Effective Technique For Removal Research Articles

Optimising miniaturised hydrocyclones for enhanced separation of microplastics

Microplastics, particularly those in the 5–20µm range, pose substantial risks in aquatic environments, yet effective removal techniques are limited. This study assesses two critical geometric parameters of a 10 mm mini-hydrocyclone: inlet radius and insertion angle. Along with the inlet velocity, they are optimised collectively to enhance the MPs’ removal. Computational Fluid Dynamics (CFD) simulations using the Mixture model and Reynolds stress model were employed to track the particle–water–air interactions, revealing the flow dynamics and absence of an air core. The Response Surface Methodology (RSM) using a Box-Behnken design of experiments was adopted to assess the impact of the geometric and operational parameters and determine the optimal design. Recovery efficiency, concentration efficiency, and split rate were recorded during experiments and compared with CFD results, showing a good agreement between experiments and CFD simulations. The resulting novel design achieved an 88.53% MPs recovery and a concentration efficiency of 1.83, which represents an obvious improvement over the commercial design’s MPs recovery efficiency of 79.97% and concentration efficiency of 1.68. Simulations reveal that the novel design shortens the path for MPs through the forced turbulence region and modifies the velocity and turbulence fields, enhancing the concentration gradient of MPs within the mini-hydrocyclone’s chamber. Moreover, the novel design exhibits a more robust response to inlet velocity variations, a crucial advantage for its application in arrays. Experiments further confirm that a matrix composed of 10 novel mini-hydrocyclones achieves 10 percentage points higher recovery efficiency than the matrix with 10 commercial mini-hydrocyclones. These findings mark a significant step towards effective MP removal, addressing a critical environmental issue.

Mixed-charged polyamide-4-sulfocalix [4] arene hollow fiber nanofiltration membranes for heavy metal removal under various pH

The presence of heavy metal ions in water sources poses significant risks to both human health and environments; hence, it is critical to develop effective and trustworthy removal techniques. This research aims to fabricate a novel hollow fiber membrane consisting of mixed-charged characteristics via the formation of a positively charged thin film composite (TFC), followed by the infiltration of 4-sulfocalix [4] arene (SCA4). The formation, architecture and separation performance of the mixed-charged nanofiltration (NF) membrane have been confirmed by various characterizations. The SCA4-0.03 NF hollow fiber membrane shows excellent rejection performance up to 99.2 % for a variety of ion removals such as common arsenate, nickel (II), and lead (II) ions over a broad pH range. Additionally, the mixed-charged membrane exhibits higher performance stability over 48 h and fouling resistance in both basic and acidic conditions. Consequently, the mixed-charged membrane described in this work is promising to treat both cationic and anionic liquids, and eliminate a variety of ecologically harmful ion species in industries.

Investigating Training Datasets of Real and Synthetic Images for Outdoor Swimmer Localisation with YOLO

In this study, we developed and explored a methodical image augmentation technique for swimmer localisation in northern German outdoor lake environments. When it comes to enhancing swimmer safety, a main issue we have to deal with is the lack of real-world training data of such outdoor environments. Natural lighting changes, dynamic water textures, and barely visible swimming persons are key issues to address. We account for these difficulties by adopting an effective background removal technique with available training data. This allows us to edit swimmers into natural environment backgrounds for use in subsequent image augmentation. We created 17 training datasets with real images, synthetic images, and a mixture of both to investigate different aspects and characteristics of the proposed approach. The datasets were used to train YOLO architectures for possible future applications in real-time detection. The trained frameworks were then tested and evaluated on outdoor environment imagery acquired using a safety drone to investigate and confirm their usefulness for outdoor swimmer localisation.

Investigation on pulsed-electrocoagulation process for the treatment of wet coffee processing wastewater using an aluminum electrode

