Palygorskite Research Articles

Effect of natural attapulgite mineral on microstructure, mechanical properties and tribological behaviors of in-situ TiB/Ti composite by SPS method

In this study, natural attapulgite (ATP) mineral powder was implanted into an in-situ synthesized TiB/Ti composite by the SPS method using Ti-Al-B-attapulgite raw powders to improve the tribological properties. The introduction of ATP improved the microstructure, mechanical properties, and tribological performance of the in-situ TiB-reinforced titanium matrix composite. The addition of 1 wt.% ATP powder has refined both the grain structure of the matrix and the size of the in-situ TiB, leading to the increase of 39.3% in matrix nanohardness and 31.4% in microhardness of the composite. During the friction process, dehydration reactions, group recombination, and tribochemical reactions occurred in the ATP minerals dispersed in the rubbing contact area of the composite, inducing the formation of a tribolayer with a smooth nanocrystalline film. The tribolayer is mainly composed of titanium oxides (TiO, TiO2, and Ti2O3), iron oxides (FeO, Fe2O3, and Fe3O4), ternary compounds (Al18B4O33 and Al2Ti7O15), oxide ceramics (Al2O3 and SiO2), solid lubricating phases (graphite and attapulgite), iron, and enstatite (MgSiO3). The nanocrystalline structure composed of FeO, Fe2O3, and TiO, as well as the strengthening effect of hard phases such as SiO2, MgSiO3, Al2O3, Al18B4O33, and Al2Ti7O15, endowed the tribolayer with a high hardness, good plasticity, and toughness. The exceptional mechanical properties and dispersed solid lubrication phases of the tribolayer resulted in the excellent tribological properties of the ATP-TiB/Ti composite.

Attapulgite-based titanosilicate zeolite-supported Ni catalyst for hydrogen production from catalytic steam reforming of toluene

Catalytic steam reforming for hydrogen production was a viable tar removal technology. The key issue of catalytic steam reforming of toluene (tar model) for hydrogen production (CSRT) was the devise and development of advantageous catalysts. In this work, attapulgite-based titanosilicate zeolite (ATS) supported Ni-based catalysts was prepared and applied into CSRT. In addition, compared with the attapulgite (ATP), attapulgite-derived silicon source (HTP) and commercial TiO2, the effects of four different supports over the catalytic performance of Ni-based catalysts for CSRT were further investigated. The structural characteristics of the prepared catalysts were revealed by various characterization methods. Amongst, N/ATS appeared the highest toluene conversion (90.71%) and H2 yield (63.57%) during 4 h of CSRT reaction, which mainly attributed to its highest surface Ni0 molar ratio. Additionally, N/ATS revealed unique resistance to carbon deposition under harsh reaction conditions. This was mainly due to the synthesized ATS had larger BET and the highest hierarchical factor (HF) of pore structure which better promoted mass and heat transfer and its unique nanocluster assembled lamellar structure better anchoring the Ni metal and inhibited sintering, while its superior dispersion of weak acidic sites resulted in less carbon deposits. This work provided a probability for the preparation of economical attapulgite-based heteroatom zeolite to support Ni for hydrogen production via steam reforming of biomass-based oxygenates.

Fluorine-free and hot water repellent superhydrophobic palygorskite: A combined experimental and molecular dynamics study

The present work investigates the wettability of dodecyltrimethoxysilane (DTMS) functionalized palygorskite (PAL) using both experimental and molecular dynamics approaches. The best superhydrophobicity was achieved at a PAL/DTMS ratio of 0.60 g/mL. Changes in wettability were simulated by varying the DTMS grafting ratio from perspectives of contact angle, interaction energy, the water molecule’s distribution characteristics, and hydrogen bonds. The results show that DTMS grafting promotes hydrophobicity, whereas excess grafting ratio declines hydrophobicity due to roughness decrease. The hot water resistance was analyzed from interaction energy, diffusion behavior, and cohesion energy, and the findings are consistent with the experimental results.

