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The presence of excessive pollutants in soil and water caused by the fast development of industry has been a challenge for the innovation of environmental remediation technologies. Nano-sized iron sulfide (FeS) particles have aroused researchers’ attention for environmental remediation over the decade owing to their high reactivity and large specific surface area. The aim of this paper is to provide a comprehensive review on the evolution of FeS nanoparticles for environmental decontamination. The synthesis for bare nano-sized FeS particles via physicochemical and biological methods, the modification for nano-sized FeS particles by coating stabilizers and loading supporting materials are described in this review. What’s more, the applications of nano-scale FeS in soil and water remediation are also discussed, including the removal of halogenated hydrocarbon, radionuclide, heavy metals, and metalloid. Meanwhile, the interaction mechanisms, namely adsorption and redox reaction between contaminants and nano-sized FeS and the effect of remediation conditions have been summarized in this review. Moreover, some future research needs are also stated such as researching the fate of FeS nanoparticle after injecting into soil and water, enhancing the mobility of nano-sized FeS in soil and water, and measuring the toxicity to the organisms.

An integrated technique of hydrothermal pretreatment coupling with deep eutectic solvent (DES) extraction was tailed to cleanly fractionate lignocellulose into three usable forms, i.e., water-soluble hemicellulose, cellulose-rich and lignin fractions, which were further upgraded to three nanomaterials, i.e., activated nanocarbons (ANCs), lignin-containing cellulose nanofibers (LCNFs), lignin nanospheres (LNSs) respectively. Almost 100% hemicellulose was solubilized in the hydrothermal pretreatment, which was used as carbon source to produce ANCs with rather high specific surface area (about 2680 m2 g−1) through in situ carbonation followed by activation. Cellulose-rich fraction was used to produce LCNFs with high aspect ratio (about 150) using facile mechanical refining. While the clean lignin fraction with enhanced amphiphilic properties was used to produce LNSs (223 nm diameter) using self-assembly method. The related mechanism was that condensed lignin could still be extracted by DES due to its excellent lignin solubility. The resulting lignin amphiphilicity provided a powerful driving force to enhance the self-assembly process thus compact LNSs was obtained. Meanwhile, the DES-swelled cellulose structure significantly facilitated the subsequent mechanical disintegration for LCNFs production. In this work, the proposed integrated technique platform realized the complete utilization concept of lignocellulosic biomass, and also provided three high-value nanomaterials product streams for downstream application towards an industrial relevant process.

Graphene oxide nanoribbons (GONRs) were synthesized and functionalized by silane molecules with different hydrophobic end-groups, and silane functionalized reduced GONR (silane-f-rGONR) coated polyurethane (PU) sponge composites were fabricated via a facile dip-coating process. Fourier-transform infrared, Raman spectrum, X-ray photoelectron spectroscopy and scanning electron microscopy demonstrated that silane molecules were successfully grafted onto GONR sheets, thus producing the ability to tune surface and physical properties of PU sponge from insulating and hydrophobic to conductive and super-hydrophobic. Cyclic compression and strain-induced electrical resistance change tests indicated that the porous silane-f-rGONR coated PU (silane-f-rGONR@PU) sponge composites exhibited excellent mechanical elasticity and durability and high sensitivity of resistance change. Furthermore, the two types of silane modified sponges showed different super-hydrophobicity and tunable oleophilicity/oleophobicity. Compared to the rGONR@PU composite with poor oil/water separation at dynamic state, these porous silane-f-rGONR@PU composites not only possessed excellent oil/solvent absorption capacity and selective oil/water separation at static state, but also showed good continuous oil/solvent pumping collection with high recyclability (>97% after 10 cycles) and outstanding oil/water separation efficiency at the dynamic shaking state. This work provides a new strategy for fabricating the super-hydrophobic, electrically conductive and mechanically flexible porous rGONR based composites, showing promising application in strain sensor and oil pollution remediation fields at different environmental conditions.

The polydopamine (PDA) coating was used to modify the surface of the PbO2/TiO2 nanotube arrays (PTNAs) by impregnation method. The obtained PDA-PbO2/TiO2 nanotube arrays (PPTNAs) coating exhibited a sandwich structure and used as anode for photoelectrochemical degradation of toluene. Generally, due to the symmetric structure and conjugation of methyl with benzene ring, the degradation of toluene was difficult to carry on. Our results show that the rate of toluene degradation can reach up to 66% at the surface of PPTNAs coating anode, it is much higher than that of the TiO2 nanotube arrays coating anode, 17%. The reduction product at cathode, hydrogen, was also measured, which is one of the valuable source of energy. In the coupled effect of applied voltage and photocatalysis on the PPTNAs anode, the degradation of toluene was carried out smoothly. The introduction of lead dioxide nanoparticles on the coated anode possessed favorable electronic conductivity in strong acid, which is benefit for a high rate of electrons transportation at the interface of TiO2 and lead dioxide. The excellent corrosion resistance of PPTNAs coating further ensured the effective degradation of toluene with long-term stability. Meanwhile, the unique adhesion of the outer PDA coating increased the contact opportunities between toluene molecules and the anode surface, and enhanced the photocatalytic activity of the PPTNAs coating anode. The applied voltage suppressed the recombination of electron-hole pairs and provided abundant reaction sites. All of these increased the photo-electro catalysis of toluene degradation. The new fabricated anode material shows good prospective application of cleaning up refractory pollutants and the resource utilization.

