Bioactivity and antimicrobial properties of chemically characterized compost teas from different green composts

Advanced application of tea residue extracts rich in polyphenols for enhancing sludge dewaterability: Unraveling the role of pH regulation

Tea polyphenols (TPs), as a kind of derivatives from tea waste, were employed as a novel environmentally friendly bio-based sludge conditioner in this study. The findings showed that when TPs were applied at a dosage of 300 mg g-1 DS, the sludge CST0/CST ratio significantly increased to 1.90. pH regulation was found to markedly affect the dewatering efficiency of sludge. At pH 4, the CST0/CST rose to 2.86, coupled with a reduction in the specific resistance to filtration (SRF) from 6.69 × 1013 m kg-1 to 1.43 × 1013 m kg-1 and a decrease in the moisture content (MC) from 90.57% to 68.75%. TPs formed complexes and precipitated sludge proteins, as demonstrated by changes in the extracellular polymeric substances (EPS), viscosity, zeta potential, and particles size distribution. The optimization significance of acidification treatment on sludge structure disintegration, the interaction of TPs with EPS, and the removal of sludge proteins were elucidated. The research provided an ideal approach for the integrated utilization of biomass resources from tea waste and highlighted the potential application of TPs as an environmentally friendly conditioner in sludge dewatering.

Seasonal studies of aquatic humic substances from Amazon rivers: characterization and interaction with Cu (II), Fe (II), and Al (III) using EEM-PARAFAC and 2D FTIR correlation analyses

Aquatic humic substances (AHS) are defined as an important components of organic matter, being composed as small molecules in a supramolecular structure and can interact with metallic ions, thereby altering the bioavailability of these species. To better understand this behavior, AHS were extracted and characterized from Negro River, located near Manaus city and Carú River, that is situated in Itacoatiara city, an area experiencing increasing anthropogenic actions; both were characterized as blackwater rivers. The AHS were characterized by 13C nuclear magnetic ressonance and thermochemolysis GC-MS to obtain structural characteristics. Interaction studies with Cu (II), Al (III), and Fe (III) were investigated using fluorescence spectroscopy applied to parallel factor analysis (PARAFAC) and two-dimensional correlation spectroscopy with Fourier transform infrared spectroscopy (2D-COS FTIR). The AHS from dry season had more aromatic fractions not derived from lignin and had higher content of alkyls moities from microbial sources and vegetal tissues of autochthonous origin, while AHS isolated in the rainy season showed more metals in its molecular architecture, lignin units, and polysacharide structures. The study showed that AHS composition from rainy season were able to interact with Al (III), Fe (III), and Cu (II). Two fluorescent components were identified as responsible for interaction: C1 (blue-shifted) and C2 (red-shifted). C1 showed higher complexation capacities but with lower complexation stability constants (KML ranged from 0.3 to 7.9 × 105) than C2 (KML ranged from 3.1 to 10.0 × 105). 2D-COS FTIR showed that the COO- and C-O in phenolic were the most important functional groups for interaction with studied metallic ions.

Lignin nanoparticles from hydrotropic fractionation of giant reed and eucalypt: Structural elucidation and antibacterial properties

A hydrotropic solution of maleic acid (MA) was exploited to fractionate giant reed (AD) and eucalypt (EUC). The pre-treatment was successful for AD, while it was unsatisfactory for EUC, likely due to unoptimized reaction conditions. Interestingly, lignin nanoparticles (LNP) were produced via spontaneous aggregation following spent liquor dilution. LNP were studied by a plethora of analytical techniques, such as thermogravimetry, electron microscopy, and Nuclear Magnetic Resonance spectroscopy (NMR). Notwithstanding LNP from both AD and EUC showed similar thermal behaviour and morphology, a greater content of aliphatic hydroxyl, carboxyl, guaiacyl and p-hydroxyphenyl moieties was reported for AD-LNP, whereas EUC-LNP had a larger amount of syringyl groups and a higher S/G ratio. Also, the 1H-DOSY NMR indicated the lower size of AD-LNP. Moreover, the LNP were found to negatively impact on the development of several human or plant pathogens, and their bioactivity was related to the occurrence of guaiacyl and p-hydroxyphenyl moieties and a lower the LNP size. We therefore found that MA delignification allows both to achieve high delignification efficiency and to obtain LNP with promising antibacterial effect. Such LNP may help counteracting the antibiotics resistance and sustain the quest for finding sustainable agrochemicals.

