Addition Of NH4NO3 Research Articles

Differential responses of soil phosphorus fractions to varied nitrogen compound additions in a meadow steppe

Nitrogen (N) addition can greatly influence soil inorganic phosphorus (Pi) and organic phosphorus (Po) transformations. However, whether and how the N compound forms may differentially affect the soil P fractions remain unclear. Here, we investigated the responses of soil Pi (labile Pi, moderately-occluded Pi, and recalcitrant Pi) and Po fractions (labile Po and stable Po) to varying addition rates of three N compounds ((NH4)2SO4, NH4NO3, and urea) in a meadow steppe in northern China. Our studies revealed that with increasing N addition rate, soil labile and moderately-occluded Pi increased, accompanied by decreases in soil recalcitrant Pi. This shift was attributed to N-induced soil acidification, which accelerated the conversion of recalcitrant Pi into labile and moderately-occluded Pi. Soil labile Po decreased with increasing rate of N addition, whilst soil stable Po was not affected. Regardless of the compound forms, N addition increased soil Olsen-P, suggesting a potential alleviation of P limitation in this grassland ecosystem. The effect of N addition on soil labile Pi was significantly greater with addition of urea than with addition of either (NH4)2SO4 or NH4NO3, indicating that urea was more efficient in enhancing soil P availability. Addition of (NH4)2SO4 imposed a more pronounced positive effect on soil moderately-occluded Pi than the addition of either NH4NO3 or urea, mainly due to the greater mobilization of recalcitrant Pi as a result of higher soil acidification strength of (NH4)2SO4. These findings underscore the importance of considering the distinct effects of different N compounds when studying grassland soil P dynamics and availability in response to N addition.

Appropriate Supply of Ammonium Nitrogen and Ammonium Nitrate Reduces Cadmium Content in Rice Seedlings by Inhibiting Cadmium Uptake and Transport

Reasonable nitrogen (N) application is a promising strategy for reducing crop cadmium (Cd) toxicity. However, the specific form of N and the required amount that affect Cd tolerance and accumulation in rice remain unclear. This study explored the influence of different N-fertilizer forms (NH4NO3, NH4Cl, and KNO3) and dosages on Cd tolerance and uptake in Cd-stressed N-sensitive and N-insensitive indica rice accessions. The results indicated that the Cd tolerance of N-sensitive indica accessions is more robust than that of N-insensitive ones. Furthermore, the shoot Cd content and Cd translocation rate in both N-sensitive and N-insensitive indica accessions decreased with an appropriate supply of NH4NO3 and NH4Cl, whereas they were comparable or slightly increased with increased KNO3. Unfortunately, we did not find significant and regular differences in Cd accumulation or translocation between N-sensitive and N-insensitive rice accessions. Consistent with the reduction of shoot Cd content, the addition of NH4NO3 and NH4Cl also inhibited the instantaneous root Cd2+ uptake. The expression changes of Cd transport-related genes under different N forms and dosages suggested that the decreased shoot Cd content, caused by the increased supply of NH4NO3 and NH4Cl, is likely achieved by reducing the transcription of OsNRAMP1 and OsIRT1. In summary, our findings reveal that an appropriate supply of NH4NO3 and NH4Cl could reduce Cd uptake and transport in rice seedlings, suggesting that rational N management could reduce the Cd risk in rice production.

CeFeO3-CeO2-Fe2O3 Systems: Synthesis by Solution Combustion Method and Catalytic Performance in CO2 Hydrogenation.

