Non-Interacting Ni and Fe Dual-Atom Pair Sites in N-Doped Carbon Catalysts for Efficient Concentrating Solar-Driven Photothermal CO2 Reduction.

Solar-to-chemical energy conversion under weak solar irradiation is generally difficult to meet the heat demand of CO2 reduction. Herein, a new concentrated solar-driven photothermal system coupling a dual-metal single-atom catalyst (DSAC) with adjacent Ni-N4 and Fe-N4 pair sites is designed for boosting gas-solid CO2 reduction with H2 O under simulated solar irradiation, even under ambient sunlight. As expected, the (Ni, Fe)-N-C DSAC exhibits a superior photothermal catalytic performance for CO2 reduction to CO (86.16 µmol g-1 h-1 ), CH4 (135.35 µmol g-1 h-1 ) and CH3 OH (59.81 µmol g-1 h-1 ), which are equivalent to 1.70-fold, 1.27-fold and 1.23-fold higher than those of the Fe-N-C catalyst, respectively. Based on theoretical simulations, the Fermi level and d-band center of Fe atom is efficiently regulated in non-interacting Ni and Fe dual-atom pair sites with electronic interaction through electron orbital hybridization on (Ni, Fe)-N-C DSAC. Crucially, the distance between adjacent Ni and Fe atoms of the Ni-N-N-Fe configuration means that the additional Ni atom as a new active site contributes to the main *COOH and *HCO3 dissociation to optimize the corresponding energy barriers in the reaction process, leading to specific dual reaction pathways (COOH and HCO3 pathways) for solar-driven photothermal CO2 reduction to initial CO production.

Performance and microbial community analysis of combined bioreactors in treating high-salinity hydraulic fracturing flowback and produced water.

The anoxic/oxic systems are a widely used biological strategy for wastewater treatment. However, little is known about the performance and microbial community correlation of different combined bioreactors in the treatment of high-COD and high-salinity hydraulic fracturing flowback and produced water (HF-FPW). In this study, the performance of Up-flow anaerobic sludge bed-bio-contact oxidation reactor (UASB-BCOR) and Fixed-bed baffled reactor (FBR-BCOR) in treating HF-FPW was investigated and compared. The results suggested the FBR-BCOR could efficiently remove COD, SS, NH4+-N, and oil pollutants, and it exhibited better resistance to the negative interference of hydraulic shock load on it. Besides, the correlation analysis first disclosed the key functional genera during the degradation process, including Ignavibacterium, Ellin6067, and Zixibacteria. Moreover, network analysis revealed that the difference of microbial co-occurrence network structure is the main driving factor for the difference of bioreactor processing capacity. This work demonstrates the feasibility and potential of FBR-BCOR in treating HF-FPW.

Plant growth-promoting rhizobacteria are important contributors to rice yield in karst soils.

The difficulty of releasing nutrients from soils in karst areas limits the yield of local crops and leads to poverty. In this study, two strains of plant growth-promoting rhizobacteria (PGPR) were isolated from the rhizosphere soil of typical plants in karst areas, which were both identified as Bacillus sp. and named GS1 and N1. And two isolates were used to construct a composite PGPR named MC1. These three strains of PGPR were used for soil inoculation in the pot experiment and field trial and their capacity to promote rice development was assessed. The results showed that MC1 inoculation exhibited notable rice growth-promoting ability in pot experiments, and, respectively, had an increment of 16.96, 18.74, and 11.50% in shoot biomass, total biomass, and rice height compared with control. This is largely attributed to PGPR's capacity to secrete phytohormones and soil enzymes, particularly urease (UE) in GS1, whose secreted UE content was significantly higher by 12.18% compared to the control. When applied to the field, MC1 inoculation not only increased rice yield by 8.52% and the available nutrient content in rice rhizosphere soil, such as available phosphorus (AP) and exchangeable magnesium (EMg); but also improved the abundance of beneficial rhizobacteria and the diversity of microbial communities in rice rhizosphere soil. Results in this study revealed that inoculated PGPR played a major role in promoting rice growth and development, and a new strategy for facilitating the growth of rice crops in agriculture was elucidated. Supplementary Information: The online version contains supplementary material available at 10.1007/s13205-023-03593-0.

Preparation of pH sensitive bacteriostatic W/O/W emulsion microcapsules.

