Incubation Test Research Articles

Deep biosphere in the Main Dolomite (Upper Permian) hydrocarbon reservoir

This study focuses on evaluating microbial activity in Main Dolomite reservoir rocks (Zechstein, Wuchiapingian– Permian) at 100°C. Core samples from two wells, one potentially microbiologically active (C-1 well, 100°C) and the other considered inactive due to high temperature (L-1 well, 155.5°C), were analysed. The core from L-1, treated similarly to C-1, was used to control for contamination. Microbial experiments and molecular analyses were performed on both core samples to ensure accurate results unaffected by laboratory processing contamination. Microbial incubation tests were successfully employed to demonstrate microbial hydrocarbon degradation and methane formation from 13C-labelled acetate. A new method for staining microorganisms from rock samples was introduced to estimate biomass. The results indicated that microorganisms from the C-1 well exhibited both hydrocarbon biodegradation and acetoclastic methanogenesis during a 3-month incubation at 100°C. Fluorescence-stained and countable microorganisms were only observed in the C-1 samples, while no biodegradation or methanogenesis occurred in reference samples from L-1 well. The study provides valuable insights into microbial activities in extreme conditions, emphasizing the importance of proper controls and techniques to ensure accurate interpretation of results.

Variations in the level of available phosphorus with changes in the status of water-soluble organic matter derived from different organic materials in soil

The combined application of organic material and phosphorus fertilizer is an effective method to enhance phosphorus use efficiency for plant growth. This is partly because the presence of water-soluble organic matter (WSOM) derived from different organic materials can enhance the level of available phosphorus in the soil; however, it is poorly understood how this level varies with changes in the WSOM status (i.e., decomposed, dissolved, and retained) in the soil depending on WSOM types. This study aimed to (i) understand how changes in the WSOM status enhances the available phosphorus level in the soil, and (ii) determine the WSOM type that contributes to such enhancement. The incubation test showed that fractions of 73%–92% and 8%–27% of WSOM-derived organic carbon were retained and dissolved, respectively, at the beginning of incubation, while 31%–45% was decomposed during the incubation period. The WSOM derived from cattle manure compost (CM) and sewage sludge compost (SSC) that was initially retained was maintained until the late stage of the incubation test, whereas that derived from hydrothermal decomposed liquid fertilizer (HDLF) was rapidly desorbed during the first 14 days of the incubation period. The available phosphorus level was higher under the combined application of CM- and SSC-derived WSOM than under the single phosphorus application throughout the incubation period, while it was high only during the first 3 days of incubation under the application of HDLF-derived WSOM. The amounts of retained organic carbon at each sampling point during the incubation period compared to those at the beginning were positively and linearly correlated to the available phosphorus levels that were enhanced by the WSOM present in the soil. This study for the first time provides quantitative experimental evidence that 1) the longer the WSOM continues to be retained, the higher the amount of available phosphorus remaining in the soil, and 2) the available phosphorus level decreases with WSOM sorption or decomposition. Furthermore, it was shown that highly humified WSOM has a great potential for the maintenance of higher available phosphorus levels. This study provides the insight that a combined application of highly humified organic materials with a chemical fertilizer is necessary for not only cost effective but also sustainable fertilization design.

Polyethylene Glycol/Pullulan-Based Carrier for Silymarin Delivery and Its Potential in Biomedical Applications.