Rare-earth orthoferrites have found wide application in thermocatalytic reduction-oxidation processes. Much less attention has been paid, however, to the production of CeFeO3, as well as to the study of its physicochemical and catalytic properties, in particular, in the promising process of CO2 utilization by hydrogenation to CO and hydrocarbons. This study presents the results of a study on the synthesis of CeFeO3 by solution combustion synthesis (SCS) using various fuels, fuel-to-oxidizer ratios, and additives. The SCS products were characterized by XRD, FTIR, N2-physisorption, SEM, DTA-TGA, and H2-TPR. It has been established that glycine provides the best yield of CeFeO3, while the addition of NH4NO3 promotes an increase in the amount of CeFeO3 by 7-12 wt%. In addition, the synthesis of CeFeO3 with the participation of NH4NO3 makes it possible to surpass the activity of the CeO2-Fe2O3 system at low temperatures (300-400 °C), as well as to increase selectivity to hydrocarbons. The observed effects are due to the increased gas evolution and ejection of reactive FeOx nanoparticles on the surface of crystallites, and an increase in the surface defects. CeFeO3 obtained in this study allows for achieving higher CO2 conversion compared to LaFeO3 at 600 °C.

Experimental investigation on the decomposition of NH4HSO4 over V2O5-WO3/TiO2 catalyst by NH4NO3 at low temperature

Deactivation by NH4HSO4 deposition is one of the major problems faced by commercial SCR catalysts at low temperatures. In this study, NH4NO3 was added to the SCR reaction atmosphere in the presence of H2O and SO2 at 250 °C, which is lower than the typical temperatures suitable for the V2O5-WO3/TiO2 catalyst. After a long test, the catalyst activity decreased from 82 % to 75 %, which is much smaller than the activity drop in the atmosphere without NH4NO3. The characterization results indicate that the addition of NH4NO3 effectively reduced the deposition of NH4HSO4 on the catalyst surface, thus weakening the degree of catalyst poisoning deactivation. In addition, we examined the effect of NH4NO3 addition on the regeneration of catalysts deactivated by NH4HSO4. The activity of the catalyst deactivated by 5 wt% NH4HSO4 recovered efficiently after the deactivated catalyst was treated by NH4NO3, NO and O2 for 1 h at 250 °C. The SEM, FTIR, and BET characterization results reveal the positive effect of NH4NO3 in promoting the decomposition of NH4HSO4.

Effects of oxidizing additives on the physical properties and ignition performance of hydrogen peroxide-based hypergolic propellants

Herein, the concept of novel hypergolic pairs for the enhanced ignition performance of hypergolic propellants is proposed. The proposed hypergolic combinations comprised ionic liquid fuels, namely, 1-ethyl-3-methyl-imidazolium-thiocyanate (EMIM SCN) and 1-butyl-3-methyl-imidazolium-thiocyanate (BMIM SCN), and hydrogen peroxide (H2O2) with oxidizing additives. LiNO3 and NH4NO3 were used as oxidizing additives, which were dissolved in 60–95 wt% H2O2 to enhance the physical properties and ignition performance. Adding the oxidizing additives decreased the theoretical performance of the hypergolic pairs, however, the presence of oxidizing additives drastically reduced the freezing point of the mixture with 95 wt% H2O2. Particularly, an abrupt change was observed in the freezing point of the mixture with the LiNO3 additive. At only 5 wt% LiNO3, the freezing point reached −30 °C. The ignition performance of the novel hypergolic pairs was significantly enhanced by the introduction of oxidizing additives. In the drop test, the LiNO3 additive exerted a substantially greater effect on the enhancement of ignition performance than that exerted by NH4NO3. Furthermore, this positive contribution was maximized with the decrease in the hydrogen peroxide concentration. Although the addition of NH4NO3 to 90 and 95 wt% H2O2 adversely affected the ignition performance, the combination of BMIM SCN and 60 wt% H2O2–containing LiNO3 extended the hypergolicity limit. This study is the first attempt to introduce nitrate salts as oxidizing additives in hydrogen peroxide with ionic fuels, including SCN anions. Nitrate salts exhibit potential to serve as additives that can be used with hydrogen peroxide to enhance the properties of oxidizers. The nitrate salt usage helps lower the freezing point of oxidizers. Further, it shortens the ignition delay time of the hypergolic pairs.

