SO Solution Research Articles

Nickel-modified sulfated zirconia catalyst: Synthesis and application for transforming waste cooking oil into biogasoline via a hydrocracking process

The synthesis of a sulfated zirconia catalyst and its modification with Ni metal was carried out and applied in the hydrocracking of waste cooking oil into biogasoline. The SO4/ZrO2 (SZ) catalyst was synthesized via a hydrothermal process using ZrOCl2·8H2O as a precursor, followed by sulfation using (NH4)2SO4 solution. The catalyst was calcined at a temperature of 600 °C. The obtained SZ catalyst was refluxed in aqueous solutions of Ni(NO3)2 with various Ni loadings (1, 2, and 3 wt% Ni), followed by reducing hydrogen gas at 400 °C to yield Ni/SZ catalysts. The impregnation of Ni on SO4/ZrO2 led to an increase in catalyst acidity, as well as their activity and selectivity for the hydrocracking process. Among ZrO2 and the synthesized catalysts, 1% Ni/SZ has the highest acidity level. The hydrocracking process was performed at 450 °C. The 1% Ni/SZ catalyst was able to selectively produce the gasoline fraction, with the conversion reaching 70.28% gasoline from 80.28% for the total liquid products. As a result, the catalyst was shown to be acceptable for industrial-scale applications.

Solubility and solvation thermodynamics of glycine, dl-alanine and l-threonine in pure aqueous and aqueous (NH4)2SO4 solution

In this article the equilibrium saturated solubility of glycine, dl-alanine and l-threonine in aqueous ammonium sulphate media at various temperatures were estimated. The standard transfer Gibbs free energies and different thermodynamic parameters were also estimated. Different interactions were analysed for the solvation of the amino acids in the experimental media to explain the mechanism of solvation. For dl-alanine and l-threonine, salting-in effect is observed at lower electrolyte concentration while at higher electrolyte concentration salting-out effect is observed at a particular temperature. The chemical stability of the amino acids in aqueous electrolyte mixture was explained to justify the experimental results.

Fabrication of superhydrophobic & catalytic bifunctional MnO2 @ Al2O3 composite ceramic membrane for oxidation of desulfurization waste solution

A novel superhydrophobic & catalytic bifunctional MnO2@Al2O3 composite ceramic membrane was prepared, and characterized for catalytic oxidation of sulfite through membrane aeration. Manganese dioxide on the ceramic membrane was fabricated via the hydrothermal synthesis method with ammonium persulfate and manganese sulfate. The three-dimensional structure and rough surface were formed by the staggered spines of sea urchins-like MnO2 particles. Stearic acid was used as the hydrophobic modifying reagent to reduce surface free energy. The synthesized composites exhibit excellent superhydrophobicity with a maximum static water contact angle of 164.9° ± 5.3°. The reaction parameters could affect the hydrophobicity by changing the morphology of MnO2. The bifunctional membrane could also promote the oxidation rate of sulfite, which was increased by 44.0% in Na2SO3 solution and 64.2% in (NH4)2SO3 solution.

Ammonia Recovery from Digestate Using Gas-Permeable Membranes: A Pilot-Scale Study

The reduction and recovery of nitrogen (N) from anaerobically digested manure (digestate) is desirable to mitigate N-related emissions, mainly ammonia and nitrate, derived from digestate land application in nutrient-saturated zones. This work reports the results of a gas-permeable membrane (GPM) pilot-scale plant to recover ammonia from digestate in the framework of the EU project Ammonia Trapping. The total ammonia nitrogen (TAN) concentration in digestate was reduced by 34.2% on average (range 9.4–57.4%). The recovery of TAN in the trapping solution in the form of a (NH4)2SO4 solution averaged 55.3% of the removed TAN, with a TAN recovery rate of 16.2 g N m−2 d−1 (range between 14.5 and 21.0 g N m−2 d−1). The TAN concentration in the trapping solution achieved a value of up to 35,000 mg N L−1. The frequent change of the trapping solution has been proven as an efficient strategy to improve the overall performance of the GPM technology.

