Removal Of Pollutants Research Articles

Recent advances on nanocellulose-graphene oxide composites: a review

AbstractNanocellulose (NC)/graphene oxide (GO) composites are attractive materials with a range of unique features obtained from the integration of NC and GO. These materials have high potential use in various sectors such as biomedicine, wastewater remediation, sensor/biosensor technology, and energy storage/conversion. The simple functionalization and modification of NC or GO afford an opportunity for tailoring these materials for anticipated applications. In wastewater treatment applications, they can be employed as reliable adsorbents for the removal of different pollutants, such as metals, dyes, oils, and pesticides as well as sensors for the detection and monitoring of these pollutants. Besides that, NC/GO composites can be applied as catalysts for catalytic degradation for a wide variety of pollutants. These materials have been also reported to be applicable in biomedical applications such as drug delivery, antibacterial and biosensing. Energy storage applications such as supercapacitors NC/GO-based materials were also utilized. This review summarizes NC/GO hybrid fabrication, characterization, and their application in different fields, i.e. sensing, energy storage, and wastewater remediation. It also covered a broad overview of the status of integrating GO with nanocellulose materials, i.e. bacterial cellulose, cellulose nanofibrils, and cellulose nanocrystals. We concluded with the challenges and outlook for NC/GO-based composites.

Metal Alloy‐Functionalized 3D‐Printed Electrodes for Nitrate‐to‐Ammonia Conversion in Zinc‐Nitrate Batteries

AbstractElectrocatalytic nitrate reduction is a promising approach to remove harmful nitrate and produce ammonia in aqueous media. Here, we demonstrate how 3D printed polymer electrodes can be electroless plated with a bimetallic NiCu alloy film suitable for sustained nitrate‐to‐ammonia reduction. Characterization by powder X‐ray diffraction, X‐ray photoelectron spectroscopy, scanning/transmission electron microscopy and energy‐dispersive X‐ray spectroscopy indicate that the electrode has a two‐layer structure consisting of polymer/ coating layer of metal alloys. The composite electrode shows high‐performance in the nitrate‐to‐ammonia electroreduction, giving NH3 Faradaic efficiencies of up to 83 % and NH3 yield rates up to 860 μg/(h cm2) at −0.38 V vs. RHE. We show that the electrode can easily be integrated into a Zn‐nitrate battery, giving a power density of 3.8 mW cm−2 with continuous NH3 production. The system combines three productive outputs, that is removal of nitrate pollutants, synthesis of valuable ammonia and generation of “green” electricity.

Organic pollutant degradation over highly efficient Mn–Mo(O,S)2 oxysulfide photocatalyst under visible light illumination

Metal oxide semiconductor photocatalysts have received remarkable consideration as a promising technology for environmental remediation and energy conversion. Oxysulfide semiconductors have narrow band gaps which are appropriate for photocatalytic removal of toxic organic pollutants under visible light illumination. For the elimination purpose of these pollutants, Mo(O,S)2, Mn(O,S)2, and Mn–Mo(O,S)2 oxysulfide catalysts containing various Mn contents were synthesized at low temperatures via a simple method. The structural, morphological, electrochemical, compositional, and optical properties of the as-synthesized catalysts were exhaustively characterized. The photocatalytic degradation activity of the bares Mo(O,S)2, Mn(O,S)2, and other Mn–Mo(O,S)2 compositions were evaluated over different types of organic pollutants under visible light illumination. The addition of Mn in Mo(O,S)2 structure improved the photodegradation activity, and Mn–Mo(O,S)2-30 was found to be the best composition with superior photodegradation performance towards the four cationic, anionic, and neutral dyes. The degradation efficiency of 10 ppm of MB, and MO dyes reach 99.7 % and 98.6 %, within 30 and 120 min, respectively. Mn–Mo(O,S)2-30 catalyst also shows a good photodegradation performance on Rh B and NR organic pollutants. According to the recycling test, the catalyst exhibited excellent performance. The photodegradation follows pseudo-first order kinetics with a rate constant of 0.097 and 0.036 min−1 for MB and MO dyes, respectively. The trapping experiment showed that superoxide anion radicals (O2•-) and holes (h+) are the responsible active species for the degradation on MO and MB, respectively. The novelty of using Mn–Mo(O,S)2-30 for various dyes degradation lies in its remarkable catalytic properties.