A new nanocomposite of copper oxide and magnetite intercalated into Attapulgite clay to enhance the radiation shielding

The effects of Magnetite (Fe3O4) on the radiation shielding properties of different nanocomposites from Attapulgite (ATP) intercalated with different copper oxide (CuO) and magnetite nano (Fe3O4) concentrations were investigated. Different nanocomposites from ATP intercalated with different copper oxide CuO and magnetite nano Fe3O4 concentrations have been synthesized and implemented toward radiation attenuation. The different percent were as the following 40% ATP + X Fe3O4 + (60%–X) CuO that abbreviated to [AT40FeXCu60-x] where X = 15.0%, 30.0%, 45.0%. The ATP and one of the prepared nanocomposites have been characterized using different techniques: FT-IR, TGA, XRD, EDX, and SEM. The density of the synthesized materials was determined. Then their radiation shielding properties were established using GEANT4 and Phy-X software in the selected range of photon energies of 0.015 – 15 MeV. The linear attenuation coefficient (μ), the mass attenuation coefficient (μm), the mean free path (MFP), the half value layer (T1/2), the tenth value layer (T1/10), the effective atomic number (Zeff), and the equivalent atomic number (Zeq) have been calculated to find out the radiation shielding characteristics of the new novel nanocomposites. The μm values were varied from 4.5894 to 0.0204 cm2 g-1 for Base, from 11.9780 to 0.02172 cm2 g-1 for AT40Fe15Cu45, from 12.5030 to 0.02190 cm2 g-1 for AT40Fe45Cu15 and finally from 12.2480 to 0.02181 cm2 g-1 for AT40Fe30Cu30 at photon energy range from 0.015 to 15 MeV. The results showed that the values of the radiation shielding parameters increased with increasing nano Fe3O4 concentration, and the AT40Fe45Cu15 sample has the highest μm and μ and lowest T1/2, T1/10 and MFP. The results of this study have important implications for the development of new radiation-shielding materials. ATP-doped Fe3O4-CuO glasses are a promising new class of radiation shielding materials with improved properties. In conclusion, the study found that the nanocomposite materials with higher nano Fe3O4 concentration have better shielding qualities against γ-rays and neutrons. The AT40Fe45Cu15 sample has the highest shielding qualities for γ-rays, while the AT40Fe30Cu30 sample has the highest fast neutron removal cross-section.

Preparation and characterization of lithium-ion sieve with attapulgite

Extracting lithium from liquid lithium resources has emerged as a research hotspot. Attapulgite (ATP), a layered materials with unique pore structure, exhibits certain ion exchange properties, and is a suitable candidate for preparing lithium-ion sieves. In this study, high value lithium-ion sieve was prepared by high temperature synthesis method using inexpensive ATP. The prepared lithium-ion sieve H-ATP-3 calcined at 400 °C was achieved optimal adsorption efficiency, which was consistent with Langmuir and pseudo-second-order model and the maximum adsorption capacity reached 29.18 mg·g−1. After 5 cycles, the adsorption capacity only decreased to 26.46 mg·g−1, still reaching 90.68 %. In the simulated Mg2+ and Li+ ion solution, the adsorption capacity was 5.689 mg·g−1 and 28.66 mg·g−1, respectively. H-ATP-3 possessed excellent selective adsorption, stability and recycling properties. During adsorption, Li+ reacted with H-ATP-3, which formed Li4SiO4, Li2SiO3 and LiAlSi2O6, forming the Li+ memory pore. After Li+ adsorption, the specific surface area decreased from 185.50 to 15.14 m2/g, indicating Li+ entered ion sieve and filled the pore. Moreover, the -OH and interlayer water in H-ATP-3 exchanged with Li+. The synthesis method is relatively simple, and has high selectivity, effectively recovering Li+ and expanding the market application prospect of attapulgite resources.