An ultra-low energy consumption continuous flow (UECF) process was used for enhanced nitrogen removal from rural sewage. The ammonia in sewage was first oxidized to nitrite in a bio trickling filter (BTFPN) supplemented with natural oxygen. A stable nitrite accumulation ratio (NAR) of 93.2% was maintained by adding 5 mg/L NH2OH every seven days. BTFPN effluent was then combined with certain portion of rural sewage (1:1.2 to 1:1.5) and introduced to an upflow anaerobic sludge blanket reactor, where the nitrogen-containing pollutants were removed by Anammox process (UASBAMX). Effluent total nitrogen (TN) of 6.7 mg/L and a TN removal efficiency of 93.7% were obtained when influent chemical oxygen demand (COD), NH4+-N and TN were 321.9, 74.2 and 82.7 mg/L, respectively. Advanced nitrogen removal, based on the desirable cooperation between Anammox bacteria (Ca. Brocadia, 2.3%) and partial denitrification bacteria (Thauera, 4.2%), was achieved over 300 days of stable operation. Considering the nitrogen balance, 57.9% of nitrate generated in Anammox was reduced to nitrite by partial denitrification, and Anammox contributed 88.1% of nitrogen removal and 7.6% of denitrification. Compared with conventional nitrification and denitrification processes, UECF requires no mechanical aeration, no external carbon, produces 76.6% less external sludge, and reduces CO2 emissions by 92.3%.

As a luxurious textile for more than five thousand years, silk fibers/products have always been favored by consumers and the markets, but the poor photostability seriously hinders its utilization in fashionable apparel. Even if enduing the functionality of silk fiber through surface modification, it is often at the expense of its comfort. Here, an ultra-thin amorphous titanium dioxide nano-film with a thickness of only five in a thousand of fiber diameter and the add-on percentage ≤ 5.33% was prepared on the surface of silk fibers/fabrics by atomic layer deposition (ALD) methods. The tensile strength of the modified silk fiber maintains 89.17% of the original fiber after exposure to UV light for 672 h. They can also withstand multi-cycle laundering and accelerate light-aging, which exhibiting an excellent UV resistance. Most importantly, the functional coating has a negligible impact on the comfortable and wearability performance of silk fibers/fabrics. In addition, ALD-coated silk fabric is also further used as an outdoor reflective cooling material and achieving a superior thermal insulation effect with the temperature reduction up to 10.1 °C.

A great amount of phenolic compounds are considered as carcinogens even at low concentrations and they are highly toxic and widely coexist in effluent discharges. It is a very meaningful work to respectively separate a few trace phenolic compounds from their aqueous solution by foam fractionation. The studies of surface activity and surface excess revealed that catechol had a stronger competitive adsorption on the bubble surface than phenol by using cetyltrimethyl ammonium bromide (CTAB) as a collector. A two-stage batch foam fractionation technology was developed for the respective separation of catechol and phenol from their diluted aqueous solution. In the first stage batch foam fractionation, catechol was effectively separated with a high enrichment ratio of 32.2 and a high removal percentage of 90.25% while the removal percentage of phenol was only 2.32% under the suitable operating conditions. A high selectivity coefficient of catechol over phenol could reach 35.25. Then, phenol existed in the residual solution, which was used as the feeding solution in the second stage. In the second stage batch foam fractionation, the small bubbles were used to enhance the adsorption of phenol. At the same time, the foam fractionation column of an inclined foam phase was used to enhance foam drainage and then phenol was effectively removed with a high enrichment ratio of 44.4 and a high removal percentage of 90.23% under the suitable operating conditions. The results indicated that it was practicable to successfully and respectively separate catechol and phenol from their aqueous solution by using the two-stage batch foam fractionation.

In this study, the removal of bisphenol A (BPA) and phosphate in zero-valent iron activated persulfate (ZVI/PS) oxidation process was investigated. Activation of PS by ZVI mainly produces strong oxidizing sulfate radicals (SO4 −) which can efficiently degrade organic contaminants. ZVI is ultimately transformed to ferric iron (Fe3+) which works as a coagulant to remove phosphate. It was demonstrated that BPA and phosphate could be simultaneously removed in this system. The oxidation of BPA in ZVI/PS process followed pseudo-first-order kinetics. The reaction rate increased with increased PS and ZVI dosage. Eight transformation products were identified using gas chromatography–mass spectrometry (GC–MS) technique. SO4 −-induced oxidative transformation of BPA included electron transfer and hydrogen abstraction mechanisms. Carbonate exhibited no obvious influence on the removal both of phosphate and BPA. Natural organic matter (NOM) showed inhibitory effect on BPA degradation but had no appreciable negative effect on phosphate removal. Simultaneous removal of BPA and phosphate was also observed in wastewater treatment plant effluent with relatively high efficiency. The results of this work indicate that ZVI/PS process could serve as a novel treatment technique for removal of trance organic contaminants and phosphate simultaneously.

