Removal Of Water Pollutants Research Articles

Recent Progress of Metal Sulfide Photocatalysts for Solar Energy Conversion.

Artificial photosynthetic solar-to-chemical cycles enable an entire environment to operate in a more complex, yet effective, way to perform natural photosynthesis. However, such artificial systems suffer from a lack of well-established photocatalysts with the ability to harvest the solar spectrum and rich catalytic active-site density. Benefiting from extensive experimental and theoretical investigations, this bottleneck may be overcome by devising a photocatalytic platform based on metal sulfides with predominant electronic, physical, and chemical properties. These tunable properties can endow them with abundant active sites, favorable light utilization, and expedited charge transportation for solar-to-chemical conversion. Here, it is described how some vital lessons extracted from previous investigations are employed to promote the further development of metal sulfides for artificial photosynthesis, including water splitting, CO2 reduction, N2 reduction, and pollutant removal. Their functions, properties, synthetic strategies, emerging issues, design principles, and intrinsic functional mechanisms for photocatalytic redox reactions are discussed in detail. Finally, the associated challenges and prospects for the utilization of metal sulfides are highlighted and future development trends in photocatalysis are envisioned.

Synthesis of cesium lead halide perovskite/zinc oxide (CsPbX3/ZnO, X= Br, I) as heterostructure photocatalyst with improved activity for heavy metal degradation.

Inorganic perovskites have been recognized as highly potent materials for the display and medical industries due to their outstanding features. However, there haven’t been many reports on their implications as a photocatalyst for the removal of heavy metals. Photocatalysis has been regarded as a significant approach for the removal of pollutants because of its great sustainability, improved efficiency, and reduced energy consumption. Here, we applied inorganic cesium lead halides (Br and I) with zinc oxide heterostructure as a photocatalyst for the first time. The heterostructure has been synthesized by the traditional hot injection strategy and its photocatalytic activity was systematically investigated. Interestingly, the CsPbX3/ZnO heterostructure as a photocatalyst has a homogeneous geometry and possesses an excellent degradation efficiency of over 50% under xenon UV-Visible light. The CsPbX3/ZnO catalyst carries superior oxidation/reduction properties and ionic conductivity due to the synergistic photogenerated charge carrier and interaction between CsPbX3 and ZnO. The recycling experiment showed the good stability of the catalysts. These findings suggest that inorganic lead halide heterostructure has the potential to be used for heavy metal degradation and water pollution removal catalysts.

Catalytic Degradation of Bisphenol A in Water by Poplar Wood Powder Waste Derived Biochar via Peroxymonosulfate Activation

A series of biochar materials was prepared through pyrolyzing poplar wood powder waste under different pyrolyzing temperatures, which were afterwards characterized in detail. Then, the poplar powder biochar (PPB) was used to degrade bisphenol A (BPA) in water via activating peroxymonosulfate (PMS). The results indicate that the activation efficiency of the prepared PPB was correlated with its surface functional groups, which were regulated by its pyrolyzing temperature. Specifically, the biochar pyrolyzed at 600 °C (PPB-600) exhibited the optimal BPA removal activity, in which 0.5 g/L of PPB-600 could remove 0.02 mM of BPA within 120 min. From the results of scavenging tests, ESR analysis and probe pollutant degradation tests, it was inferred that the BPA was degraded by non-radical singlet oxygen in the PPB/PMS system. Since PPB consumed its surface oxygen functional groups and structural defects to activate PMS, the catalytic performance of PPB was gradually reduced after several cycles. This study can provide new insight for the design and preparation of metal-free biochar catalysts from waste wood precursor for the highly-efficient removal of refractory organic pollutants in water.