Degradation of organic pollutants in hazardous spent sulfuric acid by catalytic oxidation reaction with agricultural waste-derived catalyst

The discharge of spent sulfuric acid generates significant toxic wastes and poses serious hazards to the environment. The effective treatment of spent sulfuric acid remains a great challenge because conventional thermochemical pyrolysis is limited by energy-intensive processing, high equipment investment, and severe equipment corrosion. In this study, we propose an energy-efficient and moderate catalytic oxidation reaction to treat spent sulfuric acid. During the catalytic oxidation reaction, the organic pollutants, especially refractory acid-soluble oil (ASO), in the conversion of spent sulfuric acid and ammonia wastewater were oxidized and degraded into CO2, H2O, and inorganic structures with H2O2 as the oxidant and ozone-treated activated carbon (OAC), derived from coconut shells, as a catalyst. The catalytic activity of OAC enhanced the degradation efficiency of organic pollutants under mild conditions, which was ascribed to the abundant acidic functional groups, and the anchored metal ions on the OAC promoted the generation of highly reactive radicals. The purified (NH4)2SO4 solution with an ASO removal of 96.4% and total organic carbon (TOC) removal of ~92% under the optimum conditions was used to prepare the qualified (NH4)2SO4 product. This work demonstrates the effective utilization of spent sulfuric acid and a cost-effective route to prepare catalysts from agricultural waste for the oxidative degradation of organic pollutants.

A General Strategy toward Metal Sulfide Nanoparticles Confined in a Sulfur-Doped Ti3 C2 Tx MXene 3D Porous Aerogel for Efficient Ambient N2 Electroreduction.

Three-dimensional (3D) porous MXene-based aerogel architectures have attracted great interest for many applications, despite limits in renewable energy conversion owing to the lack of multifunctionality in their components. Herein, a simple and general strategy for constructing a novel functional 3D MXene-based composite heterojunction aerogel (MS@S-MAs) is presented via divalent metal-ion assembly and subsequent thermal sulfidation, and its application in electrochemical nitrogen reduction reaction (NRR) is studied. The as-prepared MS@S-MAs comprises metal sulfide nanoparticles uniformly confined in 3D interconnected conductive S-doped MXene sheets with intimate interfacial interaction. Benefiting from the unique properties and an interfacial interaction, MS@S-MAs exhibit significantly improved NRR catalytic performance and excellent stability because of the higher exposure of electrochemically active sites coupled with easier accessibility, faster mass diffusion, and quicker carrier transport at the interface. Remarkably, CoS@S-MAs show an NH3 yield rate and a Faradaic efficiency of 12.4 µg h-1 mg-1 cat and 27.05% at the lower potential of -0.15V versus a reversible hydrogen electrode in 0.1 m Na2 SO4 solution under ambient conditions, which rivals or exceeds most of the previously reported MXene-based and Co-based catalysts. This work will open avenues to construct 3D MXene-based materials with rich functionalities for energy storage and conversion, catalysis, and other applications.

Deterioration process of high belite cement paste exposed to sulfate attack, calcium leaching and the dual actions

Deterioration process of high belite cement (HBC) paste with and without 30 wt.% fly ash, when exposed to sulfate attack, calcium leaching and the dual actions, was investigated by mass loss, expansion rate, porosity, corrosion depth, compressive strength and Vickers hardness, so did the contrastive ordinary Portland cement. Moreover, XRD, TGA, 29Si NMR, SEM and EDS linear scanning measurements were also conducted to assess the chemical attack mechanisms under corresponding aggressive conditions. Results showed that, the degradation of HBC pastes varied between different exposure conditions, and the most severely corroded samples were that exposed to (NH4)2SO4 solution with coupling sulfate attack and calcium leaching, which interacted with each other and accelerated the transfer process of sulfate ions to the cement matrix and calcium ions to external solution. Compared with ordinary Portland cement, high belite cement had a better corrosion resistance against the dual actions of sulfate attack and calcium leaching, and it could be further promoted by the moderate substitute of fly ash.

Polythionic Acids in the Wackenroder Reaction.