Restoring the structures and functions of tissues along with organs in human bodies is a topic gathering attention nowadays. These issues are widely discussed in the context of regenerative medicine. Excipients/delivery systems play a key role in this topic, guaranteeing a positive impact on the effectiveness of the drugs or therapeutic substances supplied. Advances in materials engineering, particularly in the development of hydrogel biomaterials, have influenced the idea of creating an innovative material that could serve as a carrier for active substances while ensuring biocompatibility and meeting all the stringent requirements imposed on medical materials. This work presents the preparation of a natural polymeric material based on pullulan modified with silymarin, which belongs to the group of flavonoids and derives from a plant called Silybum marianum. Under UV light, matrices with a previously prepared composition were crosslinked. Before proceeding to the next stage of the research, the purity of the composition of the matrices was checked using Fourier-transform infrared (FT-IR) spectroscopy. Incubation tests lasting 19 days were carried out using incubation fluids such as simulated body fluid (SBF), Ringer's solution, and artificial saliva. Changes in pH, electrolytic conductivity, and weight were observed and then used to determine the sorption capacity. During incubation, SBF proved to be the most stable fluid, with a pH level of 7.6-7.8. Sorption tests showed a high sorption capacity of samples incubated in both Ringer's solution and artificial saliva (approximately 350%) and SBF (approximately 300%). After incubation, the surface morphology was analyzed using an optical microscope for samples demonstrating the greatest changes over time. The active substance, silymarin, was released using a water bath, and then the antioxidant capacity was determined using the Folin-Ciocâlteu test. The tests carried out proved that the material produced is active and harmless, which was shown by the incubation analysis. The continuous release of the active ingredient increases the biological value of the biomaterial. The material requires further research, including a more detailed assessment of its balance; however, it demonstrates promising potential for further experiments.

Experimental verification of solubilization effect of soil bromine by waterlogging reduction

ABSTRACT Although the concentration of bromine in the Earth’s crust is only approximately 2 µg g−1, it is one of the most crucial elements in daily human life. On the Earth’s surface, bromine is thought to be widely transported and circulated in the hydrosphere, atmosphere, lithosphere, and biosphere. However, little is known regarding the dynamics of bromine in the terrestrial environments. In this study, waterlogging incubation tests were conducted on two soil types, Lowland soil and Andosol, to verify the solubilization effect of waterlogging on soil bromine. The amount of bromine in the soil extracts increased considerably with incubation time in Lowland soil and Andosol, proving that the soil reduction caused by waterlogging enhanced the solubilization of soil bromine. The amount of bromine solubilized by soil reduction tended to be higher in Andosols, which had a higher total bromine concentration than Lowland soil. The amount by soil reduction during the 28 days period ranged from 0.18 to 1.14 µg g−1 for the Lowland soil group and from 0.20 to 30.2 µg g−1 for the Andosol group. Solubilized bromine could not remain in the soil, and most of it leached out with the percolation water, as shown by the soil-filled column tests. To estimate the amount of bromine leached from a rice paddy field under waterlogged conditions, a percolation test was conducted using Wagner pot-cropped paddy rice plants. The results showed that 531 to 544 mg of bromine per square meter of soil surface leached during one growing season. The amount of bromine leached from the soil was much higher than the previously reported annual amount of bromine addition to land from atmospheric deposition.

Hydrocarbons, Hydrogen, and Organic Acids Generation by Ball Milling and Batch Incubation of Sedimentary Rocks

Pulverized rock samples are widely used in laboratory experiments, e.g., to assess microbial or abiotic processes in batch incubation tests. However, it is unclear if ball-milled samples accurately reflect in-situ conditions and if observed processes are affected by by-products artificially generated during the sample preparation procedure. As such, this study examined the effects of dry ball milling on the release of gases, which include C1-C4 hydrocarbons, carbon dioxide (CO2), hydrogen (H2), and low molecular weight organic acids (LMWOAs) from different sedimentary rocks. The experiments involved pulverization using a gas-tight zirconium oxide planetary ball mill followed by wet and dry batch incubation and thermal desorption up to 200 o C. During milling, all sedimentary rocks, except a low organic carbon sandstone sample, yielded methane (CH4), ethane (C2H6), propane (C3H8), butane (C4H10), H2, CO2, and unsaturated hydrocarbons, e.g., ethene (C2H4). Sandstones only yielded H2, CH4, and CO2. Stable carbon isotope signatures of these products are similar to thermogenic gases. The gases were also detected in subsequent wet incubation experiments (after gases from milling had been removed). Additionally, formate, acetate, and citrate, were detected in all samples except for sandstone. Pyruvate, malate, and succinate were also detected in some samples. Thermal desorption products of powdered limestone, shale, and pyrite concretion samples included organic acids, such as acetate and formate, which were higher in milled samples than in crushed particles (∼1 mm). The original geological thermal maturity of the studied sedimentary rock samples was low (below “oil window”) and, thus, considerably below “gas window”, suggesting that most of the detected gases were generated during ball milling. H2 generated during ball milling may be derived from the reduction of water from fluid inclusion or phyllosilicates, involving the formation of reactive mineral surfaces or radicals. Notably, the concentrations of gaseous hydrocarbons derived from milling are relatively high and comparable to “wet” gases. At the same time, these data indicate that substantial amounts of gases and LWMOAs might be artificially generated during laboratory batch experiments with milled samples. Hence, ball milled rock samples must be used with caution if assessing (bio-)geochemical processes for natural environments.