The use of conventional direct current-electrocoagulation in wastewater treatment is limited by its drawbacks, which include electrode passivation, high energy consumption, and significant sludge generation. Therefore, to address these issues, pulsed-electrocoagulation (PECP) has been developed. The PECP is an advanced wastewater treatment technique that uses intermittent electrical pulses to target and break down organic compounds in wastewater. It offers several benefits, including enhanced removal of organic compounds, reduced chemical consumption, energy efficiency, treatment of complex wastewater composition, pathogen inactivation, environmental compliance, and potential for water reuse. In this research, removal efficiency of % Chemical Oxygen Demand (COD), % Color, % Turbidity, % phosphate, and %nitrate was investigated for the wet coffee processing wastewater by using PECP and the obtained results as the COD-98.75%, color-99.92%, turbidity-99.00%, phosphate-99.02%, and nitrate-98.83%, respectively. Independent variables were the major significant factors and the optimum value was investigated and obtained at pH of 7, electrolyte dosage of 0.75 g L−1, electrolysis time of 45 min, and current of 0.45 Amp. As a result, PECP with NaCl and CaCl2 as an electrolyte is an effective treatment technique for pollutant removal from wastewater. As a consequence, the specific benefits may vary depending on the system design, operational parameters, and wastewater characteristics. The pilot-scale studies and optimization are essential for assessing PECP feasibility and performance.

Metal-Organic Framework-Based Composites for the Adsorption Removal of Per- and Polyfluoroalkyl Substances from Water.

The increasing health risks posed by per- and polyfluoroalkyl substances (PFASs) in the environment highlight the importance of implementing effective removal techniques. Conventional wastewater treatment processes are inadequate for removing persistent organic pollutants. Recent studies have increasingly demonstrated that metal-organic frameworks (MOFs) are capable of removing PFASs from water through adsorption techniques. However, there is still constructive discussion on the potential of MOFs in adsorbing and removing PFASs for large-scale engineering applications. This review systematically investigates the use of MOFs as adsorbents for the removal of PFAS in water treatment. This primarily involved a comprehensive analysis of existing literature to understand the adsorption mechanisms of MOFs and to identify factors that enhance their efficiency in removing PFASs. We also explore the critical aspects of regeneration and stability of MOFs, assessing their reusability and long-term performance, which are essential for large-scale water treatment applications. Finally, our study highlights the challenges of removing PFASs using MOFs. Especially, the efficient removal of short-chain PFASs with hydrophilicity is a major challenge, while medium- to long-chain PFASs are frequently susceptible to being captured from water by MOFs through multiple synergistic effects. The ion-exchange force may be the key to solving this difficulty, but its susceptibility to ion interference in water needs to be addressed in practical applications. We hope that this review can provide valuable insights into the effective removal and adsorption mechanisms of PFASs as well as advance the sustainable utilization of MOFs in the field of water treatment, thereby presenting a novel perspective.

Biodesulfurization of landfill biogas by a pilot-scale bioscrubber: Operational limits and microbial analysis.

Biogas serves as a crucial renewable energy vector to ensure a more sustainable energy future. However, the presence of hydrogen sulfide (H2S) limits its application in various sectors, emphasizing the importance of effective H2S removal techniques for maximizing its potential. In the present study, the limits of a pilot-scale bioscrubber for biogas desulfurization was study in a real scenario. An increase in the superficial liquid velocity resulted in significant improvements in the H2S removal efficiency, increasing from 76 ± 8% (elimination capacity of 6.2 ± 0.5 gS-H2S m−3 h−1) to 97.7 ± 0.5% (elimination capacity of 8 ± 1 gS-H2S m−3 h−1) as the superficial liquid velocity increased from 50 ± 3 m h−1 to 200 ± 8 m h−1. A USL of 161.4 ± 0.5 m h−1 was able to achieve outlet H2S concentrations as low as 3 ± 1 ppmv (H2S removal efficiency of 97 ± 1%) for 7 days. High superficial liquid velocity favoured the aerobic H2S oxidation reducing the nitrate demand. The maximum EC reached throughout the operation was 50.8 ± 0.6 gS-H2S m−3 h−1 (H2S removal efficiency of 96 ± 1%) and a sulfur production of 60%. Studies in batch flocculation experiments showed sulfur removal rates up to 97.6 ± 0.9% with a cationic flocculant dose of 75 mg L−1. Microbial analysis revealed that the predominant genus with sulfo-oxidant capacity during periods of low H2S inlet load was Thioalkalispira-sulfurivermis (61–69%), while in periods of higher H2S inlet load, family Arcobacteraceae was the most prevalent (11%).

