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Characterization of irradiation defects is of great importance to mitigate irradiation damage, reduce irradiation growth and tune mechanical properties in Zr alloys. Here, we describe a practical method to characterize the dislocation loops in irradiated Zr using conventional transmission electron microscopy (TEM). Vacancy or interstitial nature of dislocation loops is determined using the inside and outside contrast method. The habit plane of dislocation loops is determined by tilting the sample to multiple zone axes and judged based on the projected loop shape. The size of $$\left\langle a \right\rangle$$ loops is measured by tilting the sample to an edge-on position and the loop number is counted under a weak-beam dark-field TEM condition. $$\left\langle c \right\rangle$$ loops have a line contrast under viewing direction of a-axis and a circular shape under viewing direction of c-axis. In addition, a large number of triangle-shaped vacancy platelets (TVPs) were formed on the basal plane. With increasing the irradiation damage from 0.5 to 1.5 dpa, the number density of $$\left\langle a \right\rangle$$ loops keeps constant, while the number density of TVPs increased significantly, owing to the anisotropic diffusion and accumulation of point defects within basal plane. The methods introduced here are easy to follow and extend into other related investigations.

As one of the major irradiation defects, helium bubbles have a marked influence on the microstructures and mechanical properties of metals. In recent decades, many experiments and simulations have focused on helium bubbles to reveal their nucleation and growth mechanisms, dynamic evolution under stimulations, and their effects on mechanical properties. With the quick development of various in situ techniques, the abundant dynamic features of helium bubbles have been revealed. In this review, we briefly explore the related researches on the dynamic evolution of helium bubbles under simulated service conditions, such as at high temperatures, under irradiation, and upon mechanical loading. We also discuss the challenges and opportunities in revealing the dynamics of helium bubbles using in situ technologies. This short review intends to advance our understanding of the failure mechanisms of helium-irradiated metals and the basic properties of irradiation-induced helium bubbles.

Radiation-induced helium bubbles are detrimental to the mechanical properties of metals, usually causing severe hardening and embrittlement. Hexagonal close-packed (HCP) α-Zr alloys are one of the primary structural materials for nuclear applications, however, the effect of helium bubbles on their deformation and fracture behaviors still remains unexplored. Here, we found that ordered helium bubbles prefer to align along the basal plane in HCP α-Zr. Micro-scale in situ tensile tests revealed that helium bubbles less than 8 nm in size can increase the critical resolved shear stress of the prismatic slip. However, once the helium bubbles are larger than 8 nm, a bubble-softening effect happens due to a decrease in number density of helium bubbles and an increase in porosity. Once the Schmid factor of basal slip is considerably higher than prismatic slip, bubble coalescence along the basal plane becomes the major failure mode in helium-irradiated α-Zr.

The formation of hydrides challenges the integrity of zirconium (Zr) fuel cladding in nuclear reactors. The dynamics of hydride precipitation are complex. Especially, the formation of the butterfly or bird-nest configurations of dislocation structures around hydride is rather intriguing. By in-situ transmission electron microscopy experiments and density functional theory simulations, it is discovered that hydride growth is a hybrid displacive-diffusive process, which is regulated by intermittent dislocation emissions. A strong tensile stress field around the hydride tip increases the solubility of hydrogen in Zr matrix, which prevents hydride growth. Punching-out dislocations reduces the tensile stress surrounding the hydride, decreases hydrogen solubility, reboots the hydride precipitation and accelerates the growth of the hydride. The emission of dislocations mediates hydride growth, and finally, the consecutively emitted dislocations evolve into a butterfly or bird-nest configuration around the hydride.

Interface engineering is a useful method to reduce the accumulation of irradiation defects in metals. Here, we study the effect of interface on the formation of dislocation loops in helium and krypton ions irradiated nanolayered Zr-2.5Nb. Nanolaminated α/β-Zr duplex-phase structures remain stable after irradiation at 400 °C up to 20 dpa. Dislocation denuded zones with width of 30 to 40 nm are formed at interfaces. The number density and size of both a-loops and c-loops are smaller in nanolayered sample because of interface accelerating point defects recombination. These observations indicate that α/β-Zr interfaces effectively reduce dislocation loops formation.