Agronomic potential of different fermented organic composts based on agro-industrial plant waste.

Organic composts such as "bokashi", obtained from the fermentation of bran mixtures and inoculated with microorganisms, improve soil characteristics. In Brazil, the most widely used formulation for the production of this compost is obtained from a mixture of wheat and castor bean bran, but both have a high monetary cost. Replacing these components with regionally available sources represents the possibility of reducing costs and making more sustainable use of this waste. The aim of this study was to analyze the chemical characteristics and determine the availability of nitrogen for the plants. The study was divided into two stages, consisting of an incubation test in the laboratory and a bioassay in the greenhouse using forage sorghum as an indicator species. In the laboratory trial, the treatments consisted of two raw material sources with a low C/N ratio (castor bean bran-CAB and cottonseed bran-COB), corresponding to 40% of the mixture; three sources with a high C/N ratio (wheat bran-WHB or rice bran-RIB), gradually replaced by passion fruit peel bran-PFPB), corresponding to 60% of the mixture. The materials were mixed, moistened, inoculated with microorganisms (Embiotic®) and kept in sealed containers with a capacity of 620 cm3 for 21days. In the greenhouse, in addition to the aforementioned treatments, seven controls were included: no addition of organic and synthetic N sources; ammonium nitrate; CAB; COB; WHB; RIB and PFPB. In the second stage, dry mass production and N content in sorghum plant tissues were determined, and the rates of N availability were estimated. It was found that the pH of the standard compost was 4.75, and in the other formulations it ranged from 4.62 to 5.3, the highest values being observed when WHB was fully replaced by RIB There was a significant difference in the EC values, but all were well below the value considered adequate. Replacing CAB with COB and WHB with RIB and PFPB resulted in a reduction in N content and an increase in the C:N ratio. Replacing WHB with PFPB led to an increase in K content and a reduction in P and Mg content. In the bioassay, the highest biomass production was in the treatments with the fermented composts, and the highest biological recovery of N was obtained in the ammonium nitrate treatment, followed by the CAB, COB and WHB treatments.

Hg2+ removal characteristics of a strain of mercury-tolerant bacteria screened from heavy metal-contaminated soil in a molybdenum-lead mining area.

In this study, the mercury-tolerant strain LTC105 was isolated from a contaminated soil sample collected from a molybdenum-lead mine in Luanchuan County, Henan Province, China. The strain was shown to be highly resistant to mercury, with a minimum inhibitory concentration (MIC) of 32 mg·L-1. After a 24-h incubation in LB medium with 10 mg·L-1 Hg2+, the removal, adsorption, and volatilization rates of Hg2+ were 97.37%, 7.3%, and 90.07%, respectively, indicating that the strain had significant influence on mercury removal. Based on the results of Fourier infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), the investigation revealed that the primary function of LTC105 was to encourage the volatilization of mercury. The LTC105 strain also showed strong tolerance to heavy metals such as Mn2+, Zn2+, and Pb2+. According to the results of the soil incubation test, the total mercury removal rate of the LTC105 inoculation increased by 16.34% when the initial mercury concentration of the soil was 100 mg·L-1 and by 62.28% when the initial mercury concentration of the soil was 50 mg·kg-1. These findings indicate that LTC105 has certain bioremediation ability for Hg-contaminated soil and is a suitable candidate strain for microbial remediation of heavy metal-contaminated soil in mining areas.

