Alkaline Substances Research Articles

Progress in Proteomic Mass Spectrometry Studies on the Effects of Borneol and Menthol as Enhancers on Corneal Injury Repair

Cornea transparent, avascular tissue, is an important part of the refractive function. Corneal injury is the destruction of the corneal structure caused by blunt eyeball, external force, high pressure gas or fluid hitting the cornea. Common in boxing injury, ball injury, stone injury, head collision, etc. The external force directly acts on the formation of the cornea, mainly manifested as vision loss, pain, photophobia, tears, ciliary congestion and contusion corneal edema. Mild corneal damage can be restored under the strong self-healing ability of the corneal epithelium. If serious corneal damage, the corneal stromal layer will leave a scar on the cornea to affect the vision, but also likely to cause related complications, and even lead to complete blindness. Recent studies have shown that corneal alkali burn is one of the most common eye injuries. Due to the strong corrosion of alkaline substances, it can cause degeneration and dissolution of corneal tissue proteins. The lipophilic properties of alkaline substances make it difficult to limit the damage site and easy to form ulcers. In this paper, we discuss the borneol and menthol on the corneal damage repair mass spectrometry, through the influence of borneol and menthol on corneal damage repair and the preliminary test of ice and menthol can be used, in order to provide a new clinical treatment of corneal damage to the new research direction.

Investigation of seawater electrolyte on hydrogen evolution reaction from the perspective of kinetics and energy consumption using an Ni-based electrocatalyst supported on carbon nanotubes.

In this study, a Ni-based composite incorporating Ni4N and La2O3 supported on carbon nanotubes (Ni-La-Ni4N/CNT) was synthesized as an efficiency electrocatalyst towards the hydrogen evolution reaction in different electrolytes with the kinetics and energy consumption investigated in detail. The Ni-La-Ni4N/CNT exhibits overpotentials of 124 mV and 200 mV at the current density of 10 mA cm-2 in 1.0 M KOH and alkaline seawater, respectively. As quantitative comparison, the exchange current density (j°) based on Volmer-Heyrovsky-Tafel mechanism was calculated from various polarization curves, which indicated that the addition of NaCl in alkaline medium or using seawater alone reduced the reactivity of the catalyst. The activity of Ni-La-Ni4N/CNT in alkaline seawater was equal to 91% of that in 1.0 M KOH. Furthermore, dynamic polarization resistance and corresponding current were obtained by the analysis of the equivalent circuit model with the extended Kalman filter algorithm. The analysis of the resistance power at 1 mW also shows that the current between the conditions in KOH and in seawater is 2.76 times. Adding alkaline substances to seawater can narrow it to 1.19 times. These strategies provide novel approaches for inspecting the activity changes of materials in different electrochemical environments.

A Study on Deacidification Treatment of the Deteriorated Glue-Treated Hanji Using Magnesium Oxide

Hanji, a traditional Korean paper, has a porous structure and hydrophilicity due to cellulose’s hydroxyl group (-OH). A glue catcher is commonly used to prevent spreading. Glue-mixed water used for the glue catcher is prepared by mixing natural animal adhesive glue and alum (KAl(SO₄)₂•12H₂O). The alum mixed with the glue-stirred water acts as a bridge connecting the glue and prevents the ink and pigment from spreading so that the color adheres well to the Hanji paper, the base material. However, sulfate ions (SO₄SUP2-/SUP) contained in alum combine with water to form sulfuric acid, which causes acidification. It is deacidized by penetrating alkaline substances such as magnesium oxide (MgO) to prevent such acidification. After applying the glue to the Hanji paper, the deterioration proceeded. The deacidification treatment with magnesium oxide after the deterioration was carried out to evaluate the behaviors of physical, mechanical, and pH neutralization reaction of the Hanji paper, and after deacidification, the general strength properties were increased in mechanical properties. In the optical properties, the L* value increased as the deacidification treatment proceeded. It was confirmed that the pH value significantly reduced the oxidation of Korean paper in the glia count and neutralized the deacidification treatment.