Simultaneous and ultrafast removal of anionic and cationic dyes from aqueous solution by Zr-based MOFs hybridized by attapulgite and adsorption performance research

Zr-based MOFs hybridized by attapulgite (APT) were successfully prepared by simple reflux method and characterized by FTIR, BET, XRD, TGA and XPS. Both cationic and anionic dyes were efficiently, quickly and simultaneously adsorbed by UiO-66, 1%APT/UiO-66 and 5%APT/UiO-66 in 5 min. In anionic dyes (Congo red and alizarin yellow GG) and cationic dye methylene blue, adsorption capacities of UiO-66, 1%APT/UiO-66 and 5%APT/UiO-66 for Congo red were higher, 304.07, 585.00 and 394.63 mg/g, respectively. Capillary effect was adopted to explain characteristic trend of adsorption kinetic curves (first decrease and then increase of adsorption capacity in the second stage). Pseudosecond-order kinetic model and Langmuir isotherm was the best-fit model to evaluate adsorption behaviors of UiO-66, 1%APT/UiO-66 and 5%APT/UiO-66 for adsorption of Congo red. It was more favorable and effective for prepared materials to removal Congo red from solutions containing inorganic salts. When concentration of NaCl was 0.09 mol/L, adsorption capacities of 1%APT/UiO-66 were increased to 589.77, 724.56 and 635.59 mg/g, accordingly. UiO-66, 1%APT/UiO-66 and 5%APT/UiO-66 exhibited good stability and reusability. Main adsorption driving forces were hydrogen bonding interactions, π-π conjugations, electrostatic interactions and sieving effects, and adsorption driving forces of 1%APT/UiO-66 were largest. Above results indicated that UiO-66 hybridized by APT could simultaneous and ultrafast removal of anionic and cationic dyes in aqueous solution, and were potential adsorbents in practical application.

Enhancing CO2 desorption rate in rich MEA solutions by metal-modified attapulgite catalyst

To overcome the high energy consumption of the CO2-rich monoethanolamine (MEA) solution regeneration process, this study proposes to catalytically promote CO2 desorption using transition metal-modified attapulgite (ATP) composite catalysts (M/ATP, M = Ni, Zr) in a 5 M CO2-loaded MEA solution at 90 °C. The catalysts were characterized by XRD, FT-IR, BET, and Py-IR. The influences of different metals and metal salts on the activity of CO2 desorption for the ATP-based composite catalyst were studied. The findings proved that the introduction of metal oxide enhanced the activity of catalytic CO2 desorption for the ATP catalyst and reduced the relative energy requirement. Ni/ATP presented the superior catalytic activity, with an increase of 195 % and 144 % in the rate of CO2 desorption and desorption amount, respectively, compared with the noncatalytic desorption process. The excellent catalytic performance of metal-modified ATP composite catalysts was mainly due to the enhanced Brønsted acid sites. After 8 cycles of CO2 absorption–desorption experiment, the Ni/ATP catalyst still showed excellent stability. The introduction of the Ni/ATP catalyst had no adverse impact on the CO2 absorption in the MEA solution. Moreover, a possible catalytic MEA solution regeneration pathway over Ni/ATP was suggested based on FT-IR and 13C NMR measurements.

Clay-based aerogel combined with CuS for solar-driven interfacial steam generation and desalination

Solar-driven water purification is a promising technology that can effectively utilize solar energy for seawater desalination. However, poor materials are unable to meet the dense energy of solar steam generation in natural sunlight for real-time practical applications. Therefore, the demand for energy density can be increased by using improved semiconductor aerogel materials. Here, we report a simple chemical method to obtain a CuS@ATP/PS composite aerogel (named CuAP), which was made of attapulgite (ATP) and CuS loaded onto it using an N-template to give it good photothermal characteristics (CuS@ATP), and then cross-link it with potato starch (PS). The evaporation rate of CuAP-15 aerogel in pure water at 1 kW m−2 solar radiation is 1.57 kg m−2 h−1. Meanwhile, CuAP-15 aerogel showed excellent salt resistance with an evaporation rate of 1.35 kg m−2 h−1 in 20 wt% NaCl solution. And also exhibited excellent cycling durability in cycling stability tests. More importantly, the freshwater yield can reach 6.54 kg m−2 under natural light irradiation for 11 h. Therefore, CuAP aerogel has a great prospect of application in the field of seawater desalination in the future.

