigated clinical case, a significant increase in TCP has been found upon increasing the ion charge. Higher OER variations as a function of dose per fraction have also been found for low-LET ions (up to 15% varying from 2 to 8 Gy(RBE) for protons). This model could be exploited in the identification of treatment condition optimality in the presence of hypoxia, including fractionation and primary particle selection.

Fracsis: Ion fractionation and metathesis by a NF-ED integrated system to improve water recovery

Desalination of brackish and wastewater is a challenging task in case the water contains sparingly bivalent ions. To avoid membrane scaling and obtain a high water recovery, an integrated membrane process is proposed in this investigation: ion fractionation and metathesis by a nanofiltration (NF) – electrodialysis (ED) integrated system (namely “Fracsis”). In the first step, this system makes use of the advantage of NF which can fractionate the bivalent ions from the monovalent ions. Results show that the tested NF membrane has a satisfying selectivity for this application, with a retention of Na+ 38–49%, Cl− 20–38%, and Ca2+ >98%, SO42− >85%. Afterwards, both NF permeate (monovalent stream) and retentate (divalent stream) were sent to the ED for metathesis. By ED metathesis, salts with high solubility (CaCl2 and Na2SO4) were synthesized in two separate streams and hence a high water recovery was achieved. The water recovery rate may reach 98.5% in case a continuous mode is used. Finally, the operational cost was calculated on this bench scale Fracsis system. Results indicate that although the energy consumption is higher than that of a RO system, Fracsis has its advantages in a higher water recovery, lower cost on chemical consumption and sludge treatment expenditures. To a broader context, this technology may possibly be used for chemical purification and synthesis in various industries in case mixed inorganic/organic salt streams are concerned.

SU‐E‐T‐770: Tumor Control in Ion Beam Radiotherapy with Different Ions in Presence of Hypoxia

Purpose:The reduced concentration of oxygen in cells (hypoxia) results in a lower cell death rate after irradiation that can lead to treatment failure. The effect can be expressed by the oxygen enhancement ratio (OER). So far, only few attempts to include OER in treatment planning for ion beam therapy were made, which are based on the dose averaged LET estimates and do not distinguish among ion species and fractionation schemes. To overcome these limitations, we implemented a new OER model and used it to estimate tumor control in clinical cases.Methods:The model, based on the microdosimetric kinetic model, was benchmarked with in‐vitro data from different ions irradiation. It was included in the simulation of treatments of a set of clinical cases (glioblastoma) using p, Li, He, C and O ion beams. Tumor Control Probability (TCP) was estimated as a function of oxygen partial pressure, dose per fraction and primary ion type.Results:The modelized OER was found to be strongly dependent on both LET and ion type, and showed a decreasing OER for increasing dose per fraction with a slope that depends on the LET and ion type, in good agreement with the experimental data. In the clinical cases studied, an increase in TCP by increasing ion charge and dose per fraction (more than 30% variation from p to O for moderate hypoxia) was found. Higher OER decrease rates as function of dose per fraction were found for lighter ions (up to 20% varying from 2 to 8 Gy(RBE)).Conclusions:A novel modeling of the OER that explicitly includes the dependence on ion type and dose per fraction was implemented. The model was exploited to evaluate the impact of hypoxia in ion beam radiotherapy, facilitating the identification of the treatment condition optimality, including fractionation scheme and ion type.