An experimental study on microanalytical characterizations and service performances of landfill modified municipal sludge liner materials in contact with leachate

This study aimed to evaluate the long-term service performance of modified municipal dewatered sludge as a landfill liner barrier. Industrial calcium-containing solid waste was used as a modified material for sludge. The shear strength parameters (cohesion c, friction angle φ), compressive strength, and hydraulic conductivity of the modified sludge were studied using direct shear, uniaxial compression, and penetration tests. The leaching toxicity, hydration products, and microscopic morphology of the modified sludge were determined using atomic emission spectroscopy, X-ray diffraction, scanning electron microscopy, and energy dispersion spectroscopy. The corrosion mechanisms of the landfill leachate and acid-base chemical solution on the modified sludge liner barrier were revealed. Under the long-term corrosive environment of the landfill leachate and acid-base chemical solution, the shear strength parameters, i.e., cohesion (c) and friction angle (φ) had values in the ranges of 0.51 − 3.79 MPa and 6.52 − 37.58° of the modified sludge, respectively. The uniaxial compressive strength reached 2.70 − 22.92 MPa, and the permeability coefficient ranged from 0.12 × 10−8 to 3.97 × 10−8 cm/s. After long-term corrosion by landfill leachate and an acid-base chemical solution, the modified sludge liner barrier still had significant bearing capacity and water-blocking properties. Under leachate corrosion, sulfate corrosion (such as ettringite and thaumasite formation) occurred, the modified sludge and some structures were damaged. Under an acidic chemical corrosion solution, alkaline substances, such as calcium hydroxide with hydrogen ions, underwent solvent-out crystallization and chemical dissolution reactions, which caused the decomposition of hydrated gel products such as C–S–H inside the specimen. Under alkaline chemical solution corrosion, the active components in the modified sludge underwent a hydration reaction to form ettringite, C–S–H, etc.

Obtaining a Refractory Geopolymer Based on Clays and Seashells

AbstractThe synthesis of a refractory geopolymer with excellent thermal and mechanical properties to develop materials that resist temperatures above 1000 °C has become a challenge in recent years. The production of a refractory material involves the combination of clays and alkaline substances, whose formulation produces an improvement in the final properties of the refractory material. In this work, we report a Taguchi L18 design to synthesize a refractory geopolymer that exhibits the highest compressive strength, based on two natural clays from Mexico, seashells, sodium silicate and water. The prepared mixture was molded to form mini bricks, which were cured for 24 hours at room temperature. Subsequently, the bricks were dried for 4 days, and we evaluated the effect of temperature at 40 °C, 60 °C and 80 °C. Subsequently, the samples were subjected to calcination between 900 °C and 1200 °C to determine the resistance to both thermal and mechanical fracture via compression. The highest thermal resistance and compressive strength were obtained with a geopolymer formulated with 7.5 % seashells, 38.2 % Tepozán‐Bauwer clay, 30.0 % Kaolin clay, 20 % commercial sodium silicate and 4.3 % water, which was dried at 40 °C. The compressive strength was 7.28 MPa (74.2 kgf /cm2), and the thermal resistance was up to 1200 °C. In the FTIR analysis of the geopolymers calcined at 1200 °C, the influence of calcium was observed by the bands of the 800–1200 cm−1 region, where there was a greater distribution since the Si−O− bond was added. Ca was found at 950 cm−1. By adding CaCO3 in the form of seashells, the presence of the anorthite mineral phase (CaAl2Si2O8) can be identified, which originates from the degradation of calcium carbonate crystals (calcite, vaterite and aragonite) of the identified seashells using XRD. The synthesized geopolymer has potential use in the refractory and ceramic materials industry.