Performance and mechanisms of active attapulgite-supported sulfidated nanoscale zero-valent iron materials for Pb(II) removal from aqueous solution

To inhibit the oxidation, passivation, and agglomeration of nano-zero-valent iron (nZVI), a liquid phase reduction method was used to load sulfurized nZVI onto acid-modified ATP with attapulgite (ATP) as the carrier (S-nZVI@ATP). The performance and mechanism of this material were studied for Pb2+ removal in water. The S-nZVI@ATP preparation prevents the agglomeration of nZVI particles and reduces nZVI oxidation. Pb2+ removal proceeds efficiently and stably when using S-nZVI@ATP at pH values ranging from 2.5–5.5. According to the electron sharing and transfer-based pseudo-second-order kinetic model, the Pb2+ is adsorbed onto S-nZVI@ATP, and the speed control step is completed by liquid film diffusion and intraparticle diffusion. The S-nZVI@ATP mediated Pb2+ adsorption is well-described by Freundlich’s isothermal adsorption model, which is a multilayer chemical adsorption process. The temperature and initial Pb2+ concentration were varied, and it was determined that Pb2+ adsorbs on S-nZVI@ATP in an endothermic reaction. This S-nZVI@ATP composite material has high reducibility, high surface activity, and good adsorption properties for Pb2+. Tests were performed for 24 h using adsorbent (1 g l−1) in Pb2+ solution (30 ml). For an initial Pb2+ concentration of 700 mg l−1, S−1-nZVI@ATP removes 57.37% of the Pb2+ and has an adsorption capacity of 401.60 mg g−1. In addition to forming PbS and Pb(OH)2 precipitates, Pb2+ also complexes with the Fe/H oxide shell of S-nZVI@ATP, and Fe0 reduces some Pb2+ on the nZVI to Pb0. The results exhibited that S-nZVI@ATP has excellent potential as an adsorbent for the removal of Pb2+ from the industrial wastewater.

Enhanced sludge dewaterability using a bifunctional hybrid coagulant

The combination of coagulation and addition of skeleton builder is a popular pretreatment method to improve the dewaterability of sludge. In this study, a novel bifunctional inorganic/organic hybrid coagulant (CS–Si@ATP) was designed and obtained by chemically coupling a cationic starch (CS) with a popular clay, that is, attapulgite (ATP), via a silane coupling agent (APTES) for one-step conditioning of sludge. CS-Si@ATP can evidently enhance the sludge dewatering performance compared with CS, ATP, and their simple combination due to the distinct dual functions of this hybrid coagulant. The tentacle-like cationic CS in CS-Si@ATP shows efficient charge neutralization effect to aggregate and precipitate the suspended solids for further formation of compact sludge cakes. Meanwhile, the internal ATP with a stable and rigid structure acts as the skeleton builder to notably improve the filterability and permeability of the sludge cakes. The synergistic effects of CS and ATP in CS-Si@ATP, i.e., the charge neutralization of CS and the skeleton construction of ATP, cause the evidently enhanced sludge dewaterability, with a filter cake moisture content approximately 78.30% after the mechanical dewatering at 0.05 MPa. In comparison with the traditional two-step combination process by separated addition of CS and ATP, the one-step addition of CS-Si@ATP can reduce the required ATP dose nearly an order of magnitude. Thus, CS-Si@ATP has the notable advantages of simple operation, efficient utilization of ATP and evident reduction of disposal cost. This study provides an environmentally friendly and cost-effective coagulant to further improve the dewaterability of sludge.

Attapulgite-based superhydrophobic coating on aluminum alloy substrate with self-cleaning, anti-corrosion and robustness

In this paper, we fabricated a mechanically stable, self-cleaning, and corrosion-resistant superhydrophobic coating on 5083 aluminum alloy substrates based on attapulgite (ATP) clay, organosilane, and waterborne epoxy resin through air spraying technique. The surface wettability variations, micro-nano scale structures, and chemical compositions of the coating were evaluated using contact angle meter, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), energy dispersive spectroscopy (EDS), and Fourier transform infrared spectroscopy (FTIR). The results showed that the charge transfer resistance (Rct) of the spray-coated superhydrophobic surface was increased by five orders of magnitude with a corrosion inhibition efficiency of 99.99 %, indicating a significant anti-corrosion capacity. Moreover, the prepared superhydrophobic coating demonstrated enhanced coating/substrate bonding force and abrasion resistance, as they could withstand a sandpaper abrasion distance of 2800 cm, confirming the durability and robustness of the coating.