A novel adsorbent, namely, β-cyclodextrin/poly ( l -glutamic acid) supported magnetic graphene oxide (CGMG), was synthesized through a facile chemical route and its application as excellent adsorbent for 17β-estradiol (E2) removal from aqueous solution was also demonstrated. The characteristics of CGMG were investigated via using Fourier transform infrared spectrometer, X-ray photoelectron spectroscopy, Raman spectra, X-ray diffraction, vibrating sample magnetometer and Brunauer-Emmett-Teller surface area, respectively. Results indicated that CGMG was successfully prepared and the saturated magnetization could reach up to 0.09043 emu/mg. Meanwhile, investigation of adsorption behavior illustrated that the adsorption process could be better fitted by the pseudo-second-order and Langmuir models. Analysis of intraparticle diffusion model demonstrated that intraparticle diffusion was not the only rate-limiting step; however, both film diffusion and intraparticle diffusion were involved in the diffusion process. Thermodynamic study indicated that adsorption of E2 onto CGMG was spontaneous and endothermic. The E2 uptake by CGMG decreased in high pH values. However, it was insensitive to ionic strength variation (0.0–0.1 M). Moreover, the regeneration experiments illustrated that CGMG could be recovered, and it showed good recycling ability with ca. 88.7% of the initial sorption capacity after being used for sixth cycles.

Synthesizing biochar-based nano-composites can obtain new composites and combine the advantages of biochar with nano-materials. The resulting composites usually exhibit great improvement in functional groups, pore properties, surface active sites, catalytic degradation ability and easy to separation. These composites have excellent abilities to adsorb a range of contaminants from aqueous solutions. Particularly, catalytic material-coated biochar can exert simultaneous adsorption and catalytic degradation function for organic contaminants removal. Synthesizing biochar-based nano-composites has become an important practice for expanding the environmental applications of biochar and nanotechnology. This paper aims to review and summarize the various synthesis techniques for biochar-based nano-composites and their effects on the decontamination of wastewater. The characteristic and advantages of existing synthesis methods are summarized and discussed. Application of biochar-based nano-composites for different contaminants removal and the underlying mechanisms are reviewed. Furthermore, knowledge gaps that exist in the fabrication and application of biochar-based nano-composites are also identified.

With the unique advantages of lower operational and maintenance cost, the use of microbial-earthworm ecofilters (MEEs) for the wastewater treatment has been increasing rapidly in the recent years. This paper provided an overview of the research activities on the use of MEEs for removing pollutants from various wastewater throughout the world. However, the long-term effective treatment performance and sustainable operation of this system still remain a challenge since the treatment performance would be affected by design parameters, operational conditions, and environmental factors. In order to promote the treatment performance, therefore, this paper also provided and summarized the influencing factors of pollutants removal in MEEs. The design parameters and operational conditions of MEEs include earthworm species and load, filter media type, hydraulic loading rate, nutrient load, packing bed height, chemical factors and temperature. Lastly, this review highlighted the further research on these issues to improve performance and sustainability of MEEs.

In this study, a sequencing batch biofilm reactor combined with a vertical flow constructed wetland (SBBR-VFCW) system was constructed and applied to the wastewater treatment. Thalia dealbatas were planted in the VFCW. The artificial neural network (ANN) was used to simulate and predict the performance of SBBR-VFCW. The results showed that when the concentrations of COD, NH4+-N, TN and TP in the wastewater were 200.22 mg/L, 48.11 mg/L, 48.11 mg/L and 6.11 mg/L respectively, the removal efficiencies were 97.0%, 98.5%, 91.5% and 88.5%, correspondingly, which indicated that the SBBR-VFCW system can treat the wastewater effectively. According to the results of the ANN simulation analysis, the correlation coefficients (R2) were all higher than 0.99, and the root mean squared errors (RMSE) were lower than 0.0782. The concentrations of DO, NH4+-N and TP in the influent exhibited strong impacts on the effluent. This study reveals that the ANN can efficiently reflect the nonlinear function of each factor, and is suitable for the dynamic monitoring of SBBR-VFCW treatment for wastewater in various conditions.

Acidic deposition, which is mainly caused by atmospheric pollution, is one of the global environmental problems. Thinning is an effective management to improve the tree productivity, reduce the wildfire risk and maintain a healthy forest. Since thinning may reduce the effect of acidic deposition, the effect of thinning on acidic deposition was estimated. The biomass, soil properties, pH value of runoff and groundwater in both unthinned and thinned Chinese fir plantations were measured and compared over a 5-year period (2–6 years after thinning). The results indicated that acidic deposition in the Huitong State Ecosystem Research Station was serious, and it got worse with time. Forest thinning resulted in a huge change in biomass and soil properties. During the 5-year monitoring period, biomasses of understory and litter, plant species richness, coverage of undergrowth plant layer were significantly higher in thinned site than in unthinned site. Moreover, higher soil fertility as well as lower amounts of runoff and groundwater were found in thinned site. It was suggested that thinning could improve the structure of forest, leading to restoring the effluent (runoff and groundwater) pH to the normal value.