Effects of nitrogen addition and warming on nematode ecological indices: A meta-analysis

Nematodes occupy vital positions in soil food webs and are sensitive to environmental disturbances. Although soil nematode ecological indices are useful indicators of soil environmental conditions and processes, the overall effects of nitrogen addition and warming on nematode ecological indices are unclear. We conducted a meta-analysis to understand how nematode ecological indices are affected by experimental treatments: nitrogen addition and warming. The results showed that nitrogen addition significantly reduced the maturity index (MI) by 7% and the structure index (SI) by 11% but significantly increased the plant-parasitic index (PPI) by 1%. Warming reduced the channel index (CI) by 35% but did not significantly affect the other ecological indices. The effects of nitrogen addition and warming on ecological indices depended on the experimental system (ecosystem, duration, and methods) and environmental factors (mean annual temperature, precipitation, and latitude). The ecological indices were affected more by long-term than by short-term experiments. The MI consistently decreased when NH4+ or urea was added. The addition of NH4NO3 significantly increased the PPI by 1%. The response of ecological indices to nitrogen addition and warming varied among ecosystems. For example, the decrease in SI was significant only in cropland under N addition. The PPI was significantly decreased in forests under warming conditions. In addition, a high level of warming (≥2 °C) increased the MI by 10%. This synthesis increases our understanding of the effects of climate change on the soil environment and ecosystem functions.

The response of soil respiration to different N compounds addition in a saline–alkaline grassland of northern China

AbstractThe increase in atmospheric nitrogen (N) deposition has profound effects on soil respiration (SR). However, the responses of SR to the addition of different N compounds, particularly in saline–alkaline grasslands remain unclear. A 3-year controlled field experiment was conducted to investigate the responses of SR to different N compounds (NH4NO3, (NH4)2SO4 and NH4HCO3) during the growing seasons in a saline–alkaline grassland located in the agro-pastoral ecotone of northern China. Our results demonstrated that SR showed a bimodal pattern and a significant interannual difference that was regulated by air or soil temperature and precipitation. Nitrogen addition had a significant effect on SR, and the effect of N addition on SR varied yearly, which was related to seasonal precipitation. The mean SR across 3 years (2017–2019) was increased by 19.9%, 13.0% and 16.6% with the addition of NH4NO3, (NH4)2SO4 and NH4HCO3, respectively. The highest effect of NH4NO3 addition on SR across 3 years was ascribed to the highest aboveground net primary production, belowground net primary production (BNPP) and soil NO3− concentrations. SR (C loss) was significantly increased while plant productivity (C input) did not significantly change under NH4HCO3 addition, indicating a decrease in C sequestration. In addition, BNPP was the main direct factor influencing SR in this saline–alkaline grassland, and soil salinization (e.g. soil base cations and pH) indirectly affected SR through soil microorganisms. Notably, NH4NO3 addition overestimated the response of SR to N addition, and different N compounds should be considered, especially in saline–alkaline grassland.

Solventless synthesis of ZIF-L and ZIF-8 with hydraulic press and high temperature

In recent years, alternative methods to conventional synthesis of MOFs (metal-organic frameworks) have emerged due to the problematic use of solvents for both the environment and human health. Here we present the synthesis of ZIFs (zeolitic imidazolate frameworks) at high pressure by means of a hydraulic press provided with a heating mechanism. By the optimization of parameters such as temperature, time and the addition of promotor NH4NO3, a considerable increase in the reaction yield was achieved in products, neither washed nor activated, obtained since the first minute of reaction. Depending on the operation conditions, ZIF-L appeared as competing phase with ZIF-8. Upon transformation of ZIF-L into ZIF-8 in presence of ethanol, a reaction yield of 58.2% was achieved to highly crystalline ZIF-8 with a BET specific surface area of 947 m2/g. This green, fast, versatile and improved method suggests a possible way to future synthesis of other MOFs and the possibility of their industrial implementation.