Enhanced removal of hexavalent chromium and nitrate in aquifers by alkali-modified emulsified vegetable oil

The cocontamination of hexavalent chromium (Cr(VI)) and nitrate is common in groundwater, particularly in plains region. Injecting emulsified vegetable oil (EVO) into aquifer is an effective method for the simultaneous removal of Cr(VI) and nitrate from groundwater. In this study, EVO and alkali-modified emulsified vegetable oil (AM-EVO) were prepared from soybean oil and magnesium hydroxide. Characterization methods such as atomic force microscope (AFM), inverted fluorescence microscope (IFM), laser particle size analysis, and Fourier transform infrared spectroscopy (FTIR) were used to examine the microscopic morphology, particle size distribution, and surface functional groups. The remediation efficiency of EVO and AM-EVO were investigated and compared for Cr(VI) and nitrate removal in groundwater. Influencing factors on the removal of Cr(VI) and nitrate such as initial dissolved oxygen, alkaline substance type, alkaline substance existing form, and reagent dosage were studied. AM-EVO with good stability, good dispersity, and high removal efficiency was obtained with the concentrations of soybean oil, magnesium hydroxide, polyoxyethylene sorbitan monooleate (Tween-80), and sodium dodecyl sulfate (SDS) were respectively 45, 25, 9.3, and 1.75 g/L. The AM-EVO could effectively accelerate the removal of contaminants at initial pH 10 and 30 °C, 10 mg/L Cr(VI) and 350 mg/L nitrate both could be completely removed within five days. Cr(VI) was reduced by microbial secondary ferrous iron, and the apparent rate constant was increased from 0.07 day−1 to 0.41 day−1. Nitrate was reduced by denitrifying bacteria, and the degradation rate constant was increased from 2.01 day−1 to 3.65 day−1.

Effect of Pseudomonas aeruginosa on corrosion of X65 pipeline steel

Microbiologically influenced corrosion (MIC) has caused great losses to many industries. This paper aimed to study the corrosion behavior of P. aeruginosa on X65 steel. The corrosion behavior of P. aeruginosa on X65 steel under aerobic and anaerobic conditions was studied by scanning electron microscopy, energy dispersive spectrometer and electrochemical analysis techniques. The results showed that the corrosion rate of X65 steel in bacterial environment is higher than that in sterile environment. In anaerobic environment, the corrosion of P. aeruginosa is mainly secreted acidic metabolites, and alkaline substances are corroded in aerobic environment. In general, the corrosion of X65 steel by P. aeruginosa in aerobic environment is more serious than that in anaerobic environment.

Antimicrobial Peptides Prediction method based on sequence multidimensional feature embedding.

Antimicrobial peptides (AMPs) are alkaline substances with efficient bactericidal activity produced in living organisms. As the best substitute for antibiotics, they have been paid more and more attention in scientific research and clinical application. AMPs can be produced from almost all organisms and are capable of killing a wide variety of pathogenic microorganisms. In addition to being antibacterial, natural AMPs have many other therapeutically important activities, such as wound healing, antioxidant and immunomodulatory effects. To discover new AMPs, the use of wet experimental methods is expensive and difficult, and bioinformatics technology can effectively solve this problem. Recently, some deep learning methods have been applied to the prediction of AMPs and achieved good results. To further improve the prediction accuracy of AMPs, this paper designs a new deep learning method based on sequence multidimensional representation. By encoding and embedding sequence features, and then inputting the model to identify AMPs, high-precision classification of AMPs and Non-AMPs with lengths of 10-200 is achieved. The results show that our method improved accuracy by 1.05% compared to the most advanced model in independent data validation without decreasing other indicators.

Effect of Different Acid and Base Potassium Ferrate Pretreatment on Organic Acid Recovery by Anaerobic Digestion of Sludge.

Potassium ferrate has strong oxidation in both acid and alkali environments, which has attracted extensive attention. However, the impact of the pH environment on this coupling process with the goal of resource recovery has not received attention. Under the goal of the efficient recovery of organic acid, the changes of solid-liquid characteristics of sludge after acid and alkaline ferrate pretreatment and during anaerobic digestion were discussed. The results showed that compared with blank control groups, after alkaline ferrate pretreatment, the volatile suspended solids (VSSs) decreased the most, reaching 28.19%. After being pretreated with alkaline ferrate, the sludge showed the maximum VFA accumulation (408.21 COD/g VSS) on the third day of digestion, which was 1.34 times higher than that of the acid ferrate pretreatment. Especially in an alkaline environment, there is no need to add additional alkaline substances to adjust the pH value, and the effect of sludge reduction and acid production is the best.

