Oxalate Precipitation Research Articles

Rhubarb: A novel model plant to study the conundrum of calcium oxalate synthesis

The study investigated calcium oxalate (CaOx) crystal composition, accumulation, synthesis, and degradation in five rhubarb species from the North-Western Indian Himalayas. Techniques like optical and scanning electron microscopy (SEM), SEM-energy-dispersive X-ray spectroscopy (SEM-EDS), inductively coupled plasma-optical emission spectrometry (ICP-OES), X-ray diffraction spectroscopy (XRD), and real-time (qRT-PCR) expression analysis of strategic genes were used to understand the processes of oxalate synthesis and precipitation. Results showed crystals tend to accumulate around vascular bundles in all species, irrespective of size, indicating a consistent pattern. Crystal synthesis and accumulation were stress-driven, linked to substrate composition, and in planta soluble oxalate and calcium levels, paralleling oxalate precursors. Based on their availability, CaOx crystals precipitated heavy metals mostly associated with its weddellite form. Crystal content correlated positively with mRNA levels of calcium/oxalate/ascorbate-related and stress-responsive genes, and negatively with oxalate oxidation/decarboxylation genes. CaOx crystals were suggested as potential biominerals for addressing heavy metal stress in agriculture.

The rapid photochemical reduction of U(VI) at high uranium concentrations relevant to spent nuclear fuel recycle processes

An Advanced PUREX process for the recycling of spent nuclear fuel is currently under active development in the UK. Its key aims are to avoid pure separated plutonium at all stages of the process to enhance the level of proliferation resistance, and to achieve a single cycle flowsheet that has a smaller plant footprint with consequent decreases in the capital cost and secondary wastes generated. Addressing these aims, a significant feature of the process is the co-treatment of U and Pu and thus the in situ co-conversion of mixed actinide metal nitrate solutions into oxide powders, suitable for the fabrication of new mixed metal oxide (MOx) fuel. The baseline industrial process for plutonium recovery is by oxalate precipitation; however, in order to quantitatively recover both U and Pu the uranium must be in the U(IV) oxidation state due to the high solubility of U(VI) oxalate. The first stage of this co-conversion, the development of which is reported on here, is the rapid, clean photochemical co-reduction of a mixed U(VI)/Pu(IV) nitrate stream to U(IV)/Pu(III).Here we describe a study of the reduction of U(VI) in preparation for mixed U(VI)/Pu(IV) reduction trials. Exploiting the photochemistry of U, we demonstrate the convenient and efficient photo-excitation and chemical reduction of U(VI) upon exposure to 407 nm wavelength light in the presence of alcohol-based reductants. Using a purpose built laboratory-scale photochemical reactor, U(VI) solutions of up to process-relevant concentrations of 630 mmol/dm3 (150 g/l) U have been successfully converted to a U(IV) product, achieving a conversion efficiency of ∼98% within 1.5–15 min when using propan-2-ol as a sacrificial reductant. Modelling of the dependence of the rate of U(IV) generation on initial U(VI) concentration reveals the importance of light penetration depth and effective solution mixing in determining the efficiency of the photochemical process at high U-loadings. It also reveals that the photoreduction of U(VI) to U(IV) occurs by two sequential 1-electron reductions: (i) the photochemically driven reduction of UO22+ to UO2+ by propan-2-ol, which itself is oxidised to form an α-hydroxyalkyl radical, immediately followed by (ii) a second chemical reduction of UO22+ to UO2+ and/or UO2+ to U4+ by the so-formed radical. With the addition of a nitrous acid scavenger to prevent re-oxidation of the photochemically generated U(IV), a stable product is maintained indefinitely, and the solution is suitable for subsequent oxalate co-precipitation as part of a MOx fuel fabrication process.

Recovering Co3O4 from waste choline chloride/ethylene glycol electrolyte containing Co(II) ions along with solvent regeneration