Biochar induces different responses of intracellular and extracellular antibiotic resistance genes and suppresses horizontal transfer during lincomycin fermentation dregs composting

This study aims to indicate the influence of biochar on extracellular and intracellular ARGs (e/iARGs) variation and proliferation during lincomycin fermentation dregs (LFDs) compost. Biochar addition made iARGs keep reducing but eARGs increase to the maximum at the middle thermophilic phase and reduce at the end of the compost. Compared to control 3.15-log and 5.42-log reduction of iARGs and eARGs were observed, respectively. Biochar addition, bacterial community, and MGEs were the major contributors to iARGs and eARGs removal, with the contribution percentages of 38.4%, 31.0%, 23.7%, and 27.2%, 29.1%, and 34.9%, respectively. Moreover, biochar significantly inhibited eARGs transformation and RP4 plasmid conjugative transfer among E. coli DH5α and Pseudomonas aeruginosa HLS-6. The underlying mechanism involved in broken cell membranes of bacteria, and altered expression of oxidative stress genes and save our souls (SOS) response-related genes. The results indicated that biochar addition in composting could limit the dissemination of ARGs.

Differential impacts of interactions between Serendipita indica, Chlorella vulgaris, Ulva lactuca and Padina pavonica on Basil (Ocimum basilicumL.)

Plant biostimulants (PBs) are used globally to increase crop yield and productivity. PBs such as (Serendipita indica) or algal extracts stimulate and accelerate plant physiological processes. The physiological, ecological, and biochemical effects of (Serendipita indica) or algal extracts individually and in combination on basil plant (Ocimum basilicum L.) were investigated. Macroalgae samples were collected from Abu Qir, Alexandria, Egypt. The growth parameters, chlorophyll index, and biochemical composition of basil were analyzed at 90th day. The (Chlorella vulgaris) + (Serendipita indica) (MI + F) treatment increased chlorophyll index by 61.7% (SPAD) compared to control. (Chlorella vulgaris) had the highest growth hormones, including GA3 at 158.2 ppb, GA4 at 149.1 ppb, GA7 at 142.6 ppb, IAA at 136.6 ppb, and TC at 130.9 ppb, while (Ulva lactuca) had the lowest. The MI + F treatment yielded the highest essential oil and antioxidant values. Treatment with (Chlorella vulgaris) increased S. indica colonization by 66%. In contrast, Ulva lactuca and (Padina Pavonica) inhibited S. indica colonization by 80% and 40%, respectively. (Ulva lactuca) and (Padina Pavonica) inhibited S. indica colonization by 80% and 40%, respectively. Combined treatments had a greater influence on basil performance than the individual treatments. The evidence of synergistic/additive benefits to plants performance due to the interactive effects of (Chlorella vulgaris) and (Serendipita indica) had been studied. Complementary modes of action between (Chlorella vulgaris) and (Serendipita indica), through their components newly emerging properties on basil, may explain observed synergistic effects. This study explores the potential of microbial-algal interactions, particularly (Chlorella vulgaris) and (Serendipita indica), as innovative plant biostimulants. These interactions demonstrate positive effects on basil growth, offering promise for more effective microbial-based formulations to enhance crop productivity and sustainability in agriculture. These novelties will help create a second generation of PBs with integrated and complementary actions.

