Sulfate Hexahydrate Research Articles

Change of crystallinity and optical transmittance of K2Ni(SO4)2·6H2O single crystal by heat treatment

Potassium nickel sulfate hexahydrate (KNISH) was prepared and grown as single crystal from the supersaturated aqueous solution at 309 K using slow evaporation method. Thermal measurements were achieved for the prepared crystal. The dehydration process, structural phase transitions and melting point of the obtained material were detected. Crystal structure and optical transmittance of KNISH crystal were studied through heat treatment. At 370 K, the dehydration process started to convert KNISH to the anhydrous phase KNIS and the crystallinity decreased gradually until the material became totally amorphous at 383 K. The anhydrous KNIS stayed at the amorphous state from 383 K to 629 K where it transformed again to the crystalline state with different structure. The heat treatment under dehydration temperature did not affect the efficiency of KNISH crystal for using as ultraviolet light filter and sensor. Above dehydration temperature, the obtained anhydrous phase KNIS is not suitable for these applications.

Cradle to gate life-cycle assessment of battery grade nickel sulphate production through high-pressure acid leaching

The rising global demand for high-purity nickel (Ni) sulphate, primarily used in lithium-ion batteries, is largely met by processing Indonesian laterite ores via hydrometallurgy. However, this supply chain is associated with significant environmental challenges and lack of transparent industrial data. This study uses a cradle-to-gate life cycle assessment (LCA) approach to quantify the greenhouse gas (GHG) emissions and energy use associated with the production of mixed hydroxide precipitate (MHP) from low-grade Indonesian laterites via high-pressure acid leaching (HPAL), which is then refined in China for the production of battery-grade nickel sulphate hexahydrate (NiSO4·6H2O, NSH). Fifteen impact categories are analyzed using established impact assessment and allocation (mass and economic) methods. The analysis reveals that feed preparation/HPAL and purification are the stages that contribute most to environmental impacts and in particular to global warming potential (GWP). Mass allocation results in higher environmental impacts, with 36.8 kg CO2-eq per 1 kg of Ni in NSH for GWP, compared to 33.8 kg CO2-eq per 1 kg of Ni in NSH when economic allocation is used. Sensitivity analysis shows a potential reduction (up to 13 %) in key impact categories if production of NSH is fully integrated in Indonesia or a greener electricity mix is used. Overall, our results indicate that the production of MHP in Indonesia and its refinement to NSH in China has a GWP about two times higher than the global average. Given the limited number of LCA studies for the production of battery-grade nickel, this study highlights major environmental concerns for the NSH production process from Indonesian laterites and identifies opportunities for improvement, towards a more sustainable global battery supply chain.

Nitrogen Requirement and Nitrogen Form Preference by Radermachera hainanensis and R. sinica Plug Seedlings

Abstract Radermachera hainanensis Merr. and R. sinica Hemsl. are popular foliage plants raised from seeds. Nitrogen fertilizer can significantly influence medium pH and EC, plug seedling growth, and photosynthesis. Plug seedlings of both species, each with one pair of leaves, were subjected weekly to nutrient solutions with nitrogen (N) concentrations ranging from 0 to 32 mM. Nitrogen-deficient plants exhibited the lowest leaf area, SPAD-502 value, and shoot dry weight but the highest root-to-shoot ratio. Leaf area, SPAD-502 value, and root and shoot dry weights increased with increasing N concentration up to 12-16 mM, and gradually decreased thereafter. Well-grown plants with 12-16 mM N exhibited peak maximal fluorescence (Fm), photochemical quenching (qP) and the lowest minimal fluorescence (Fo) and non-photochemical quenching (qN). Seedlings received nutrient solutions with varying proportions of NH4-N: NO3-N (0:100, 25:75, 50:50, 75:25, and 100:0, in percentages) at 16 mM N. Both species exhibited reduced leaf area, SPAD-502 value, and plant dry weights when supplied with only NO3-N or NH4-N. Maximum growth was achieved at a 50% NH4-N: 50% NO3-N ratio. Species used in this study: Golden jasmine tree, Radermachera hainanensis Merr.; China Doll, Radermachera sinica Hemsl. Chemicals used in this study: ammonium nitrate; sodium dihydrogen phosphate; potassium sulphate; potassium nitrate; magnesium sulfate heptahydrate; calcium sulfate dihydrate; calcium nitrate tetrahydrate; ammonium sulfate; boric acid anhydrous; potassium chloride; ferrous sulfate heptahydrate; disodium ethylenediaminetetraacetic acid dihydrate; copper sulfate pentahydrate; zinc sulfate heptahydrate; molybdic acid; manganese sulfate monohydrate; nickel sulfate hexahydrate; sodium hydroxide.

