Pilot-scale field studies on activated microbial remediation of petroleum-contaminated soil.

Soil contamination by petroleum, including crude oil from various sources, is increasingly becoming a pressing global environmental concern, necessitating the exploration of innovative and sustainable remediation strategies. The present field-scale study developed a simple, cost-effective microbial remediation process for treating petroleum-contaminated soil. The soil treatment involves adding microbial activators to stimulate indigenous petroleum-degrading microorganisms, thereby enhancing the total petroleum hydrocarbons (TPH) degradation rate. The formulated microbial activator provided a growth-enhancing complex of nitrogen and phosphorus, trace elements, growth factors, biosurfactants, and soil pH regulators. The field trials, involving two 500 m3 soil samples with the initial TPH content of 5.01% and 2.15%, were reduced to 0.41% and 0.02% in 50 days, respectively, reaching the national standard for cultivated land category II. The treatment period was notably shorter than the commonly used composting and bioaugmentation methods (typically from 8 to 12 weeks). The results indicated that the activator could stimulate the functional microorganisms in the soil and reduce the phytotoxicity of the contaminated soil. After 40 days of treatment, the germination rate of rye seeds increased from 20 to 90%, indicating that the microbial activator could be effectively used for rapid on-site remediation of oil-contaminated soils.

Microbial enhanced oil recovery (MEOR): recent development and future perspectives.

After conventional oil recovery operations, more than half of the crude oil still remains in a form, which is difficult to extract. Therefore, exploring and developing new enhanced oil recovery (EOR) technologies have always been priority research in oilfield development. Microbial enhanced oil recovery (MEOR) is a promising tertiary oil recovery technology that has received widespread attention from the global oil industry in recent years due to its environmental friendliness, simplicity of operation, and cost-effectiveness. This review presents the: principle, characteristics, classification, recent development, and applications of MEOR technology. Based on hundreds of field trials conducted worldwide, the microbial strains, nutrient systems, and actual effects used in these technologies are summarized, with an emphasis on the achievements made in the development and application of MEOR in China in recent years. These technical classifications involve: microbial huff and puff recovery (MHPR), microbial flooding recovery (MFR), microbial selective plugging recovery (MSPR), and microbial wax removal and control (MWRC). Most of them have achieved good results, with a success rate of approximately 80%. These successful cases have accumulated into rich experiential indications for the popularization and application of MEOR technology, but there are still important yet uncertain factors that hinder the industrialization of this technology. Finally, based on the extensive research and development of MEOR by the authors, especially in both laboratory and industrial large scales, the main challenges and future perspectives of the industrial application for MEOR are presented.

Water compatible supramolecular polymers: recent progress.

Water compatible supramolecular polymers (WCSPs) combine aqueous compatibility with the reversibility and environmental responsiveness of supramolecular polymers. WCSPs have seen application across a number of fields, including stimuli-responsive materials, healable materials, and drug delivery, and are attracting increasing attention from the design, synthesis, and materials perspectives. In this review, we summarize the chemistry of WCSPs from 2016 to mid-2021. For the sake of discussion, we divide WCSPs into five categories based on the core supramolecular approaches at play, namely hydrogen-bonding arrays, electrostatic interactions, large π-conjugated subunits, host-guest interactions, and peptide-based systems, respectively. We discuss both synthesis and polymer structure, as well as the underlying design expectations. The goal of this overview is to deepen our understanding of the strategies that have been exploited to prepare WCSPs, as well as their properties and uses. Thus, a section devoted to potential applications is included in this review.

Characteristics and Environmental Response of White Secondary Mineral Precipitate in the Acid Mine Drainage From Jinduicheng Mine, Shaanxi, China.

The study focuses on the white secondary mineral precipitate and its environmental response formed in acid mine drainage (AMD) at Jinduicheng Mine (Shaanxi, China). The mineral composition of white precipitate was characterized by Scanning electron microscopy-energy dispersive spectrometer (SEM-EDS), X-ray photoelectron spectroscopy (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), Inductively coupled plasma-atomic emission spectrometer (ICP-AES), chemical quantitative calculation and PHREEQC software. The white precipitate was a kind of amorphous crystal with the characteristics of a fine powder, and its main elements were O, Al, S, F, OH- and SO42- groups. Moreover, by comparing the mole number of chemical elements, the main mineral composition of the white precipitate was closest to basaluminite. The geochemical simulation result of the PHREEQC software verified that the white precipitate was basaluminite. According to the analysis of water quality characteristics of water samples, basaluminite can reduce the ions content in the AMD and enrich Cu, Ni, Mo, Cr and F ions, showing an excellent self-purification capacity of the water body. These results are helpful to improve the understanding of secondary mineral and its environmental response, and are of great significance for the environmental protection and sustainable development of mining area.