Electrocoagulation as a Possible Treatment for Wastewater Contaminated with Microplastics - A Review

Microplastics (MPs) have arisen as an omnipresent pollutant that damages the aquatic ecosystem, raising serious concerns. It has become a massive challenge since MPs have the ability to biomagnify and thereby harm human health, biodiversity, aquatic species, and the environment. Therefore, innovative technologies are needed to efficiently remove MPs. Membrane technologies can be quite effective in the removal of MPs. Furthermore, hybrid membrane techniques such as advanced oxidation processes (AOPs), membrane fouling, electrochemical processes, and adsorption processes can be used to improve efficiency. Electrocoagulation is considered an effective wastewater treatment technique for MPs removal, with the advantages of low cost, independence of chemicals, and ease of operation. The main aim of this work is to demonstrate the potential of electrocoagulation to remove MPs from wastewater and provide an overview of the sources and toxicity of MPs found in wastewater. This study also evaluates various physical, chemical, and biological treatment methods for removing MPs from wastewater.

Morchella Effectively Removes Microcystins Produced by Microcystis aeruginosa.

Microcystins (MCs) produced by Microcystis aeruginosa are harmful to animal and human health, and there is currently no effective method for their removal. Therefore, the development of biological approaches that inhibit cyanobacteria and remove MCs is needed. We identified strain MB1, confirmed as Morchella, using morphological and mole-cular evolution methods. To assess the impact of strain MB1 on M. aeruginosa, we conducted an experiment in which we inoculated M. aeruginosa with Morchella strain MB1. After their co-cultivation for 4‍ ‍d, the inoculation with 0.9696‍ ‍g MB1 completely inhibited and removed M. aeruginosa while concurrently removing up to 95% of the MC content. Moreover, within 3‍ ‍d of their co-cultivation, MB1 removed more than 50% of nitrogen and phosphorus from the M. aeruginosa solution. Therefore, the development of effective biological techniques for MC removal is paramount in safeguarding both the environment and human well-being. We herein successfully isolated MB1 from its natural habitat. This strain effectively inhibited and removed M. aeruginosa and also reduced the content of nitrogen and phosphorus in the M. aeruginosa solution. Most importantly, it exhibited a robust capability to eliminate MCs. The present results offer a new method and technical reference for mitigating harmful algal blooms.

Unraveling the contemporary use of microbial fuel cell in pesticide degradation and simultaneous electricity generation: a review.

Pesticide is an inevitable substance used worldwide to kill pests, but their indiscriminate use has posed serious complications to health and the environment. Various physical, chemical, and biological methods are employed for pesticide treatment, but this paper deals with microbial fuel cell (MFC) as a futuristic technology for pesticide degradation with electricity production. In MFC, organic compounds are utilized as the carbon source for electricity production and the generation of electrons which can be replaced with pollutants such as dyes, antibiotics, and pesticides as carbon sources. However, MFC is been widely studied for a decade for electricity production, but its implementation in pesticide degradation is less known. We fill this void by depicting a real picture of the global pesticide scenario with an eagle eye view of the bioremediation techniques implemented for pesticide treatment with phytoremediation and rhizoremediation as effective techniques for efficient pesticide removal. The enormous literature survey has revealed that not many researchers have ventured into this new arena of MFC employed for pesticide degradation. Based on the Scopus database, an increase in annual trend from 2014 to 2023 is observed for MFC-implemented pesticide remediation. However, a novel MFC to date for effective remediation of pesticides with simultaneous electricity generation is discussed for the first time. Furthermore, the limitation of MFC technology and the implementation of MFC and rhizoremediation as a clubbed system which is the least applied can be seen as promising and futuristic approaches to enhance pesticide degradation by bacteria and electricity as a by-product.

Prospects of green adsorbent produced from avocado seed via hydrothermal carbonization for treatment of dye wastewater

The adsorption process is a highly effective operational technique for dye removal from industrial wastewater. At present, the commercial adsorbents employed for removing dyes are manufactured via a slow pyrolysis process, which is time-consuming and requires more energy. Hydrothermal carbonization, on the other hand, is a highly efficient alternative method of synthesizing adsorbents that consumes less time and energy while producing effective adsorbents. This study synthesized adsorbents from avocado seeds via hydrothermal carbonization, followed by chemical activation. The adsorption study revealed that the avocado seed adsorbent has the highest color removal of 80 % using 3.5 g/L of adsorbent at acidic pH under optimized conditions. In conclusion, hydrochar from the avocado seed is a potential green adsorbent for the treatment of dye wastewater.