Separation of nickel and iron from ferronickel via sulfuric acid leaching and hydrothermal precipitation

ABSTRACT Here, a hydrometallurgical process was proposed to separate nickel (Ni) and iron (Fe) from ferronickel. The effects of different factors, namely hydrothermal temperature, initial Fe2+ concentration, and Ni2+ concentration, on the hematite precipitation process, were detail investigated. Ferronickel powders were leached using a 120 g/L H2SO4 solution at 85 °C for 8 h. The final pH of the leaching solution was controlled at 3.0−4.5, and the Fe2+ concentration was maintained at 50−60 g/L. Copper from the ferronickel powder was first leached in the early stage of the leaching process, and then it was reduced by an excess of ferronickel powder, leading to its enrichment in the leaching residue. Approximately 50 g/L of Fe ions was successfully removed and precipitated as hematite containing 60% Fe, 0.3% Ni, and 1.5% S during hydrothermal precipitation at 200 °C for 3 h. Through evaporation crystallization at 90 °C for 8 h, large particles of nickel sulfate hexahydrate (NiSO4·6H2O) containing 19.4% Ni, 0.074% Fe, and 10.69% S were obtained. Moreover, through freezing crystallization at −8 °C for 1 h, smaller particles of NiSO4·6H2O product containing 20.3% Ni, 0.014% Fe, and 11.13% S were synthesised.

Correction: Optical and mechanical stability of Tutton’s salt crystal of Cu2+ doped ammonium cobalt(II) sulfate hexahydrate

Correction: Optical and mechanical stability of Tutton’s salt crystal of Cu2+ doped ammonium cobalt(II) sulfate hexahydrate

Optical and mechanical stability of Tutton’s salt crystal of Cu2+ doped ammonium cobalt(II) sulfate hexahydrate

Optical and mechanical stability of Tutton’s salt crystal of Cu2+ doped ammonium cobalt(II) sulfate hexahydrate

Preparation and Characterization of Nickel Ferrite (NiFe<sub>2</sub>O<sub>4</sub>) Nanoparticles by Surfactant-Free Electrochemical Method

Nickel ferrite (NiFe2O4) Nanoparticles have been synthesized by a simple surfactant-free electrochemical method at room temperature using iron plates as the cathode and anode electrode. nickel sulfate hexahydrate solution used as the electrolyte has a concentration of 0.04 M and pH 10. The voltage applied varied from 6, 9, and 12 V. We found that voltage and hydroxyl ions (OH-) presence have an important role in the formation of nickel ferrite nanoparticles. Particle size can be controlled by voltage. Nickel ferrite nanoparticles were produced in the form of gray powder and exhibited ferromagnetic properties. Material produced exhibits spinel oxide characteristics that confirms nickel ferrite presence. Nickel ferrite produced are nearly spherical with narrow size distribution having the size that can be classified as nanomaterial. Good electrochemical performance is legitimately observed for NiFe2O4 prepared in this work. This simple method is promising as a facile synthesis method for nickel ferrite nanoparticles.

Comprehensive Exploration of Optics and Magnetism in a Hydrothermally Synthesized Nickel(II) Complex.

The hydrothermal reaction of 2-MeIm (2-MeIm: 2-methylimidazole) with nickel sulfate hexahydrate in methanol afforded a mononuclear complex formulated as [Ni(SO4)(2-MeIm)2(H2O)3]·CH3OH (1). The title compound was described by X-ray single-crystal diffraction, thermal assessment, IR, and UV-vis spectroscopy. The crystal structure of 1 is composed of segregated [Ni(SO4)(2-MeIm)2(H2O)3] neutral entities and a solvent methanol molecule. Two (2-MeIm) ligands, a sulfate group, and a water molecule reside in the equatorial positions of the vertices in this 6-fold coordination. Two aqua ligands lay in the apical positions, resulting in a subtly distorted octahedral framework, as was supported by spectroscopic analysis. The complex's self-assembly is firmly governed by robust O-H···O/N-H···O interactions. Further details on these bonds have been furnished via Hirshfeld surface scrutiny and 2D fingerprint plots. As proven by TGA/DSC analysis, raising the temperature of 1 above 60 °C instigates progressive decomposition stages, which culminates in the production of metal oxide as the ultimate product at 700 °C. The optical analysis suggests the dielectric nature of the material with large direct and indirect gap energies of 5.25 and 4.96 eV, respectively. The results of magnetic studies suggest that 1 undergoes a transition to a magnetically ordered state below 6 K.