This experiment was done to study the zeolite molecular sieve as a drug-binding effector, the non-antibiotic drug potassium diformate uniformly disperse in the internal aqueous phase of the 'egg box' structure formed by pectin-calcium ions. With oil phase as the intermediate phase and Xanthan gum Chitosan as the external water phase, the W/O/W type sustained release bacteriostatic microcapsules with pH response were prepared and characterized by Fourier transform infrared, thermogravimetric, SEM, and TEM. It can be obtained through characterization experiments that the inner water phase, oil phase, and outer water phase were formed by observation, and W/O/W emulsion microcapsules were obtained and the bacteriostasis effect of microcapsules was verified by bacteriostasis experiment. The permeance experiment showed that the molecular sieve was successfully coated in the microsphere. Studying on drug release mechanism and sustaining release performance of composite emulsion microcapsules. In vitro drug release study showed that the encapsulation efficiency and drug loading rate of microcapsules were improved by adding molecular sieve, reaching 12.31% and 61.55%, respectively. At the same time, we observed that the drug release rate slowed down during the simulated intestinal release process, and the drug release kinetics were in line with the first-order kinetic model and Ritger-Peppas model equation. Experiments had proven that the drug-loaded microcapsules exerted a significant bacteriostatic effect on Escherichia coli, Staphylococcus aureus, and Bacillus subtilis, with the highest antibacterial rates of 97.25%, 94.05%, and 95.93%, respectively. Therefore, the composite emulsion microcapsules can be used as a new controlled-release drug delivery system in vivo.

Construction of pH-sensitive sodium alginates/sodium carboxymethyl cellulose/zeolite P composite hydrogel microspheres loaded with potassium diformate.

As a substitute for feed antibiotics, potassium diformate (KDF) can effectively inhibit bacterial overgrowth in the gastrointestinal tract. To avoid the sudden release of KDF in the stomach, this article proposes a new controlled drug delivery system for controlled drug release. In this system, P-type zeolite molecular sieve (Zeolite P) and drug KDF are combined and embedded into the hydrogel microspheres of sodium alginate (ALG) and sodium carboxymethyl cellulose (CMC). In addition, ALG/CMC/Zeolite P composite hydrogel microspheres were prepared with Ca2+ as the crosslinking agent. The structure, composition, morphology, and thermal stability of the hydrogel microspheres were systematically characterized. The effect of the composition ratio of ALG and CMC on the swelling properties of the hydrogel microspheres was also investigated. The results revealed that ALG and CMC form a hydrogen bond and chelate with Ca2+ to form a double crosslinked network structure. Thus, Zeolite P can be effectively encapsulated in the hydrogel microspheres to form a dense three-dimensional network structure. Particularly, Zeolite P helps in improving the thermal stability of microspheres, balance the swelling properties, and control the release of KDF. The drug release results and release kinetics reveal that the ALG/CMC/Zeolite P composite hydrogel has higher drug release in an environment with pH 7.4. The release kinetics follow the Ritger-Peppas model and the first-order kinetic model, which indicates that the composite hydrogel has good specific pH sensitivity. In vitro antibacterial experiments revealed that the composite hydrogel microspheres have broad-spectrum antibacterial activity, and certain inhibitory effects on Escherichia coli, Staphylococcus aureus, and Bacillus subtilis.

Preparation and properties of environmentally benign waterborne polyurethane composites from sodium-alginate-modified nano calcium carbonate.

Well-dispersed inorganic nanoparticles in organic polymers are critical in the preparation of high-performance nanocomposites. This study prepared a series of waterborne polyurethane (WPU)/calcium carbonate nanocomposites using the solution blending method. Next, FT-IR, TG-DTG and XRD tests were carried out to confirm that the biopolymer sodium alginate (SA) was successfully encapsulated on the surface of the calcium carbonate nanoparticles, and that SA achieved satisfactory surface modification of the calcium carbonate nanoparticles. The Zeta and ultraviolet (UV) absorbance test results reveal that SA-modified nano calcium carbonate (MCC) had good dispersion stability in water. The effects of the MCC dosage on the composite mechanical properties, thermal stability, and cross-sectional morphology observed by scanning electron microscopy, and the water resistance of the nanocomposite were investigated. The results reveal that the incorporation of 3wt% of MCC in WPU had stable distribution, which led to a 54% increase in the tensile strength of the nanocomposite, while maintaining excellent elongation at break (2187%) and increasing the maximum decomposition temperature to 419.6 °C. Importantly, the improved water resistance facilitates the application of this environmentally benign composite material in humid environments.