Highly performant nanocomposite cryogels for multicomponent oily wastewater filtration

This paper reports the fabrication of multifunctional composite cryogels that simultaneously remove oil and dye from polluted water through gravity-driven filtration. The cryogels were prepared via cryopolymerization of a poly(sodium acrylate) (PSA) and graphitic carbon nitride nanosheets (CNNs) mixture. Although the different CNNs concentrations tested do not significantly affect the morphology of the hybrid cryogels (PSA_CNN), they do influence their optical properties, with the PSA_CNN hybrid fabricated with the lower CNNs concentration (i.e., PSA_CNN1) to demonstrate the best photoactive properties. PSA_CNN1 presents attractive wetting properties such as fast and high swelling capacity, rapid water permeability, and underwater superoleophobicity. We found that the presence of CNNs enhances the methylene blue (MB) adsorption capacity of the hybrid cryogel. When used for the gravity-driven filtration of oil–water, dye-water, and oil-dye-water mixtures, the hydrogel composite can purify efficiently and rapidly the water, and its performance is maintained after diverse filtration cycles. Its photocatalytic self-cleaning property enables it to be cleaned before the next filtration cycle when exposed to visible light irradiation. The herein presented approach is expected to be an insightful contribution to the field of multicomponent oily wastewater filtration, offering inspiration for the design of photoactive hydrogel-based 3D filters for the simultaneous removal of water pollutants through cost-effective and energy-safe processes.

Molecular engineering of a synergistic photocatalytic and photothermal membrane for highly efficient and durable solar water purification

In recent years, the solar-driven interfacial evaporation system (SIES) has obtained a lot of interest as a potential solution to freshwater scarcity. However, the organic pollutant residues affected the practical application of the distillate generated by SIES. Herein, a solar interfacial membrane (AuNPs@g-C3N4/CMF) (AMF) for desalination and removal of multiple water pollutants was prepared by generating Au-doped carbon nitride (AuNPs@g-C3N4) directly on the carbonized melamine (CMF) through a co-calcination process. The designed membrane features excellent light absorption, efficient water supply, and low thermal conductivity. All the above advantages of the AMF membrane contributed to an outstanding evaporation rate (1.675 kg m-2 h-1) and high photothermal conversion efficiency (94.03%) under 1 sun irradiation. For seawater desalination, the membrane performed well in removing ions from simulated seawater and demonstrated good stability during long-term desalination. Meanwhile, the membrane still exhibits a high evaporation rate (1.24 kg m-2 h-1) even in a 10% salt solution environment. Owing to the photocatalysis capability of AuNPs@g-C3N4, the AMF membrane also performs effectively in the removal of organic dyes and formaldehyde.

Construction of a novel Ag2O/P-g-C3N4 p-n type heterojunction for efficient degradation of organic pollutants under visible light irradiation

It is critical to design efficiently stable photocatalysts for removing organic waste from water. Herein, a sequence of Ag2O/Phosphors-doped g-C3N4 (AgO/PCN) composites with p-n heterojunctions were successfully prepared via facile chemical deposition for photocatalytic degradation of Rhodamine 6G (Rh 6G) and Levofloxacin (LVFX). The resultant composites with an optimal AgO/PCN ratio of 2:1 could degrade approximately 99 % of Rh 6G and 83 % of LVFX in 50 and 120 min, respectively, under visible light irradiation, which is obviously more than pure Ag2O and Phosphors-doped g-C3N4. The increased performance of photocatalysis could be because of the broadened light absorption range originated from Ag0 surface plasmon resonance effect (SPR) and the accelerated separation efficiency of electron-hole pair via p-n junction. Radical trapping and Electron Paramagnetic Resonance experiments confirmed that O2− and h+ were the chief active species, and OH was the minor active species for Rh 6G degradation process. Therefore, a plausible mechanism theorized on the basis that the synergistic effect of surface plasmon resonance and p-n heterojunction for increased photocatalytic activity is proposed. This work advances a novel idea for establishing highly efficient catalysts via synergizing surface plasmon resonance and p-n heterojunction, paving the way for efficient photocatalytic removal of organic pollutants in water.

