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•PMS activation with novel FeOCl was efficient for removal of NASIDs.•Key role of ·OH and 1O2 were confirmed at acid and basic pH.•Cycles of Fe2+ /Fe3+ were answerable for ROS ...generation.•The calculated toxicity of DBPs decreased with pH increase.
Iron oxychloride (FeOCl) is utilized as a activator of peroxymonosulfate (PMS) for the degradation of paracetamol (APAP) and phenacetin (PNCT) in response to the water pollution by persistent pharmaceuticals. The degradation process was well fitted with a pseudo-first order kinetic pattern, and the excellent catalytic performance towards APAP (100 % removal) and PNCT (86.5 % removal) was obtained in the presence of 0.2 g/L FeOCl and 2.0 mM PMS at pH 7.0 in 30 min. In-situ electron spin resonance (ESR) and scavenging tests revealed the generation of a series of ROS (·OH, SO4−, O2−, 1O2), which was highly dependent on pH. Besides, the non-radical pathways process involved 1O2 was dominant in APAP oxidation, while both ·OH and 1O2 are significant in PNCT removal. Furthermore, the formation of disinfection by-products (DBPs) during post-chlorination showed neglectable increment at neutral and alkaline condition with FeOCl/PMS pre-oxidation, and the calculated cytotoxicity would experience a continuous deterioration with pH increase. These results displayed high efficiency of FeOCl/PMS system in micropollutants degradation and a relatively comprehensive activation process of PMS, which may promote practical application in environmental remediation.
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•Inorganic basalt fiber was modified with CPAM as carrier media.•Huge amount of biomass was harvested on the modified BF surface.•The extended DLVO theory was introduced to interpret ...the initial adhesion behavior.•Contributions of different interaction energy to bacteria adhesion was quantified.
Surface properties of carrier are critical for microorganism initial adhesion and biofilm formation in wastewater treatment. Until now, there are few reports on adhesion behaviors between bacteria and inorganic fiber surface. In this study, inorganic basalt fiber (BF) was modified with cationic polyacrylamide (CPAM) to make surface more hydrophilic and positively charged. The initial adhesion behaviors of BF modified with CPAM (CMBF) were interpreted by thermodynamics and extended Derjaguin–Landau–Verwey–Overbeek (DLVO) theory. According to the total interaction energy calculated by the extended DLVO theory, insurmountable energy barrier between BF and Escherichia coli (E. coli) made irreversible adhesion unachievable due to hydrophobicity and electronegativity of BF, but allowed reversible adhesion at second minimum. By contrast, the energy barrier between CMBF and E. coli could be overcome allowing irreversible bacterial adhesion and thus a huge amount of biomass because of hydrophilicity and electropositivity of CMBF. The results showed the total interaction energies were dominated by Lewis acid-base and electrostatic interactions and coating BF with CPAM could promote initial bacterial adhesion on carrier surface. Overall, the extended DLVO theory provides a comprehensive tool to interpret initial adhesion behaviors between bacteria and inorganic fibers.
The water loss and soil erosion in the Pisha sandstone region in the middle reaches of the Yellow River are extremely severe, leading to extremely harmful effects on the ecological environment and ...safety of the lower reaches. In this paper, the effects of the slope angle (20, 30, and 40°), rainfall intensity (20, 50, and 80 mm/h), and vegetation coverage (10, 30, and 50%) on the erosion characteristics of the Pisha sandstone slopes are studied using indoor-simulated rainfall tests. The results show that the infiltration into the Pisha sandstone is only 10~15%. It is found that rainfall intensity has the most significant effect on runoff, which gradually increases with increasing rainfall intensity. Vegetation significantly affects runoff reduction when the rainfall intensity is low (approximately 20 mm/h), but this effect decreases with increasing rainfall intensity. Rainfall intensity has an extremely significant effect (
P
< 0.01) on the sediment yield, followed by vegetation coverage, and slope angle. When the vegetation coverage is approximately 50%, the reduction in sediment yield reaches approximately 70%. Additionally, the sediment reduction benefit is more significant than the runoff reduction benefit. The presence of the eroded gullies on slopes with vegetation is less compared to that on the bare slopes. Therefore, relatively high vegetation coverage (≥ 50%) is required for soil and water conservation in Pisha sandstone area. The findings will provide some reference for Pisha sandstone conservation.