Polymeric surfactant micelle structure modulated by ionic liquids

The very low volatility, high thermal and chemical stability, and broad range of intermolecular interactions that many ionic liquids (ILs) exhibit render them promising as solvents or additives in diverse applications. We are interested in the self-assembly in ionic liquids of amphiphiles, in particular those of the poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) block polymer family, commercially available as Poloxamers or Pluronics. We consider here aqueous solutions of a relatively hydrophobic PEO-PPO-PEO block copolymer (Pluronic P123, EO20PO70EO20) with the representative ionic liquids ethylammonium nitrate (EAN) (protic IL) or 1-butyl-3-methylimidazolium tetrafluoroborate (BmimBF4) (aprotic IL). We further compare the effects of ionic liquid electrolytes to those of the classic electrolyte ammonium nitrate (NH4NO3). We report on the block copolymer micelle structure ascertained from analysis of small-angle neutron scattering (SANS) data, and discuss the observed IL effects in the context of the underlying intermolecular interactions. Opposite effects on micelle structure are observed upon addition of EAN or NH4NO3 compared to BmimBF4: an increase in the micelle core radius and association number, and a decrease in the micelle shell thickness indicating dehydration upon addition of EAN or NH4NO3; a decrease in the micelle core radius and association number, and an increase in the shell thickness indicating increased solvation upon addition of BmimBF4. A temperature increase leads to similar effects on the micelle structure as the addition of the kosmotropic electrolytes EAN and NH4NO3. This study for the first time reports PEO-PPO-PEO micelle structure in IL-water mixtures, and utilizes it to proxy the operating intermolecular interactions and the role that ILs play in the self-assembly process.

Interactions of cationic surfactant cetyl-trimethyl ammonium bromide with ammonium nitrate: Surface and thermodynamic studies

The study of interactions between surfactant and salt in aqueous solutions has attracted significant interest in recent years because of their widespread applications and relatively complex behavior. This work reports the systematic study of surface phenomenon and self-aggregation behavior of cationic surfactant cetyltrimethyl ammonium bromide (CTAB) with ammonium nitrate (NH4NO3) salt. Surface and thermodynamic properties of cationic surfactant CTAB with NH4NO3 were investigated at different temperatures using different techniques such as conductometry and surface tensiometery. The surface tension measurement was carried out to find out the critical micelle concentration, free energy of adsorption, free energy of micellization, minimum area per molecule, and surface excess concentration. The study reveals that the process of micellization is spontaneous and exothermic in nature. Conductance measurement was carried out to determine critical micelle concentration, degree of ionization and degree of counter ion binding. Addition of NH4NO3 to the surfactant solutions increase the values of degree of ionization and degree of counter ion binding, although it lowers the values of critical micelle concentration showing that the process of micellization is more favorable and spontaneous. The study is very helpful to develop better understanding about interaction between electrolyte and surfactant, which are used in many applications and in different processes (e.g., pharmaceutical, industrial foaming, drug solubilization, oil recovery, and medium for metal nanoparticle formation).

Regulation by the Pitcher Plant Sarracenia purpurea of the Structure of its Inquiline Food Web

Phytotelmata, the water-filled habitats in pitcher plants, bromeliad tanks, and tree-holes, host multitrophic food webs that are model experimental systems for studying food-web structure and dynamics. However, the plant usually is considered simply as an inert container, not as an interacting part of the food web. We used a manipulative field experiment with a response-surface design to determine effects of nutrient enrichment (multiple levels of NH4NO3, PO4, and captured prey), top predators (removed or present), and the plant itself (with or without plastic tubes inserted into the pitchers to isolate the food web from the plant) on the macrobial food web within the modified leaves (“pitchers”) of the carnivorous pitcher plant Sarracenia purpurea. Connection to the plant, addition of NH4NO3, and removal of the top predator significantly increased the food web's saturation, defined as its trophic depth and number of interactions. No effects on food-web saturation resulted from addition of PO4 or supplemental prey. Plants such as S. purpurea that create phytotelmata are more than inert containers and their inhabitants are more than commensal inquilines. Rather, both the plant and the inquilines are partners in a complex network of interactions.