Waste to Wealth Approach: Improved Antimicrobial Properties in Bioactive Hydrogels through Humic Substance-Gelatin Chemical Conjugation

Exploring opportunities for biowaste valorization, herein, humic substances (HS) were combined with gelatin, a hydrophilic biocompatible and bioavailable polymer, to obtain 3D hydrogels. Hybrid gels (Gel HS) were prepared at different HS contents, exploiting physical or chemical cross-linking, through 1-ethyl-(3-3-dimethylaminopropyl)carbodiimide (EDC) chemistry, between HS and gelatin. Physicochemical features were assessed through rheological measurements, X-ray diffraction, attenuated total reflectance (ATR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, and scanning electron microscopy (SEM). ATR and NMR spectroscopies suggested the formation of an amide bond between HS and Gel via EDC chemistry. In addition, antioxidant and antimicrobial features toward both Gram(-) and Gram(+) strains were evaluated. HS confers great antioxidant and widespread antibiotic performance to the whole gel. Furthermore, the chemical cross-linking affects the viscoelastic behavior, crystalline structures, water uptake, and functional performance and produces a marked improvement of biocide action.

Humic substances derived from unconventional resources: extraction, properties, environmental impacts, and prospects

Humic substances comprise up to 70% of the total organic matter in soils, between 50 and 80% of the dissolved organic matter in water, and about 25% of dissolved organic matter in groundwater. Elucidation of the complex structure and properties of humic substances requires advanced analytical tools; however, they are of fundamental importance in medicine, agriculture, technology, and the environment, at large. Although they are naturally occurring, significant efforts are now being directed into their extraction owing to their relevance in improving soil properties and other environmental applications. In the present review, the different fractions of humic substances were elucidated, underlying the mechanisms by which they function in soils. Furthermore, the extraction processes of humic substances from various feedstock were illustrated, with the alkali extraction technique being the most widely used. In addition, the functional group and elemental composition of humic substances were discussed. The similarities and/or variations in the properties of humic substances as influenced by the source and origin of feedstock were highlighted. Finally, the environmental impacts of humic substances were discussed while highlighting prospects of humic acid production. This review offers enormous potential in identifying these knowledge gaps while recommending the need for inter- and multidisciplinary studies in making extensive efforts toward the sustainable production of humic substances.

Effects of persulfate-assisted hydrothermal treatment of municipal sludge on aqueous phase characteristics and phytotoxicity

Hydrothermal technology (HT) has received much attention in recent years as a process to convert wet organic waste into hydrochar. The aqueous phase (HTAP) produced by this process is still a burden and has become a bottleneck issue for HT process development. In this study, we provide the first investigation of the HTAP characteristics, phytotoxicity, and their correlation with persulfate (PS) (PS, 2.0 mmol/g TS)-assisted municipal sludge HT. The results showed that PS accelerated the hydrolysis of protein substances and increased the concentration of NH₄⁺ by 13.4% to 190.5% and that of PO₄^3- by 24.2% to 1103.7% in HTAP at hydrothermal temperatures of 120 to 240 °C. PS can reduce the phytotoxicity of HTAP by reducing aldehydes, ketones, N heterocyclic compounds, and particle size and by increasing its humification index. The maximum values of the root length and biomass of pakchoi (Brassica chinensis L.) seedlings occurred when electrical conductivity was 0.2 mS/cm of HTAP. This work provided a new strategy for the selection and design of HTAP management strategies.

Use of Natural Agents and Agrifood Wastes for the Treatment of Skin Photoaging

Photoaging is the premature aging of the skin caused by repeated exposure to ultraviolet (UV) rays. The harmful effects of UV rays-from the sun or from artificial sources-alter normal skin structures and cause visible damage, especially in the most exposed areas. Fighting premature aging is one of the most important challenges of the medical landscape. Additionally, consumers are looking for care products that offer multiple benefits with reduced environmental and economic impact. The growing requests for bioactive compounds from aromatic plants for pharmaceutical and cosmetic applications have to find new sustainable methods to increase the effectiveness of new active formulations derived from eco-compatible technologies. The principle of sustainable practices and the circular economy favor the use of bioactive components derived from recycled biomass. The guidelines of the European Commission support the reuse of various types of organic biomass and organic waste, thus transforming waste management problems into economic opportunities. This review aims to elucidate the main mechanisms of photoaging and how these can be managed using natural renewable sources and specific bioactive derivatives, such as humic extracts from recycled organic biomass, as potential new actors in modern medicine.