Adsorption Performance and Mechanism of Synthetic Schwertmannite to Remove Low-Concentration Fluorine in Water.

Fluorine (F) in water has a negative effect on the environment and human health. Schwertmannite has potential remediation to contamination in solution. In this study, the adsorption mechanism and influencing factors of synthetic schwertmannite for low-concentration F were studied through batch experiments. The results suggested that the adsorption of F by schwertmannite reached equilibrium after about 60 min, and the adsorption efficiency exceeded 94%. The experimental data can be best-fit by the pseudo-second-order kinetic and Langmuir models well. Schwertmannite showed effective adsorption at pH 4, dosage 1.5 g L-1, low temperature, and low concentration of co-existing anion. The adsorption process was a spontaneous and exothermic reaction, which was dominated by chemical adsorption. FT-IR and XPS spectra analysis revealed that F adsorption on schwertmannite through the surface complexation and anion exchange reaction between SO42- and OH- with F-, especially the primary role of OH-. The results can provide theoretical support for the schwertmannite application in the treatment of F-containing wastewater.

NH4+-N/NO3--N ratio controlling nitrogen transformation accompanied with NO2--N accumulation in the oxic-anoxic transition zone.

Although nitrogen (N) transformations have been widely studied under oxic or anoxic condition, few studies have been carried out to analyze the transformation accompanied with NO2--N accumulation. Particularly, the control of mixed N species in N-transformation remains unclear in an oxic-anoxic transition zone (OATZ), a unique and ubiquitous redox environment. To bridge the gap, in this study, OATZ microcosms were simulated by surface water and sediments of a shallow lake. The N-transformation processes and rates at different NH4+-N/NO3--N ratios, and NO2--N accumulations in these processes were evaluated. N-transformation process exhibited a turning point. Simultaneous nitrification and denitrification occurred in its early stage (first 10 days, dissolved oxygen (DO) ≥ 2 mg/L) and then denitrification dominated (after 10 days, DO < 2 mg/L), which were not greatly affected by the NH4+-N/NO3--N ratio, on the contrary, the transformation rates of NH4+-N and NO3--N were distinctly affected. The NH4+-N transformation rates were positively correlated with the NH4+-N/NO3--N ratio. The highest NO3--N transformation rate was observed at an NH4+-N/NO3--N ratio of 1:1 with organic carbon/NO3--N of 3.09. The NO2--N accumulation, which increased with the decrease in NH4+-N/NO3--N ratio, was also controlled by organic carbon concentration and type. The peak concentration of NO2--N accumulation occurred only when the NO3--N transformation rate was particularly low. Thus, NO2--N accumulation may be reduced by adjusting the control parameters related to N and organic carbon sources, which enhances the theoretical insights for N-polluted aquatic ecosystem bioremediation.

Batch Adsorption and Column Leaching Studies of Aniline in Chinese Loess Under Different Hydrochemical Conditions.

Through batch adsorption and column leaching experiments, this study aimed to investigate the adsorption and transport behavior of aniline in loess and related mechanism under different hydrochemical conditions. Batch experiments results indicated that aniline adsorption reached equilibrium after about 120 min, and the adsorption fitted the pseudo-second-order kinetic and Freundlich models well. The adsorption was spontaneous and exothermic process, indicating the aniline adsorbed by inherent colloidal particles (ICPs) tended to transport. Low pH value, ionic strength and temperature benefitted the adsorption. Column experiments results under different ionic strengths (100, 10 and 1 mM) confirmed the potential transport of aniline. The FT-IR spectra have further suggested that aniline was adsorbed by the ICPs through hydrogen-bond, hydrophobic effect and cation exchange interactions. Low ionic strength was advantageous for the adsorption of aniline in loess and the stabilities of ICPs in solution, but enhanced the co-transport probability of ICPs with aniline in loess.

Batch Adsorption and Column Transport Studies of 2,4,6-Trinitrotoluene in Chinese Loess.