Changes in the structure of red mud and black nickel mud after activation

This paper deals with the evaluation of the structure of selected hazardous wastes from the production of metals, namely waste from the production of aluminium - red mud and waste from the production of nickel - black nickel mud. In environmental applications, red mud and black nickel mud are likely to be used after activation. The samples were activated using hydrochloric acid to study the structure properties before and after the treatment. Both of these wastes have suitable adsorption and catalytic properties that could be positively affected by the activation of their surfaces. The morphology of the samples was documented by scanning electron microscope, phase analysis was performed using diffraction techniques, and the content of elements was determined by EDX analysis. Also, FTIR analysis of the samples was performed. Activation increases the specific surface area of samples, which is beneficial in many environmental applications, such as in the adsorptive removal of pollutants. Treatment of samples changes the surface properties of the adsorbent, such as electrostatic, hydrophobic, and hydrophilic. The activation creates a new surface structure and thus affects its properties. EDX analysis confirmed the high content of Fe, Al, Si and Ti, which are responsible for good adsorption and catalytic properties. X-ray diffractograms have shown only slight changes in the structure of wastes after activation. The results of SEM confirmed the changes in the surface structure and the creation of new active centres necessary for the successful adsorption process. The FTIR analysis determined the changes in the structure of the samples mainly due to the thermal degradation of C=O and O-Si-O bonds.

Aspergillus niger as an efficient biological agent for separator sludge remediation: two-level factorial design for optimal fermentation.

The booming palm oil industry is in line with the growing population worldwide and surge in demand. This leads to a massive generation of palm oil mill effluent (POME). POME is composed of sterilizer condensate (SC), separator sludge (SS), and hydro-cyclone wastewater (HCW). Comparatively, SS exhibits the highest organic content, resulting in various environmental impacts. However, past studies mainly focused on treating the final effluent. Therefore, this pioneering research investigated the optimization of pollutant removal in SS via different aspects of bioremediation, including experimental conditions, treatment efficiencies, mechanisms, and degradation pathways. A two-level factorial design was employed to optimize the removal of chemical oxygen demand (COD) and turbidity using Aspergillus niger. Bioremediation of SS was performed through submerged fermentation (SmF) under several independent variables, including temperature (20-40°C), agitation speed (100-200 RPM), fermentation duration (72-240 h), and initial sample concentration (20-100%). The characteristics of the treated SS were then compared to that of raw sludge. Optimal COD and turbidity removal were achieved at 37°C 100 RPM, 156 h, and 100% sludge. The analysis of variance (ANOVA) revealed a significant effect of selective individual and interacting variables (p<0.05). The highest COD and turbidity removal were 97.43% and 95.11%, respectively, with less than 5% error from the predicted values. Remarkably, the selected optimized conditions also reduced other polluting attributes, namely, biological oxygen demand (BOD), oil and grease (OG), color, and carbon content. In short, this study demonstrated the effectiveness of A.niger in treating SS through the application of a two-level factorial design.

Mechanical Enhancement and Water Treatment Efficiency of Nanocomposite PES Membranes: A Study on Akçay Dam Water Filtration Application.

