Form Of NH4Cl Research Articles

A closed loop recycling strategy for sustainable recovery of group 11 metals (Cu, Au, and Ag) from waste PCBs: An amalgamation of low-temperature NH4Cl roasting, HCl leaching and cementation

Circular economy is not a choice but a necessity for every sector with growing demand and limited resources. E-waste, being considered as a strategic resource because of its enriched metallic content the implementation of effective utilization is necessary, but not at the cost of the environment. Therefore, to maximize resource recovery and minimize environmental impact, a closed-loop approach was proposed for the recovery of group 11 metals from waste printed circuit boards (WPCBs). Herein, a combination of low-temperature NH4Cl roasting, HCl leaching, and cementation methods was employed for the separation of metals. The NH4Cl roasting assisted in altering metals to metal chlorides, whereas HCl solvates produced metal chlorides. Ultimately, cementation methods were employed for individual separation of metals from leached solution. The obtained results revealed that >98% Cu, 86% Ag, and 76% Au were extracted under optimum conditions (Temperature of 260 °C, roasting time of 2.5 h, NH4Cl dose of 2 g/g, and 2 M HCl). Further, a three-step cementation technique was employed for the separation of Au, Ag, and Cu using Ag, Cu, and Fe as sacrificial metals, respectively. Finally, all the reagents used in the process were recovered in the form of NH4Cl and Fe(OH)2 making a closed-loop process.

Ammoniacal nitrogen concentration by osmotically assisted reverse osmosis

Ammoniacal nitrogen is a commonly encountered nitrogenous pollutant produced by industrial processes present in wastewater. In this work, model wastewater containing ammoniacal nitrogen (in the form of NH4Cl) was used as a feed solution in the demonstration of osmotically assisted reverse osmosis (OARO) using a multi-stage hollow fiber membrane module setup. The OARO process aimed to dewater the model wastewater and effectively concentrate the ammoniacal nitrogen in solution for easier recovery. Split feed OARO, wherein the feed stream is split either into the concentrated retentate or refluxed back into the permeate side flowing counter-current with the feed, was conducted and the influence of several operational parameters, such as applied pressure, feed flow rate, reflux ratio, on the concentration process was investigated. Also, the properties of the feed solution, i.e. initial feed concentration and presence of other ionic species, such as NaCl, were also tested. Higher concentration efficiency was observed at the following conditions: higher applied pressure, lower flow rate, and higher reflux ratio. The use of low concentrated feed solutions might be useful to decrease the applied pressure and the occurrence of internal concentration polarization was also avoided. The results in this work show that OARO could be a practical membrane-based process for enrichment and recovery of ammoniacal nitrogen from wastewater to further realize a circular economy, in which waste materials such as ammoniacal nitrogen are recovered and reused to produce valuable products.

Nitrogen recovery from a palladium leachate via membrane distillation: System performance and ammonium chloride crystallization

Ammonia leaching process was often used to separate precious and rare-earth metals during their recovery via hydrometallurgy, resulting in the generation of nitrogen-rich leachate. Therefore, it is significantly important to recover the nitrogen from the leachate for reuse. In this work, we explored the treatment of palladium leachate (PL) via direct contact membrane distillation (DCMD) for nitrogen recovery. Effects of temperature and pH on system performance and nitrogen recovery mainly in the form of ammonium chloride (NH4Cl) were evaluated. Results showed that DCMD performance decline caused by membrane scaling was primarily impacted by feed temperature rather than pH. The higher temperature, the more severe membrane scaling occurrence. However, there was little to no effect of initial pH on distillate flux decline. Nitrogen in the form of NH4Cl was successfully recovered from PL, which was significantly influenced by initial pH. The weight of NH4Cl obtained ranged from 17.4 to 21.5 g/L under various operating conditions, and the purity of the NH4Cl was up to 97.4%, near the industrial grade, at feed temperature of 40°C and initial pH of 8.5. Additionally, results of gas chromatography-mass spectrometry (GC–MS) revealed that the primary dissolved organic matter (DOM) in the virgin PL were tetradecanoic acid and isosorbide. Our results suggest that DCMD can be used as a promising and feasible solution for nitrogen recovery from the PL.