Efficiently recovering critical metals from secondary resources is crucial to decreasing the environmental impact of mineral-resource mining and reducing production costs and process energy consumption. Herein, we propose a simple and comprehensive approach to recycle Co3O4 from waste choline chloride/ethylene glycol (named Ethaline) electrolyte containing Co(II) ions along with solvent regeneration. Through the rational coordination adjustment using water, [CoCl4]2− complex in the Ethaline-based electrolyte is transformed to [CoCl2(H2O)4]0 and [CoCl2(H2O)5]+ to facilitate precipitation separation. Adding oxalic acid (OA) as a precipitator can reach 97.1% cobalt recovery efficiency with a high value-added Co3O4 rod-like structure obtained by calcining the oxalate precipitate. In addition, the water-containing solvent can be regenerated via reduced pressure distillation with a high recovery efficiency of up to 98.0%. FT-IR and 1H NMR characterizations verify that the regenerated Ethaline exhibits good structural stability. Impressively, the proposed recovery path shows high recovery efficiencies for both cobalt and Ethaline in various practical Co(II) ion-containing electrolytes. This study establishes a novel technical pathway for the resource utilization of metal-bearing waste Ethaline electrolytes, which shows an excellent prospect in solvent recycling after metal processing.

Fruit waste-derived lixiviant: A viable green chemical for lithium-ion battery recycling

Fruit peel discards from various sources are harnessed as a renewable waste biomass feedstock for lithium-ion battery (LIB) recycling, showcasing the potential for green chemical production. Extractive methods, including hot water treatment, ultrasonic-assisted hydrolysis, and fermentation, produce a fruit peel-derived lixiviant (FL) to extract valuable metals from industrial-grade spent LIB black mass. The FL obtained through fermentation using various fruit peels (e.g. orange, mango, papaya, honeydew, lemon, and pomelo) could effectively leach more than 90% of cobalt and lithium from LCO black mass, without the need for synthetic chemicals. Additionally, the use of oxalate precipitation could recover the leached cobalt ions from orange peel-derived FL at a high yield of around 85%. The cathode material regenerated from cobalt precipitate coupled with LiOH supplementation exhibits excellent electrochemical performance with a capacity retention of 93% after 140 cycles. Overall, this proposed method of using FL-enabled LIB recycling offers a significant new opportunity for a more resource-efficient circular and sustainable economy.

Pilot Scale Testing of Lignite Adsorption Capability and the Benefits for the Recovery of Rare Earth Elements from Dilute Leach Solutions

Naturally occurring organic materials containing humic acids show a strong affinity towards rare earth elements (REE) and other critical elements. Leaching experiments on lignite coal waste produced from construction sand production revealed that the contained REEs were associated with the organic matter. Furthermore, adsorption studies revealed that the lignite waste was capable of extracting REEs from a model solution and increased the REE content of the lignite waste by more than 100%. As such, this study aimed to utilize the lignite waste to adsorb REEs from pregnant leach solutions and acid mine drainage sources having low REE concentrations and subsequently leach the lignite material to produce pregnant leach solutions containing relatively high amounts of REEs, which benefits the performance and economic viability of downstream separation and purification processes. An integrated flowsheet was developed based on this concept and tested at a pilot scale. The pregnant leachate solution (PLS) was generated from a heap leach pad containing 2000 tons of Baker seam coarse refuse. The pilot scale circuit was comprised of aluminum precipitation, adsorption using the waste lignite, and rare earth-critical metal (RE-CM) precipitation stages in succession. The results indicated that the aluminum precipitation stage removed over 88% and 99% of the Al and Fe, respectively. The adsorption stage increased the REE content associated with the waste lignite from 457 ppm to 1065 ppm on a whole mass basis. Furthermore, the heavy REE (HREE) content in the feedstock increased by approximately 250%, which raised the percentage of HREE in the REE distribution by 19 absolute percentage points. In addition to the REEs, concentrations of other critical elements such as Mn, Ni, and Zn also improved by 75%, 37%, and 250%, respectively. Bench-scale tests revealed that increasing the solids concentration in the waste lignite and PLS mix from 1% to 20% by weight enhanced the adsorption efficiency from 32.0% to 99.5%, respectively. As such, a new flowsheet was proposed which provides significantly higher REE concentrations in the PLS that can be fed directly to solvent extraction and/or oxalic acid precipitation and, thereby, enhancing process efficiency and economics.