Enhanced photocatalytic organic pollutant degradation and H2 evolution reaction over carbon nitride nanosheets: N defects abundant materials

Post thermal treatment of bulk graphitic carbon nitride (g-C3N4) by ammonia gas acts as a significant structure regulation approach, while pure ammonia-assisted g-C3N4 synthesis from precursors like melamine is rarely investigated. Here we prove the synthesis of N-defects abundant carbon nitride nanosheets (ACN) through a one-pot thermal polymerization of melamine in pure ammonia gas, for photocatalytic organic pollutant removal in water and H2 evolution applications. Compared to bulk g-C3N4 (BCN), ACN-550 (ACN prepared at 550 °C) exhibited thin-layered porous morphology with higher surface area and abundant N defects, resulting in wider distribution of active sites. Moreover, the abundant N defects in the heptazine heterocycle structure could change the electronic structure of g-C3N4, leading to more efficient transport of photogenerated charge carriers and enhanced photoreduction potential, which gives rise to notable improvement activities in photocatalytic reaction. With superoxide ion radical and photoinduced holes as the predominant reactive species, ACN-550 realized efficient photocatalytic bisphenol A (BPA) degradation, which is 1.6- and 4.7-fold high over commercial TiO2 (P25) and BCN, respectively. ACN-550 exhibited excellent reusability and stability in five consecutive photocatalytic BPA degradation tests. In photo-reductive H2 production system by ACN-550, 761.8 ± 4.3 μmol/h/g H2 was produced, which was 11.6-fold as high as that by BCN.

Nanoporous Carbon from Oil Palm Leaves via Hydrothermal Carbonization-Combined KOH Activation for Paraquat Removal.

In this study, nano-porous carbon was completely obtained from oil palm leaves (OPL) by hydrothermal pretreatment with chemical activation, using potassium hydroxide (KOH) as an activating agent. Potassium hydroxide was varied, with different ratios of 1:0.25, 1:1, and 1:4 (C: KOH; w/w) during activation. The physical morphology of nano-porous carbon has a spongy, sponge-like structure indicating an increase in specific surface area and porosity with the increasing amount of KOH activating agent. The highest specific surface area of OPL nano-porous carbon is approximately 1685 m2·g−1, with a total pore volume of 0.907 cm3·g−1. Moreover, the OPL nano-porous carbon significantly showed a mesoporous structure designed specifically to remove water pollutants. The adsorptive behavior of OPL nano-porous carbon was quantified by using paraquat as the target pollutant. The equilibrium analyzes were explained by the Langmuir model isotherm and pseudo-second-order kinetics. The maximum efficiency of paraquat removal in wastewater was 79%, at a paraquat concentration of 400 mg·L−1, for 10 min in the adsorption experiment. The results of this work demonstrated the practical application of nano-porous carbon derived from oil palm leaves as an alternative adsorbent for removing paraquat and other organic matter in wastewater.

Composite TiO2 films modified by CeO2 and SiO2 for the photocatalytic removal of water pollutants.

TiO2 particles of high photocatalytic activity immobilised on various substrates usually suffer from low mechanical stability. This can be overcome by the utilisation of an inorganic binder and/or incorporation in a robust hydrophobic matrix based on rare-earth metal oxides (REOs). Furthermore, intrinsic hydrophobicity of REOs may result in an increased affinity of TiO2-REOs composites to non-polar aqueous pollutants. Therefore, in the present work, three methods were used for the fabrication of composite TiO2/CeO2 films for photocatalytic removal of dye Acid Orange 7 and the herbicide monuron, as representing polar and non-polar pollutants, respectively. In the first method, the composition of a paste containing photoactive TiO2 particles and CeCl3 or Ce(NO3)3 as CeO2 precursors was optimised. This paste was deposited on glass by doctor blading. The second method consisted of the deposition of thin layers of CeO2 by spray coating over a particulate TiO2 photocatalyst layer (prepared by drop casting or electrophoresis). Both approaches lead to composite films of similar photoactivity that of the pure TiO2 layer, nevertheless films made by the first approach revealed better mechanical stability. The third method comprised of modifying a particulate TiO2 film by an overlayer based on colloidal SiO2 and tetraethoxysilane serving as binders, TiO2 particles and cerium oxide precursors at varying concentrations. It was found that such an overlayer significantly improved the mechanical properties of the resulting coating. The use of cerium acetylacetonate as a CeO2 precursor showed only a small increase in photocatalytic activity. On the other hand, deposition of SiO2/TiO2 dispersions containing CeO2 nanoparticles resulted in significant improvement in the rate of photocatalytic removal of the herbicide monuron.