Enhanced remediation of fracturing flowback fluids by the combined application of a bioflocculant/biosurfactant-producing Bacillus sp. SS15 and its metabolites.

Fracturing flowback fluids (FFFs), which is generated from the process of oil and gas exploitation, is one of the major environmental concerns. In this study, a bacterial strain, Bacillus sp. SS15, capable of producing both bioflocculant (BF) and biosurfactant (BS), was isolated from oil-contaminated mudflat sediment. The BS produced by SS15 was identified as lipopeptide, which could reduce the surface tension of water from 74.2 mN/m to 36.6 mN/m with a critical micelle concentration of 44.4 mg/L. It also exhibited strong tolerance against a wide range of pH (2-12), temperature (4-60 °C), and salinity (0-100 g/L). Meanwhile, the BF produced by SS15 exhibited high flocculating activity (84.9%) for kaolin suspension, and was confirmed to be thermostable, salt-tolerant, and alkaliphilic. The combined treatment of bioremediation (introducing SS15 and BS) followed by flocculation (introducing BF) greatly promoted the removal of chroma (85.7% reduction), suspended solids (94.4% reduction), chemical oxygen demand (84.9% reduction), n-alkanes (50.0% reduction), and polycyclic aromatic hydrocarbons (66.5% reduction), respectively. The genome analysis showed that strain SS15 possessed abundant genes related to the synthesis of carbohydrate, protein, and lipid, which might play an important role in BF and BS synthesis. The findings in this study demonstrated that Bacillus sp. SS15 has promising prospect in the remediation of FFFs.

Clostridium weizhouense sp. nov., an anaerobic bacterium isolated from activated sludge of petroleum wastewater.

A Gram-stain-positive, anaerobic, spore-forming, rod-shaped (0.4-0.6 µm×2.5-3.2 µm), flagellated bacterium, designated strain YB-6T, was isolated from activated sludge of an anaerobic tank at Weizhou marine oil mining wastewater treatment plant in Beihai, Guangxi, PR China. The culture conditions were 25-45 °C (optimum, 37 °C), pH 4-12 (pH 7.0) and NaCl concentration of 0-7 % w/v (0%). Strain YB-6T grew slowly in petroleum wastewater and removed 68.2 % of the total organic carbon in petroleum wastewater within 10 days. Concentrations of naphthalene, anthracene and phenanthrene at an initial concentration of 50 mg l-1 were reduced by 32.8, 40.4 and 14.6 %, respectively, after 7 days. Phylogenetic analysis of the 16S rRNA gene sequence indicated that strain YB-6T belongs to Clostridium cluster I and is most closely related to Clostridium uliginosum CK55T (98.5 % similarity). The genome size of strain YB-6T was 3.96 Mb, and the G+C content was 26.5 mol%. The average nucleotide identity value between strain YB-6T and C. uliginosum CK55T was 81.9 %. The major fatty acids in strain YB-6T were C14 : 0 FAME, C16 : 0 FAME and summed feature 4 (unknown 14.762 and/or C15 : 2 FAME). The main polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, five unidentified aminophospholipids, one unidentified glycolipid and one unidentified aminolipid. Diaminopimelic acid was not detected in the strain YB-6T cell walls. Whole-cell sugars mainly consisted of ribose and galactose. Based on the results of phenotypic and genotypic analyses, strain YB-6T represents a novel species of the genus Clostridium, for which the name Clostridium weizhouense sp. nov. is proposed. The type strain is YB-6T (=GDMCC 1.2529T=JCM 34754T).

Two-step hydrothermal synthesis and conversion mechanism of zeolite X from stellerite zeolite.

We investigated the conversion mechanism of stellerite zeolite to zeolite X under two-step hydrothermal conditions. To elucidate the conversion mechanism, solid products were separated from the mixtures at different crystallization times and characterized by XRD, FESEM, FT-IR, Raman, solid-state NMR, XRF, and TEM. The results indicate that in this reaction process, the Si, Al, and Na in the gel solid phases were continuously dissolved and transformed into the gel-liquid-phase. When the concentration of each component reached supersaturation in the gel-liquid-phase, Si, Al, and Na were transferred to the surface of the gel-solid-phase, and nucleation and crystallization occurred on the surface. Abundant nuclei were formed during the second hour of the crystallization. As the crystallization time increased, the nuclei rapidly grew into zeolite X crystals, and the relative crystallinity of zeolite X reached a maximum when the crystallization time reached 4 h. These phenomena indicate that the formation mechanism of zeolite X is a liquid-phase conversion mechanism.