FaERF2 activates two β-1,3-glucanase genes to enhance strawberry resistance to Botrytis cinerea

Ethylene response factor (ERF) is a class of plant-specific transcription factors that play an important role in plant growth, development, and stress response. However, the underlying mechanism of strawberry ERFs in pathogenic responses against Botrytis cinerea (B. cinerea) remains largely unclear. In this study, we isolated FaERF2, a nucleus-localized ERF transcription factor from Fragaria x ananassa. Transiently overexpressing FaERF2 in strawberry fruits significantly enhances their resistant ability to B. cinerea, while silencing FaERF2 in strawberry fruits enhances their susceptibility to B. cinerea. In addition, we found that FaERF2 could directly bind to the cis-acting element GCC box in the promoters of two β-1,3-glucanase genes, FaBG-1 and FaBG-2, and activate their expression. Finally, both strawberry fruits transient expression followed by B. cinerea inoculation assays and recombinant protein incubation tests collectively substantiated the inhibitory effect of FaBG-1 and FaBG-2 on B. cinerea mycelium growth. These results revealed the molecular regulation mechanism of FaERF2 in response to B. cinerea and laid foundations for creating disease-resistance strawberry cultivar through genome editing approach.

An efficient and scalable melt fiber spinning system to improve enzyme-based PET recycling

Chemical recycling technologies based on hydrolase enzymes that can depolymerize PET thermoplastic are emerging, yet these approaches require the polymer to be low crystallinity to achieve high conversion. To prepare the polymer for enzymatic depolymerization, current processes rely on melting and cryomilling PET at depressed temperatures to reduce crystallinity and prevent annealing during micronization; however, these approaches require large capital investment in costly equipment, and are not easily incorporated into intermediate-scale, distributed systems. Here, we describe a melt fiber spinning system that achieves significant reduction in crystallinity for real-world PET feedstocks without the need for any active cooling, and can easily be scaled up or down as needed. Single-use water bottles and drinking cups are tested, where they are extruded, drawn and spooled as thin fibers that cool by passive heat dissipation rapidly enough to quench the polymer to low crystallinity (<10%). Additionally, we estimate the fiber spinning also increases the feedstock surface-area-to-volume ratio by up to 15-fold, which further benefits heterogenous enzyme biocatalysis. In small scale PET hydrolase enzyme incubation tests, fiber spinning increased monomer released from PET by 4-fold for drinking cups and 10-fold for water bottles compared to shredded-only controls. Finally, we also show that this system can scale to >300 gs, with the potential for much larger scales, and allows for >95% depolymerization in a larger 20 liter bioreactor run.

Detection and quantification of aflatoxins in farmers’ stored rice seeds in some selected areas of Bangladesh

Detection and quantification of total aflatoxins in farmers’ stored rice seeds at different storage intervals in two cropping seasons (Boro 2017–2018: cv. BRRI Dhan28 and cv. BRRI Dhan29 and Aman 2017: cv. BR 11 and cv. BRRI dhan49) was focused in this study. Aflatoxin was quantified in two cropping seasons (Boro and Aman). Blotter incubation test was conducted for fungal prevalence assessment and a one-step lateral flow immune-chromatographic assay was used to quantify the aflatoxins. Seed moisture content ranged from 11.59 to 13.32% and aflatoxin concentrations ranged from 2.41 to 11.12 ppb. Variation in fungal contamination in stored seeds was correlated with seed moisture content. The moisture content in stored rice seeds increased with storage time and was positively correlated with fungal infestation and toxin production. The findings of this study indicate that moisture content of stored rice seeds and storage duration are determining factors for aflatoxin contamination.