Relieving pressure from coral reefs: Artificial oyster rocks can replace reef rocks used for biological filtration in marine aquariums

Natural reef rocks have been harvested from the wild for decades to supply the marine aquarium trade. These rocks have been used in home aquariums mostly as substrate to safeguard biological filtration, especially for nitrification. Producing artificial rocks can be a sustainable alternative to the harvest of natural reef rocks from the wild, thus promoting coral reefs conservation. Nonetheless, there is a lack of scientific knowledge on standard formula to prepare artificial rocks, as well as on their potential to promote nitrification. The use of oyster shells, a by-product from oysters’ aquaculture, appears as a promising ecological and economic approach to produce artificial live rocks. Thus, we aimed to develop a standard formula to produce artificial rocks made with oyster shells and test its potential use as a substrate for biological filtration in marine aquariums. For that, we prepared artificial oyster rocks with different sized fragments of oyster shells and compared their ability to promote nitrification of ammonium nitrogen with that of natural reef rocks and fragmented oyster shells. The formula was set at 1 g of dried cement (white Portland cement with limestone) per 3.1 g of dried oyster shell fragments. The volume of water used to prepare this mix was set as 50% of the cement weigh. Our results indicate that artificial rocks made with oyster shells and cement display an ability to promote nitrification similar to that of natural reef rocks, promoting a slight decrease in pH and without releasing PO4–P. All treatments with substrate were able to oxidize up to 21 mg.L−1 of TAN (total ammonia nitrogen, initially added in the form of NH4Cl) within a 48-h interval. In other words, it is possible to safely assume that all tested substrates oxidized an average of ∼4.4 ± 0.1 μg of TAN.g−1.h−1. Thus, our results support that artificial rocks made with white Portland cement and oyster shell fragments are a sustainable option to safeguard a suitable biological filtration in marine aquariums.

Seasonal Characteristics and Source Analysis of Water-Soluble Ions in PM2.5 of Anyang City

We explore the characteristics and sources of water-soluble ions in aerosol fine particulate matter (PM2.5) samples collected from Anyang, China, during typical seasonal months from 2018 to 2019. Nine water-soluble ions (Na+, NH4+, K+, Mg2+, Ca2+, F-, Cl-, NO3-, and SO42-) were analyzed. The analysis of PM2.5, water-soluble ion concentration levels, anion-cation balance, nitrogen oxidation rate (NOR), sulfur oxidation rate (SOR), and ion correlation showed that the annual average concentrations of PM2.5 and water-soluble ions in Anyang were (85.81±45.43) μg·m-3 and (48.21±30.04) μg·m-3, respectively. Concentrations of ions were ranked as:NO3- > SO42- > NH4+ > Cl- > K+ > Ca2+ > Na+ > Mg2+ > F-. The annual average concentration of the sum of NH4+, NO3-, and SO42- was (42.72±27.87) μg·m-3, which accounted for 87.14% of total water-soluble ions. Moreover, NH4+ was highly related to SO42- and NO3-. The mean values of the nitrogen oxidation rate (NOR) and sulfur oxidation rate (SOR) were 0.25 and 0.37, respectively. These results suggest that these ions were the result of secondary formation. The anion-cation charge equivalent value was 0.75-0.94, which indicates that the sampled aerosols were alkaline. NH4+ mainly existed in the form of (NH4)2SO4 and NH4NO3 in spring, summer, and autumn, whereas in winter it mainly existed in the form of NH4Cl. The results of principal component analysis indicated that secondary aerosols, coal combustion, biomass burning, and dust were the main sources of the water-soluble ions in Anyang during the sampled periods.

A waterborne chemical cue from Gulf toadfish, Opsanus beta, prompts pulsatile urea excretion in conspecifics

The Gulf toadfish (Opsanus beta) has a fully functional ornithine urea cycle (O-UC) that allows it to excrete nitrogenous waste in the form of urea. Interestingly, urea is excreted in a pulse across the gill that lasts 1–3h and occurs once or twice a day. Both the stress hormone, cortisol, and the neurotransmitter, serotonin (5-HT) are involved in the control of pulsatile urea excretion. This and other evidence suggests that urea pulsing may be linked to toadfish social behavior. The hypothesis of the present study was that toadfish urea pulses can be triggered by waterborne chemical cues from conspecifics. Our findings indicate that exposure to seawater that held a donor conspecific for up to 48h (pre-conditioned seawater; PC-SW) induced a urea pulse within 7h in naïve conspecifics compared to a pulse latency of 20h when exposed to seawater alone. Factors such as PC-SW intensity and donor body mass influenced the pulse latency response of naïve conspecifics. Fractionation and heat treatment of PC-SW to narrow possible signal candidates revealed that the active chemical was both water-soluble and heat-stable. Fish exposed to urea, cortisol or 5-HT in seawater did not have a pulse latency that was significantly different than seawater alone; however, ammonia, perhaps in the form of NH4Cl, was found to be a factor in the pulse latency response of toadfish to PC-SW and could be one component of a multi-component cue used for chemical communication in toadfish. Further studies are needed to fully identify the chemical cue as well as determine its adaptive significance in this marine teleost fish.