A biosurfactant-producing yeast Rhodotorula sp.CC01 utilizing landfill leachate as nitrogen source and its broad degradation spectra of petroleum hydrocarbons.

Biosurfactants (BSs) are known for their remarkable properties, however, their commercial applications are hampered partly by the high production cost. To overcome this issue, a biosurfactant producing strain, Rhodotorula sp.CC01 was isolated using landfill leachate as nitrogen source, while olive oil was determined as the best sole carbon source. The BS produced by Rhodotorula sp.CC01 had oil displacement diameter of 19.90 ± 0.10 cm and could reduce the surface tension of water to 34.77 ± 0.63 mN/m. It was characterized as glycolipids by thin layer chromatography, FTIR spectra, and GC-MS analysis, with the critical micelle concentration of 70 mg/L. Meanwhile, the BS showed stability over a wide range of pH (2-12), salinity (0-100 g/L), and temperature (20-100 °C). During the cultivation process, BS was produced with a maximum rate of 163.33 mg L-1 h-1 and a maximum yield of 1360 mg/L at 50 h. In addition, the removal efficiency of NH4+-N reached 84.2% after 75 h cultivation with a maximum NH4+-N removal rate of 3.92 mg L-1 h-1. Moreover, Rhodotorula sp.CC01 has proven to be of great potential in remediating petroleum hydrocarbons, as revealed by chromogenic assays. Furthermore, genes related to nitrogen metabolism and glycolipid metabolism were found in this strain CC01 after annotating the genome data with KEGG database, such as narB, glycoprotein glucosyltransferase, acetyl-CoA C-acetyltransferase, LRA1, LRA3, and LRA4. The findings of this study prove a cost-effective strategy for the production of BS by yeast through the utilization of landfill leachate.

Enhanced bioremediation of diesel oil-contaminated seawater by a biochar-immobilized biosurfactant-producing bacteria Vibrio sp. LQ2 isolated from cold seep sediment.

This study investigated the effect of immobilized biosurfactant-producing bacteria on the bioremediation of diesel oil-contaminated seawater. Initially, a biosurfactant-producing bacterium, LQ2, was isolated from a marine cold-seep region, and identified as Vibrio sp. The biosurfactant produced by LQ2 was characterized as a phospholipid, exhibiting high surface activity with strong stability. Meanwhile, the inoculation of biochar-immobilized LQ2 demonstrated superior efficiency in removing diesel oil (94.7%, reduction from 169.2 mg to 8.91 mg) over a seven-day period compared to free-cell culture (54.4%), through both biodegradation and adsorption. In addition, the microbial growth and activity were greatly enhanced with the addition of immobilized LQ2. Further experiment showed that degradation-related genes, alkB and CYP450-1, were 3.8 and 15.2 times higher in the immobilized LQ2 treatment, respectively, than those in the free cell treatment. The findings obtained in this study suggest the feasibility of applying immobilized biosurfactant-producing bacteria, namely LQ2, in treating diesel oil-contaminated seawater.

Isolation and characterization of biosurfactant-producing Serratia marcescens ZCF25 from oil sludge and application to bioremediation.

A biosurfactant (BS) is a surface-active metabolite that is secreted by microbial metabolism, and can be used as a substitute for chemically synthesized surfactants. The first and most critical step to the successful application of BSs is to isolate bacterial strains with strong BS-producing capabilities. In this study, a BS-producing Serratia marcescens ZCF25 was isolated from the sludge of an oil tanker. Through polyphasic characterization using Fourier-transform infrared spectroscopy, thin layer chromatography, and gas chromatography-mass spectrometry, the produced BS was classified as a lipopeptide; it can decrease the water surface tension from 72.0 to 29.50 mN m-1 and has a critical micelle concentration of 220 mg/L. The BS showed a high tolerance over a wide range of pH (2-12), temperature (50-100 °C), and salinity (10-100 g/L). Furthermore, the inoculation of S. marcescens ZCF25 with fracturing flowback fluids could significantly (P < 0.05) reduce the chemical oxygen demand, concentration of alkanes, and concentration of polycyclic aromatic hydrocarbons, with removal efficiencies of 48.9%, 65.57%, and 64%, respectively. This is the first study on the application of BS-producing S. marcescens to treat fracturing flowback fluids. S. marcescens ZCF25 is a promising candidate for use in various industrial and bioremediation applications. Graphical abstract.