Dissolved organic matter evolution can reflect the maturity of compost: Insight into common composting technology and material composition

Dissolved organic matter (DOM) can clearly reflect composting components changes, thus it is supposed to indicate the humification process during composting. To demonstrate this, three compost mixtures and two techniques were arranged. DOM evolution was detected by three spectral techniques. X-ray diffraction (XRD) showed that the crystal structure substances decreased gradually during the composting, including cellulose, struvite, sylvine, quartz, and calcite; Specifically, the struvite was found, which was conducive to the fixation of nitrogen and phosphorus. Fourier transform infrared spectroscopy (FTIR) and three-dimensional fluorescence spectroscopy (3D-EEM) further showed that pig manure-based mixtures, added cabbage, and windrow composting are beneficial to sugar, protein, fulvic acid, and soluble microbial by-products decompose and humic acids produce. This process was closely related to the change of physical-chemical parameters (temperature; pH; moisture content; and NH₄⁺-N content) and maturity index (C/N ratio, E₄/E₆ and GI). Therefore, DOM evolution could quickly reflect the maturity process of compost. In subsequent research, the quantitative analysis of DOM components can be considered to modify DOM spectral parameters, or to build a model, so as to achieve rapid evaluation of compost maturity.

Humic substances from composted fennel residues control the inflammation induced by Helicobacter pylori infection in AGS cells

Helicobacter pylori (H. pylori) is a common human pathogen causing inflammation. Recent studies have suggested a sophisticated interplay between mitochondria, innate immunity and inflammatory response, thus proposing mitochondrial disfunction as the hallmark of severe inflammatory disorders. In this study, humic substances isolated from composted fennel residues (HS-FEN) were tested as potential therapeutical strategy to restore the mitochondrial physiology and control the inflammation associated with H. pylori infection. The molecular features of HS-FEN were characterized by infrared spectrometry, thermochemolysis-GC/MS, NMR spectroscopy, and high-performance size-exclusion chromatography (HPSEC), which revealed the presence of aromatic polyphenolic components arranged in a rather stable conformation. In vitro results showed antioxidant and anti-inflammatory properties of HS-FEN, that was found to increase the expression level of OPA-1 and SOD-2 genes and in AGS cells stimulated with H. pylori culture filtrate (Hpcf) and concomitantly decrease the expression level of Drp-1 gene and IL-12, IL-17 and G-CSF proteins. The hydrophobic features of HS, their conformational arrangement and large content of bioactive molecules may explain the beneficial effects of HS-FEN, that may potentially become an interesting source of anti-inflammatory agents capable to counteract or prevent the H. pylori-related inflammatory disorders.

Quality Attributes of Sesame Butter (Tahini) Fortified with Lyophilized Powder of Edible Mushroom (Agaricus blazei)

Sesame butter (tahini) is a common appetizer and food additive in the Mediterranean basin. Pathogenic strains and mycotoxin content are the most hazardous issues in the final product. This investigation aimed to enhance the quality and safety properties of tahini products against microbial hazards and mycotoxins. Local samples of tahini were evaluated for natural contamination, including mycotoxin level determinations. Agaricus blazei was utilized as a bioactive source and evaluated for the bioactive content of laccase, B-glucan, antioxidant activity, and phenolic content, as well as antimicrobial and antioxidant potency. Two fortification ratios (0.5% and 1.0%) were chosen to apply Agaricus in tahini sesame as a model. Chemical composition, color attributes, sensory properties, emulsion, and oxidative stability were evaluated for the fortified samples versus the control. The results reflected increments of protein (22.91 ± 0.64% to 29.34 ± 0.96%), fiber content (3.09 ± 0.05% to 6.27 ± 0.06%), emulsion stability (84.9 ± 1.24% to 95.41 ± 0.56%), oxidative stability, and bioactive group content. The fortification process is reflected by the absence of Salmonella, Listeria, and E. coli bacteria from contaminated samples after 30 days of storage. The water activity for 1.0% fortification (0.154 ± 0.001) was recorded as lower than the control sample (0.192 ± 0.002). Moreover, the degradation of aflatoxins and zearalenone content was recorded during storage. The degradation ratio reached 68% and 97.2% for 0.5% and 1.0% fortifications, respectively, while zearalenone degradation recorded a decline of 26.7% and 33.7%, respectively, for the same fortification ratios. These results recommended 1.0% lyophilized mushroom fortification as a quality and ameliorative safety treatment for tahini products.