Polymeric membranes are widely used in water treatment because of their ease of fabrication and low cost. The flux and purification performance of membranes can be significantly improved by incorporating appropriate amounts of nanomaterials into the polymeric membrane matrices. In this study, neat poly(ether sulfone) (PES), PES/nano copper oxide (CuO), and PES/nano zinc oxide (ZnO) membranes are fabricated via phase inversion. The pure water flux of the neat PES membrane, which is 355.14 L/m2·h, is increased significantly with the addition of nano-CuO and nano-ZnO, and the pure water fluxes of the nanocomposite membranes vary in the range of 392.65-429.74 L/m2·h. Moreover, nano CuO and nano ZnO-doped PES nanocomposite membranes exhibit higher conductivity, color, total organic carbon, boron, iron, selenium, barium, and total chromium removal efficiencies than neat PES membranes. The membrane surfaces examined by Scanning Electron Microscopy (SEM) after water filtration revealed that those containing 0.5% wt. nano CuO and nano ZnO are more resistant to fouling than the membrane surfaces containing 1% wt. nano CuO and nano ZnO. Based on the results of this study, 0.5% wt. nano ZnO-doped PES membrane is found to be the most suitable membrane for use in water treatment due to its high pure water flux (427.14 L/m2·h), high pollutant removal efficiency, and high fouling resistance. When the mechanical properties of the membranes are examined, the addition of CuO and ZnO nanoparticles increases the membrane stiffness and modulus of elasticity. The addition of 0.5% and 1% for CuO leads to an increase in the modulus of elasticity by 57.95% and 324.43%, respectively, while the addition of 0.5% and 1% for ZnO leads to an increase in the modulus of elasticity by 480.68% and 1802.43%, respectively. At the same time, the tensile strength of the membranes also increases with the addition of nanomaterials.

Unraveling the Potential of Microbial Flocculants: Preparation, Performance, and Applications in Wastewater Treatment

Microbial flocculants (MBFs), a class of eco-friendly and biodegradable biopolymers produced by various microorganisms, have gained increasing attention as promising alternatives to conventional chemical flocculants in wastewater treatment and pollutant removal. This review presents a comprehensive overview of the current state of MBF research, encompassing their diverse sources (bacteria, fungi, and algae), major categories (polysaccharides, proteins, and glycoproteins), production processes, and flocculation performance and mechanisms. The wide-ranging applications of MBFs in removing suspended solids, heavy metals, dyes, and other pollutants from industrial and municipal wastewater are critically examined, highlighting their superior efficiency, selectivity, and environmental compatibility compared to traditional flocculants. Nonetheless, bioflocculants face significant challenges including high substrate costs, low production yields, and intricate purification methodologies, factors that impede their industrial scalability. Moreover, the risk of microbial contamination and the attendant health implications associated with the use of microbial flocculants (MBFs) necessitate thorough evaluation. To address the challenges of high production costs and variable product quality, strategies such as waste valorization, strain improvement, process optimization, and biosafety evaluation are discussed. Moreover, the development of multifunctional MBF-based flocculants and their synergistic use with other treatment technologies are identified as emerging trends for enhanced wastewater treatment and resource recovery. Future research directions are outlined, emphasizing the need for in-depth mechanistic studies, advanced characterization techniques, pilot-scale demonstrations to accelerate the industrial adoption of MBF, and moreover, integration with novel wastewater treatment processes, such as partial nitrification and the anammox process. This review is intended to inspire and guide further research and development efforts aimed at unlocking the full potential of MBFs as sustainable, high-performance, and cost-effective bioflocculants for addressing the escalating challenges in wastewater management and environmental conservation.

New Insights into Materials for Pesticide and Other Agricultural Pollutant Remediation.

The increase in the world population and the intensification of agricultural practices have resulted in the release of several contaminants into the environment, especially pesticides and heavy metals. This article reviews recent advances in using adsorbent and catalytic materials for environmental decontamination. Different materials, including clays, carbonaceous, metallic, polymeric, and hybrid materials, are evaluated for their effectiveness in pollutant removal. Adsorption is an effective technique due to its low cost, operational simplicity, and possibility of adsorbent regeneration. Catalytic processes, especially those using metallic nanoparticles, offer high efficiency in degrading complex pesticides. Combining these technologies can enhance the efficiency of remediation processes, promoting a more sustainable and practical approach to mitigate the impacts of pesticides and other agricultural pollutants on the environment. Therefore, this review article aims to present several types of materials used as adsorbents and catalysts for decontaminating ecosystems affected by agricultural pollutants. It discusses recent works in literature and future perspectives on using these materials in environmental remediation. Additionally, it explores the possibilities of using green chemistry principles in producing sustainable materials and using agro-industrial waste as precursors of new materials to remove contaminants from the environment.