Simulation and experimental investigation on one-step process for recovery of valuable metals and preparation of clean mineral wool from red mud

Red mud (RM) is a hazardous alumina industrial solid waste and its utilization faces three major challenges, namely, efficient recovery of valuable metals, favorable control of hazardous substances, and complete utilization of residues. We simultaneously achieved the three goals in a short one-step process, which was inspired by green chemistry principles and focused on multi-objective coupled control. Iron-based metal elements were recovered in reduction smelting process to produce pig iron. Molten slags after smelting were rapidly cooled and fiberized to produce mineral wool and hazardous alkaline substances were immobilized in vitreous fibers. The smelting-reduction process, fibration capacity of RM-based molten slags, and performance and environmental impact of prepared mineral wool were investigated using thermodynamic, molecular dynamics simulations, and experimental methods. The results indicated the recovery rate of Fe could reach above 87%. The obtained mineral wool showed satisfactory properties with the fibrosis rate of around 73%–92%, the mean fiber diameter of 1.57–5.62 μm, and the mean fiber tensile strength of 1520–6700 MPa. The highest Na+ leaching concentration was under 1.42 mg/L and the solidification rate of Na+ in different samples was above 99.8%. This paper provided a fresh approach to achieve clean and high value-added utilization of RM.

Preparation Technology and Properties of Carbon-Reinforced Recycled Aggregate Concrete and Mortar

Crushing the demolished waste concrete as aggregate to prepare fresh concrete may cause aggregate internal damage leading to strength reduction. To counter this issue, in the current study, the recycled aggregate is mixed with nano-calcium oxide in a vacuum reactor, and then a high concentration of carbon dioxide is introduced to fill the internal damages of the recycled aggregate. A layer of hydrophilic alkaline substance is formed on the surface of recycled aggregate to absorb carbon dioxide, which improves the strength of recycled aggregate particles and the bonding performance of aggregate-cement interface area. The test results show that the mechanical properties of recycled aggregate particles are improved after vacuum carbon strengthening, and the vacuum carbon strengthening effect of recycled aggregate with large particle size is more obvious. Compression strength of concrete and mortar prepared by vacuum carbon-reinforced aggregate is observed to be 13.6% and 30% higher than ordinary recycled concrete, respectively. Also, the proposed recycled aggregate improvement method manifests a 21.1% reduction in carbon emissions. These findings offer crucial parameters for the engineering use of recycled concrete, promote new ideas to reduce carbon emissions caused by fresh concrete production, and provide an important reference for the sustainable recycling of waste concrete.

Investigation on stabilization/solidification characteristics of lead-contaminated soil using innovative composite model of cement and soda residue

The cement solidification/stabilization method of heavy metal contaminated soils has been promoted in engineering practice and applied on a large scale for site remediation, but it still reveals some scientific problems in the current complex and variable global extreme climate. To solve these problems, this study used waste soda residue as a composite additive, and established an innovative composite model (cement-soda) to remediate lead-contaminated soil. The innovative composite model for unconfined compressive strength (UCS) and toxic leaching properties under different conditions were investigated As well as curing and leaching mechanisms are discussed, and future industrial practice was evaluated. The results showed that the addition of soda residue improved the early (20 days) UCS of the composite curing agent for lead-contaminated soil by an average of 23.1% MPa. The UCS strength was 0.96 MPa, which was the maximum when the percentage of soda residue composite was 40%. The concentration of Pb2+ in the leachate of the cement-soda residue (CSH) composite curing agent was greatly reduced (average 3.28 times) compared with that of a single cement in the same situation, with an average leached Pb2+ concentration of 1.87 mg·L−1. This finding indicates that the addition of alkali residue improved the curing effect. The curing mechanism was divided into four steps, mainly a complex physicochemical reaction between the CSH composite and soil particles. The leaching mechanism of CSH to aqueous solution is mainly the consumption of acid ions by alkaline substances. Collectively, this study will provide scientific data to support potential lead-containing soil in site remediation technologies and future large-scale engineering applications.