Distribution, horizontal transfer and influencing factors of antibiotic resistance genes and antimicrobial mechanism of compost tea

Compost tea was alternatives of chemical pesticide for green agriculture, but there were no reports about antibiotic resistance genes (ARGs) in compost tea. This study investigated the effect of livestock manures, sewage sludge, their composting products and liquid fermentation on ARGs, mobile genetic elements (MGEs), metal resistance genes (MRGs) and antimicrobial properties of various compost tea. The results showed aerobic liquid fermentation reduced ARGs by 65.93 % and 45.20 % in the compost tea of chicken manure and sludge, enriched ARGs by 8.57 % and 37.41 % in the compost tea of pig manure and bovine manure, and increased MGEs and MRGs by 1.25 × 10^-5-5.53 × 10^-3 and 2.03 × 10^-5-2.03 × 10^-3 in the four compost tea. The correlation coefficient of tetracycline and sulfonamide resistance genes between compost product and compost tea were 0.98 and 0.91. aadA2-02, sul2 and tetX abundant in the compost tea were positively correlated with MGEs and MRGs. Furthermore, liquid fermentation enriched the potential host of tetracycline and vancomycin resistance genes. Tetracycline resistance genes occupied 62.7 % of total ARGs in the compost tea. Alcaligenes and Bacillus enriched by 0.78-39.31 % in the four compost tea, which metabolites had high antimicrobial activity. The potential host of ARGs accounted for 42.1 % bacteria abundance in the four compost tea.

Recent trends and advances in composting and vermicomposting technologies: A review

Composting technologies have come a long way, developing from static heaps and windrow composting to smart, artificial intelligence-assisted reactor composting. While in previous years, much attention has been paid to identifying ideal organic waste streams and suitable co-composting candidates, more recent efforts tried to determine novel process-enhancing supplements. These include various single and mixed microbial cultures, additives, bulking agents, or combinations thereof. However, there is still ample need to fine-tune the composting process in order to reduce its impact on the environment and streamline it with circular economy goals. In this review, we highlight recent advances in integrating mathematical modelling, novel supplements, and reactor designs with (vermi-) composting practices and provide an outlook for future developments. These results should serve as reference point to target adjusting screws for process improvement and provide a guideline for waste management officials and stakeholders.

Effect of using mycotoxin-detoxifying agents in dairy cattle feed on natural whey starter biodiversity

Natural whey cultures (NWC) are undefined multiple-strain bacterial starter communities that can be affected by even small changes along the entire dairy chain. We applied a multidisciplinary approach to investigate how the addition of 2 mycotoxin-detoxifying agents [sodium smectite and lignocellulose-based material (B1); leonardite and betaine (B2)] to cow diets modified the microbiota of the NWC in manufacture of a Grana-like cheese. Microbiological and flow cytometry analyses showed that the content and viability of lactic acid bacteria (LAB) and the total whey microbiota were not affected by the detoxifying agents, and Streptococcus thermophilus, Lactobacillus helveticus, and Limosilactobacillus fermentum were the dominant taxa. Random amplified polymorphic DNA-PCR fingerprinting and metagenomic analysis highlighted differences in the bacterial community of the NWC and in the relative abundance of Bacteroidetes that increased when B1 and B2 were included in the diet. Two of 6 St. thermophilus biotypes were detected only in control samples; conversely, none of the Lb. helveticus biotypes found in control samples were isolated from B1 and B2. In vitro tests showed that the 2 binders did not significantly affect the development of St. thermophilus, but they stimulated the growth of Lb. helveticus strains recovered only from B1 and B2 NWC. The addition of binders in cow feed can affect the LAB biotypes present in NWC.