Sustainable Use of Marine Macroalga Sargassum muticum as a Biosorbent for Hazardous Crystal Violet Dye: Isotherm, Kinetic and Thermodynamic Modeling

The pollution of aquatic bodies by synthetic dyes is regarded as one of the most significant environmental issues, which has prompted greater research into effective and sustainable removal techniques. Even though there have been major efforts in the previous few decades, more study is still necessary to fully examine the long-term performance and usable applicability of adsorbents and different adsorption techniques for the removal of dye. In the present study, a brown marine macroalga Sargassum muticum was used as an effective and sustainable biosorbent for the crystal violet (CV) dye removal from aqueous solutions. The biosorbent was characterized by analysis of SEM, EDX, and FTIR. In order to evaluate the optimum conditions of CV biosorption, several parameters have been examined as a function of contact time, algal dose, initial concentration of CV, and pH. The maximum CV removal was obtained at 60 min contact time, 10 g/L algal dosage, 30 mg/L initial concentration of CV, and pH 6. The isothermal models of Langmuir, Freundlich, Dubinin-Radushkevich, and Temkin are best explained the equilibrium data obtained. At the optimum conditions, the maximum biosorption capacity of the algal biomass achieved from the Langmuir model was 39.1 mg/g. The kinetic adsorption models were also better explained using the pseudo-second-order and Elovich model, and the effect of the boundary layer was indicated using the intraparticle diffusion model as well as the chemisorption-controlled biosorption process. Thermodynamically, the process of CV biosorption was shown to be random, spontaneous, and endothermic. Furthermore, the proposed mechanism of CV dye biosorption onto algal biomass is regulated by hydrogen bond formation, electrostatic interaction, and ion exchange. These findings revealed that the biomass of S. muticum is a sustainable and promising material for the biosorption of water pollutants.

Wet removal of elemental mercury by acid-assisted electrochemical oxidation method

As a global pollutant, mercury emission is increasingly restricted in recent years. It is urgent to explore a new and efficient mercury removal technology for coal-fired power plants. A new acid-assisted electrochemical oxidation (AEO) technique for mercury removal was proposed using platinum plate as cathode and fluorine-doped tin dioxide (FTO) glass as anode. The effects of acid type, acid concentration, applied direct current (DC) voltage, electrolyte type, SO2, NO and O2 on the Hg0 removal efficiency were carried out. The results indicated that the mercury removal efficiency increased with the increase of DC voltage and nitric acid concentration. When the concentration of nitric acid increased to 0.15 mol/L, the mercury removal efficiency remained unchanged. SO2 and NO inhibited the removal of Hg0 in AEO system, but the inhibition was reversible. Compared with the mercury removal efficiency under single experimental conditions, the mercury removal efficiency of electrochemical oxidation can reach 96% under the experimental conditions of 0.1 mol/L nitric acid and 4V DC voltage, suggesting that the synergistic effect of nitric acid and DC voltage plays a key role. According to the experimental results, the mechanism of Hg0 removal in AEO system was analyzed. At the anode, Hg0 was oxidized by hydroxyl radical (.OH) generated by the oxidation reaction on the anode surface. At the cathode, dissolved oxygen or O2 adsorbed on the surface of Pt is reduced to form anionic superoxide radicals (.O−2). Moreover, parts of .O−2 would produce .OH with the aid of electron at acidic condition. Free radicals capture experiments showed that .O−2 and .OH were the main active substances for the removal of Hg0 by acid-assisted electrochemical method. The research is helpful for the development of effective electrochemical techniques for industrial mercury removal and recycling of industrial acid waste.

Underwater versus conventional endoscopic mucosal resection for colorectal lesions: An updated meta-analysis of randomized controlled trials.

Background and study aims Colorectal malignancy is a leading cause of death. Conventional endoscopic mucosal resection (CEMR) is a strategy used to resect precancerous lesions that involves injecting fluid beneath a polyp to create a gap for resection. Underwater endoscopic mucosal resection (UEMR) is a newer method that forgoes injection, instead filling the intestinal cavity with water to facilitate polyp resection. Our aim was to compare the safety and efficacy of these approaches by synthesizing the most contemporary evidence. Methods PubMed, Embase, and Cochrane libraries were searched from inception through November 11, 2022 for randomized controlled trials (RCTs) comparing UEMR and CEMR for resection of colorectal lesions. The primary outcome was the rate of en bloc resection and secondary outcomes included recurrence, procedure time, and adverse events (AEs). Results A total of 2539 studies were identified through our systematic literature search. After screening, seven RCTs with a total of 1581 polyps were included. UEMR was associated with significantly increased rates of en bloc resection (RR 1.18 [1.03, 1.35]; I 2 = 76.6%) versus conventional approaches. No significant differences were found in procedure time, recurrence, or AEs. Conclusions UEMR is a promising effective technique for removal of colorectal lesions. The most contemporary literature indicates that it improves en bloc resection rate without increasing procedure time, recurrence, or AEs (PROSPERO ID CRD42022374935).