In present study, batch and column tests were conducted to investigate the kinetic and thermodynamic characteristics of the adsorption and transport of 2,4,6-trinitrotoluene (TNT) in Chinese loess with specific focus on the role of inherent colloid particles. Batch tests showed that a lot of TNT was absorbed in suspended colloid particles, and its adsorption reached equilibrium after about 10 h, the adsorption process can be best-fit by the pseudo-second order kinetic and Freundlich model. The adsorption was spontaneous, endothermic process, implying the adsorbed TNT is likely to release from soil matrix. These portend that the adsorbed TNT has a potential to co-transport with inherent colloid particles in loess. The column tests identified the potential, and showed TNT transport had obvious retardation effect, which may be ascribed to the release and transport of inherent colloidal particles as a key carrier. These findings are helpful to evaluate the loess interception and antifouling performance.

Photoinduced [3 + 2] Cycloadditions of Aryl Cyclopropyl Ketones with Alkynes and Alkenes.

The five-membered ring skeleton is one of the most pivotal in the area of pharmaceutical and natural products. [3 + 2] cycloadditions of cyclopropyl and unsaturated compounds are a highly efficient and atom-economical way to build a five-member compound. The previous works about the kind of [3 + 2] cycloadditions usually utilized metal or organic small molecule catalysts. However, an ideal [3 + 2] cycloaddition reaction that smoothly happens without any additives and catalysts under mild conditions is underdeveloped. Hence, we report [3 + 2] cycloadditions of aryl cyclopropyl without any additives and catalysts under purple LED. In this method, a broad scope of cyclopropyl, alkyne, and alkene was very compatible, especially drug derivatives ibuprofen and Ioxoprofen, to obtain the corresponding cycloaddition product with a good yield up to 93%.

Iron-Catalyzed Csp2-Csp3 Cross-Coupling via Double Decarboxylation: One Step Synthesis of Remote Polar Alkenes.

Herein, we report an efficient photoinduced iron-catalyzed strategy for cross-couplings of alkyl carboxylic and acrylic acids, which provides a powerful tool for the synthesis of a variety of alkenes with polar functional groups. This novel synthetic methodology can also be applied to the preparation of ketones by using α-keto acids. Mechanistic experiments revealed preliminary mechanistic details. Diverse functionalization could be achieved, which may help streamline the synthesis of complex analogues for drug discovery.

In-situ noncovalent interaction of ammonium ion enabled C-H bond functionalization of polyethylene glycols.

The noncovalent interactions of ammonium ion with multidentate oxygen-based host has never been reported as a reacting center in catalytic reactions. In this work, we report a reactivity enhancement process enabled by non-covalent interaction of ammonium ion, achieving the C-H functionalization of polyethylene glycols with acrylates by utilizing photoinduced co-catalysis of iridium and quinuclidine. A broad scope of alkenes can be tolerated without observing significant degradation. Moreover, this cyano-free condition respectively allows the incorporation of bioactive molecules and the PEGylation of dithiothreitol-treated bovine serum albumin, showing great potentials in drug delivery and protein modification. DFT calculations disclose that the formed α-carbon radical adjacent to oxygen-atom is reduced directly by iridium before acrylate addition. And preliminary mechanistic experiments reveal that the noncovalent interaction of PEG chain with the formed quinuclidinium species plays a unique role as a catalytic site by facilitating the proton transfer and ultimately enabling the transformation efficiently.

Brønsted acid-catalyzed decarboxylative redox amination: formation of N-alkylindoles from azomethine ylides by isomerization.

A Brønsted acid-catalyzed decarboxylative redox amination involving aldehydes with 2-carboxyindoline for the synthesis of N-alkylindoles is described. The decarboxylative condensations of aldehydes with 2-carboxyindoline produce azomethine ylides in situ, which then transform into N-alkylindoles by isomerization.

Nitrogen species control the interaction between NO3--N reduction and aniline degradation and microbial community structure in the oxic-anoxic transition zone.

Contrary to the fact that NO3--N can serve as electron acceptor to promote organics degradation, it was also found NO3--N reduction does not necessarily promote organics degradation. We speculate nitrogen (N) species may control the interaction between NO3--N reduction and organics degradation via shifting related microbial community structure. To prove the hypothesis, oxic-anoxic transition zone (OATZ) microcosms simulated by lake water and sediment were conducted with the addition of N species (NO3--N, NO2--N, and NH4+-N) and aniline as typical organics. High-throughput sequencing was used to analyze the microbial community structure and functional enzyme in the microcosms. Results show that, NO2--N inhibited NO3--N reduction while enhanced aniline degradation. For NH4+-N, it promoted NO3--N reduction when NH4+-N/NO3--N concentration ratio ≤ 2 and inhibited aniline degradation when NH4+-N/aniline concentration ratio ≥ 0.5. The presence of NO2--N or NH4+-N weakened the interaction between NO3--N reduction and aniline degradation, which might be caused by significant changes in the diversity and abundance of microbial communities controlled by N species. The microbial mechanism indicates that NO2--N weakened the interaction by affecting both denitrification enzyme activity and electron transfer capability, while NH4+-N weakened the interaction mainly by affecting electron transfer capability. These results imply that N species, as well as other electron acceptors and donors, in the contaminated OATZ should be fully considered, when performing in situ remediation technology of NO3--N reduction.