Electrochemical Deposition of Pd/Ag for Electrocatalytic Applications

Palladium-based alloys play an important role in many industrial applications, e.g. for the production and conversion of hydrogen (1). Palladium based catalysts show high reactivity both for the oxygen reduction reaction (ORR) and alcohol oxidation reaction respectively. One of the major drawbacks related to the hydrogen permeability in Pd is the blistering of Pd films at high concentrations of hydrogen. One effective method against this problem is to stabilize the Pd by alloying it (2). In general, alloys are promising materials because many of their chemical and electronic properties can be varied in a systematic way by changing the composition (1,2).Pd/Ag alloys can act as selective hydrogenation catalysts. Furthermore, they are also used in electrical contacts. The alloys with the composition Ag0.23Pd0.77 are important with regard to hydrogen diffusion and these alloys are employed industrially as a H2 purification membranes. Pd/Ag nanoparticles also show promising applications as a novel activator for electroless copper deposition.This paper will present the electrodeposition of Pd/Ag layers from different electrolytes with different complexing agents onto brass, mild steel, gold and glassy carbon (GC) substrates, in order to determine the optimum conditions and the parameters for the deposition of alloys with a tailored composition. Cyclic voltammetry was carried out in sulfuric acid containing methanol to determine the electrocatalytic activities of the deposited Pd/Ag structures. Further characterizations were performed using SEM coupled with EDX and XRF, in order to investigate morphologies and compositions of the alloys. Shiny deposits with a globular morphology and good adhesion were obtained. The ratio of Pd/Ag ion concentration in different electrolytes proved to be very important for the quality of the deposits. The addition of NH4NO3 improved the ionic conductivity of the bath, but it also acted as a complexing agent for Pd2+ and Ag2+. Without its addition, the Ag/Pd deposits will tend to grow in the form of dendrites and sheet crystals.The Pd/Ag deposits showed good electrocatalytic activity for the oxidation of methanol. That would render them promising candidates as anode materials in direct methanol fuel cells.(1) Y. Xiao, B. Weng, G. Yu, J. Wang, B. Hu and Z. Chen, J. Appl. Electrochem. 36 (2006) 807-812.(2) B. Sturzenegger and J. Cl. Puippe, Platinum Metals Rev. 28 (1984) 117-124.

The effect of biochar and nutrients on efficiency of anthracene remediation in soil by <i>Bacillus subtilis</i> and <i>Streptomyces sp</i>

Bioremediation has been found as an effective way to remove PAHs contaminants. Biochar and nutrients as effective factors can raise removal percent. The effect of these two factors was investigated for remediation of anthracene in the presence and absence of two microorganisms named Bacillus subtilis and Streptomyces sp. To study biochar impression, a sandy loam soil was mixed with biochar (10% w: w). Nutrients effect was studied by addition of K2HPO4 and NH4NO3 to the soil. Anthracene degradation was quantified using gas chromatography. The highest rate of removal was observed for the incubation of Bacillus sabtilis with the addition of biochar and nutrients. Bacillus sabtilis had decreased the soil Anthracene by 92%, and Streptomyces sp. bacteria with the same condition could degrade by 90.71% after 90 days. This study shows, the addition of biochar and nutrients could increase the anthracene bioremediation by 11 and 7% respectively.

The effect of biochar and nutrients on efficiency of anthracene remediation in soil by <i>Bacillus subtilis</i> and <i>Streptomyces sp</i>

Bioremediation has been found as an effective way to remove PAHs contaminants. Biochar and nutrients as effective factors can raise removal percent. The effect of these two factors was investigated for remediation of anthracene in the presence and absence of two microorganisms named Bacillus subtilis and Streptomyces sp. To study biochar impression, a sandy loam soil was mixed with biochar (10% w: w). Nutrients effect was studied by addition of K2HPO4 and NH4NO3 to the soil. Anthracene degradation was quantified using gas chromatography. The highest rate of removal was observed for the incubation of Bacillus sabtilis with the addition of biochar and nutrients. Bacillus sabtilis had decreased the soil Anthracene by 92%, and Streptomyces sp. bacteria with the same condition could degrade by 90.71% after 90 days. This study shows, the addition of biochar and nutrients could increase the anthracene bioremediation by 11 and 7% respectively.