Combined modification of asphalt with organic attapulgite (OATT) and polyurethane (PU): preparation, properties and modification mechanisms

Polyurethane (PU) and attapulgite (ATT) have been proven to have good effects on asphalt modification. This study proposes to use both PU and organic attapulgite (OATT) to prepare a modified asphalt, aiming to improve the comprehensive performance of asphalt and study the synergistic modification effect of PU and OATT on asphalt. Firstly, the structure and composition of ATT and OATT were determined by X-ray diffraction, scanning electron microscope, and Fourier transform infrared spectroscopy. Then the OATT/PU modified asphalt was investigated in terms of compatibility, basic physical properties, high- and low-temperature rheological properties, and high-temperature stability. Results indicated that the organic modifier was successfully grafted onto ATT. OATT and PU present a good synergy in asphalt and play a significant role in improving the high- and low-temperature performance of modified asphalt. The addition of OATT led to significant and consistent improvement in the high-temperature performance of the OATT/PU modified asphalt. At the same time, the increase of OATT content also helps to improve the low-temperature performance of the modified asphalt. Finally, the optimum contents of modifiers are recommended. The modified asphalt 3 wt%OATT/7wt%PU is suggested for areas with long duration of high temperatures, while 3 wt%OATT/9wt%PU is suggested for areas with long duration of low temperatures.

The preparation of cerium nitrate and attapulgite based superhydrophobic epoxy coatings for the corrosion protection of Q355 mild steel surface

The current research focus is to design a robust micro/nano-structured superhydrophobic epoxy coating to improve the wetting and anti-corrosion behavior of Q355 mild steel in harsh environment and obtain desired properties of self-healing and self-cleaning. Modified attapulgite (APT) and cerium nitrate based high-performance corrosion inhibitor ODA/PDA/APT-Ce3+ (OPACe3+) coatings were synthesized by the addition of dopamine (DA) and octadecylamine (ODA) which resulted in excellent corrosion inhibition by enhancing the corrosion protection performance of metal alloy and improving the water contact angle of the synthesized epoxy based OPACe3+ coating to more than 160°. While wettability and corrosion protection were strongly associated with cerium nitrate and DA content, the surface microstructure of coated steel samples were relevant to attapulgite quantity. Moreover, the OPACe3+ surface coating demonstrated good self-healing properties to counter chemical deterioration in harsh environment after being exposed for several hours to 3.5 wt% sodium chloride, acidic and alkaline solution. It was able to regain its superhydrophobic properties following hot air flow over the coating surface. The OPACe3+ epoxy coatings displayed long-lasting and outstanding self-healing performance in terms of its wettability and electrochemical stability.

Preparation and performance of superhydrophobic surfaces with low surface energy modified attapulgite

Material modification with low surface energy can offer lower surface free energy on micro- and nano-rough structures, which is necessary for developing superhydrophobic surfaces. Based on experiment and molecular simulation, the composite systems of attapulgite (APT) modified by alkylamine, alkylammonium salt and stearic acid were prepared. Combine surface free energy, electrostatic potential distribution, self-diffusion coefficient, and interfacial formation energy to favor the superhydrophobic composite system, and the interaction between low surface materials and attapulgite was explained. The results demonstrate that the hydrophobicity of APT are clearly modified by alkyl amine, alkyl ammonium salt, and stearic acid, and that when the molecular number of low surface energy monomers increases, the surface free energy of the composites first decreases and then increases. At the ideal concentration, the contact angles of alkyl amine/APT and SA/APT composites are all greater than 150°, and the antifouling performance is excellent. Finally, compounding technology was used to further optimize the superhydrophobic composite system. It was discovered that the hydrophobicity and antifouling properties of the composite system were superior to those of the monomer, and the octadecylamine/SA/APT composite system performed optimally at a contact angle of 167.54°.