Dissolved oxygen disturbs nitrate transformation by modifying microbial community, co-occurrence networks, and functional genes during aerobic-anoxic transition.

No consensus has been achieved among researchers on the effect of dissolved oxygen (DO) on nitrate (NO3--N) transformation and the microbial community, especially during aerobic-anoxic transition. To supplement this knowledge, NO3--N transformation, microbial communities, co-occurrence networks, and functional genes were investigated during aerobic-anoxic transition via microcosm simulation. NO3--N transformation rate in the early stage (DO ≥2 mg/L) was always significantly higher than that in the later stage (DO <2 mg/L) during aerobic-anoxic transition, and NO2--N accumulation was more significant during the anoxic stage, consistent with the result obtained under constant DO conditions. These NO3--N transformation characteristics were not affected by other environmental factors, indicating the important role of DO in NO3--N transformation during aerobic-anoxic transition. Changes in DO provoked significant alterations in microbial diversity and abundance of functional bacteria dominated by Massilia, Bacillus, and Pseudomonas, leading to the variation in NO3--N transformation. Co-occurrence network analysis revealed that NO3--N transformation was performed by the interactions between functional bacteria including symbiotic and competitive relationship. In the presence of oxygen, these interactions accelerated the NO3--N transformation rate, and bacterial metabolization proceeded via increasingly varied pathways including aerobic and anoxic respiration, which was demonstrated through predicted genes. The higher relative abundance of genes narG, narH, and napA suggested the occurrence of coupled aerobic-anoxic denitrification in the early stage. NO3--N transformation rate decreased accompanied by a significant NO2--N accumulation with the weakening of coupled aerobic-anoxic denitrification during aerobic-anoxic transition. Structural equation modeling further demonstrated the relationship between DO and NO3--N transformation. DO affects NO3--N transformation by modifying microbial community, bacterial co-occurrence, and functional genes during aerobic-anoxic transition.

Ligand-free copper-catalyzed C(sp3)-H imidation of aromatic and aliphatic methyl sulfides with N-fluorobenzenesulfonimide.

A novel and efficient process has been developed for copper-catalyzed C(sp3)-H direct imidation of methyl sulfides with N-fluorobenzenesulfonimide(NFSI). Without using any ligands, various methyl sulfides including aromatic and aliphatic methyl sulfides, can be transformed to the corresponding N-((phenylthio)methyl)-benzenesulfonamide derivatives in good to excellent yields.

Concise synthesis of α-cyano tetrahydroisoquinolines with a quaternary center via Strecker reaction.

A concise synthesis of α-cyano tetrahydroisoquinolines with a quaternary center via the Strecker reaction was successfully realized by employing TMSCN as cyano source and KF as fluoride source, furnishing the products with up to 99% yield. An isomerization of α-cyano tetrahydroisoquinoline was observed under alkaline conditions to give the isomer via [1,3]-H shift.

Synthesis of α,α-Disulfenylated Aldehydes via Oxidative Transformation of Tertiary Amines.

A method for the copper-catalyzed regioselective ß-functionalization of tertiary amines with thiophenols has been developed. The control experiments and primary studies show that a thiyl radical is involved in the reaction, and the method provides a novel and direct approach to synthesize C(sp(3))-S bonds without a directing group under ligand-free conditions.

Copper-mediated S-N formation via an oxygen-activated radical process: a new synthesis method for sulfonamides.

Copper-mediated direct S-N formation using readily available starting materials via an oxygen-activated radical process has been developed. This method provides a novel and direct approach for synthesis of sulfonamides under air conditions.

Copper-catalyzed direct amidation of heterocycles with N-fluorobenzenesulfonimide.

A highly efficient amidation reaction of heterocycles with N-fluorobenzenesulfonimide (NFSI) has been developed, presumably proceeding via C-H bond activation. Cuprous iodide was employed as the catalyst, and various α-amidated heterocycle derivatives have been generated in good to excellent yields. This chemistry endowed an economic method of synthesis of valuable amidated heterocycles through a direct C-N bond-coupling processes.