The effects of the wet-dry cycles on the chemical compositions, microstructure, and mechanical properties of Pisha sandstone were experimentally investigated in the current study. A series of ...uniaxial compression tests were conducted to validate the deterioration of the mechanical property of specimens after wet-dry cycles. In addition, the evolutions of the mineral compositions and microstructure characteristics were confirmed by X-ray diffraction (XRD) and scanning electron microscope (SEM). Experimental results indicated that with the increase of wet-dry cycles, the mechanical properties of Pisha sandstone gradually decrease. After five wet-dry cycles, the uniaxial compressive strength, elastic modulus, and fracture energy of specimens were reduced by 41.06%, 62.39%, and 31.92%, respectively. The failure mode of the specimen changes from inclined shear failure to peel failure. Compared to the initial specimens, the relative content of primary minerals after five wet-dry cycles declined by 5.94%, and the relative content of clay minerals after five wet-dry cycles increased by 54.33%. Additionally, the porosity of samples exhibits a positive correlation with wet-dry cycles. Compared to the initial specimens, the porosity of specimens after five wet-dry cycles increased by 176.32%. Finally, a prediction model of the correlation between uniaxial compressive strength and porosity is proposed and verified.
Feldspathic sandstone is a type of sandstone that is severely eroded by wind, rainfall, and gravity forces. The land surface in feldspathic area is degraded and covered with extremely low vegetation ...coverage. In this study, we propose a type of hydrophilic polyurethane (W-OH) to control its erosion and conduct the experiment to evaluate the consolidation performances. The results showed that the cementing materials (such as montmorillonite) are the main reason for the vulnerability of feldspathic sandstone to erosion, which expands by absorbing water. Additionally, the organic content is extremely low and is not suitable for vegetation growth. However, when the different concentrations of W-OH solution were sprayed on the feldspathic sandstone surface, the solution could penetrate in several minutes and form a flexible and porous consolidation layer. The anti-scourability index (
K
) of the layer could increase from approximately 0.2 to 1.0 which significantly increased the water resistance. The water retention benefit increased by 50%. In the simulated rainfall test, the sediment yield reduction in the treated slopes sprayed with the W-OH solution could reach 99% compared with that on the control slopes. The SEM images indicated that the W-OH solution enveloped the feldspathic sandstone particles and connected them tightly together. Therefore, the consolidation layer could decrease water erosion rate and reduce evaporation.
After phenanthrene contaminated soil is treated by g-C3N4 under visible light, the toxicity of contaminated soil was significantly reduced.
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•Soil remediation method based on g-C3N4 is ...technologically feasible.•g-C3N4 can release O2− to degrade the phenanthrene in contaminated soil under visible light irradiation.•The toxicity of phenanthrene contaminated soil can be significantly reduced by g-C3N4.
An environmental-friendly soil remediation method based on the g-C3N4 has been developed to remediate phenanthrene contaminated soil. g-C3N4 has been synthesized by three different precursors including urea, dicyandiamide, and melamine via the conventional thermal polymerization method. Under visible light or natural sunlight, g-C3N4 exhibits excellent photocatalytic activity for the degradation of phenanthrene in contaminated soil at circumneutral pH. Compared with g-C3N4 synthesized by dicyandiamide and melamine, g-C3N4 synthesized by urea has the highest surface areas and degradation activity of phenanthrene in soil. After phenanthrene contaminated soils were treated by g-C3N4, the ecotoxicity of soils was preliminarily evaluated by cultivating plant (lettuce) and raising earthworms (Eisenia fetida). Phenanthrene contaminated soil (200 mg/kg) exhibits obvious toxicity which the growth of lettuce has been inhibited significantly and earthworms can not even survive. Under visible light or natural sunlight, g-C3N4 synthesized by three different precursors can remarkably reduce the toxicity of phenanthrene contaminated soil, which was demonstrated by the lettuce growth indexes, involving leaf length, stem length, root length, and fresh weight, and earthworms’ mortality and weight loss. However, compared with the other two g-C3N4 synthesized by dicyandiamide or melamine, g-C3N4 synthesized by urea presents clear relative toxicity on lettuces and earthworms.
An energy-efficient and environmentally friendly nitrogen fixation process is urgently needed to solve problems of high energy consumption and high emissions in the traditional ammonia industry. In ...this work, a Z-scheme porous g-C
3
N
4
/ZnFe
2
O
4
photocatalyst was synthesized, characterized and employed for N
2
photofixation. Temperature programmed desorption characterization confirmed that the adsorption capacity of nitrogen was improved for the porous structure. From N
2
photofixation evaluation experiments, the highest ammonia production efficiency can reach 147.33 μmol/L within 120 min. Photocatalytic performance is greatly improved because of the increasing of specific surface areas, enhancement of N
2
adsorption ability and synergistic effect of Z-scheme photocatalytic system. In the ammonia production process of the research, visible light is used as energy; N
2
and H
2
O are used as raw materials, which possesses a good application potential due to the advantages of being energy-efficient, environmentally friendly and pollution-free.