Adsorption of As(V) from Aqueous Solution on Chitosan-Modified Diatomite.

A novel chitosan (CS)-modified diatomite (Dt) was prepared by a simple mixture in the mass ratio to remove As(Ⅴ) from aqueous solution in this research. The CS-modified Dt adsorbent was characterized by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and X-ray powder diffraction (XRD) analysis. The parameters to influence the adsorption of As(Ⅴ) ion were studied under such conditions as kinetics, adsorption isotherm, and pH effect. The results revealed that adsorption of As(Ⅴ) was initially rapid and the equilibrium time was reached after 40 min. The optimal value of the pH was 5.0 for better adsorption. The equilibrium data were well fitted to the Langmuir isotherm compared to the Freundlich isotherm, and exhibited the highest capacity and removal efficiency of 94.3% under an initial As(Ⅴ) concentration of 5 mg/L. The kinetic data were well described by the pseudo-second-order model. In addition, 0.1 M NaOH has the best desorption efficiency of As(V) adsorbed on CS-modified Dt, and the removal efficiency of As(V) was still higher than 90% when after six adsorption-desorption cycles. These results showed that the CS-modified Dt could be considered as a potential adsorbent for the removal of As(V) in aqueous solution.

Clostridium beihaiense sp. nov., an anaerobic bacterium isolated from activated sludge.

A Gram-positive, strictly anaerobic, rod-shaped bacterium, designated YB-7T, was isolated from activated sludge of an anaerobic baffled reactor pond in Weizhou terminal wastewater treatment plant, Beihai, Guangxi, China. Strain YB-7T grew at pH 5.0-12.0 (optimum, pH 7.0), 20-45 °C (37 °C) and NaCl concentration of 0-5 % w/v (optimum, 5 %). 16S rRNA gene sequence analysis results showed that strain YB-7T belonged to the genus Clostridium and it was most closely related to Clostridium tetanomorphum DSM 4474T (96.9 % similarity). The DNA-DNA relatedness of strain YB-7T to Clostridium tetanomorphum DSM 4474T was 47.4 %. The DNA G+C content of strain YB-7T was determined to be 32.3 mol%, and the predominant cellar fatty acid (>10 %) was C16 : 0. Polar lipids of strain YB-7T included diphosphatidylglycerol, phosphatidylethylethanolamine, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine, two unidentified aminophospholipids, two unidentified phospholipids and unidentified lipids. The results of this study supported the conclusion that strain YB-7T should be assigned to a new member of the genus Clostridium, for which the name Clostridium beihaiense sp. nov. is proposed. The type strain is YB-7T (=CICC 24109T=KCTC 15555T).

Effect of multilayer substrate configuration in horizontal subsurface flow constructed wetlands: assessment of treatment performance, biofilm development, and solids accumulation.

This study investigates the influence of multilayer substrate configuration in horizontal subsurface flow constructed wetlands (HSCWs) on their treatment performance, biofilm development, and solids accumulation. Three pilot-scale HSCWs were built to treat campus sewage and have been operational for 3 years. The HSCWs included monolayer (CW1), three-layer (CW3), and six-layer (CW6) substrate configurations with hydraulic conductivity of the substrate increasing from the surface to bottom in the multilayer CWs. It was demonstrated the pollutant removal performance after a 3-year operation improved in the multilayer HSCWs (49-80%) compared to the monolayer HSCW (29-41%). Simultaneously, the multilayer HSCWs exhibited significant features that prevented clogging compared to the monolayer configuration. The amount of accumulated solids was notably higher in the monolayer CW compared to multilayer CWs. Further, multilayer HSCWs could delay clogging by providing higher biofilm development for organics removal and consequently, lesser solids accumulations. Principal component analysis strongly supported the visualization of the performance patterns in the present study and showed that multilayer substrate configuration, season, and sampling locations significantly influenced biofilm growth and solids accumulation. Finally, the present study provided important information to support the improved multilayer configured HSCW implication in the future.