Soil microorganisms play an important role in the detrimental impact of biodegradable microplastics on plants

Biodegradable plastics were developed to mitigate environmental pollution caused by conventional plastics. Research indicates that biodegradable microplastics still have effects on plants and microorganisms as their non-biodegradable counterparts, yet the effects on vegetable crops are not well-documented. Additionally, the function of soil microorganisms affected by biodegradable microplastics on the fate of microplastics remains unverified. In this study, Brassica chinensis was cultivated in soil previously incubated for one year with low-density polyethylene (LDPE-MPs) and poly (butylene adipate-co-terephthalate) microplastics (PBAT-MPs) at 0.05 % and 2 % concentrations. High concentrations of PBAT-MPs significantly reduced the biomass to 5.83 % of the control. The abundance of Methyloversatilis, IS-44, and UTCFX1 in the rhizosphere bacterial community increased significantly in the presence of PBAT-MPs. Moreover, these microplastics significantly enhanced soil enzyme activity. Incubation tests were performed with three PBAT plastic sheets to assess the function of the altered bacterial community in the soil of control (Control-soil) and soil treated with high concentrations of PBAT-MPs (PBAT-MPs-soil). Scanning Electron Microscopy and Atomic Transfer Microscopy (SEM/ATM) results confirmed enhanced PBAT degradation in the PBAT-MPs-soil. PICRUST2 analysis revealed that pathways related to substance degradation were upregulated in the PBAT-MPs-soil. Furthermore, a higher percentage of strains with PBAT-MPs-degrading ability was found in PBAT-MPs-soil. Our results confirm that PBAT-MPs significantly inhibit the growth of vegetable crops and that soil bacterial communities affected by PBAT-MPs are instrumental in degrading them.

Retention time and organic loading rate as anaerobic co-digestion key-factors for better digestate valorization practices: C and N dynamics in soils

The growing use of anaerobic co-digestion (AcoD) in processing organic waste has led to a significant digestate production. To effectively recycle digestate back into soils, it is crucial to understand how operational variables in the AcoD process influence the conversion of organic matter (OM). To address this, a combination of biochemical fractionation and various soil incubation tests were employed to assess the stability of OM in digestates generated from anaerobic continuous reactors fed with a food waste-hay mixture and operating at different hydraulic retention times (HRT) and organic loading rates (OLR). This study revealed that digester performance and operating parameters impacted carbon dynamics in soils. A decrease in the carbon mineralization in soils when increasing the HRT was reported (48 ± 4 % for 70 days compared to 59 ± 1 % for 42 days). Specific HRT and OLR values were found to be linked to carbon accessibility and complexity, confirming that longer HRT lead to higher OM removal and increased complexity in soluble OM, despite minor discrepancies in relative carbon distribution. Furthermore, comparable rates of nitrogen mineralization in soils were observed for all digestates, consistent with the accessibility of nitrogen from the particulate OM. Nevertheless, AcoD converted substrates with the potential to immobilize nitrogen in soils into fast-acting fertilizers. In summary, this study underscores the importance of controlling the AcoD performances to evaluate the suitability of digestates for sustainable agricultural practices.

Linking metabolomics to machine learning reveals the metabolic fates of the refractory industrial pollutant 1-Hexadecene

In order to solve the low removal efficiency of 1-Hexadecene in industrial wastewater treatment plants and fill the knowledge gap of its microbial metabolic mechanisms, this work studied the 1-Hexadecene degrading microorganisms enrichment and its metabolic pathway using continuous bioreactors and batch incubation tests. With the successful enrichment of hexadecene-degrading microorganisms, the biodegradation rates of 1-Hexadecene at 50–200 mg/L could range from 58.6 % to 72.5 %. The 16S rRNA fragment and microbial community analysis identified Flavihumibacter, Gemmatimonas, and Caulobacter as putative 1-Hexadecene degraders. Through mass spectrum qualification analysis, Principal component analysis and orthogonal partial least squares discriminant analysis, totally 81 featured metabolites associated with 1-Hexadecene biogradation were screened out. The machine learning based support vector machines and random forests further identified 18 biomarkers during those featured metabolites. Based on the coupling metabolomics analysis with machine learning, three potential metabolic pathways with Heptane, 2,5-dimethyl hexane, 3-ethyl-3-methyl-heptane as the respective end products were proposed through biomarkers. These results provide new insights for the analysis of metabolic pathway of 1-Hexadecene, and theoretical support for the bioaugmentation of its treatment processes.