N-acyl homoserine lactones (AHLs) enhanced removal of cadmium and other pollutants by algae-bacteria consortia

Signal transduction is an important mode of algae-bacteria interaction, in which bacterial quorum sensing (QS) may affect microalgal growth and metabolism. Currently, little is known whether acyl homoserine lactones (AHLs) released by bacteria can affect the pollutant removal by algae-bacteria consortia (ABC). In this study, we constructed ABC using Chlorella vulgaris (Cv) with two AHLs-producing bacteria and investigated their performance in the removal of multiple pollutants, including chemical oxygen demand (COD), total nitrogen (TN), phosphorus (P), and cadmium (Cd). The AHLs-producing bacteria, namely Agrobacterium sp. (Ap) and Ensifer adherens (Ea), were capable of forming a symbiosis with C. vulgaris. Consortia of Cv and Ap with ratio of 2:1 (Cv2-Ap1) showed the optimal growth promotion and higher removal of Cd, COD, TN, and P compared to the C. vulgaris monoculture. Cv2-Ap1 ABC removed 36.1–47.5% of Cd, 94.5%–94.6% COD, 37.1%–56.0% TN, and 90.4%–93.5% P from the culture medium. In addition, increase of intracellular neutral lipids and extracellular protein, as well as the types of functional groups on cell surface contributed to Cd removal and tolerance in the Cv2-Ap1 ABC. Six AHLs were detected in the Cv2-Ap1 culture. Among these, 3OC8-HSL and 3OC12-HSL additions promoted the ABC growth and enhanced their Cd accumulation. These findings may contribute to further understanding of AHL-mediated communication between algae and bacteria and provide support bioremediation efforts of metal-containing wastewater.

Nitrate and ammonium removal in constructed wetlands: Experimental insights and zero-dimensional numerical modeling

Constructed wetlands (CWs) have emerged as effective wastewater treatment systems, mimicked natural wetland processes but engineered for enhanced pollutant removal efficiency. Ammonium (NH4+) and nitrate (NO3−) are among common pollutants in wastewater, posing significant environmental and health risks. The primary objective of this study is to compares the performance of CWs using gravel and three sizes of natural pumice, along with phragmites australis, in horizontal and horizontal-vertical CWs for nitrate and ammonium removal in the complementary treatment of domestic wastewater. Additionally, the study aims to develop and validate a numerical model using MATLAB software to predict the removal efficiency of these pollutants, thereby contributing to the optimization of CW design and operation. The model operates as a zero-dimensional model based on the law of mass conservation, treating the wetland as a completely mixed reactor, thus avoiding complexities associated with solute movement in porous media. It accurately could predict removal efficiency of chemical, biochemical, and biological indicators while considering active and passive absorption mechanisms by plant uptake. Notably, the determination of coefficients in the model equation does not rely on potentially error-prone laboratory measurements due to sampling issues. Instead, optimization techniques alongside field data robustly estimate these coefficients, ensuring reliability and practicality. Results indicate that higher pollutant concentrations increase reaction rates, particularly enhancing CW efficiency in ammonium removal. Pumice, especially in larger sizes, exhibits superior absorption due to increased porosity and surface area. Overall, the model accurately predicts nitrates concentrations, demonstrating its potential for CW performance optimization and confirming the significance of effective pollutant removal strategies in wastewater treatment.

Removal and detection of phenols through an SPE-HPLC method using microporous organic networks as adsorbent.

The design and development of a facile synthesis approach to construct novel materials for the rapid adsorption and removal of environmental pollutants are of significant interest. In this work, we report the rational design and facile synthesis of magnetic core-shell-based microporous organic networks, Fe3O4@MON-TBPT-TEB (TTMON, achieved by reacting 2,4,6-tris(p-bromophenyl) triazine and 1,3,5-triethynylbenzene) and Fe3O4@MON-TBPM-DEBP (TDMON, achieved by reacting tetrakis (4-bromophenyl) methane and 4-4'-diethynylbiphenyl). These MONs possessed excellent dispersity, electrostatic attraction as well as plenty of π-π and hydrophobic interaction sites enabled them to efficiently absorb targeted environmental pollutants. TTMON and TDMON exhibited excellent adsorption capacities of 440 and 510 mg g-1, respectively, at 25 °C for 2,4,6-trichlorophenol (TCP). TCP, 2,4-dichlorophenol (DCP), 2-naphthol (2-NT) and 4-nitrophenol (4-NP) from aqueous solution were treated by both MONs, followed by their analysis with high-performance liquid chromatography (HPLC). For TDMON, the proposed SPE-HPLC-UV method showed an LOD of 0.03 μg L-1, LOQ of 0.11 μg L-1, and a wide linear range of 1-1000 μg L-1 for TCP. The adsorption kinetics, thermodynamics, isotherms, effect of pH and humic acid (HA), ionic strength, regeneration, and reusability of the MONs were also studied. The results revealed that the novel-designed MONs have potential applications as efficient adsorbents in sample pretreatment.