Effect of pH on Precipitation of Ferronickel Leaching Solution by Using MgO for Mixed Sulfate Precipitate Synthesis

The increasing demand for electric vehicles affects the high demand for nickel-based batteries, including Nickel Manganese Cobalt (NMC) batteries. Generally, NMC is processed from high-quality ore (sulfide ore) to produce nickel (II) sulfate hexahydrate or NiSO4.6H2O. But sulfide ore face scarcity due to a long history of mining and exploitation. Thus, laterite-type nickel ore can be an alternative to nickel resources. This study aims to produce mixed sulfate precipitates from a ferronickel leaching solution that can be utilized further to produce NiSO4.6H2O. Also, this research will study the pH effect of the precipitation process on the product's elemental composition, recovery, and compounds formed. The precipitation process was conducted using 5% MgO (weight basis) with a pH range of 2.5 to 6.5 with one increment. The mixed sulfate precipitates were characterized using AAS, EDX, and XRD. When using a pH of 3.5, a nickel concentration of 1473.00 ppm, nickel recovery of 23.02%, and Nickel grade of 3.18% could be obtained. As a result, the phase of NiSO4.6H2O was formed. Also, the other phases were formed after precipitation, such as CoSO4, FeSO4, and MgSO4.

Role of Cooling Temperature on Impurities Precipitation of Metal Sulfate Solution Derived from Crude Ferronickel Leaching Using MgO

Nickel is used as a raw material for Nickel Manganese Cobalt (NMC) batteries as a compound of Nickel Sulphate Hexahydrate (NiSO4.6H2O). This study used nickel laterite as ore. A hydrometallurgical process carries out Ferronickel to extract nickel concentrate. The first step is leaching using 2M H2SO4 solution for 6 hours with a stirring speed of 200 rpm at 90°C. The leached solution was then neutralized using a neutralizing agent MgO 5% w/w until it reached a pH of 3.5. The neutralized filtrate was then filtered to separate the filtrate and the residue. The neutralization process produces magnesium sulfate salt (MgSO4), which is an impurity. Next, the cooling temperature method is used to precipitate MgSO4 crystals. In this study, the variation of the MgSO4 cooling temperature used was -5, 0, and 5 °C. Subsequently, crystallization was carried out to produce NiSO4.6H2O. The highest nickel recovery (59.61%) can be achieved using a cooling temperature of -5 °C. Also, by using -5 °C of cooling temperature, the nickel content of crystal product is 2.75%. The crystallization product still contains other compounds, such as MgSO4, FeSO4, and CoSO4.

Allergic or Not: Final Interpretation of Doubtful Patch Test Reactions From the North American Contact Dermatitis Group, 2019-2020.

Background: Doubtful patch test reactions generally do not meet criterion for positivity in patch testing. However, the North American Contact Dermatitis Group (NACDG) allows for doubtful reactions to be coded with a final determination of "allergic/positive" based on the temporal pattern, appearance, known characteristics of the allergen, and/or other supportive patch test reactions. Objectives: To analyze NACDG data from the 2019-2020 patch test cycle to identify patterns in the interpretation and relevance of doubtful reactions. Methods: The frequency and proportions of doubtful reactions were tabulated and analyzed for patterns. Statistical analyses were limited to allergens with ≥30 doubtful reactions to ensure adequate sample size. Results: Of patch-tested patients, 31.9% (1315/4121) had ≥1 doubtful reaction. Of 2538 total doubtful reactions, 46% (n = 1167) had a final interpretation of "allergic/positive." The allergens with the highest proportion of doubtful reactions at the final visit were hydroperoxides of linalool 1% (4.5%), fragrance mix I 8.0% (3.9%), and cetrimonium chloride 0.5% (3.4%). Methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) 0.02% (P < 0.001), MI 0.2% (P < 0.001), nickel sulfate hexahydrate 2.5% (P = 0.001), and neomycin sulfate 20.0% (P = 0.003) doubtful reactions were more likely to be interpreted as allergic than nonallergic. Methyldibromoglutaronitrile/phenoxyethanol 0.2% (P < 0.001), oleamidopropyl dimethylamine 0.1% (P < 0.001), formaldehyde 2.0% (P < 0.001), cetrimonium chloride 0.5% (P < 0.001), benzophenone-4 (sulisobenzone) 10% (P < 0.001), iodopropynyl butylcarbamate 0.5% (P < 0.001), cocamidopropyl betaine 1.0% (P = 0.002), and benzisothiazolinone 0.1% (P = 0.012) doubtful reactions were less likely to be interpreted as allergic. Of the 1167 doubtful reactions interpreted as allergic, 84.9% had current relevance. Conclusions: Doubtful reactions were common and approximately one half were coded with a final interpretation of "allergic/positive." Of those, most were clinically relevant. MCI/MI, MI, nickel, and neomycin were more likely to be interpreted as allergic.