Synergistic Effect of Ferrate with Various Water Processing Techniques—A Review

The use of ferrate has been demonstrated as a highly efficient technique for the removal of pollutants in water and wastewater treatment. While most of the published work about ferrate investigated the treatment performance by ferrate alone, new applications of ferrate expand to the synergistic application of ferrate with other techniques such as membrane separation, sulphur-based chemical use, UV radiation, ozonation, acidification, and other chemical additives. This paper aims to review and explore the treatment performance and reaction mechanisms associated with synergistic applications of ferrate. The main objective of this study is to conduct case studies on the synergistic application of ferrate with other water processes. It was found that the efficiency of water treatment increased significantly by the synergistic application of ferrate, and this is attributed to the alleviation of membrane fouling, the activating the formation of more radical oxidative species, enhanced coagulation, and the potential improvement of micropollutants’ biodegradability. Therefore, the stated ferrate technology holds high potential for improving the efficiency of water treatment and other environmental remediation processes. Further studies are required to explore a more feasible combination of ferrate with other techniques and expand the understanding of the working mechanisms of the known synergistic applications of ferrate.

Photocatalytic removal of pharmaceutical water pollutants by TiO2 - Carbon dots nanocomposites: A review.

Pharmaceuticals are becoming increasingly more relevant water contaminants, with photocatalysts (such as TiO2) being a promising approach to remove these compounds from water. However, TiO2 has poor sunlight-harvesting capacity, low photonic efficiency, and poor adsorption towards organic pollutants. One of the emerging strategies to enhance the photocatalytic performance of TiO2 is by conjugating it with fluorescent carbon dots. Herein, we performed a critical review of the development of TiO2 - carbon dots nanocomposites for the photocatalytic removal of pharmaceuticals. We found that carbon dots can improve the photocatalytic efficiency of the resulting nanocomposites, mostly due to increasing the adsorption of organic pollutants and enhancing the absorption in the visible range. However, while this approach shows significant promise, we also identified and discussed several aspects that need to be addressed before this strategy could be more widely used. We hope that this review can guide future studies aiming to the development of enhanced photocatalytic TiO2 - carbon dots nanocomposites.

Magnetic nanomaterials: Greener and sustainable alternatives for the adsorption of hazardous environmental contaminants

The global water resources have been considerably damaged by organic and inorganic pollutants generated as a result of fast urbanization and industrialization. Toxic contaminants in water pose a serious health threat to both humans and aquatic life. In terms of cost and performance, current remediation technologies are inadequate for eliminating low-concentration contaminants. Nanomaterials have unique advantages in this regard, including precisely adjustable surface areas, durability, and biocompatibility. Also, the surface functionalization of the nanoparticles can facilely be carried out to increase their selectivity and specificity towards a variety of pollutants. Among various nanomaterials the magnetic nanoparticles (MNPs) are promising class of nanomaterials due to their biocompatible, target-specific, easily regenerable, and reusable characters. They also feature simple separation techniques, high surface-to-volume ratios, and high adsorption rates. Based on these features their implication in wastewater treatment has dragged an enhanced amount of attention for the researchers. Therefore, MNPs provide a simple, low-maintenance alternative to traditional adsorbents for extracting contaminants from wastewater. Magnetic separation can reduce the environmental impact of MNPs in final effluents by managing the concentration of nanoadsorbents. MNPs are now in the development stage, however they are a promising treatment alternative for large-scale water treatment plants. The main objective of the present review is to focus on the efforts being carried out in the application of MNPs for the remediation of hazardous pollutants including organics, heavy metal ions, pharmaceutics, dyes, radioactive elements, and pathogens. Furthermore, the review present critical assessment and overview of a variety of magnetic nanomaterials and their applications to water and wastewater treatment. Finally, the feasibility of structure-property relationships, adsorption mechanisms, modeling for the removal of water pollutants, legality and toxicity, economic assessments, and future research directions for the complete utilization of MNPs are also discussed in detail.