Ammonium chloride as nitrogen source in sugarcane harvested without burning

The great difficulty of incorporation of N fertilizers into the "green sugarcane" system causes concern and since urea is the most commonly used source, there is the risk of loosing NH3 through volatilization. For this reason, a field experiment was undertaken (in a Hapludox Typic) with the objective of evaluating the agronomic efficiency of ammonium chloride on stubble of the second ratoon (SP89 1115), as well as its residual effect on the subsequent cycle (third ratoon). The experimental design was randomized blocks with four replications. Treatments consisted of three N rates (60, 120 and 180 kg ha-1 N) in the form of NH4Cl, in addition to a control treatment without the addition of N fertilizer. The ratoon cane of the second cutting was harvested in November 2006 and the treatments were applied in December 2006. The second ratoon was harvested mechanically in November 2007 and in December 2007, 450 kg ha-1 of the NPK mixture 20-05-19 was applied, providing 90, 22 and 86 kg ha-1 N, P2O5 and K2O, respectively, for the purpose of evaluating the effect of residual-N from the treatments implanted in December 2006. An increase in the rates of N-NH4Cl had a positive effect on the leaf concentrations of P, Mg and S. Stalk yield (MSS - Mg ha-1 of sugarcane stalks) and sugar (MSH - Mg ha-1 of sucrose) in the November 2006 harvest responded linearly to the increase of N doses in the form of NH4Cl. In relation to the effect of residual-N in the 2007/2008 harvest, it was observed, in general, that the concentrations of macronutrients in the sugarcane leaf +1 were within the range considered adequate in the state of São Paulo, Brazil. The residual-N of the NH4Cl doses resulted in a significant reduction in stalk (MSS) and sugar (MSH) production. It may be concluded that the NH4Cl source at a dose of 120 kg ha-1 N in ratoon fertilization of the second cutting was agronomically efficient, presenting, however, less efficiency of residual-N in the subsequent cycle.

Determination of Pb and Cd in water by potentiometric stripping analysis (PSA)

The aim of this work was to determine the content of cadmium(II) and lead(II) in drinking spring and well waters from rural part of south Serbia, as in a tap water. We have examined the Jablanica river water as well, which is passing by close to the wells. The analysis of metal ions were carried out simultaneously in examined samples of water using a computerized potentiometric stripping analyzer (PSA) of domestic design and manufacture (Faculty of Technology, Novi Sad and “Electrouniverzal”, Leskovac). PSA, an electroanalytical technique with high sensitivity and selectivity, applied using mercury thin film electrode, as a working electrode, by standard addition method in the presence of two supporting electrolytes to adjust pH values of examined samples. In the first case, the pH values of examined samples were adjusted at 2 by hydrochloric acid and in the second, the pH values were adjusted at 5.6 by acetate buffer contained 1.0 M NH 4Ac/0.5 M HCl in addition of 1.0 mol/dm 3 chloride ions in form of NH 4Cl. The deposition potentials from −1.0 to −1.3 V were examined, in order to define the optimal electrolysis potential, and pre-electrolysis time of 15 min were used. The procedure was applied to water samples and the results were compared with Graphite Furnace Atomic Absorption Spectrometry (GF-AAS) as reference method.

Stimulating effect of earthworm excreta on the mineralization of nitrogen compounds in soil

The effect of excreta of earthworm species Aporrectodea caliginosa and Eisenia fetida on the mineralization of nitrogen compounds in soils has been studied. A single application of excreta obtained from three earthworms in one day increased the formation of nitrate nitrogen compounds in the soil by 10–50%. The application of ammonium nitrogen (in the form of NH4Cl) in amounts equivalent to the ammonium nitrogen content in the daily excreta of three earthworms had the same effect on the mineralization of nitrogen compounds. The effect of earthworm excreta, as well as the effect of ammonium nitrogen, on the nitrification process was an order of magnitude higher than their contribution to the formation of nitrates due to the oxidation of the introduced ammonium. Hence, ammonium—an important component of the earthworm excreta—can exert a stimulating effect on nitrification processes in the soil and produce long-term cumulative effects that are much more significant than the direct effect of this nitrogen compound.