Polythionic acids, whose general formula is H2SnO6, with n greater than 2, were discovered in the aqueous solution of SO2 and H2S, known as the Wackenroder liquid. Their reactions with each other and with other reagents are, mostly, difficult to characterize, since such compounds readily decompose and interconvert, especially in solution. Nevertheless, they play an important role in technical applications (e.g., gold leaching, magnesium milling, cooling in metal processing) and in reactions of inorganic chemistry of sulfur. A few years ago, Shell–Paques/Paqell patented the first industrial process for the biological conversion of H2S into a colloidal mixture of sulfur and polythionates. Such hydrophilic sulfur can be used as a fertilizer and soil improver in agriculture in all but alkaline soils. Recently, Eni S.p.A. has developed to bench plant scale a new process, the HydroClaus process for the conversion of H2S into an acidic hydrophilic slurry of sulfur and polythionate ions. Such a slurry can be used as a soil improver where the very alkaline soil pH hinders the cultivation. The aim of this work is to study the laboratory-scale production of polythionates in view of the novel HydroClaus process scale-up at the industrial level. After the literature related to polythionates and their characterization has been revised, the sulfur-based mixture has been synthesized and the polythionate ions concentration has been determined. Also, the effect of the reaction operating conditions has been investigated to assess how they can influence the nature and the distribution of products in solution.

Microbial effect on water sorptivity and sulphate ingress by Bacillus megaterium on mortars prepared using Portland Pozzolana cement.

To determine the effect of direct embedment of Bacillus megaterium into Portland pozzolana cement mortars on water sorptivity and diffusivity coefficient of sulphate ions. Prisms with a water/cement ratio of 0·5 were prepared by blending Portland Pozzolana cement with the requisite volume of a B. megaterium (microbial) solution whose concentration was 1·0×107 cells per ml. Mortar prisms of 160mm×40mm×40mm were fabricated for this study. Mortars cured for 28days were exposed to 0·2465moll-1 Na2 SO4 solution using accelerated ion migration test method for 36-h session using a 12V DC power source. Sulphate ion concentration was then determined through the ingressed mortar at 10mm interval. A minimum water sorption gain of 0·61% was observed on the prism prepared with and cured in microbial solution. A maximum of 0·0289 and a minimum of 0·0093 water sorptivity coefficients were exhibited by the control prism and microbial prisms, respectively. The microbial prisms exhibited the lowest apparent diffusion coefficient (Dapp ) of 4·5179×10-11 m2 s-1 . Direct incorporation of B. megaterium in mortar preparation, curing or both regimes significantly retarded water sorption and lowered sulphate ion ingress. The inclusion of this bacterial in the mortar further complements the pozzolana pore structure benefits. This novel B. megaterium bacteria which can survive and cause biocementation within hydrating cement mortar when not encapsulated would result in a green innovation. Once adopted and applied in real-life scenario, it would promote construction of durable, safe, resilient and affordable shelter.

Karakterisasi Biochar dari Ampas Tebu dan Kemampuan Penyerapan Nitrogen Sebagai Amelioran Pada Tanah Gambut Secara In Vitro

Research has been carried out on the characterization of biochar pores produced from bagasse through a pyrolysis process at a temperature of 110oC for 4 hours, using the Scaning Electron Microscopy-Energy Dispersive X-Ray (SEM-EDX) method. The biochar of sugarcane pulp produced is then tested for its ability to absorb nitrogen content (% N-total), with the source of N is urea fertilizer through the Kjedhal method based on SNI (2801: 2010), and the source of nitrogen from a solution of ammonium sulfate (NH4)2SO4 by the titrimetric method. The SEM measurement results showed that the biochar pores were uniform and micro-sized, while the peat pores were macro in size and irregular. EDX results show that biochar is composed of 100% carbon, while peat soil consists of carbon compounds (C), Oxygen (O) Silica (Si) and Aluminum (Al). Both of biochar and peat have moisture content of 0.38% and 11.79%, ash content of 2.42% AND 24.44%, volatile content of 0.53% and 5.23% of bound or fixed carbon (cf) of 97.02% and 58.53%. The results of the biochar capacity test applied to peat soils can increase the pH of the peat from 5 to 6.5 with the ability to absorb N-total from urea (NH2)2CO and N-total fertilizer sources from ammonium sulfate (NH4)2SO4 solution of 38% - 66%, and 56.5% -84.5%.