Valorization of lignins from energy crops and agro-industrial byproducts as antioxidant and antibacterial materials

BACKGROUND

Developing eco-friendly antioxidant and antimicrobial substances originating from biomass residues has recently attracted considerable interest. In this study, two lignosulfonates and various oxidized water-soluble lignins were investigated for their antioxidant properties, as assessed by ABTS, DPPH and Folin-Ciocalteu methods, and their antimicrobial activity against some bacterial strains responsible for human pathologies.

RESULTS

The lignosulfonates showed the largest antiradical/antimicrobial capacity, whereas the other substrates were less effective. The observed antioxidant/antibacterial properties were positively correlated with lignin aromatic/phenolic content. The positive correlation between antiradical and antimicrobial activities suggests that lignin scavenging capacity was also involved in its antibacterial activity. A greater antimicrobial performance was generally observed against Gram-positive bacterial strains, and it was attributed to the intrinsic larger susceptibility of Gram-positive bacteria to lignin phenols. A significant though lesser inhibitory activity was also found against Escherichia coli.

CONCLUSION

Our results confirmed the dependence of lignin antioxidant/antibacterial power on its extraction method and chemical structure, as well as on the type of bacterial strains. Identifying the relationship between lignin molecular composition and its antioxidant/antibacterial features represents an advance on the potential future use of renewable and eco-compatible lignin materials in nutraceutical, pharmaceutical and cosmetic sectors. © 2021 Society of Chemical Industry.

Antiflammatory activity and potential dermatological applications of characterized humic acids from a lignite and a green compost

Long-term exposure to air pollution has been associated with the development of some inflammatory processes related to skin. The goal of modern medicine is the development of new products with antiflammatory action deriving from natural sources to improve environmental and economic sustainability. In this study, two different humic acids (HA) were isolated from from lignite (HA-LIG) and composted artichoke wastes (HA-CYN) and characterized by infrared spectrometry, NMR spectroscopy, thermochemolysis-GC/MS, and high-performance size-exclusion chromatography (HPSEC), while their antiflammatory activity was evaluated on HaCaT cells. Spectroscopic results showing the predominance of apolar aliphatic and aromatic components in HA-LIG, whereas HA-CYN revealed a presence of polysaccharides and polyphenolic lignin residues. The HA application on human keratinocyte pre-treated with Urban Dust revealed a general increase of viability suggesting a protective effect of humic matter due to the content of aromatic, phenolic and lignin components. Conversely, the gene expression of IL-6 and IL-1β cytokines indicated a significant decrease after application of HA-LIG, thus exhibiting a greater antiflammatory power than HA-CYN. The specific combination of HA protective hydrophobic components, viable conformational arrangements, and content of bioactive molecules, suggests an innovative applicability of humic matter in dermatology as skin protectors from environmental irritants and as antiflammatory agents.

Selection of sensitive seeds for evaluation of compost maturity with the seed germination index

The seed germination index (GI) is a widely used indicator of compost maturity and is a required index in many national standards. However, seeds of different species vary markedly in sensitivity to the biological toxicity of compost. Therefore, suitable seed selection is essential for evaluation of compost maturity with the GI. This study systematically investigated the germination percentage and root length for seeds of 17 species incubated in deionized water for 48 h at 25 °C in the dark. Based on the germination percentage, seeds of eight species (white radish, cucumber, fruit radish, edible rape, round radish, hybrid cucumber, cress, and Chinese cabbage) were selected for determination of the GI of chicken manure composted with differing proportions of tobacco powder and mushroom substrate. The GI of hybrid cucumber seeds showed a significant positive correlation with temperature and pH, and a significant negative correlation with E₄/E₆ ratio and ammonium-nitrogen content. The change in GI of hybrid cucumber seeds during composting and the GI value at the completion of composting were consistent with other maturity indicators. Among the tested seeds, the biological toxicity of the compost was best characterized by hybrid cucumber seeds, which thus represented a sensitive and reliable seed suitable for evaluation of compost maturity with the GI.