Fully coating of Mg3B2O6 in nonaqueous solution on Ni-rich LiNi0.8Co0.1Mn0.1O2 secondary particles to improve cycling stability of lithium-ion batteries

Surface coating is an effective strategy to suppress side reactions at the electrode/electrolyte interface and improve cycling stability of the Ni-rich LiNixCoyMn1-x-yO2 electrodes. It is difficult to prepare a complete coating layer on the secondary particles by traditional methods, due to the alkaline substances and oxidative property on surface. In this work, a coating process of Mg3B2O6 running counter to traditional routes was designed to modify LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode material. In a weak polar ethanol medium, BH4- ions are uniformly lain on particle surface by the interaction between its electronegativity and oxidizing surface, which also change the charge state into negative atmosphere around the NCM811 surface. Then Mg2+ ions are also completely dispersed by the mutual attraction between metal cations and the hydrolyzed BO3-. Then a full surface coverage of Mg3B2O6 was prepared in situ on the NCM811 secondary particles. The complete coating layer protects the surface crystal structure of the NCM811 and limits the irreversible phase transition. The optimized composite with a suitable coverage of 1 % Mg3B2O6 exhibits enhanced rate capability and excellent cycling performance. At a high current density of 10C, it delivers a specific capacity of 162.7 mAh g−1. Especially, it maintains 160.6 mAh g−1 after 400 cycles at a high cut-off voltage of 4.5 V at 1C with a retention of 80.3 %. In addition, Mg3B2O6 is a non-toxic and non-polluting material. The simple coating process with low-cost raw materials as well as mild operating conditions endow this technology with potential practical application value.

Investigation on self-sustained combustion, NOx emissions, and ash characteristics of coal slime in a lab-scale fluidized bed

Incineration of coal slime in the fluidized bed boiler is an efficient means of energy recovery and environmental protection. In this study, combustion behaviors and NOx emissions of coal slime were studied using a lab-scale fluidized bed reactor. Besides, the fundamental characteristics of coal slime and its ash were explored coupled with a particle size analyzer, X-Ray Diffraction (XRD), thermogravimetric analysis (TGA), automatic specific surface, porosity analyzer, etc. It revealed that the range of 350–640 °C was the main mass loss stage with more than 92% of the total loss during combustion through the thermogravimetric analysis, guaranteeing good burnout performance. The challenges of fluidization and burnout of C-type particles accounting for 36.59% of coal slime were solved by mixing the water with coal slime to enhance its agglomeration and thermal explosion. Through the coupling of multiple operating parameters such as primary and secondary air rate, secondary air height, the oxygen content of flue gas, etc., reasonable furnace temperature and reduction zone distribution can be achieved. In addition, it was found that the migrations of most heavy metals are correlated with the proportion of fine particles in coal slime during combustion. The high content of alkaline substances of coal slime leads to a slightly slagging propensity below 900 °C due to the prevention of eutectics formation. Pore analysis implies that bottom ash and fly ash show different trends in the specific surface area and pore volume compared to the coal slime during combustion.

Immobilization of chalcone chemosensor into plasma-pretreated recycled polyester fibers toward multi-stimuli responsive textiles for detection of ammonia