A novel ion exchange-electrodialysis hybrid system to treat rare-earth oxalic precipitation mother liquid: Contamination reduction, efficient Y3+ recovery, and acid separation

A novel ion exchange process combined with selective electrodialysis (SED) process has been demonstrated to not only efficiently recover low concentration rare-earth elements (REEs) and separate hydrochloric acid, but also significantly reduce membrane fouling. Two resins with different functional groups were selected for pretreatment and recovery of Y3+ from Y rare-earth oxalic precipitation (Y REOP) mother liquor. CH-93 resin showed a Y recovery rate of over 94 %, and the Y recovery efficiency remained above 90 % after 5 cycles. The mother liquor treated with resin (R-T) and the untreated mother liquor (W-R-T) were subjected to acid separation via SED, and membrane fouling was systematically evaluated. Compared with W-R-T group, the hydrochloric acid recovery efficiency of R-T group increased by 21.01 % (12 V), and the unit energy consumption decreased by 54.30 % (12 V). The results of 3D fluorescence excitation-emission matrix (3D-EEM) and fluorescent region integration (FRI) showed the dissolved organic matter (DOM) on AEM and CEM in R-T group both decreased by >45 %. The AEM of W-R-T group showed the highest fluorescence intensity ratio in V region (36 %), indicating humic acid-like substances were the main cause of AEM fouling. Generally, this study provides a new approach for the resource utilization of REOP mother liquor.

Semicontinuous Process of Rare Earths Recovery from End-of-Life NdFeB Magnets on a Large Laboratory Scale

Hydrometallurgical methods for NdFeB recycling typically consist of several unit operations and require the extensive use of energy, water and chemicals which may negatively affect the applicability of these methods on an industrial scale. Based on the data from our previous studies, a simplified process of rare earth elements (REE) recovery from spent NdFeB magnets was developed further. The possibility of regenerating the leaching agent, as well as water recovery, in the process was investigated. This study also investigates a possibility of scaling up the recycling process developed on a laboratory scale. The leaching and precipitation stages were tested on a larger scale, where about 1 kg of end-of-life magnets was used as feed to the leaching step. In this study, end-of-life magnets were obtained from the manual disassembly of computer hard disc drives. After disassembly, the magnets were demagnetized, broken into pieces and fed to the leaching process. In the following step, rare earths were precipitated in the form of oxalates. The rare earths’ precipitation efficiency reached a maximum of 95.6%. The results showed that the co-precipitation of Fe highly depends on the amount of oxalic acid used as the precipitant. Smaller losses of Fe were achieved while using a stoichiometric amount of oxalic acid in relation to the REE present in the solution. At the end of the investigated process, rare earth oxalates were calcinated to oxides and their purity was investigated. The recirculation of a solution after oxalate precipitation and acid regeneration was tested with hydrochloric and sulfuric acids used as leaching agents. Solution recirculation was found to be possible only in the case of hydrochloric acid.

Recovery of Rare Earth Elements from the Leaching Solutions of Spent NdFeB Permanent Magnets by Selective Precipitation of Rare Earth Oxalates

After mechanical pre-treatment, the typical hydrometallurgical route of NdFeB magnet recycling starts with leaching in acidic solutions. However, due to the high concentration of iron ions in the leaching solution, the selective recovery of rare earths from the solution is challenging. In our work, the selective precipitation of rare earth oxalates as a potential separation method was proposed. The precipitation of neodymium oxalate was first tested on model solutions, which was then followed by experimental tests carried out on real solutions after the leaching of NdFeB magnets. The recovery of rare earths in the form of oxalates was investigated with the use of different amounts of oxalic acid in relation to its stoichiometric amount. The most efficient separation of rare earths was observed in the case where sulfuric acid was used for leaching. The use of oxalic acid in stoichiometric amounts resulted in the precipitation of about 93% of all rare earths present in the solution, whereas the concentration of Fe and other elements (Ni, Co, and B) practically did not change. An increase in oxalic acid of 20% and 40% more than the stoichiometric amount (100%) led to the increase in the precipitation efficiency of rare earths to 96.7% and 98.1%, respectively. However, the use of oxalic acid in a 1.4 ratio caused a 7% decrease in Fe concentration, which suggests Fe co-precipitation. In order to investigate a possibility of further increasing the separation of rare earths from iron, an additional method was tested, in which iron was first oxidized from Fe2+ to Fe3+ before the precipitation of rare earth oxalates.