[Correlations Between Substrate Structure and Microbial Community in Subsurface Flow Constructed Wetlands].

To identify the microbial factors that cause the differences in the purification performance of constructed wetlands with different substrate structures, the relationship between the substrate structure and the microbial community composition in horizontal subsurface flow constructed wetlands (HSSFCWs) was studied by high throughput sequencing. The results revealed that the purification performance of a six-layer constructed wetland (CW6), of which the permeability coefficient gradually increased from the surface layer to the bottom layer, was the highest among the three constructed wetland systems. The average concentrations of COD, TN, NO3--N, and NH4+-N in the effluent were 39, 11, 0.35, and 4 mg·L-1, respectively. The monolayer structure constructed wetland (CW1) had the worst purifying efficiency, with average effluent concentrations of 95, 21, 0.60 and 12 mg·L-1 for COD, TN, NO3--N, and NH4+-N, respectively. The results of the high-throughput sequencing showed that the number of microbial OTUs in multilayer structure wetlands was slightly lower than that in the monolayer structure wetland, but the relative abundance of the dominant phylum Proteobacteria and the nitrifying and denitrifying bacteria in the genus was significantly higher than the monolayer structure wetland. The results of PCA and heatmap indicated that there were significant differences in the spatial distribution of microbes in the genus of Proteobacteria in CW3 and CW6, which facilitated the degradation of pollutants. No significant differences were found in the community structure of CW1.

Treatment of high-strength corn steep liquor using cultivated polyvinyl alcohol gel beads in an anaerobic fluidized-bed reactor.

Polyvinyl alcohol (PVA) gel beads cultivated in an upflow anaerobic sludge-blanket reactor treating synthetic corn steep liquor (CSL) wastewater were used to seed a lab-scale anaerobic fluidized-bed (AFB) reactor also treating CSL. Under steady-state conditions in the AFB reactor, a COD removal efficiency in excess of 96% was achieved at an organic loading rate (OLR) of 25 g/l/d with a hydraulic retention time (HRT) of 10 h. Furthermore, a removal efficiency of 91% was achieved at an OLR of 27.5 g/l/d with an HRT of only 6 h. With a biomass attachment 1.02 g VSS/g PVA-gel beads, the biomass concentration in the AFB reactor was approximately 610 g/l, while for natural granules only 100 g/l is considered possible. Over the study period, the granular PVA gel turned from black to gray while the biomass attached on the outer surface of the beads also changed in composition. In addition, observations of the interior of the gel beads showed that colonization had progressed well into the core, indicating that effective substrate diffusion occurred within the PVA-gel matrix under the good substrate-microorganism contact conditions provided by the AFB reactor.

Solubility and stability of barium arsenate and barium hydrogen arsenate at 25 degrees C.

The inconsistency among current thermodynamic data of Ba3(AsO4)2(c) and BaHAsO4.H2O(c) led the authors to obtain independent solubility data of barium arsenate by both precipitation and dissolution experiments. Low and neutral pH (3.63-7.43) favored the formation of BaHAsO4.H2O(c). Both BaHAsO4.H2Oc and Ba3(AsO4)2(c) formed at the neutral pH conditions (7.47, 7.66), whereas Ba3(AsO4)2(c) was the only solid phase precipitated at high pH (13.03, 13.10). The Ba3(AsO4)2(c) precipitate acquired at 50 degrees C appeared as small leafy crystal, while the Ba3(AsO4)2(c) solid precipitated at 25 degrees C comprised granular aggregate with some smaller crystal clusters. XRD and SEM analyses of Ba3(AsO4)2(c) and BaHAsO4.H2O(c) indicated that the solids were indistinguishable before and after the dissolution experiments. In the present work, the solubility products (Ksp) for Ba3(AsO4)2(c) and BaHAsO4.H2O(c) were determined to be 10(-23.53)(10(-23.01) to 10(-24.00)) and 10(-5.60)(10(-5.23) to 10(-5.89)), respectively. DeltaGf degrees for Ba3(AsO4)2(c) and BaHAsO4.H2O(c) were calculated to be -3113.40 and -1544.47 kJ/mol, respectively. There was no difference between the solubility products of the leafy and the granular Ba3(AsO4)2(c) solids.