Currently the investigation on recycled cement concrete aggregate has been widely conducted, while the understanding of the recycled polymer concrete aggregate is still limited. This study aims to ...fill this knowledge gap through the experimental investigation on mechanical and durability performance. Specifically, the remolded polyurethane stabilized Pisha sandstone was collected as the recycled polymer concrete aggregate. The remolded Pisha sandstone was then applied to re-prepare the polyurethane-based composites. After that, the mechanical performance of the prepared composites was first examined with unconfined and triaxial compressive tests. The results indicated that the Pisha sandstone reduces the composite's compressive strength. The reduction is caused by the remained polyurethane material on the surface of the remolded aggregate, which reduces its bond strength with the new polyurethane material. Aiming at this issue, this study applied the ethylene-vinyl acetate (EVA) to enhance the bond performance between the polyurethane and remolded sandstone. The test results indicated both the unconfined and triaxle compressive strength of the polyurethane composites were enhanced with the added EVA content. Furthermore, the durability performance of the EVA-modified composites were examined through freeze-thaw and wet-dry cycle tests. The test results indicated the EVA could enhance the polyurethane composites' resistance to both wet-dry and freeze-thaw cycles. Overall, the modification with EVA can compensate for the strength loss of polyurethane composites because of the applied remolded aggregate and enhance its sustainability.
Stabilization of the loose and fragile Pisha with the hydrophilic polyurethane material has been proved to be a time and cost-efficient protocol for the conservation of soil and water. However, the ...undesirable durability performance of the original W-OH binder material deteriorate its long-term conservation ability, especially under the freeze-thaw cycles. This study aims to improve the freeze-thaw durability performance of the W-OH composites through mixture design optimization and material modification. This study first investigates the correlation between the freeze-thaw resistance of the W-OH/Pisha sandstone composites and the concentration of the applied W-OH solution. The test results indicated both the compressive strength and elastic modulus of the W-OH based composites would decrease with freeze-thaw cycles and the samples prepared with higher concentration W-OH solution own better freeze-thaw resistance. Meanwhile, the elastic modulus of the W-OH composites decreased almost linearly with the freeze-thaw cycles, which is in accordance with the linear increase of the porosity of samples determined with the ultra-depth-of-field microscope. Based on these mechanism analyses, the modification of the W-OH material was further conducted with the Ethylene-vinyl acetate (EVA) and air entrainer. The compressive strength test results indicate both the added EVA can enhance the freeze-thaw durability of the W-OH composites, which can be caused by the improved cohesion strength of the W-OH binder due to enhanced density. Similarly, the freeze-thaw durability of the W-OH composites was also enhanced with added air entrainer, which provided extra space for the freezing expansion. The research results of this study can enhance the freeze-thaw durability of the stabilized Pisha sandstone and its long-term conservation ability on soil and water.
•The freeze-thaw resistance of the polyurethane stabilized sandstone was obtained for guiding the field application.•A non-destructive protocol was built with the ultra-depth-of-field microscope to examine the freeze-thaw damage.•Both the Ethylene-vinyl acetate and air entrainer can enhance the freeze-thaw resistance of the stabilized sandstone.•It is found the freeze-thaw cycles mainly lead to cohesion damage instead of adhesion failure in the stabilized sandstone.
The feasibility of preparing coal gangue-based geopolymer mortar (CGBGM) with composite-activated coal gangue was experimentally explored in this paper. The effects of water-to-binder ratio (W/B), ...alkali content (A), and slag content (S) on the fluidity and performances of the CGBGM were experimentally investigated. The ANOVA method was employed to evaluate the significance level of influenced factors. Moreover, the microstructure, element compositions, and qualitative microanalysis of the CGBGM at various curing ages were verified by ESEM-EDS. Test results denoted that the mechanical properties of the CGBGM are superior to that of ordinary Portland cement mortar (OPCM). The flexural and compressive strength of the CGBGM rapidly increases before 7 d and then tends to slow afterward. According to the impact degree on the flexural and compressive strength of the CGBGM, the S is ranked first, followed by the A, and finally the W/B. The flexural and compressive strength of specimens with 40% slag increased by 45.97% and 90.75%, respectively, compared to the control group. However, the A and W/B have little effect on flexural strength. In addition, the hydration productions filled in the crevice and healed the entrapped microcracks in the hardened paste with the increase in curing ages, forming a dense microstructure. The Ca/Si decreased from 0.5 at 3 d to 0.06 at 28 d, and the Ca/Al decreased from 0.25 at 3 d to 0.05 at 28 d. Finally, the difference in drying shrinkage behavior between the CGBGM and OPCM was systematically analyzed.
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