Depolymerization and leachability of spent videotape for cobalt recovery

Cobalt is a widely used technology-enabling metal that is dominantly recovered as a by-product of copper and nickel. However, mainly because of its economic importance and high supply risks, it is classified as a critical raw material in Europe, increasing the importance of the utilization of secondary cobalt resources. This work presents a study of the recovery of a pure form of cobalt oxalate from spent low-grade VHS videotapes (0.35 wt% of cobalt). Firstly, depolymerization of the videotape was conducted by alkaline hydrolysis resulting in 94.5% polyethylene (PET) depolymerization yield (T = 150 °C, p = 6.9 bar, [NaOH] = 1 mol L-1). Secondly, metal-rich residue (2.3 wt% of cobalt, 54.5 wt% of iron) of alkaline hydrolysis was subjected to hydrometallurgical leaching in two acids (H2SO4 and H3PO4) at 1 M (S/L = 10 g L−1, t = 5 min, T = 80 °C). In the subsequent oxalate precipitation study, 99.9% purity and 98.0% yield of cobalt precipitate could be achieved. This study provides insight into the technical feasibility of the combined alkaline hydrolysis and hydrometallurgical recovery of cobalt from secondary videotape resources.

Insights into the interfacial structure of Cu/ZrO2 catalysts for methanol synthesis from CO2 hydrogenation: Effects of Cu-supported nano-ZrO2 inverse interface

The performance of Cu-based catalysts in the low temperature CO2 conversion to methanol highly correlates with interfacial structure. In this paper, the interfacial structure of Cu/ZrO2 catalysts is tuned by changing the molar ratio and precipitation sequence of Cu and Zr precursors in the oxalate precipitation method. Structural characterizations demonstrate that the interface structure gradually transforms from the conventional ZrO2-supported nano-Cu interface to the Cu-supported nano-ZrO2 inverse interface with the ascending Cu/Zr ratio. The space–time yield (STY) of methanol over 90 molCu% Cu/ZrO2 inverse catalyst is 518 gCH3OH/kgcat/h, which far exceeds that of the optimized 40 molCu% Cu/ZrO2 catalyst (351 gCH3OH/kgcat/h). The inverse catalyst also exhibits the best methanol selectivity and lowest apparent activation energy. The correlation of the exposed Cu surface area, Cu particle size, and CO2 adsorption capacity with STYmethanol reveal that there is an optimal coverage of fine ZrO2 particles and the Cu supported nano-ZrO2 inverse configuration is a more suitable structure for methanol synthesis from CO2. High-pressure in situ DRIFTS experiment shows that the adsorbed formate and methoxy intermediates over 90 molCu% Cu/ZrO2 inverse catalyst are more reactive for further hydrogenation. In addition, the inverse configuration is more favorable for the methanol desorption from surface. The enhanced hydrogenation ability and relatively weak oxygenates adsorption of Cu-supported nano-ZrO2 interface is probably the main reasons for the improved catalytic performances of inverse catalysts.

Recovery of bismuth and other metals from blast furnace dust by leaching with oxalic acid-based deep eutectic solvent and precipitation

Eutectic solvents, with the advantages of easy synthesis, high chloride content, non-aqueous environment, and low costs are the most promising alternatives to ionic liquids for leaching and recovery of metals from waste resources. The leaching of bismuth has been mainly conducted using chlorinated salts and strong acids in previous studies. The use of conventional ionic liquids can be costly. In addition, there has only been limited research into developing strategies for the recovery of bismuth from blast furnace (BF) dust using a deep eutectic solvent (DES) made of choline chloride and oxalic acid. In this work, an oxalic acid-based deep eutectic solvent was used for selective recovery of bismuth from blast furnace dust. A leaching efficiency of 94.9% Bi was achieved at the most suitable conditions (stirring speed: 300 rpm, liquid-solid ratio: 5 mL/g, temperature: 70°C, time: 20 h). The zinc and iron which are impurities in the leach solution were removed by hydrolysis and photoinduced reduction process, and the by-products of ZnC2O4·2H2O and FeC2O4·2H2O had purities of 86.6% and 96.8%, respectively. Another hydrolysis was employed to recover Bi(III) from the leach solution and the product of BiOCl was obtained with a total Bi recovery efficiency of 89.1%. The proposed process in this work is resource-saving and friendly to the environment.

SLC26 family: a new insight for kidney stone disease.

The solute-linked carrier 26 (SLC26) protein family is comprised of multifunctional transporters of substrates that include oxalate, sulphate, and chloride. Disorders of oxalate homeostasis cause hyperoxalemia and hyperoxaluria, leading to urinary calcium oxalate precipitation and urolithogenesis. SLC26 proteins are aberrantly expressed during kidney stone formation, and consequently may present therapeutic targets. SLC26 protein inhibitors are in preclinical development. In this review, we integrate the findings of recent reports with clinical data to highlight the role of SLC26 proteins in oxalate metabolism during urolithogenesis, and discuss limitations of current studies and potential directions for future research.