Superfast adsorption and high-performance tailored membrane filtration by engineered Fe-Ni-Co nanocomposite for simultaneous removal of surface water pollutants

Increased urbanization and industrialization have adversely affected surface water sources. A wide range of pollutants exists in surface water bodies, thus making them inappropriate to consume without any treatment. Although numerous water treatment methods have been explored, they are either expensive or produce serious health issues. To address these problems, the current study focuses on exploring the potential of Fe-Ni-Co nanocomposite for the simultaneous removal of six water pollutants (total dissolved solids (TDS), total organic carbon (TOC), turbidity, lead (Pb), cadmium (Cd), and chromium (Cr)), through batch adsorption and membrane filtration process. During batch adsorption, Box-Behnken design (BBD) under Response Surface Methodology was studied to optimize adsorption parameters and their interactive impact on pollutant removal. The results indicated the effectual removal of pollutants (around 70% for TDS and TOC, 98.5% for turbidity, and almost complete removal for heavy metals) within 22 min. For membrane filtration studies, M-0.75 (containing 0.75% Fe-Ni-Co loading) exhibited excellent removal of different contaminants (66.1%, 75.4%, 98.7%, 97.2%, 97.7% and 100% for TDS, TOC, turbidity, Pb, Cd and Cr, respectively). Moreover, performance comparison of synthesized nanocomposite adsorbent and fabricated membranes, with the existing literature also exhibited the exceptional ability of Fe-Ni-Co nanocomposite for water purification from multiple contaminants through adsorption and membrane filtration technique and thus, can be a potential candidate for practical application in water treatment.

Preparation of High-Porosity B-TiO2/C3N4 Composite Materials: Adsorption-Degradation Capacity and Photo-Regeneration Properties.

Adsorption can quickly remove pollutants in water, while photocatalysis can effectively decompose organic matter. B-TiO2/g-C3N4 ternary composite photocatalytic materials were prepared by molten method, and their adsorption–degradation capability under visible light conditions was discussed. The morphology of the B-TiO2/g-C3N4 materials was inspected by SEM, TEM, BET, and EDS, and the results showed that close interfacial connections between TiO2 and g-C3N4, which are favorable for charge transfer between these two semiconductors, formed heterojunctions with suitable band structure which was contributed by the molten B2O3. Meanwhile, the molten B2O3 effectively increased the specific surface area of TiO2/C3N4 materials, thereby increasing the active sites and reducing the recombination of photogenerated electron–hole pairs and improving the photocatalytic degradation abilities of TiO2 and g-C3N4. Elsewhere, the crystal structure analysis (XRD, XPS, FTIR) results indicated that the polar -B=O bond formed a new structure with TiO2 and g-C3N4, which is not only beneficial for inhibiting the recombination of electron holes but also improving the photocatalytic activity. By removal experiment, the adsorption and degradation performances of B-TiO2/g-C3N4 composite material were found to be 8.5 times and 3.4 times higher than that of g-C3N4. Above all, this study prepared a material for removing water pollutants with high efficiency and provides theoretical support and experimental basis for the research on the synergistic removal of pollutants by adsorption and photocatalysis.