Fast-dissolving calcium carbonate particles as a high-performance lime for amelioration of agricultural acidic soils

Effective soil management is essential for maximizing crop yields, as soil fertility plays a pivotal role in this process. Unfortunately, liming and fertilization practices are frequently ineffective, leading to overdoses and unnecessary product waste. Liming is essential for correcting soil acidity, mitigating aluminum toxicity, and promoting nutrient bioavailability before fertilizer application. This study explores the potential of vaterite, a highly soluble CaCO3 polymorph, as a sustainable liming agent. Vaterite particle synthesis is challenging because of its poor stability and rapid phase transformation into calcite, therefore, we analyze the effects of precursor concentration, Ca2+/CO32- ratio, and stirring rate on vaterite morphology and content in a reactive precipitation process through screening and D-optimal experimental designs, resulting in a design space to tailor the conditions that promote vaterite particles with a high dissolution profile at the lowest possible cost. To assess the efficacy of fast-dissolving CaCO3 particles, a comparative incubation test was conducted in andisol-type soil with a high buffering capacity. The results demonstrated that vaterite particles were capable of quickly adjusting the soil pH in the first few days using 360% fewer conventional liming agents. This innovative strategy aligns with Precision Agriculture principles, enabling efficient crop production while minimizing the environmental impact.

Cadmium immobilization in soil using phosphate modified biochar derived from wheat straw

The phosphate-modified biochar (BC) immobilizes cadmium (Cd), yet little is known about how phosphate species affect Cd detoxification in contaminated soils. We developed phosphate-modified biochar through the pyrolysis of wheat straw impregnated with three types of phosphate: mono‑potassium phosphate (MKP), dipotassium hydrogen phosphate (DKP), and tripotassium phosphate (TKP). The Cd adsorption mechanism of modified biochar was investigated by biochar characterization, adsorption performance evaluation, and soil incubation tests. The results demonstrated that the efficiency of biochar in immobilizing Cd2+ followed the order: TKP-BC > DKP-BC > MKP-BC. The TKP-BC had the highest orthophosphate content, the fastest adsorption rate, and the largest adsorption capacity (Langmuir) of 257.28 mg/g, which is 6.31 times higher than that of the unmodified BC (CK). In contrast, pyrophosphate was predominant in MKP-BC and DKP-BC. The primary adsorption mechanism for Cd2+ was precipitation, followed by cation exchange, as evidenced by the formation of CdP minerals on the BC surface, and an increase of K+ in solution (compared to water-soluble K+) and a decrease of K+ in the biochar during adsorption. Desorption of Cd from the TKP-BC after adsorption was 9.77 %–12.39 % at a pH of 5–9, much lower than that of CK. The soil incubation test showed the diethylenetriaminepentaacetic acid extracted Cd of TKP-BC, MKP-BC, and DKP-BC was reduced by 67.93 %, 18.41 % and 31.30 % over CK, respectively. Using the planar optodes technique, we also found that TKP-BC had the longest effect enhancing in situ soil pH. This study provides a theoretical basis for developing heavy metal pollution control technology using green remediation materials and offers insights into the remediation mechanisms.

Hybrid Coatings Based on Polyvinylpyrrolidone/Polyethylene Glycol Enriched with Collagen and Hydroxyapatite: Incubation Studies and Evaluation of Mechanical and Physiochemical Properties.