Effects of high contents of dielectric inclusions on ferroelectricity in dielectric-ferroelectric nanocomposites with dimethylammonium aluminum sulfate hexahydrate

The present study is devoted to analyzing effects of high contents (85 wt.%) of dielectric inclusions, including nanocellulose and silicon dioxide nanoparticles, on ferroelectricity of composites which are made by combining dimethylammonium aluminum sulfate hexahydrate with each of them. The obtained results revealed that in the case of using nanocellulose, the ferroelectricity was not detected in fresh composite samples, but then gradually appeared over time. Meanwhile, the ferroelectricity was not observed in the composite with silicon dioxide during the observation time.

A Comparative Study on the Influence of Nanocellulose and Silicon Dioxide Nanoparticles on the Properties of a Metal–Organic Framework of Dimethylammonium Aluminum Sulfate Hexahydrate

In our research described here, for the first time, the influence of a soft inclusion of nanocellulose on the properties of dimethylammonium aluminum sulfate hexahydrate was investigated. For comparison, a harder inclusion of silicon dioxide nanoparticles was also used to combine with the dimethylammonium aluminum sulfate hexahydrate. The analyses of data for fresh samples of the composites revealed many similar anomalies created by the influences of the cellulose and silicon dioxide, including an increase in phase transition temperature, an anomalous relaxation and polarization switching. However, over time, the anomalous properties were not stable in the case of the samples containing nanocellulose, which, we suggest, was associated with the softness of the cellulose.

Patch Testing With Nickel, Cobalt, and Chromium in Patients With Suspected Allergic Contact Dermatitis.

Background: Allergic contact dermatitis is frequently caused by metals, including multiple metals simultaneously. Objectives: To assess characteristics and associations of positive and clinically relevant patch test (PT) reactions with solitary and concurrent metal sensitization. Methods: A retrospective analysis of PT results for nickel, cobalt, and/or chromium from the North American Contact Dermatitis Group between 2001 and 2018 (n = 43,522). Results: 18.0% had a positive/allergic reaction to nickel sulfate hexahydrate, 7.3% to cobalt chloride hexahydrate, and 3.0% to potassium dichromate. 87.9% patients had a currently relevant reaction to 0, 9.4% to 1, and 2.7% to multiple metals tested. Patients with 1 versus no currently relevant reactions to metal were more likely to have a primary dermatitis site of trunk, feet, and ears; patients with currently relevant reactions to multiple metals had more dermatitis affecting the trunk and ears. Metal sources varied by co-reacting metal, especially for patients with cobalt and chromium allergy. Jewelry was the most commonly identified source of nickel and cobalt for both solitary and concurrent metal allergy. Conclusions: Sensitization to multiple metals occurred in 6% of patients. Allergen sources varied between patients with sensitivity to 1 metal versus those who had concurrent sensitivity to cobalt and/or chromium.

Recycling of hazardous jarosite residues based on hydrothermal crystal transformation

Jarosite [MeFe3(SO4)2(OH)6] is a typical non-ferrous smelting slag produced in the process of iron removal from hydrometallurgical solution, which contains a large number of valuable and toxic metal elements. Treating the complex and hazardous jarosite residue in an economically and environmentally sound way has always been an urgent problem. A novel one-step hydrothermal treatment method was proposed in this paper for recycling of jarosite residues. It can be seen from the XRD and TEM results that jarosite residues could be completely transformed into hematite crystal particles under hydrothermal conditions at temperature above 220℃. Meanwhile, other valuable metal components (such as nickel sulfate hexahydrate) entrained in the residue will be dissolved in the aqueous solution, which can be reused in the hydrometallurgical process. Through phase composition analysis of the hydrothermal process, it is concluded that jarosite was firstly pyrolyzed to generate Fe3+. The obtained Fe3+ was then hydrolyzed to Fe (OH)3, which was transformed into Fe2O3 through dehydration condensation and directional arrangement. Further roasting the hematite particles, the obtained product contained 62.57 % of Fe, but only 0.21 % of S and 0.04 % of As, which meets the requirements of raw materials for iron making. In addition, compared with the current international standard ISO 1248:2006 (E), the obtained hematite particles with nanometer size and single crystal structure can be used as iron oxide red pigment. Overall, the one-step hydrothermal treatment of jarosite residues followed by reduction roasting not only realizes the economic recycling of the metal resources, but also solves the stacking problem of those hazardous residues.