Preparation and properties of PVC composites filled with walnut shell powder hybrid attapulgite

AbstractIn order to reveal the effect of alkali treatment of walnut shell (WS) powder and attapulgite (ATP) hybrid filling on the properties of WS/polyvinyl chloride (PVC) composites, and to compare the effects of different reinforcement methods, WS/PVC composites were prepared by single screw melt extrusion. Furthermore, analysis was conducted on the chemical composition, thermal stability, microstructure, and physical, mechanical and wear resistance properties of composites. The results showed that ATP hybrid can enhance the performance of WPC more effectively than alkali treatment, unmodified WS blended with ATP composites have the best physical, mechanical properties, abrasive wear resistance, as well as lower water absorption, compared with the untreated, the tensile strength, bending strength and impact strength increased by 24%, 8%, and 21%, respectively. In addition, the composites of ATP hybrid alkali treated WS have the best thermal stability, and its pyrolysis residue is 15.64% higher than untreated composites. The study found that ATP have a larger potential to enhance the properties of composites than alkali treatment.Highlights Chemical treatment and inorganic mineral particle filling were used to enhance the properties of the WS/PVC composites. The experimental results showed that attapulgite can maximize the properties of the composites without alkali treatment. This means that attapulgite filling is a more effective and environmentally friendly and simple method to enhance the properties of composites than alkali treatment. The wear failure modes of the composites are mainly micro‐indentation and micro‐cutting.

Lanthanum and magnesium activated palygorskite for adsorption of phosphate in piggery wastewater.

Removing phosphate from wastewater can help alleviate eutrophication. Therefore, in this study, lanthanum and magnesium were loaded onto the thermally modified palygorskite (PAL) using a coprecipitation method, and a composite material was prepared for phosphate recovery. In the pH range of 2-7, the material can effectively adsorb the phosphate. In the kinetic experiment, the material was able to rapidly adsorb phosphate within 4 h of the beginning of the reaction. The adsorption isotherm result of the material was in accordance with Freundlich isotherm model. When pH was 7, the theoretical maximum adsorption capacity was 20.4 mg P/g. When phosphate coexisted with CO32- and HCO3-, the adsorption was significantly inhibited. In the adsorption-desorption experiment, the material can be reused at least five times after elution with 1 mol/L of sodium hydroxide solution. The equilibrium adsorption capacity of the material for total phosphorus in piggery wastewater was 7.25 mg P/g, achieving a total phosphorus removal rate of 95.3%. The characterization of XRD, FT-IR and XPS suggested that phosphate was mainly exchanged with La-OH in the material, forming an amorphous LaPO4 complex.

Super-amphiphobic arabic gum-based coatings on textile for on-demand oily and dye wastewater treatment

Different membrane materials have broadly been constructed for oil-containing water separation, but most of preparation routes involve corrosive or toxic chemicals and especially many materials have only single superwetting property. Herein, a novel and eco-friendly cellulose-based textile membrane is developed by incorporating the composite coating consisting of arabic gum (AG), attapulgite (APT), and iron (Fe) onto cellulose textiles. The functionalized textile is superoleophobic underwater and superhydrophobic underoil. As a result, the textile prewetted with water or oil can be employed to separate light oil layer/water and heavy oil layer/water mixtures, respectively, and the separation efficiency to the two types of mixtures is larger than 98.3 %. Results also reveal that the decorated textile possesses superior stability and recyclability in purifying oily wastewater. More importantly, such coated textile is capable of filtrating water-soluble contaminants (dyes) from polluted water. Due to the versatility and environmental compatibility of product as well as the accessibility as agricultural and forestry product as raw materials, the advanced textiles may offer effective solutions to oily wastewater purification and water-soluble contaminant removal.

Degradation of malachite green by g-C3N4-modified magnetic attapulgite composites under visible-light conditions.