Effect of Fluoride Ion on the Corrosion of 304 Stainless Steel in (NH4)2SO4 Solution Containing Chloride Ions

Effect of Fluoride Ion on the Corrosion of 304 Stainless Steel in (NH4)2SO4 Solution Containing Chloride Ions

Efficient development of silk fibroin membranes on liquid surface for potential use in biomedical materials

Silk fibroin (SF) protein is versatile for the application of biomaterials due to its excellent mechanical properties, biocompatibility and biodegradability. However, the efficient way to fabricate SF membranes with special structure is still challenging. Here, we develop an efficient and simple way to create SF membranes on the liquid (i.e. subphase) surface. It is essential to prepare highly concentrated SF solution with low surface tension by dissolving the degummed SF powders in 6% (w/v) LiBr/methanol solution by one step. 95 wt% polyethylene glycol (PEG) 200 and 30 wt% (NH4)2SO4 are the subphases, on which the SF solution spreads quickly, generating nonporous and microporous SF membranes (SFM-1 and SFM-2), respectively. PEG 200 causes more ordered molecular packing (β-sheets) in SFM-1. While Fast diffusion and denaturation of SF on (NH4)2SO4 solution lead to the formation of microporous, water-unstable membrane SFM-2. Both membranes have good transparency, hydrophilicty, and mechanical properties. To fabricate antibacterial biomaterials, we design a composite membrane by SFM-1 and SFM-2 sandwiching a layer of hydroxypropyl trimethylammonium chloride chitosan (HACC) to provide antibacterial functions. The sandwich membrane has good cell viability and antibacterial properties, showing potential use for biomedical materials.

Effects of Concentration of Pore Solution on Stability of Ion-Absorbed Rare Earth Ore Aggregate

The continuous change in solution concentration in ore pores during in situ mineral leaching influences the stability of ore aggregate. In this study, influences of the concentration of ammonium sulfate ((NH4)2SO4) solution on the interaction forces between ore particles were calculated. On this basis, the mechanism by which (NH4)2SO4 solution concentration influences the stability of ore aggregate was analyzed. Furthermore, an empirical formula for estimating the critical (NH4)2SO4 solution concentration for aggregation and dispersion of ore body aggregates with different grain composition was proposed. Some major conclusions were drawn. First, for ore bodies with an initial particle size of less than 0.075 mm, the interaction force between particles was net attraction, with the distance range of this force increasing as the concentration of (NH4)2SO4 solution increased from ≤0.001 to 0.16 mol·L−1, aggregation of ore particles occurring within this distance range. Secondly, for ore bodies with initial particle size of less than 0.075 mm, the interaction force between particles was net attraction, but with the distance range of this force decreasing when the (NH4)2SO4 solution concentration increased from 0.16 to 0.28 mol·L−1, dispersion of ore particles occurring beyond this distance range. Thirdly, for ore bodies with particle sizes of less than 0.038, 0.075 and 0.1 mm, the cation exchange capacity (CEC) was 9.13, 8.96, and 8.8 cmol·kg−1, respectively, and the critical (NH4)2SO4 solution concentration affecting the aggregation and dispersion of ore bodies was 0.12, 0.16, and 0.20 mol·L−1, respectively.

Isolation and purification of polar compounds from Eupatorium fortunei Turcz by high-speed counter-current chromatography

In traditional Chinese therapy, the decoction of herbal products is commonly used as a therapeutic drug, which takes water as the extraction medium and contains many hydrophilic compounds. The main compounds reported in Eupatorium fortunei Turcz were volatile oils. However, polar constituents of its decoction were less studied. In this paper, polar compounds in aqueous extract of E. fortunei Turcz were isolated by counter-current chromatography combined with a macroporous resin column. By the system of n-butanol/acetonitrile/(273 mg/mL) (NH4)2SO4 solution (3:1:4.4, v/v/v), 205.0 mg of 10% ethanol fraction was separated to yield 2.4 mg of the trans-coumaric acid-3-O-β-D-glucoside with the purity of 95.0%. By the system of n-hexane/ethyl acetate/water (1:4:5, v/v/v), 92.0 mg of ethanol fraction was separated to yield 11.3 mg of trans-o-coumaric acid with a purity of 94.2%. Through the isolation and identification of compounds of characteristic peaks, it was effective to provide a theoretical basis for qualitative identification and quantitative determination of maker compounds in the research of quality assessment for E. fortunei Turcz.