Disadvantage of interaction between cellulose and a classical hydrogen-bonded ferroelectric of dimethylammonium aluminum sulfate hexahydrate

Despite the state-of-the-art advantages of cellulose in improving the quality of electrical and electronic materials, this natural material does not always bring positive effects. The present work aims at filling this gap. For this purpose, a novel ferroelectric nanocomposite based on a classical ferroelectric metal-organic framework of dimethylammonium aluminum sulphate hexahydrate with a dielectric inclusion of cellulose nanoparticles was synthesized. The study on structure and dielectric properties revealed that the cellulose caused a strong depression of ferroelectricity at temperatures of lower than 115 K when interacting with functional groups of the ferroelectric component.

Growth, structural effects, and non-linear and spectroscopic properties of nanocomposites based on α-NiSO4·6H2O single crystals with TiO2 nanoparticles or sols

Nanocomposites based on nickel sulfate hexahydrate α-NiSO4·6H2O (NSH) with titanium (IV) oxide introduced in the form of nanoparticles (Hombifine N: anatase; Degussa P25: 85 % anatase + 15 % rutile; η-phase: 86 % η - phase + 14 % anatase, NSH:Ti(1)) or sols (NSH:Ti(2)) are synthesized for the first time. X-ray diffraction study reveals a single-phase nature of samples, the full occupancy of all crystallographic sites in the NSH:Ti(1) structures, and the presence of Ti4+ ions in interstitial sites near the vacant Ni site in the NSH:Ti(2) structures. A crystallization of the nanosized η-phase of the composition TiO2-x × mH2O directly in the NSH:Ti(1) crystalline matrix with the formation of TiO2 with the rutile structure, facilitated by the structural-geometric correspondence of 2D projections of NSH and rutile, is observed for the first time. The presence of TiO2 in the interblock space of NSH:Ti(1) crystals affects the unit cell parameters due to the induced stresses, which is practically not described in the literature. The intensity of SHG signals of NSH:Ti varies depending on both the prehistory of TiO2 samples and the crystal state, single-crystal or powdered, of the object under study: the highest values were observed for the NSH:Ti(2) powder with the lowest content of titanium ions. The UV–VIS study reveals similar absorption and transmission bands, but with little difference in band width and intensity, for NSH, NSH:Ti(1) and NSH:Ti(2), which can be perspective for UV filters operating in the solar-blind range.

Effects of nickel supplementation on nutrient utilization, mineral balance, haematology and antioxidant status of crossbred dairy calves

BackgroundNickel has been identified as an important newer trace mineral playing essential role in animals however, its precise mechanism of action in the body is yet to be determined. Interaction of Ni with other essential minerals is suggested in reports limited to lab animals and needs to be explored further in large animals. AimThis study was conducted to study the influence of Ni supplementation at different levels, on minerals and health status of crossbred dairy calves. MethodTwenty-four Karan Fries crossbred (Tharparkar × Holstein Friesian) male dairy calves were selected based on body weight (137.09 ± 5.68) and age (10.78 ± 0.61) and were divided into 4 treatment groups (n = 6) given basal diet supplemented with 0 (Ni0), 5 (Ni5), 7.5 (Ni7.5) and 10 (Ni10) ppm Ni/kg of DM. Nickel was supplemented in the form of nickel sulphate hexahydrate (NiSO4.6 H2O) solution. To ensure the intake of the required amount of nickel by each animal, the calculated quantity of solution was mixed with 250 g concentrate mixture and offered individually to the calves. The calves were fed total mixed ration (TMR) consisting of green fodder, wheat straw and concentrate mixture in the ratio of 40:20:40 and the nutritional requirements were met according to NRC (2001) guidelines. Growth performance was recorded at fortnightly interval whereas, plasma minerals, haematology, antioxidant and immunity parameters were studied at monthly interval during the 150-day experimental period. Nutrient utilization and mineral balances were estimated with the help of a metabolism trial conducted at the end of feeding trial. ResultsSupplementation of Ni exhibited no influence on dry matter intake (DMI), body weight, average daily gain (ADG) and nutrient digestibility of dairy calves. However, the absorption and balance of minerals such as Ni, Fe, Cu, Zn and their respective plasma concentration increased (P < 0.05) with Ni supplementation and highest values were observed in calves fed 10 mg Ni/kg DM. The red blood cell (RBC) count, haemoglobin (Hb) concentration, haematocrit (HCT) and activity of superoxide dismutase (SOD) and catalase antioxidant enzymes showed highest increase (P < 0.05) in calves supplemented with Ni at level of 10 mg/kg DM as compared to other treatment groups. However, white blood cell (WBC) count, glutathione peroxidase (GPx), total antioxidant status (TAS), total immunoglobulins and IgG plasma concentration remained unaltered with addition of different levels of Ni in the diet of calves. ConclusionsThe supplementation of Ni at level of 10 mg/kg DM shows a positive effect on status of trace minerals such as Fe, Cu, Zn and improves the physiological conditions and health status of crossbred dairy calves indicated by improved haematology and antioxidant parameters.