Removal of Nitrogen Pollutants in the Chemical Looping Process: A Review

Removal of Nitrogen Pollutants in the Chemical Looping Process: A Review

Effect of monocultures and polycultures of Typha latifolia and Heliconia psittacorum on the treatment of river waters contaminated with landfill leachate/domestic wastewater in partially saturated vertical constructed wetlands

Partially Saturated Vertical Constructed Wetlands (PSV-CWs) are novel wastewater treatment systems that work through aerobic and anaerobic conditions that favor the removal of pollutants found in high concentrations, such as rivers contaminated with domestic wastewater and landfill leachate. The objective of the study was to evaluate the efficiency of PSV-CWs using monocultures and polycultures of Typha latifolia and Heliconia psittacorum to treat river waters contaminated with leachates from open dumps and domestic wastewater. Six experimental units of PSV-CWs were used; two were planted with Typha latifolia monoculture, two with Heliconia psittacorum monoculture and two with polycultures of both plants. The results indicated better organic matter and nitrogen removal efficiencies (p < 0.05) in systems with polycultures (TSS:95%, BOD5:83%, COD:89%, TN:82% and NH4+:99%). In general, the whole system showed high average removal efficiencies (TSS:93%, BOD5:79%, COD:85%, TN:79%, NH4+:98% and TP:85%). Regarding vegetation, both species developed better in units with monocultures, being Typha latifolia the one that reached a more remarkable development. However, both species showed high resistance to the contaminated environment. These results showed higher removals than those reported in the literature with conventional Free Flow Vertical Constructed Wetlands (FFV-CWs), so PSV-CWs could be a suitable option to treat this type of effluent.

Performance Evaluation of Sequential Batch Biofilm Reactor for the treatment of Grey Water

&lt;p&gt;The performance of a Sequential Batch Biofilm Reactor (SBBR) for the treatment of grey water was evaluated using two different bio-carries under different aeration duration. Two biofilm carriers such as fujino spiral and loofah sponge was used for biofilm formation in the reactor. The study demonstrated that the SBBR system, when operated with both biofilm carriers, effectively removed contaminants from grey water. The aeration time of 45 minutes demonstrated the highest removal efficiencies for organic matter, and suspended solids for the both biofilm carrier i.e., fujino spiral and loofah sponge. Comparing the two biofilm carriers, the Fujino spiral showed strong biofilm attachment and demonstrated excellent performance in pollutant removal. The removal efficiencies of COD, BOD, TS, TDS was found out to be 94%, 93%, 72%, 73% respectively. On the other hand, the loofah sponge exhibited slightly lower performance compared to the Fujino spiral. However, it still proved to be an effective biofilm carrier, providing a suitable substrate for biofilm development and contributing to grey water treatment. The removal efficiencies of COD, BOD, TS, TDS was found out to be 92%, 93%, 65%, 63% respectively.&lt;/p&gt;

Significant enhancement on ammonia removal by thermal/peroxymonosulfate system with bromide ion: Performance, influencing factors and mechanism