Ammonium Hydroxide Detoxification of Spruce Acid Hydrolysates

When dilute-acid hydrolysates from spruce are fermented to produce ethanol, detoxification is required to make the hydrolysates fermentable at reasonable rates. Treatment with alkali, usually by overliming, is one of the most efficient approaches. Several nutrients, such as ammonium and phosphate, are added to the hydrolysates prior to fermentation. We investigated the use of NH4OH for simultaneous detoxification and addition of nitrogen source. Treatment with NH4OH compared favorably with Ca(OH)2, Mg(OH)2, Ba(OH)2, and NaOH to improve fermentability using Saccharomyces cerevisiae. Analysis of monosaccharides, furan aldehydes, phenols, and aliphatic acids was performed after the different treatments. The NH4OH treatments, performed at pH 10.0, resulted in a substantial decrease in the concentrations of furfural and hydroxymethylfurfural. Under the conditions studied, NH4OH treatments gave better results than Ca(OH)2 treatments. The addition of an extra nitrogen source in the form of NH4Cl at pH 5.5 did not result in any improvement in fermentability that was comparable to NH4OH treatments at alkaline conditions. The addition of CaCl2 or NH4Cl at pH 5.5 after treatment with NH4OH or Ca(OH)2 resulted in poorer fermentability, and the negative effects were attributed to salt stress. The results strongly suggest that the highly positive effects of NH4OH treatments are owing to chemical conversions rather than stimulation of the yeast cells by ammonium ions during the fermentation.

Chemical forms and sources of extremely high nitrate and chloride in winter aerosol pollution in the Kanto Plain of Japan

The spatial distributions, chemical forms, and potential sources have been investigated for extremely high concentrations of Cl - and NO - 3 in aerosols collected during an extensive study for winter pollution episodes in the Kanto Plain of Japan. Air monitoring are conducted at 10 sites including the rooftops of skyscrapers during two measurement periods in November–December 1991. Similarity in the diurnal variation patterns of NO - 3 among the sampling sites suggests that its precursor HNO 3 is formed by reactions in the atmosphere, while difference in the maximum concentration of Cl - between the sites indicates the presence of local sources. Measurements at ground level and on the rooftops of skyscrapers show that the pronounced diurnal variations of both components are phenomena occurring in the layer extending from the ground surface to at least 200 m height. Intensified measurements at two ground sites indicate that (1) NO - 3 and non sea-salt Cl - are predominantly in the fine mode, (2) [NO - 3] + [Cl -] and [NH + 4] are in equivalence, (3) gaseous HCl, HNO 3, and NH 3 are in equilibrium with particulate NH 4Cl and NH 4NO 3. From these results, it is concluded that measured Cl - and NO - 3 are predominantly in the form of NH 4Cl and NH 4NO 3, respectively. The behavior of peroxyacetyl nitrate (PAN) indicates that HNO 3, the precursor of NO - 3, is produced in the photochemical reactions of the NO x -hydrocarbons system. The elevated concentration of NO 2 measured simultaneously in the pollution episodes is regarded as an alternative form of O 3 produced in photochemical reactions. As the precursor of Cl - in aerosols, sources of HCl are discussed, and the emission from incineration of domestic and industrial waste in the area is estimated.

Increasing deamination reactions in soil with pyridoxal-5'-phosphate

Amino acid N accounts for ca 30–45% of the total soil N content and represents a potentially-available nutrient source for plant growth. Previous investigations have demonstrated that amino acid deamination in soil is catalyzed by pyridoxal-5'-phosphate (PLP) in the absence of any enzyme. Batch experiments using soils managed under different land uses and tillage regimes were conducted in which 3 g soil was amended with 1.9 or 9.6mM PLP and 19.2 mM NaN 3 and kept at 35 C for 24 h. Maximum NH + 4-N production (2.7 mg kg −1 soil) occurred in Melton soil previously managed as pasture. Comparison of Palouse soil previously managed under conventional, minimum or no-tillage regimes showed no differences in NH 4 +-N production with tillage and relatively little NH + 4-N production as a result of substrate limitations. In a second set of experiments, soil columns containing a 40 g soil-sand mixture (1:1. w:w) were maintained for 29 weeks at a water potential of −0.08 MPa. Soil columns were incubated without organic matter addition, or were amended with l g wheat straw or alfalfa. PLP or pyridoxine (Pd) addition to the columns at weeks 2 and 14 resulted in the detection of increased inorganic N in the leachate most likely as a result of PLP or Pd mineralization. Amounts of inorganic N produced by PLP- and Pd-treated soils never exceeded N produced by soils treated with an equivalent amount of N in the form of NH 4Cl. Inorganic N produced in the leachate of PLP- or Pd-amended soil columns also never exceeded N expected as a result of PLP and Pd mineralization. PLP does not appear to be a useful soil amendment to catalytically increase inorganic N production from the organic N pool.