To overcome the limitation of powder TiO 2 , the TiO 2 -impregnated glutaraldehyde-crosslinked alginate beads (TIGCAB) were prepared. The TIGCAB were characterized by DC, DBM, SEM, BET, XRD, Raman and TG. These synthesized beads were applied to reduce toxic Cr(VI) to Cr(III) in acidic aqueous solution under UV irradiation. In the system without TIGCAB or UV light, no chromium reduction was observed. The reduction rate of Cr(VI) was about 8% when the system was exposed to UV irradiation with blank beads. Photoreduction rate of Cr(VI) decreased with increasing pH. The reduction efficiency of Cr(VI) decreased with the increase of initial Cr(VI) concentration in the range of 5–20 mg L −1 . Fe(III) ions improved the photoreduction of Cr(VI) because they can promote the trapping of electrons and holes. Moreover, TIGCAB can maintain full photoreduction activity for at least three cycles. The results show that TIGCAB are promising materials for the photoreduction of Cr(VI) from acidic aqueous solution in environmental pollution cleanup.

Graphene oxide has received world-wide attention due to its exceptional physicochemical properties. Herein, a sulfonated magnetic graphene oxide composite (SMGO) was synthesized from graphene oxide and was used as adsorbent for removing Cu(II) ions from aqueous solution. The composite was characterized by TEM, EDS, particles size, BET, TG-DTA, FT-IR, and Raman. It can be separated and recovered easily using magnetic separation technology. The effects of operating parameters such as pH, Cu(II) concentration and temperature on the Cu(II) adsorption were investigated by using a response surface methodology (RSM). Optimum Cu(II) uptake of 62.73 mg g−1 was achieved at pH 4.68, Cu(II) concentrations 73.71 mg L−1, and temperature 50 °C. The adsorption process can be well described by the pseudo-second order kinetic model. The experimental data of isotherm followed the Langmuir isotherm model. Moreover, the thermodynamic parameters calculated from the temperature-dependent isotherms indicated that the adsorption reaction was an endothermic and spontaneous process. All results indicate that the SMGO is a promising adsorbent for the efficient removal of copper ions from wastewater.

High-energy particles’ radiation produces a large number of radiation defects in material, such as interstitial atoms, vacancies, dislocation loops, voids and helium bubbles. The formation and evolution of massive radiation defects cause the instability of microstructure in metal, which further degrades its mechanical performance. Interface engineering is an effective method to tune the radiation resistance of metal and alloy. By introducing a large number of grain boundaries, phase interfaces, free surfaces, etc., the recombination probability of radiation-induced vacancies and interstitial atoms increases, thereby reducing the accumulation of radiation defects, improving the structural stability of the metal and eliminating the harmful effects of radiation. In this paper, we briefly review the recent progress of the mechanisms of interactions between several typical interfaces and various types of irradiation defects. The influence of interface structure, irradiation condition and defect character on their interaction behavior are reviewed and discussed. We also propose some critical questions about the radiation damage to material which remain to be understood. It is necessary to combine multidisciplinary techniques, knowledge and theories in order to fully understand the mechanism of radiation damage and design the advanced radiation-tolerant materials.

A novel biochar/MgAl-layered double hydroxides composite (CB-LDH) was prepared for the removal of crystal violet from aqueous solution by pyrolyzing MgAl-LDH pre-coated ramie stem (Boehmeria nivea (L.) Gaud.). Pyrolysis played dual role for both converting biomass into biochar and calcining MgAl-LDH during the pyrolysis process. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray analysis (EDS), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) and zeta potential analysis were used to characterize the CB-LDH. The results of characterization suggested that the calcined LDH was successfully synthesized and coated on biochar. The resulted CB-LDH had higher total pore volume and more functional groups than the pristine biochar. Adsorption experimental data fitted well with the pseudo-second order kinetics model and the Freundlich isotherm model. The rate-controlled step was controlled by film-diffusion initially and then followed by intra-particle diffusion. Thermodynamic analysis showed that the adsorption of crystal violet was a spontaneous and endothermic process. The higher pH and temperature of the solution enhanced the adsorption performance. CB-LDH could also have excellent ability for the removal of crystal violet from the actual industrial wastewater and groundwater with high ionic strength. LDH adsorption, electrostatic attraction, pore-filling, π-π interaction and hydrogen bond might be the main mechanisms for crystal violet adsorption on CB-LDH. The results of this study indicated that CB-LDH is a sustainable and green adsorbent with high performance for crystal violet contaminated wastewater treatment and groundwater remediation.