Salt/current-triggered stabilization of β-cyclodextrins encapsulated host-guest low-molecular-weight gels

Host-guest supramolecular gels were developed via the self-assembly of inclusion complexes (ICs) of β-cyclodextrins/phenylboronic acid gelator (PBA). Salts and current were involved in the self-assembly to stabilize the host-guest gels. The stability of the gels was greatly improved after salts were added. The stable time of gels was extended from 2.5 h to 120 h with the addition of NH4NO3 at the concentration of 2.5 × 10−2 g/mL. The morphology of the gel was affected by the concentrations of NH4NO3. SEM images revealed that the gels were three-dimensional nanofibrous networks, the sizes of fibers decreased with decreasing NH4NO3 concentrations, which affected the stability of gels, further proved by the rheological properties of gels. More stable gels were obtained with current stimulation, the stable time of the gel was increased from 2.5 h to 55 h with current by adding NaBF4. The current also exhibited significant influence on the aggregation as the voltage varied (0–500 mV) with a constant concentration of salts. The result showed the self-assembly process of host-guest gel could be well controlled via the addition of salts and current to desired morphology and stability.

Solvent extraction of molybdenum (VI) from spent hydroprocessing catalyst

This article investigated extraction process of molybdenum (VI) from acid leaching solution to explore the basic data for the recovery of Mo resources from spent hydroprocessing catalyst. The extractant 2‐ethylhexyl phosphonic acid mono‐2‐ethylhexyl ester (P507) was adopted as the extractant, and the effects of specific operating parameters on Mo extraction and stripping were systematically investigated. The Mo extraction was greater than 99.5%, and the co‐extraction of Al and Co were less than 0.2% under optimal conditions. The corresponding stripping processes were also performed focusing on reducing phase‐separation time and preventing third‐phase generation. Almost 100% (>99%) Mo was easily stripped using 0.9 mol/L NH3·H2O with the addition of NH4NO3 ranging from 0.3 to 1.2 mol/L. Saturation extraction capacity method was applied to explore extraction mechanism. Results indicated that the molar ratio of Mo to P507 in the saturated organic phase was approximately 1:1, so the extraction reaction can be expressed as follows: urn:x-wiley:19447442:media:ep13169:ep13169-math-0001 urn:x-wiley:19447442:media:ep13169:ep13169-math-0002 © 2019 American Institute of Chemical Engineers Environ Prog, 38:e13146, 2019

Enhanced activity of Ni/SiO2 catalyst in dry reforming of CH4 via a modified impregnation method

A modified impregnation method with the addition of NH4NO3 was employed to prepared the supported Ni catalyst (denoted as Ni/SiO2-N). And the obtained catalyst exhibited an improved catalytic activity and stability in DRM at 800°C with GHSV of 48 L⋅gcat.−1⋅h−1 and CH4/CO2/N2 = 9/9/2. The XRD and H2-TPR results showed that the Ni/SiO2-N catalyst was possessed with smaller Ni particles and stronger metal-support interaction than Ni/SiO2 catalyst prepared by the common impregnation method, leading to the better catalytic performance. It is the decomposition of NH4NO3 which can generate extra heat in a short time during the catalyst preparation process that make the change in structure and performance of catalyst.