Polyester fibers were applied in different fields, including automotives, plastic furniture, packaging, and medical devices. This can be attributed to its low-cost, good resistant to moisture and chemicals, good resistance to electricity and fatigue, easily repaired from damages, fade-resistant, high flexural and impact strength, and easy manufacturability. However, polyester fibers are inherently stain resistant as they have no active dye sites. Thus, it is impossible to dye polyester after extrusion. Herein, we report the development of novel strategy to produce multichromic polyester textiles by plasma-assisted dyeing with novel chalcone chemosensor disperse dyestuff. Thin layer of chalcone probe was incorporated onto the polyester fiber surface after plasma activation, which creates active dye sites on the fiber surface. Novel hydrazonotriazole chemosensor was synthesized by reflux a mixture of 1, 2, 3-triazole and hydrazine derivatives. Hydrochloric acid was employed as a catalytic agent, whereas absolute ethanol was used as a solvent. Various methods were utilized to prove the structure of the synthesized chemosensor, including Nuclear Magnetic Resonance (NMR), Fourier transform infrared spectroscopy (FTIR) and elemental analysis. The findings indicated that the hydrazonotriazole-dyed polyester (HPET) fibers exhibited satisfactory colorfastness properties, UV protection and antimicrobial properties. Additionally, the dyed polyester fibers demonstrated high importance to build up portable device for onsite colorimetric determination of gaseous and aqueous ammonia, which has been able to cause damages to man organs and even death. The hydrazone group can selectively detect ammonia over other alkaline substances. The limit of detection of the dyed polyester fibers ranged between 5 and 150 ppb of aqueous ammonia, displaying a color switch from yellow (435 nm) to blue (584 nm) as proved by CIE Lab parameters, absorption spectra and color strength (K/S). The dye particle exhibited diameters in the range of 33–86 nm, whereas polyester fibers exhibited a fiber diameter of 75–125 μm, indicating high porosity and large surface area.

Encapsulation of Vitamin B12 by Complex Coacervation of Whey Protein Concentrate-Pectin; Optimization and Characterization.

Vitamin B12 (VB12) is one of the essential vitamins for the body, which is sensitive to light, heat, oxidizing agents, and acidic and alkaline substances. Therefore, the encapsulation of VB12 can be one of the ways to protect it against processing and environmental conditions in food. In this work, the influence of pectin concentration (0.5–1% w/v), whey protein concentrate (WPC) level (4–8% w/v) and pH (3–9) on some properties of VB12-loaded pectin–WPC complex carriers was investigated by response surface methodology (RSM). The findings showed that under optimum conditions (1:6.47, pectin:WPC and pH = 6.6), the encapsulation efficiency (EE), stability, viscosity, particle size and solubility of complex carriers were 80.71%, 85.38%, 39.58 mPa·s, 7.07 µm and 65.86%, respectively. Additionally, the formation of complex coacervate was confirmed by Fourier-transform infrared (FTIR) spectroscopy and atomic force microscopy (AFM). In addition, it was revealed that the most important factor in VB12 encapsulation was pH; at a pH < isoelectric point of WPC (pH = 3), in comparison with higher pH values (6 and 9), a stronger complex was formed between pectin and WPC, which led to an increase in EE, lightness parameter, particle size and water activity, as well as a decrease in the zeta-potential and porosity of complex carriers.

Bio-solubilization of Yunnan lignite by Penicillium ortum MJ51 and characterization of its products

In this study, a newly discovered fungal strain Penicillium ortum MJ51 was isolated from lignite collected from a coal mine in Yunnan Province, China. The strain was then utilized to convert solid Yunnan lignite to liquid value-added chemicals. It solubilized 36.4% of the raw lignite and 82.0% of lignite pretreated with nitric acid within 8 days. The extracellular metabolites and enzymes secreted by MJ51 were detected dynamically, along with an analysis of the organic element composition, Fourier-transform infrared spectroscopy, and gas chromatography-mass spectrometry of the raw lignite, pretreated lignite, and their bio-solubilized residues and soluble fractions. The results suggested that extracellular metabolites including alkaline substances and surfactants, secreted by MJ51 were the primary contributors to the depolymerization of lignite, because the lignite-solubilization ability of MJ51 was correlated with pH and surface tension of the culture. Moreover, extracellular enzymes, such as lignin peroxidase and esterase, secreted by MJ51 participated in the degradation of lignite despite their poor activity. Furthermore, MJ51 could introduce CO into the structure of raw lignite in the same way as HNO3. Under the associated action of extracellular alkaline substances, surfactants, and enzymes, the hydrogen bond in coal was rebuilt, the complex aromatic skeletons were opened, and the attached long aliphatic side chain was cut off. The pretreated lignite could be thoroughly degraded by MJ51 than raw lignite as it had a lower degree of aromatic condensation, shorter aliphatic side chain and more carbonyl groups. The soluble bio-solubilized fractions of lignite contained aliphatic and aromatic compounds, and their derivatives.