Although thermal-activated peroxymonosulfate (PMS) system possesses good performance on the removal of organic pollutants, thermal/PMS system exhibited poor capacity to remove ammonia nitrogen (NH4+-N). This study demonstrated the huge enhancement on the removal of NH4+-N by thermal/PMS system with the commonly coexistent bromide ion (Br-). The elimination of NH4+-N by thermal/PMS/Br- system fitted the pseudo-zero-order kinetics model well, while the corresponding kobs in the presence of 200 μM Br- was 5.76 times greater than that by thermal/PMS system. Bromine (HBrO) was confirmed as the dominant oxidant responsible for removing NH4+-N and TN, while the radicals of HO⋅, SO4⋅- and Br⋅ were also generated but made minor contribution to removing NH4+-N. HBrO was mostly produced by PMS reacting directly with Br-, while these radicals were produced from the cleavage of the O-O bond in PMS and the reaction between PMS and HBrO under high temperature. Thermal/PMS/Br- system exhibited superior performance on TN removal (up to 90 %) than that by thermal/PMS system (less than 5 %) and Cl--enhanced system (about 80 %). The main removal product of NH4+-N was identified as the environmentally friendly gas of N2, although nitrate was also detected. Neutral pH condition was the optical pH for NH4+-N removal. Increasing reaction temperature, PMS dosage and Br- concentration were beneficial to accelerating the removal of NH4+-N. Cations of Cu2+ and Fe3+, anions of SO42-, CO32- and NO3-, humic acid and the actual water matrix of landfill leachate negligibly influenced the removal of NH4+-N, while Cl- exhibited strong enhancement on NH4+-N removal. In summary, this study provided an effective method to improve the oxidizing capacity of thermal/PMS system, especially for NH4+-N removal in wastewater containing Br-.

Optimizing malachite green adsorption with Co-PTC metal organic framework: Insights into mechanisms and performance

The removal of organic pollutants from aqueous environments has garnered significant attention in environmental science and engineering. Metal-organic frameworks (MOFs) have emerged as promising materials for this purpose due to their intriguing structures, high surface area, and perpetual porosity. In this study, we investigate the adsorption performance of Co-based MOF for the removal of malachite green (MG), a common organic dye pollutant. The MOF, abbreviated as Co-PTC is synthesized via a one-pot green approach using perylene-3,4,9,10-tetracarboxylic dianhydride (PTC) as the ligand at room temperature. Basic to advanced characterization techniques are employed to elucidate the structure and interactions within the MOF. Through a comprehensive analysis, the underlying mechanisms governing the adsorption process are explored, and optimization studies have been carried out. Co-PTC in minute amounts exhibits an adsorption capacity of 79.3 % selectively for MG in 50 min. The kinetics and isotherm models governing the adsorption process are well investigated.

Red mud/steel slag three-dimensional electrochemical system for the removal of organic pollutant with Na2S2O3 as electrolyte: Contribution of •OHads

The dynamic changes in the iron redox cycle (Fe2+/Fe3+) played a crucial role in the electro-Fenton degradation of organic pollutants. The synthesis of composite particle electrodes RMSSx:y from a mixture of steel slag (SS) and red mud (RM) was applied in a three-dimensional electrochemical system for the remediation of hydrochloric tetracycline (TCH) in wastewater, utilizing Na2S2O3 as an electrolyte. Further, some investigations were conducted to determine the effects of RM/SS, electrolyte, particle electrode dosage, cell voltage, and pH on TCH degradation efficiency. Under optimal conditions such as 8 g/L RMSS5:5 particle electrodes, a cell voltage of 4 V, an initial pH of 3, and 6 mM Na2S2O3 electrolyte, the degradation rate of TCH in wastewater was 98.3 %. Meanwhile, its total organic carbon (TOC) was reduced by 88 % within 60 min. Cyclic experiments with consistently high degradation efficiency demonstrated the stability of the particle electrode RMSS5:5. The practical applicability of RMSS5:5 was further confirmed through its successful treatment of various industrial wastewaters, including dyeing (DW), chemical (CW), and pharmaceutical (PW) effluents, achieving chemical oxygen demand (COD) removal rates of 67.8 %, 67.6 %, and 65.0 % respectively. The enhancement of TCH degradation through the utilization of Na2S2O3 as the electrolyte was primarily attributed to the complexation and reduction effects exerted by S2O32- ions. These effects prevented the leaching and precipitation of iron ions, facilitated the reduction of Fe (III), and consequently enabled •OHads to play a dominant role in the degradation process. These findings demonstrated the potential of RMSS5:5 in efficiently degrading emerging contaminants, thereby offering an innovative approach for utilizing SS and RM as functional materials in electro-Fenton processes.