A vessel-inside-vessel microwave-assisted digestion method based on SO3 generation in situ for the mineral determination of fatty samples

Vessel-inside-vessel microwave-assisted acid digestion was developed for the analysis of samples with high-unsaturated fat content. For the first time, thermal decomposition of (NH4)2S2O8 solutions was evidenced for SO3 generation in situ and gas-phase modification in pressurized digestion flasks. NMR analysis demonstrated the oxidative effect of SO3 on olefin double bonds despite incomplete mineralization of oil samples. In this context, (NH4)2S2O8 decomposition was used in association with HNO3 solutions for sample digestion and mineral determination in edible oils (safflower, coconut, flaxseed, and chia). For all oils, dissolved organic carbon (DOC) contents lower than 5% m m-1 were obtained under optimum conditions: 210 °C with an irradiation time of 40 min, 7.0 mol L-1 HNO3 and 2.0 mol L-1 (NH4)2S2O8 in 0.9 mol L-1 H2SO4. Thus, a DOC reduction of about 70% was reached compared to digestions using only HNO3 at the same conditions. Additionally, a time reduction of up to three-fold was achieved compared to typically demanding edible oil digestions. The proposed method allowed the determination of As, Cd, Cr, Mn, Ni, and Pb in edible vegetable oil samples by ICP-MS. Accuracy was evaluated against the reference method, and no significant difference was observed (p = 0.05), with wide linear ranges and good linearity (r ≥ 0.999) and LOD ranging from 0.48 (As) to 2.41 (Cd) μg L-1.

Persulfate enhanced photoelectrochemical oxidation of organic pollutants using self-doped TiO2nanotube arrays: Effect of operating parameters and water matrix

This study investigated the influence of adding peroxydisulfate (PDS) to a photoelectrocatalysis (PEC) system using self-doped TiO2 nanotube arrays (bl-TNAs) for organic pollutant degradation. The addition of 1.0 mM PDS increased the bisphenol-A (BPA) removal efficiency of PEC (PEC/PDS) from 65.0% to 85.9% within 1 h. The enhancement could be attributed to the high formation yield of hydroxyl radicals (·OH), increased charge separation, and assistance of the sulfate radicals (SO4·−). The PDS concentration and applied potential bias were influential operating parameters for the PEC/PDS system. In addition, the system exhibited a highly stable performance over a wide range of pH values and background inorganic and organic constituents, such as chloride ions, bicarbonate, and humic acid. Further, the degradation performance of the organic pollutant mixture, including BPA, 4-chlorophenol (4-CP), sulfamethoxazole (SMX), and carbamazepine (CBZ), was evaluated in 0.1 M (NH4)2SO4 solution and real surface water. The degradation efficiency increased in the order of CBZ < SMX < 4-CP < BPA in the PEC and PEC/PDS systems with both water matrices. Compared with the PEC system, the PEC/PDS (1.0 mM) system showed a threefold higher pseudo first-order reaction rate constant for BPA among pollutant mixtures in surface water. This was attributed to enhanced ·OH production and the selective nature of SO4·−. The pseudo first-order reaction rate constants of other pollutants, i.e., 4-CP, SMX, and CBZ increased ca. twofold in the PEC/PDS system. The results of this study showed that the PEC/PDS system with bl-TNAs is a viable technology for oxidative treatment.

Canopy processing of N deposition increases short-term leaf N uptake and photosynthesis, but not long-term N retention for aspen seedlings.

Forest canopies can retain nitrogen (N) from atmospheric deposition. However, most empirical and modeling studies do not consider the processing of the N deposited in the canopy. To assess whether N deposition through canopy will alter the plant's N uptake and retention, we conducted a 3-yr mesocosm experiment by applying (15 NH4 )2 SO4 solution to aspen sapling canopies or directly to the soil. We found that 15 N-NH4+ applied to the canopy was directly taken up by leaves. Compared with the soil N application, the canopy N application resulted in higher photosynthesis but lower N retention of the plant-soil system in the first growing season. Plant biomass, N concentration, and leaf N resorption were not significantly different between the canopy and soil N applications. The partitioning of retained 15 N among plant components and soil layers was similar between the two treatments 3 yr after the N application. Our findings indicated that the canopy N processing could alter leaf N supply and photosynthesis in the short term but not N retention in the long term. Under natural conditions, the chronic N deposition could continuously refill the canopy N pool, causing a sustained increase in canopy carbon uptake. Canopy N processing needs to be considered for accurately predicting the impact of N deposition.