Surface functionalization of bamboo leave mediated synthesized SiO2 nanoparticles: Study of adsorption mechanism, isotherms and enhanced adsorption capacity for removal of Cr (VI) from aqueous solution

Green synthesis of nanoparticles (NPs) provides economic and environmental benefits as an alternative to chemical or physical methods. Furthermore, the surface properties of such NPs can be modulated by means of the functionalization with different groups making them suitable for various advanced functional applications including water pollutants removal using adsorption technique. In the present work, an eco-friendly synthesis route for nano-adsorbent SiO2 NPs and subsequent surface modifications for enhanced adsorption capacity in removal of Cr(VI) ions from aqueous solution are reported. The green synthesis of SiO2 NPs was carried out using simple bamboo leaves followed by surface modification with amine (A-SiO2) and carboxylic (C–SiO2) functional groups with aim to study the effect of functionalization on adsorption capacity. These nano-adsorbents were characterized by FTIR, SEM, XPS, BET, and zeta potential. and adsorption of Cr(VI) was studied at varying parameters i.e. NPs mass, contact time, and solution pH. The investigation shows interesting results revealing the importance of interactions between the surface functional groups on SiO2 NPs and Cr(VI) species as well as experimental conditions for the choice of surface modifier to achieve a maximum adsorption capacity. The adsorption mechanism has been studied using Langmuir, Freundlich and Temkin adsorption isotherms. The maximum adsorption capacity has been achieved in the case of A-SiO2 NPs which was found to 174 mg/g and much higher than that of SiO2 and C–SiO2 NPs attributed to the selective adsorption and pH conditions. Additionally, A-SiO2 NPs exhibit excellent recyclability indicating their suitability for promising and long term potential applications. This study provides a novel, simple and cost-effective synthesis/surface engineering technology for producing high performance recyclable nano-adsorbents for adsorptive removal of Cr(VI).

Efficient and reductive removal of bromate using a novel and stable nanoscale zero-valent iron embedded in N-doped carbon derived from metal-organic frameworks

Nanoscale zero-valent iron (nZVI) has drawn great interest in the remediation of contaminated waters. In this study, we prepared a novel and stable nZVI embedded in N-doped carbon matrix (nZVI@MOF-CN) using a facile direct carbonization method, in which an iron-containing metal-organic framework (MOF) served as both the iron and carbon sources, and melamine as the nitrogen source. The nZVI@MOF-CN composites were used in the removal of bromate in water, which could be effectively reduced by the surface electrons transferred from nZVI to the carbon encapsulation layer due to the Schottky-Mott effect. Doped nitrogen significantly facilitated the reduction of bromate by nZVI, because it enhanced the nZVI dispersion and bromate adsorption, and modulated the carbon matrix conductivity. The bromate reduction activity of nZVI@MOF-CN was more than 50 times higher that of its un-doped counterpart and a commercial nZVI. Moreover, owing to the protection of carbon encapsulation layer, nZVI@MOF-CN exhibited good stability and reusability. The leached concentration of iron ions of nZVI@MOF-CN was less than 5% of the commercial nZVI under the same reaction conditions. Commercial nZVI almost completely lost its bromate reduction activity after use (3% reduction efficiency in the examined time frame), while nZVI@MOF-CN maintained a reduction efficiency of 61%. The nZVI@MOF-CN could be effectively regenerated by hydrogenation reduction. After five reaction-regeneration cycles, nZVI@MOF-CN still achieved a bromate reduction efficiency of approximately 80%. These results suggest that MOF-derived nZVI materials are highly reactive and stable for the reductive removal of pollutants in water.

Highly porous seeding-free boron-doped ultrananocrystalline diamond used as high-performance anode for electrochemical removal of carbaryl from water

Boron-doped diamond (BDD) electrodes are regarded as the most promising catalytic materials that are highly efficient and suitable for application in advanced electrochemical oxidation processes targeted at the removal of recalcitrant contaminants in different water matrices. Improving the synthesis of these electrodes through the enhancement of their morphology, structure and stability has become the goal of the material scientists. The present work reports the use of an ultranano-diamond electrode with a highly porous structure (B-UNCDWS/TDNT/Ti) for the treatment of water containing carbaryl. The application of the proposed electrode at current density of 75 mA cm−2 led to the complete removal of the pollutant (carbaryl) from the synthetic medium in 30 min of electrolysis with an electric energy per order of 4.01 kWh m−3 order−1. The results obtained from the time-course analysis of the carboxylic acids and nitrogen-based ions present in the solution showed that the concentrations of nitrogen-based ions were within the established maximum levels for human consumption. Under optimal operating conditions, the proposed electrode was successfully employed for the complete removal of carbaryl in real water. Thus, the findings of this study show that the unique, easy-to-prepare BDD-based electrode proposed in this study is a highly efficient tool which has excellent application potential for the removal of recalcitrant pollutants in water.