Coating materials offers an intriguing solution for imparting inert implants with additional bioactive characteristics without changing underlying parameters such as mechanical strength. Metallic implants like endoprostheses or polymeric implants can be coated with a thin layer of bioactive film capable of stimulating bone-forming cells to proliferate or release a drug. However, irrespective of the final implantation site of such a coating biomaterial, it is necessary to conduct detailed mechanical and physicochemical in vitro analyses to determine its likely behavior under biological conditions. In this study, polymeric and composite coatings with hydroxyapatite obtained under UV light underwent incubation tests in four different artificial biological fluids: simulated body fluid (SBF), artificial saliva, Ringer's fluid, and water (as the reference fluid). The potentiometric and conductometric properties, sorption capacity, and degradation rate of the coatings were examined. Furthermore, their hardness, modulus of elasticity, and deformation were determined. It was demonstrated that the coatings remained stable in SBF liquid at a pH value of around 7.4. In artificial saliva, the greatest degradation of the polymer matrix (ranging between 36.19% and 39.79%) and chipping of hydroxyapatite in the composite coatings were observed. Additionally, the effect of ceramics on sorption capacity was determined, with lower capacity noted with higher HA additions. Moreover, the evaluation of surface morphology supported by elemental microanalysis confirmed the appearance of new apatite layers on the surface as a result of incubation in SBF. Ceramics also influenced mechanical aspects, increasing hardness and modulus of elasticity. For the polymer coatings, the value was 11.48 ± 0.61, while for the composite coating with 15% ceramics, it increased more than eightfold to a value of 93.31 ± 11.18 N/mm2. Based on the conducted studies, the effect of ceramics on the physicochemical as well as mechanical properties of the materials was determined, and their behavior in various biological fluids was evaluated. However, further studies, especially cytotoxicity analyses, are required to determine the potential use of the coatings as biomaterials.

Effect of dry-wet alternation on the adsorption of dissolved organic matter by soil minerals

Dry-wet alternation has an essential effect on soil minerals' adsorption of dissolved organic matter. In this study, kaolin, illite, and hematite were subjected to 0, 1, 3, and 6 dry-wet alternation incubation tests, respectively, and the changes in the characterization of the three minerals were explored by using a BET specific surface area analyzer and an X-ray diffractometer. The effects of different dry-wet alternation treatments on the adsorption of tannic acid and glucose as the representatives of dissolved organic matter were investigated by isothermal and kinetic adsorption tests as well as by different model-fitting methods. The effects of different dry-wet alternation treatments on the adsorption of tannic acid and glucose by the three minerals were investigated by isothermal and kinetic adsorption tests and different model fitting methods. The results showed that alternating dry-wet treatment could change the three minerals' specific surface area and average pore diameter to different degrees. Still, the spacing of the crystal layers did not change significantly. The dry-wet alternation did not alter the adsorption process and tannic acid and glucose adsorption mode. Still, it affected the equilibrium adsorption amount to different degrees, which was illite&gt;hematite&gt;kaolin, and the intensity of the effect was mainly affected by the decrease of the specific surface area of the minerals, which was not related to the change of the average pore diameter and the spacing of the crystal layers.

Iron oxyhydroxide catalyzes production of artificial humic substances from waste biomass