Links between microbial compositions and metabolites during aerobic composting under amoxicillin stress was evaluated by 16S rRNA sequencing and gas chromatography-mass spectrometry: Benefit for the plant growth

The purpose of this study was to identify the relationship between core bacteria and metabolites during aerobic composting and analyze the effects of metabolites on plant growth. The results revealed that amoxicillin might affect the generation and transformation of metabolites by reconstructs the bacterial communities. The peak area ratios (PAR) of esters and fatty acids (FAs) were increased, while sterols decreased during composting. Furthermore, the correlation analysis showed that the production of FAs, esters and sterols is strongly correlated with Oceanobacillus, Corynebacterium, Psychrobacter, Xanthomonadaceae, Pusillimonas and Gracilibacillus. Moreover, 36 key metabolites were screened out, the PAR of the propanoic acid ethyl ester and oleic acid that benefit plant growth were increased in amoxicillin groups. However, the PAR of environmental pollutants, such as n-hexadecanoic acid and 3β, 5β-Cholestan-3-ol is the opposite. Therefore, composting can eliminate the environmental risks caused by antibiotic residues in feces and promote plant growth.

Significantly Enhancing the Lithium Ionic Conductivity of Metal-Organic Frameworks via a Postsynthetic Modification Strategy

Metal-organic frameworks (MOFs), due to their possessing a porous structure, are potential candidates for solid-state ionic conduction materials. Moreover, uncoordinated carboxylic acid groups (-COOH) of MOFs can be used as postsynthetic modification sites, which are favorable for lithium ion exchange. Herein, we synthesized a unique multiple carboxylic zinc metal-organic framework (Zn-MOF-COOH) containing uncoordinated carboxylic acid groups. Zn-MOF-COOLi was synthesized through deprotonation using LiOH via a straightforward acid-base reaction at room temperature (RT), thereby exhibiting better good electrochemical properties. The lithium ionic conductivity (σ) increased from 1.81 × 10^-5 to 1.65 × 10^-4 S·cm^-1, lithium ion transference number (t_Li⁺) rose from 0.67 to 0.77, and the electrochemical window improved from 2.0-5.5 to 1.5-6.5 V. This work offers a new strategy to improve the σ of MOFs and a new perspective toward manufacturing of high-performance solid-state ionic conduction materials.

Insights on Molecular Characteristics of Hydrochars by 13C-NMR and Off-Line TMAH-GC/MS and Assessment of Their Potential Use as Plant Growth Promoters

Hydrochar is a carbon-based material that can be used as soil amendment. Since the physical-chemical properties of hydrochar are mainly assigned to process parameters, we aimed at evaluating the organic fraction of different hydrochars through ¹³C-NMR and off-line TMAH-GC/MS. Four hydrochars produced with sugarcane bagasse, vinasse and sulfuric or phosphoric acids were analyzed to elucidate the main molecular features. Germination and initial growth of maize seedlings were assessed using hydrochar water-soluble fraction to evaluate their potential use as growth promoters. The hydrochars prepared with phosphoric acid showed larger amounts of bioavailable lignin-derived structures. Although no differences were shown about the percentage of maize seeds germination, the hydrochar produced with phosphoric acid promoted a better seedling growth. For this sample, the greatest relative percentage of benzene derivatives and phenolic compounds were associated to hormone-like effects, responsible for stimulating shoot and root elongation. The reactions parameters proved to be determinant for the organic composition of hydrochar, exerting a strict influence on molecular features and plant growth response.