Enhancement on amorphous phase in solid biopolymer electrolyte based alginate doped NH4NO3

The present work deals with the development of solid biopolymer electrolyte (SBE) system using a promising biopolymer, namely, alginate doped with various amount of ammonium nitrate (NH4NO3). The SBE system has been successfully prepared via the solution-casting method. The Fourier transform infrared (FTIR) analysis carried out suggests that interaction has occurred between alginate and NH4NO3 via COO−. The X-ray diffraction analysis (XRD) also discloses that the addition of NH4NO3 affects the alginate SBE system by reducing the crystallinity and transforming it to an amorphous phase. The ionic conductivity of SBE system has been measured using electrical impedance spectroscopy (EIS), and it was found to achieve a maximum value of 5.56 × 10−5 S cm−1 at ambient temperature (303 K) for a sample containing 25 wt.% NH4NO3. The SBE system was found to obey the Arrhenius behavior where the system is thermally activated, and the differential scanning calorimetry (DSC) analysis demonstrated the decreased in glass transition temperature (Tg) upon the addition of the dopant. The mobility (μ) and diffusion coefficient (D) were found to affect the ionic conductivity trend as observed via IR-deconvolution approach. The alginate–NH4NO3 SBE sample with the highest conductivity has a transference number tion of 0.97 which further indicates that the conduction species is a cation.

Corrosion behavior of AZ31 magnesium alloy in the chloride solution containing ammonium nitrate

Corrosion behavior of AZ31 magnesium alloy in NH4NO3-containing chloride solution was investigated by immersion tests, hydrogen evolution collection, electrochemical measurements, and microscopic observation. Addition of NH4NO3 accelerates corrosion due to the deterioration of Mg(OH)2 by NH4+ and the promotion of cathodic NO3− reaction, which is supported by the buffering effect of NH4+. Hydrogen evolution is suppressed with addition of high concentrations of NH4NO3, attributed to the preferential occurrence of NO3− reduction. Loose and cracked corrosion products, which are mainly composed of Mg2(OH)3Cl·4H2O and magnesium hydroxy carbonates, form in the NH4NO3-containing environment. When the NH4NO3 concentration is between 0.005 and 0.03 M, autocatalytic pitting corrosion occurs due to the synergistic effects of Cl−, NH4+, and NO3− at the specific concentration range. The H+ (supplied by NH4+ hydrolysis), Cl− in combination with the depolarization effect of NO3− support the autocatalytic growth and eventually perforate the alloy. With the addition of NH4NO3 higher than 0.05 M, corrosion pits with shallow-dish shape form initially and then evolves into general corrosion, because general corrosion is promoted by the decrease of solution pH, suppression of Mg(OH)2 precipitation, and enhancement of cathodic reactions.

Biochar-mediated regulation of greenhouse gas emission and toxicity reduction in bioremediation of organophosphorus pesticide-contaminated soils

Abstract Organophosphorus pesticides (OPPs) are a set of toxic persistent organic pollutants (POPs) present in the environment. Recently, biochar-mediated bioremediation has exhibited many advantages over conventional methods for the remediation of pesticide-contaminated soil. In the present study, biochar and nitrogen fertilizer (NH4NO3) were employed to remediate OPP-contaminated soil and the greenhouse gas (GHG) emission during 90 days of incubation was investigated. After thermal desorption treatment, the content of organophosphorus pesticides reduced from 175.61 μg·kg− 1 to 62.68 μg·kg− 1. The addition of NH4NO3 in the following bioremediation led to larger reduction (34.35%) of the pesticide concentration than that of biochar (31.90%) for the contaminated soils with thermal desorption treatment, while the simultaneous addition of biochar and NH4NO3 led to the largest reduction of pesticide concentration (11.07%) for the soil without thermal desorption treatment. The addition of biochar and NH4NO3 only slightly increased the emission rate of GHGs from the soil without thermal treatment, but remarkably increased the emission rate of GHGs from the soil after thermal treatment. In most cases, the addition of NH4NO3 is more effective than biochar to promote the degradation of pesticide, but also exhibited higher GHG emission. The microbial community analysis suggests that the enhanced degradation of pesticide is mainly owing to the increased activity of microorganism.