One‐Step Spraying Fabrication of Superomniphobic Coatings with Anti‐Flame, Anti‐Corrosive, and Mechanochemically Durable Ability

AbstractA durable and high‐quality superomniphobic coating that gives good repellency to water and organic liquid with lower surface tension is critical for basic research and practical applications. Although it has made significant progress, incorporating flame retardancy without sacrificing its superomniphobicity and durability remains a challenge. Here, these challenges are addressed by one‐step spraying suspension consisting of epoxy resin, micro/nano‐particles, and flame retardant. The durability and flame retardancy can be regulated by adjusting the mass ratio of different components and curing temperature. The resulting coating possesses good superomniphobicity (repelling liquids with surface tension as low as 21 mN m−1) and mechanochemical durability even under severe environments such as harsh abrasion, high temperature, erosion of aqua regia, and other strong alkaline substances. In addition, the coating is resistant to metal corrosion and exhibits excellent flame retardance ability. Combined with this convenient spraying process, the coating is more conducive to realizing industrial production.

Continuous and effective treatment of heavy metal in acid mine drainage based on reducing barrier system: A case study in North China

The acid mine drainage (AMD) resulting from human mining activities has adversely affected across the worldwide. The heavy metals and acidity contained in AMD cause great harm to the ecological environment, which are difficult to remove at low cost and effectively. In this study, the acid regulation and heavy metal removal of AMD were investigated by using the reducing barrier system constructed with common industrial wastes of activated sludge and fly ash as the reaction medium. The optimized results indicate that more than 99% of Cu2+ and 100% of Zn2+ in the AMD are effectively removed, as well as a neutral pH of AMD is achieved. It was attributed to alkaline substances in the reducing barrier system regulate the pH of AMD effectively, while the reducing atmosphere created by the self-respiration of microorganisms in the system reduces SO42− to S2− and HS−, achieving the purpose of removing heavy metal ions by forming the precipitation of metal sulfides. Based on SEM-EDS, BET, FITR and Zeta potential characterizations, the removal mechanism of metal ions by the reducing barrier system were systematically elaborated. Moreover, the long-term effectiveness of the reducing barrier system is evaluated by several repeated simulated leaching experiments. This discovery achieves the purpose of “treating waste with waste” and provides an environmentally friendly, economic and long-term treatment method for local AMD.

Effect of nanoparticles on desulfurization/regeneration performance of deep eutectic solvent based nanofluid system

Using choline chloride as hydrogen bond acceptor and urea as hydrogen bond donor, the deep eutectic solvent (DES) was prepared, and different alkaline substances were added to obtain two alkaline DES systems with different viscosities. SiO2 nanoparticles were introduced into the above two systems to construct different DES-based nanofluid systems: ethanolamine-deep eutectic solvent (E-DES-NF) system and polyethyleneimine-deep eutectic solvent (P-DES-NF) system. The viscosity of the nanofluid system was measured, and it was found that with the increase of the proportion of nanoparticles, the viscosity of both nanofluids increased firstly and then decreased. The hydrogen sulfide absorption experiment was carried out to explore the effect of nanoparticles on the desulfurization and regeneration performance of different nanofluid systems. The experimental results showed that the DES system synthesized in this study can maintain 100% removal rate for at least 40 min. The desulfurization and regeneration performances were improved simultaneously after the addition of moderate nanoparticle. In the E-DES system, when the mass fraction of SiO2 nanoparticles was 0.1%, the highest desulfurization performance was conducted. Besides, the addition of an appropriate amount of water was found to be beneficial to the regeneration of exhausted desulfurizer of E-DES-NF system. In the P-DES-NF system, the optimal mass fraction of SiO2 nanoparticles was confirmed as 0.01%. Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy and X-ray diffraction were used for the characterization of the nanofluid systems as well as SiO2 nanoparticles before and after absorption as well as after multiple absorption–regeneration cycles. The morphology of SiO2 nanoparticles itself had little changes. A large amount of liquid substances were found gather on the surface of nanoparticles, and with the increase of the number of absorption–regeneration cycles, the surface attachment gradually decreased.