Enhanced Photocatalytic Ozonation Using ModifiedTiO2 withDesignedNucleophilic and Electrophilic Sites.

Photocatalytic ozonation is considered to be a promising approach for the treatment of refractory organic pollutants, but the design of efficient catalyst remains a challenge. Surface modification provides a potential strategy to improve the activity of photocatalytic ozonation. In this work, density functional theory (DFT) calculations were first performed to check the interaction between O3 and TiO2-OH (surface hydroxylated TiO2) or TiO2-F (surface fluorinated TiO2), and the results suggest that TiO2-OH displays better O3 adsorption and activation than does TiO2-F, which is confirmed by experimental results. The surface hydroxyl groups greatly promote the O3 activation, which is beneficial for the generation of reactive oxygen species (ROS). Importantly, TiO2-OH displays better performance towards pollutants (such as berberine hydrochloride) removal than does TiO2-F and most reported ozonation photocatalysts. The total organic carbon (TOC) removal efficiency reaches 84.4% within two hours. This work highlights the effect of surface hydroxylation on photocatalytic ozonation and provides ideas for the design of efficient photocatalytic ozonation catalysts.

Novel polyferric titanium silicate/chitosan composite flocculant for organic polymeric pollutant removal: optimization, performance and mechanism

A novel inorganic-organic composite flocculant polyferric titanium silicate/chitosan (PFTS/CTS) was successfully synthesized in this study. The optimal preparation parameters of flocculant were optimized by orthogonal experiment with organic polymer polyacrylamide (PAM) removal rate as the evaluation index. The results shows that the examined preparation parameters are in the order of aging time > m(Fe + Ti):m(CTS) > n(Fe + Ti):n(Si), and the best experimental formula is that aging time = 2 days, m(Fe + Ti):m(CTS)=5 and n(Fe + Ti):n(Si)=0.5. The obtained PAM (50 mg/L) removal rate is 78.7% under the selected suitable wastewater treatment condition. Compared with the single CTS, PFTS and polyferric silicate (PFS), PFTS/CTS exhibits superior flocculation performance. The reason for the improvement of flocculation performance of PFTS/CTS can be attributed to its good crystallinity, special scaly accumulation structure and high positive charge, as well as the synergistic effect of inorganic flocculant and organic flocculant in the PFTS/CTS flocculant, which is successfully composited through coordination bond between titanium ions of PFTS and hydroxyl or amino groups of CTS. The main mechanism of treating PAM by PFTS/CTS is physical and chemical effect including micro-flocs are formed through chelate, charge neutralization and adsorption in the first process, and then the larger particles are formed by bridging, wrapping and sweeping. In addition, the flocs of treating PAM using PFTS/CTS are dense and large, its formation and the sedimentation are fast. The prepared flocculant exhibits eminent application prospects in the field of PAM wastewater.

Biochar Meets Single-Atom: A Catalyst for Efficient Utilization in Environmental Protection Applications and Energy Conversion.

Single-atom catalysts (SACs), combining the advantages of multiphase and homogeneous catalysis, have been increasingly investigated in various catalytic applications. Carbon-based SACs have attracted much attention due to their large specific surface area, high porosity, particular electronic structure, and excellent stability. As a cheap and readily available carbon material, biochar has begun to be used as an alternative to carbon nanotubes, graphene, and other such expensive carbon matrices to prepare SACs. However, a review of biochar-based SACs for environmental pollutant removal and energy conversion and storage is lacking. This review focuses on strategies for synthesizing biochar-based SACs, such as pre-treatment of organisms with metal salts, insertion of metal elements into biochar, or pyrolysis of metal-rich biomass, which are more simplistic ways of synthesizing SACs. Meanwhile, this paper attempts to 1) demonstrate their applications in environmental remediation based on advanced oxidation technology and energy conversion and storage based on electrocatalysis; 2) reveal the catalytic oxidation mechanism in different catalytic systems; 3) discuss the stability of biochar-based SACs; and 4) present the future developments and challenges regarding biochar-based SACs.