GO-SWCNT Buckypapers as an Enhanced Technology for Water Decontamination from Lead

Water decontamination is an important challenge resulting from the incorrect disposal of heavy metal waste into the environment. Among the different available techniques (e.g., filtration, coagulation, precipitation, and ion-exchange), adsorption is considered the cheapest and most effective procedure for the removal of water pollutants. In the last years, several materials have been tested for the removal of heavy metals from water, including metal-organic frameworks (MOFs), single-walled carbon nanotubes (SWCNTs), and graphene oxide (GO). Nevertheless, their powder consistency, which makes the recovery and reuse after adsorption difficult, is the main drawback for these materials. More recently, SWCNT buckypapers (SWCNT BPs) have been proposed as self-standing porous membranes for filtration and adsorption processes. In this paper, the adsorption capacity and selectivity of Pb2+ (both from neat solutions and in the presence of other interferents) by SWCNT BPs were evaluated as a function of the increasing amount of GO used in their preparation (GO-SWCNT buckypapers). The highest adsorption capacity, 479 ± 25 mg g−1, achieved for GO-SWCNT buckypapers with 75 wt.% of graphene oxide confirmed the effective application of such materials for cheap and fast water decontamination from lead.

Mix design methods for pervious concrete based on the mesostructure: Progress, existing problems and recommendation for future improvement

High porosity endues pervious concrete with outstanding performances as water permeability, pollutant removal, and noise reduction, which make pervious concrete a sustainable material for wide application fields, but a uniform mix design method for pervious concrete is not established yet. This review is conducted to integrate the useful findings in the publication and search the efficient method for the mix design of pervious concrete. The quantitative relationships between the mechanical and hydraulic properties and the mesoscopic parameters of pervious concrete provides the foundation for the property estimation during the mix design of pervious concrete, and the existing model could quantitatively characterize the mesostructure of pervious concrete consisting of cement paste and aggregate. The paste thickness is an important parameter to the final mesostructure of pervious concrete. The film-forming ability test provides an effective approach to select the suitable W/C and dosage of chemical admixture. Based on the previous finding in the publications, the mixture of pervious concrete could be quantitatively controlled from fresh to hardened state, and a systematic mix design method for pervious concrete is suggested. The suggested method would conduce to better control the quality of pervious concrete and greatly reduce the number of trail batching.

Removal of chemical and microbial water pollutants by cold plasma combined with Ag/TiO2-rGO nanoparticles

This study aimed to investigate the synergistic effect of the cold atmospheric plasma (CAP) and heterogeneous photocatalytic processes in an aqueous solution to enhance water purification efficacy and reduce the energy cost required by CAP. 0.1% Ag/TiO2-reduced graphene oxide (rGO) nanoparticles (NPs) photo-composite were prepared and fully characterized. Data showed that Ag nanoparticles and the rGO play an important role in increasing the efficiency of the whole treatment process and the photo-composite (0.1% Ag/TiO2-1% rGO at 400 °C) revealed the highest phenol removal rate with excellent reusability. Also, complete inactivation (~ 5log10 reduction) of both E. coli and S. aureus by NPs was observed without CAP exposure, whereas a minimal effect (0.1–0.5 log10) on viruses (Adenovirus (AdV), rotavirus, and ɸX174) was observed after 10 min incubation. Interestingly, the photocatalytic virus inactivation test was promising, as it resulted in > 4.7log10 reduction of AdV at 2 min treatment, whereas < 1log10 could be reduced using only CAP at the same treatment time. Accordingly, we believe that this work could provide new insights into how the synergy between CAP and 0.1% Ag/TiO2-1% rGO photo-composite in aqueous media imposes a great potential for environmental applications, such as water purification and microbial inactivation.