Production of artificial humic substances (AHS) from waste biomass will contribute to environmental protection and agricultural productivity. However, there is still a lack of a faster, more efficient and eco-friendly way for sustainable production. In this study, we proposed a method to accelerate the production of AHS from cotton stalks by mild pyrolysis and H2O2 oxidation in only 4 hours, and investigated the formation of AHS during biomass transformation. We found that the process increased the aromatic matrix and facilitated biomass transformation by enhancing the depolymerization of lignin into micromolecular phenolics (e.g., guaiacol, p-ethyl guaiacol, etc.). The optimum conditions of pyrolysis at 250 °C and oxidation with 6 mL H2O2 (5 wt%) yielded up to 19.28 ± 1.30 wt% artificial humic acid (AHA) from cotton stalks. In addition, we used iron oxyhydroxide (FeOOH) to catalyze biomass transformation and investigated the effect of FeOOH on the composition and properties of AHS. 1.5 wt% FeOOH promoted the increased content of artificial fulvic acid (AFA) in AHS from 10.1% to 26.5%, eventually improving the activity of AHS. FeOOH raised the content of oxygen-containing groups, such as carboxylic acids and aldehyde, and significantly increased polysaccharide (10.94%–18.95%) and protein (1.95%–2.18%) derivatives. Polymerization of amino acid analogs and many small-molecule carbohydrates (e.g., furans, aldehydes, ketones, and their derivatives) promoted AFA formation. Finally, carbon flow analysis and maize incubation tests confirmed that AHS were expected to achieve carbon emission reductions and reduce environmental pollution from fertilizers. This study provides a sustainable strategy for the accelerated production of AHS, which has important application value for waste biomass resource utilization.

Experimental investigation of mold growth risk among typical residential indoor materials: Case study in coastal city, China

Mold growth poses significant threats to building structures and occupant health, particularly in regions with high air humidity. Existing mold prediction models involve fewer categories of building materials and are less reliable in predicting complex real environments. This research investigated mold growth risk of ten typical residential indoor materials. Firstly, this work carried out meticulous sampling in a residential building, followed by incubation tests in a controlled mold incubator, and evaluated by the mold growth index. The results revealed varying degrees of mold growth risk among different materials at different relative humidity (RH) levels. Paints exhibited a generally low susceptibility to mold contamination, while panels and wallcovering displayed a higher risk of mold growth. Under high humidity, mold growth was observed in the panels on the first day of inoculation. Conversely, 25 % of the latex paints did not reach index 1 at the end of the experiment. The results showed that below 75 % RH at 25 °C was a safe area for all experimental materials. Moreover, experimental results indicated that a lag approximately one-week in the appearance of mold was observed when the RH was reduced by 10 %. However, the final mold growth index did not differ by more than one grade after the test cycle.

Nanocrystalline iron hydroxide lignocellulose filters for arsenate remediation.

Harmful levels of environmental contaminants, such as arsenic (As), persist readily in the environment, threatening safe drinking water supplies in many parts of the world. In this paper, we present a straightforward and cost-effective filtration technology for the removal of arsenate from potable water. Biocomposite filters comprised of nanocrystalline iron oxides or oxyhydroxides mineralized within lignocellulose scaffolds constitute a promising low cost, low-tech avenue for the removal of these contaminants. Two types of iron oxide mineral phases, 2-line ferrihydrite (Fh) and magnetite (Mt), were synthesized within highly porous balsa wood using an environmentally benign modification process and studied in view of their effective removal of As from contaminated water. The mineral deposition pattern, minerology, as well as crystallinity, were assessed using scanning electron microscopy, transmission electron microscopy, micro-computed X-ray tomography, confocal Raman microscopy, infrared spectroscopy, and X-ray powder diffraction. Our results indicate a preferential distribution of the Fh mineral phase within the micro-porous cell wall and radial parenchyma cells of rays, while Mt is formed primarily at the cell wall/lumen interface of vessels and fibers. Water samples of known As concentrations were subjected to composite filters in batch incubation and gravity-driven flow-through adsorption tests. Eluents were analyzed using microwave plasma optical emission spectroscopy (MP-AES) and inductively coupled plasma mass spectrometry (ICP-MS). By subjecting the filters to a flow of contaminated water, the time for As uptake was reduced to minutes rather than hours, while immobilizing the same amount of As. The retention of As within the composite filter was further confirmed through energy-dispersive X-ray mappings. Apart from addressing dangerously high levels of arsenate in potable water, these versatile iron oxide lignocellulosic filters harbor tremendous potential for addressing current and emerging environmental contaminants that are known to adsorb on iron oxide mineral phases, such as phosphate, polycyclic aromatic hydrocarbons or heavy metals.