Production of High-Quality Graphene Using a Novel Electrochemical Intercalation-Exfoliation Approach

Large scale production of graphene has recently received a great deal of attention because of its interesting properties and wide range of potential applications. Conventional chemical exfoliation approaches, such as Hummer’s method,provides cost-effective pathway for large scale production, however, the method suffers from several key challenges such as the usage of corrosive and toxic solution, high processing temperature, long duration, and the poor quality of graphene produced which severely affects its potential applications. Recently, electrochemical exfoliation of graphene has been proposed for a high production yield with better quality. The electrochemical method involves two steps: 1) intercalation of ionic species between the graphene layers, followed by 2) oxidation of these ionic species under an anodic voltage into gas molecule enabling exfoliation of graphene flakes from the graphite electrode.1 In this study we examine a new approach to the intercalation, using an intercalating ion that has received very little attention and has not been evaluated for electrochemical exfoliation. The intercalation was followed by exfoliation in (NH4)2SO4 solution leading to the production of graphene flakes. The resultant graphene was found to have less disrupted sp2 lattice structure, with a high yield of about 95 % of graphene, along with high electrical conductivity and a low oxidation level (with a C:O ratio of about 15, determined by XPS). In addition, the presence of nitrogen and sulfur moieties in the resulting graphene structure can act as an electrocatalyst2 for applications such as the oxygen reduction reaction. Thus, the as-prepared graphene could be used for a range of electrochemical applications.

Preparation and characterization of gelatin films by transglutaminase cross-linking combined with ethanol precipitation or Hofmeister effect

In this study, the gelatin films were prepared by dehydration with ethanol precipitation or Hofmeister effect via absolute ethanol or saturated (NH4)2SO4 solution after transglutaminase (TG) cross-linking. The prepared gelatin films remained the integrity after heat treatments (boiling or high-temperature sterilization), and had a low water vapor permeability (WVP) due to TG cross-linking. Ethanol precipitation improved the mechanical, water barrier (water solubility) and visual sensory (color difference and transparency) properties of the gelatin films especially at a high gelatin concentration, which was due to the increase of hydrogen bonding and triple helix content, and ethanol decolorization effect, respectively. The tensile strength (TS) and elongation at break (EAB) were increased by 155.28% and 72.73% than in oven-dried gelatin film (15% gelatin concentration). The results of thermo-gravimetric analysis (TGA) and thermal shrinkage suggested the enhanced thermal stability of films induced by ethanol precipitation due to more orderly internal structure. Although mechanical properties and thermal shrinkage of gelatin films could also be improved by Hofmeister effect, the (NH4)2SO4 migrated to films after dehydration, especially at a low gelatin concentration, which limits the application of this method. The present results indicated that TG cross-linking combined with ethanol precipitation can serve as an effective method to obtain gelatin films with good thermal stability and mechanical, visual sensory and water barrier properties.

Ring opening of methylenecyclopropanes with halides in liquid sulfur dioxide

Methylenecyclopropanes (MCP) undergo ring opening reactions with group I and II metal halides and ammonium halides in liquid SO2 to afford homoallylic halides, which are versatile reagents in organic synthesis. The developed reaction conditions are compatible with acid-labile substrates such as N-Boc-protected compounds. Liquid SO2 is a polar reaction medium with Lewis acid properties that solubilizes inorganic salts. The unique properties of SO2 were demonstrated by control experiments: 1) upon performing the reactions with the aforementioned salts in conventional solvents, the MCP ring opening was not observed either in the presence of catalytic amounts of H3PO4 (similar pKa to that of H2SO3), or in the absence of H3PO4; 2) a solution of SO2 in THF exhibited similar properties to that of liquid SO2.