Water resources are seriously threatened by dye wastewater, and the removal of the dye molecules from the wastewater has garnered considerable interest. People have favored photocatalytic technology in recent years for the treatment of dye wastewater. In this work, attapulgite (ATP) was used as a carrier, Fe3O4 and g-C3N4 were grafted onto ATP, and the surface was then modified with polyethyleneimine (PEI) to produce photocatalyst ATP-Fe3O4-g-C3N4-PEI, which was used in Malachite green (MG) dye wastewater. The structure and surface properties of the composites were analyzed and characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray spectrum (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Uv-vis spectrum analysis, zeta potential measurement, and vibrating-sample magnetometry (VSM) analysis. The removal performance of ATP-Fe3O4-gC3N4-PEI for MG was studied, and the removal mechanism was explored and revealed. It has been shown that the heterojunction formed by Fe3O4 and g-C3N4 can inhibit the compounding of photogenerated electrons and holes, effectively improving the performance of the ATP-Fe3O4-g-C3N4-PEI. Electron paramagnetic resonance (EPR) analysis confirmed that ATP-Fe3O4-g-C3N4-PEI could generate hydroxyl radicals (·OH) and superoxide radicals (·O2-) to degrade the MG. It was believed that ATP-Fe3O4-g-C3N4-PEI could generate hydroxyl radicals (·OH) through the photocatalysis and the Fenton reaction of the composite materials. Under the action of H+, ·O2-, and ·OH, the removal rate of MG by ATP-Fe3O4-g-C3N4-PEI exceeded 98 % at an optimal condition. The intermediate products and degradation pathways of MG degradation were also inferred by LC-MS analysis. These results showed that the prepared photocatalyst has excellent degradation performance for MG and could be used in dye wastewater treatment.

Experimental study and chemical affinity model on the inhibition of CO2 gas hydrate formation

Natural gas and water can form complex cage crystals in oil and gas pipelines under certain conditions. The natural gas hydrate formed after crystal clustering can block the pipeline and affect the operation efficiency of the pipeline, and even cause equipment damage, bringing economic and security problems to enterprises. In the present study, we experimentally investigated the inhibition of CO2 formation hydrate using attapulgite (ATP) and glucose (GLC). The kinetic influence on the formation of CO2 hydrate by the complex pairing of kinetic inhibitor ATP is conducted under the working conditions of 277.15 K and 3.5 MPa. The effect of compound inhibitors on the temperature and pressure conditions, growth process and gas consumption of hydrate formation are revealed. The chemical affinity model of CO2 hydrate formation under a compound inhibitor system is derived and established based on experimental studies. The results show that the combination of GLC and ATP can inhibit the formation of CO2 hydrate to varying degrees, prolong the induction time of hydrate, and reduce the consumption of CO2. The optimized experimental studies demonstrate that the best inhibitory compound system is 15 mg/mL GLC + 1.00 mg/mL ATP. Compared with the pure water system and single 15 mg/mL GLC system, the induction time is extended by 122.61% and 122.23%, while the gas consumption is reduced by 23.72% and 3.41%. The results provide new ideas and methods for the prediction of hydrate formation in the compound inhibitor system for the safe operation of oil and gas pipelines.

Effects of synthesis parameters on the performance of crosslinked Co-polymers with clays for conformance control

Conformance control or water shut-off is a technique used to improve oil recovery. During conformance control, polymers block high permeability water areas and redistribute water drive toward unswept oil zones. In this study, co-polymers (denoted ATP-PGV/AM-co-AMPS) were synthesized using acrylamide (AM) and 2-acrylamide-2-methylpropane sulfonic acid (AMPS) as the monomers, polyethylene glycol (PEG)-200 and methylenebisacrylamide (MBA) as the crosslinkers, attapulgite (ATP) and bentonite (PGV) as the clay types, and ammonium persulfate (APS) as the initiator, in addition to paraffin oil and surfactants. Samples were synthesized using inverse emulsion polymerization with different concentrations of monomers, crosslinkers, and clays, and they were characterized using Fourier-transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX). FTIR spectra of the samples confirmed the existence of sulfonate and hydroxyl groups, which are important for polymer swelling. SEM-EDX images indicated that the morphology and elemental composition were different before and after swelling, confirming the occurrence of swelling. Moreover, samples were placed in sodium chloride solution (20,000 ppm) for 7 days to evaluate swelling at both room temperature and 90 °C. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were used to determine the thermal characteristics of the microparticles. Finally, rheological measurements were used to assess the deformation and rheological behavior of the hydrogels. The results showed that after 1 day, good swelling without loss of mechanical strength was achieved with the composite synthesized using 10% AM, 15% AMPS, 6% PGV, and 10% ATP.