Control of Sodium Oxalate Precipitation by Ammonium/Quaternary Ammonium Compounds in the Gibbsite Precipitation Stage of Bayer Liquor

Control of Sodium Oxalate Precipitation by Ammonium/Quaternary Ammonium Compounds in the Gibbsite Precipitation Stage of Bayer Liquor

Extraction of high purity magnetite from bauxite residue

Bauxite residue is a byproduct of the alumina industry and is characterized by high alkalinity and very fine particle size. Currently, there is a low volume utilization of bauxite residue as an additive in the construction industries, and only 3–4 % of the total volume produced annually (160 million tons) is utilized effectively. Bauxite residue is mainly composed of iron oxide along with oxides of aluminum, calcium, sodium, silicon, and titanium. A high fraction of iron in bauxite residue makes it a potential alternative source. However, recovery of high purity iron products with high recovery is technically challenging. The present work is focused on the recovery of iron from bauxite residue in the form of high purity magnetite through a hydrometallurgical approach. Bauxite residue is first neutralized after leaching with mild hydrochloric acid, followed by the leaching of iron with oxalic acid and photochemical reduction of leach liquor to obtain ferrous oxalate precipitate, which is further converted to high purity magnetite. Three different bauxite residue samples with different mineralogical compositions were used, and a comparative study is presented to illustrate the flexibility of the process toward different grades of bauxite residue.

Steady state population balance modelling of precipitation processes: Nucleation, growth and size-dependent agglomeration

In this work a numerical methodology to solve the steady state Population Balance Equation (PBE) is developed. Three crystallisation mechanisms are included, namely: nucleation, size-independent growth and size-dependent loose agglomeration. The numerical method is based on the discretisation of the crystal size as distributed variable. In order to describe the loose agglomeration, the numerical methodology solves two PBE: one including the nucleation and growth mechanisms and one accounting for the agglomeration process. From the first PBE, liquid phase composition, supersaturation, developed crystal surface and Crystallite Size Distribution (CSD) are obtained. Similarly, the second PBE leads to the Agglomerate Size Distribution (ASD). The study of the size-dependant agglomeration kernel induces an additional numerical difficulty due to the dependency of both PBE and agglomeration kernel on the particle size. An accelerated fixed point algorithm based on the crossed secant method is adapted to overcome the difficulty and accurately solve the agglomeration PBE. The oxalic precipitation of uranium is simulated using this numerical methodology. First, the experimental results of a reference case are compared with the numerical predictions in terms of particle size distribution, mean size, mass fraction and moments. Then, the operating conditions are varied in order to test the algorithm robustness and performances. In all cases, the crossed secant method ensures the size-dependent agglomeration PBE solution and properly predicts the ASD. The developed numerical methodology predicts the mean particle size under the experimental uncertainty in a reasonable computation time and number of iterations.

Dose-Dependent Dual Effect ofMorus nigraL. Extract on Urinary Parameters of Hypertensive Rats.

This study investigated the diuretic and antiurolithic effects of the hydroalcoholic extract obtained from Morus nigra L. leaves (HEMN) in female hypertensive rats. The rats were treated orally with vehicle (VEH), hydrochlorothiazide (HCTZ), or HEMN. After 8-h, the urine was analyzed. Besides, the precipitation of calcium oxalate (CaOx) was induced in the urine. The HEMN, at a dose of 0.03 mg/g, increased the volume of urine compared to the VEH-treated group and increased the urinary content of Cl-, without altering the excretion of Na+ and K+. Besides, HENM reduced the elimination of Ca2+ in the urine. On the other hand, at a dose of 0.1 mg/g, it significantly reduced the volume of urine excreted, thus suggesting an antidiuretic effect dependent on the dose used. Similarly, HEMN at concentrations of 1 and 3 mg/mL reduced CaOx crystals' formation in monohydrate and dihydrate forms. However, with the increase in the concentration of HEMN to 10 mg/mL, a significant increase in the formation of CaOx crystals was found. In conclusion, M. nigra extract has a dose-dependent dual effect on urinary parameters, which may have a diuretic and antiurolithic effect at lower doses or the opposite effect at higher doses.