Effect of Time Stepping in the Filtering Process on the Synthesis of Nickel Sulfate Powder from Blast Furnace Ferronickel

The demand for nickel manganese cobalt (NMC)-type batteries is increasing along with the need for global electric vehicles, such as electric cars. Nickel used in the manufacture of NMC batteries is Nickel (II) sulfate hexahydrate (NiSO4.6H2O). Therefore, it is necessary to study how to synthesize nickel sulfate powder from blast furnace ferronickel to provide an alternative source of nickel sulfate and increase the added value of blast furnace ferronickel products. This study aims to analyze the effect of variations in the time difference of stepped filtering sludge on the precipitated filtrate. This study uses a nickel source from the ferronickel derived from the sintering and smelting process using a Mini Blast Furnace to synthesize nickel sulfate. First, the ferronickel was ground and sieved to pass 50 mesh size. Then, the leaching process was performed using a mixture of 120 mL H2SO4 (2M) and 30 mL H2O2 (30%) with a stirring speed of 200 rpm for 6 h for each 2 g ferronickel. Next, the precipitation process was carried out using CaCO3 powder to pH 3.01 at 90 °C. The precipitation solution was held at 90 °C for 24 h, and stepped filtering of the precipitate formed with variations of 2, 4, 6, and 8 h (the total time is kept the same, i.e., 24 h). The crystallization results were then washed and dried at 70 °C for 2 h. Based on X-Ray Fluorescence (XRF), the best results were obtained in stepped filtering variation every 8 h with 50.23% Ni content and 90.5% Ni separation efficiency. Based on XRD, the nickel sulfate powder product has the compound NiSO4.6H2O. In addition, nickel sulfate products also contain CoSO4, one of the compounds needed to manufacture NMC batteries. However, nickel sulfate powder products still contain impurity compounds like FeSO4 and CaSO4.

Role of miR-24-3p and miR-146a-5p in dendritic cells’ maturation process induced by contact sensitizers

MiRNAs are non-coding RNA molecules that regulate gene expression at the post-transcriptional level. Although allergic contact dermatitis has been studied extensively, few studies addressed miRNA expression and their role in dendritic cell activation. The main aim of this work was to investigate the role of miRNAs in the underlying mechanism of dendritic cell maturation induced by contact sensitizers of different potency. Experiments were conducted using THP-1-derived immature DCs (iDCs). Contact allergens of different potency were used: p-benzoquinone, Bandrowski’s base, and 2,4-dinitrochlorobenzene as extreme; nickel sulfate hexahydrate, diethyl maleate and 2-mercaptobenzothiazole as moderate; and α-hexyl cinnamaldehyde, eugenol, and imidazolidinyl urea as weak. Selective inhibitor and mimic miRNAs were then used and several cell surface markers was evaluated as targets. Also, patients patch tested with nickel were analyzed to determine miRNAs expression. Results indicate an important role of miR-24-3p and miR-146a-5p in DCs activation. miR-24-3p was up-regulated by extreme and weak contact allergens, while miR-146a-5p was up-regulated by weak and moderate contact allergens and down-regulated only by the extreme ones. Also, the involvement of PKCβ in contact allergen-induced miR-24-3p and miR-146a-5p expression was demonstrated. Furthermore, the expression of the two miRNAs maintains the same trend of expression in both in vitro and in human conditions after nickel exposure. Results obtained suggest the involvement of miR-24 and miR-146a in DCs maturation process in the proposed in vitro model, supported also by human evidences.