Water-based hybrid graphene oxide nanoribbon (GONR)/montmorillonite (MMT)/polyethylene glycol (PEG) networks were prepared by using a facile bio-inspired low-temperature evaporation induced assembling process. Multiple non-covalent and covalent interactions together with a high orientation level of MMT were constructed in the hybrid PEG/MMT/GONR networks. As a result, the hybrid networks exhibit synergistic reinforcing and toughening efficiencies when compared with the composites modified with the single-phase filler, e.g. 152% and 167% increase in tensile strength for the optimized ternary composites in comparison with those of the binary composites. Moreover, the nacre-like hybrid networks show excellent flame resistance and structural stability in a flame due to the formation of interconnected and compact char after combustion, which can be applied as protective coatings to combustible materials. The hybrid coatings not only improve the flame-retardant property (e.g. ~46% decrease in heat release rate at 30 wt%) of the combustible PU foam materials significantly, but also provide ideal fire alarm responses (e.g. rapid flame detection of ~2 s and effective fire early warning signals in pre-combustion). Owing to the green and versatile synthesis scheme, excellent mechanical performance and flame resistance, these hybrid PEG/MMT/GONR networks are promising widespread application.

Lightweight polydimethylsiloxane (PDMS) foam materials with outstanding mechanical flexibility and high-temperature stability as well as excellent flame resistance are attractive for various potential applications. However, incorporation of conventional flame retardants needs high filling content and usually induces compromise of other important performance, limiting their practical application significantly. In addition, the problems of complicated procedure and environmental pollution of the traditional processing are imperative but challenging. Here, we report a facile and green in-situ surface-assembly approach to construct two types of graphene oxide (GO) derivative (i.e. sheet and nanoribbon) coatings bonded onto the PDMS foam surface and investigate their discrepancies in thermal and mechanical and flame-retardant properties of the two nanocomposite systems. Interestingly, surface-assembling ultralow loading (≤0.10 wt%) of two GO derivatives can produce significant improvements in thermal stability and flame retardancy of the PDMS foam without affecting its density and elasticity. Typically, ~31% and ~40% reduction in peak heat release rate and ~80% and ~95% improvement in total smoke release were achieved for 0.10 wt% GONR and GO sheet, respectively. Based on the burnt surface zone observation and analysis, the synergistic flame-retardant mechanisms and their differences between the PDMS molecules and two GO derivatives were discussed and clarified. This work provides a new understanding for design and development of green and large-scale fabrication of flame retardant PDMS foam nanocomposite materials.

Frequent fire disasters have not only caused massive casualties, irreparable property and priceless artefacts loss, but also create severe environmental damage. Therefore, it is imperative, but also challenging, to obtain excellent fire resistance and efficient early-warning alarm response in precombustion of combustible materials. In this work, a green flame-retardant graphene oxide (GO) based paper/coating is designed and constructed via using a facile 3-methacryloxypropyltrimethoxysilane and L-ascorbic acid (LAA) co-functionalization strategy. The optimized co-modified GO network shows good structure stability and improves the flame retardancy of combustible materials. Further, such GO network can provide an ultrafast flame detection signal of only ~1 s and ideal fire early warning responses (e.g. a low responsive temperature of ~120 °C and an extremely rapid responsive time of ~7 s at 300 °C) in precombustion which are among the best performances of the state-of-the-art fire alarm sensors. Moreover, the transformation of silane molecules into a compact protective layer on sheets and the resistance transition of insulating GO network into conductive reduced GO path promoted by LAA molecules are clarified. This work provides a novel strategy and paradigm to achieving excellent flame resistance and ideal fire early warning response of GO network for fire safety and prevention applications.

Ag + -loaded polystyrene (PS) nanofibrous membranes were prepared by electrospinning combined with crosslinking, sulfonation, and ion-exchange. The adsorption experiments of thiophene were carried out using the fibrous membranes with maximum silver ion loading. The membranes were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and UV–vis diffuse reflectance spectroscopy (UV–vis). The characterization results suggested that the silver ions were successfully loaded on the PS nanofibers. With increase of the sulfonation time, the ion-exchange capacity (IEC) of membranes increased first and then decreased. The IEC could reach the maximum value when sulfonation time of membranes was 60 min, and the loading amount of silver ion was about 5.7 mmol/g. The obtained Ag + -loaded PS nanofibrous membranes were used to adsorb the thiophene and the results indicated that the thiophene can be removed effectively. The functionalized electrospun membrane used as the adsorption media of removing thiophene can enrich the adsorbent species and its high adsorption due to the large specific surface could supply broad application prospects for deep desulfurization.