Reductive Leaching of Low-Grade Manganese Ores from Way Kanan Using Corncob As Reductant

The processing of mining products in indonesia has not been utilized optimally. One of them is manganese ore. Way kanan is one of indonesia's potential manganese ore sites. The manganese leaching study used a -200 mesh way kanan manganese ore that was reacted with sulfuric acid at concentrations of 0.1 M, 0.5 M, and 1 M, as well as corncob as a reductant. To separate the dissolved iron in the leaching process, the manganese sulfate solution was purified with sodium hydroxide and then filtered to have a manganese sulfate solution free of iron. Manganese was precipitated using oxalic acid. The manganese oxalate precipitation was calcined at a temperature of 350 °c for two hours. The best manganese extraction obtained at 92.3% was at a sulfuric acid concentration of 1 M, a temperature of 80 °c, and a solution volume of 400 ml. Calcination of manganese oxalate converted the material into hausmannite (Mn3O4).

Diversity and Composition of Culturable Microorganisms and Their Biodeterioration Potentials in the Sandstone of Beishiku Temple, China.

Microbial colonization on stone monuments leads to subsequent biodeterioration; determining the microbe diversity, compositions, and metabolic capacities is essential for understanding biodeterioration mechanisms and undertaking heritage management. Here, samples of epilithic biofilm and naturally weathered and exfoliated sandstone particles from different locations at the Beishiku Temple were collected to investigate bacterial and fungal community diversity and structure using a culture-based method. The biodeterioration potential of isolated fungal strains was analyzed in terms of pigmentation, calcite dissolution, organic acids, biomineralization ability, and biocide susceptibility. The results showed that the diversities and communities of bacteria and fungi differed for the different sample types from different locations. The population of culturable microorganisms in biofilm samples was more abundant than that present in the samples exposed to natural weathering. The environmental temperature, relative humidity, and pH were closely related to the variation in and distribution of microbial communities. Fungal biodeterioration tests showed that isolated strains four and five were pigment producers and capable of dissolving carbonates, respectively. Their biomineralization through the precipitation of calcium oxalate and calcite carbonate could be potentially applied as a biotechnology for stone heritage consolidation and the mitigation of weathering for monuments. This study adds to our understanding of culturable microbial communities and the bioprotection potential of fungal biomineralization.

Separation of Hydrochloric Acid and Oxalic Acid from Rare Earth Oxalic Acid Precipitation Mother Liquor by Electrodialysis.

In this study, the hydrochloric acid from rare earth oxalic acid precipitation mother liquor was separated by electrodialysis (ED) with different anion exchange membranes, including selective anion exchange membrane (SAEM), polymer alloy anion exchange membrane (PAAEM), and homogenous anion exchange membrane (HAEM). In addition to actual wastewater, nine types of simulated solutions with different concentrations of hydrochloric acid and oxalic acid were used in the experiments. The results indicated that the hydrochloric acid could be separated effectively by electrodialysis with SAEM from simulated and real rare earth oxalic acid precipitation mother liquor under the operating voltage 15 V and ampere 2.2 A, in which the hydrochloric acid obtained in the concentrate chamber of ED is of higher purity (>91.5%) generally. It was found that the separation effect of the two acids was related to the concentrations and molar ratios of hydrochloric acid and oxalic acid contained in their mixtures. The SEM images and ESD-mapping analyses indicated that membrane fouling appeared on the surface of ACS and CSE at the diluted side of the ED membrane stack when electrodialysis was used to treat the real rare earth oxalic acid precipitation mother liquor. Fe, Yb, Al, and Dy were found in the CSE membrane section, and organic compounds containing carbon and sulfur were attached to the surface of the ACS. The results also indicated that the real rare earth precipitation mother liquor needed to be pretreated before the separation of hydrochloric acid and oxalic acid by electrodialysis.

A molecular understanding of citrate adsorption on calcium oxalate polyhydrates.

Calcium oxalate precipitation is a common pathological calcification in the human body, whereby crystallite morphology is influenced by the chelating properties of biological ions such as citrate. It has been suggested that citrate could steer oxalate formation towards its dihydrated form and away from the monohydrated form, which was identified as a major cause for disease. To assess the influence of the citrate ion on the resulting calcium oxalate, surface energies were calculated at the dispersion-corrected density functional level of theory for both monohydrated and dihydrated calcium oxalate. Different adsorption geometries were considered by varying the attacking angle of citrate as well as by considering the citrate ion on top of an adsorbed water layer or penetrating the water layer. The obtained results were compared to ab initio molecular dynamics simulations and experimental scanning electron microscope images. A strong preference for citrate adsorption on calcium oxalate dihydrate was observed, suggesting medical applications for the treatment of such pathological calcifications.