Investigating the enhanced photocatalytic degradation of bromophenol blue using Ni/Zn co-doped Strontium Oxide nanoparticles synthesized via hydrothermal method

Excessive exposure of human to organic contaminants from industrial effluents calls for the implementation of effective pollutants removal techniques. This article investigates the photocatalytic degradation of bromophenol blue dye using Strontium oxide nanoparticles co-doped with Nickel and Zinc. Hydrothermal synthesis produced the nanoparticles, which were subsequently characterized using various analytical techniques. UV/Visible revealed absorption peaks at 294 nm, 306 nm, 311 nm, and 318 nm, while FTIR spectroscopy identified stretching peaks at 416 cm-1, 588 cm-1, and 856 cm-1 for Ni-O and Sr-O bonds. The nanoparticles displayed diameters ranging from 30.50 nm to 36.97 nm. EDX analysis confirmed the elemental composition, with Sr and O comprising of approximately 82.02 %, and Ni and Zn approximately 3.21%. Photocatalytic degradation experiments demonstrated that SrO nanoparticles 85.42% degradation efficiency, while co-doped SrO nanoparticles achieved an impressive 97.97% degradation efficiency. This work highlights the potential co-doped SrO nanoparticles as a promising solution for the efficient removal of organic pollutants from the industrial wastewater, addressing environment contamination concerns.

Remediation of cadmium and chromium using modified Vitex doniana waste plant Seed's biochar in quarry site surface water

Industrial effluents contain hazardous combinations of suspended particulates and dissolved solids in various ratios; the wastewater from cementitious material production activities is no exception. Since heavy metals seriously threaten environmental and human health, developing effective and economical removal techniques is imperative. Due to its efficiency and effectiveness in absorbing heavy metals, biochar has attracted research attention. Therefore, this study used modified biochar from Vitex doniana seeds to remove cadmium (Cd) and chromium (Cr) in cement-producing activities area surface water. The enhancement and functionalization of the modified Vitex doniana seed biochar (MVDS) over the Vitex doniana seed biochar (VDS) were characterized using SEM-EDX, proximate analysis, FTIR, and BET. In the first 60 ​min of adsorption experiments, the MVDS biochar performed best, with an 85.0% removal efficiency and a 338.6 ​mg ​g−1 total cadmium adsorption capacity, whereas the first 45 ​min revealed an 84.1% removal efficiency and a 328.0 ​mg ​g−1 total chromium adsorption capacity. The adsorption process was more multilayer heterogeneous from the isotherm studies, which is evident in the best fitting of the Freundlich model compared to the Temkin and Langmuir models. Additionally, the Pseudo Second order (PSO) kinetic model provided the best explanation for the adsorption process, and the thermodynamics investigation confirmed the viability and spontaneity of the process. The modified biochar from Vitex doniana waste plant seeds successfully removed cadmium and chromium from surface water and can be used for water treatment.

Ultra-efficient removal of methylene blue, oxytetracycline, and lead(II) by activated carbon derived from black cumin (Nigella sativa) processing solid waste

Accumulating dyes, drugs, and heavy metals in water creates a lasting environmental problem that affects living things in different ecosystems. Their removal is imperative for environmental necessity in a habitable world. Adsorption with carbonaceous materials produced especially for the evaluation of agricultural wastes is a low-cost and effective removal technique. This study is related to the investigation of the adsorbing performance of a new activated carbon (BAC) synthesized from black cumin (Nigella sativa) processing solid waste (BW) under optimal conditions determined by single-step carbonization/activation with potassium carbonate to remove methylene blue, oxytetracycline, and lead (II) in an aqueous medium. Their optimum adsorption conditions were decided based on the maximum effects of important operational parameters. Experimental kinetic and isotherm findings for each adsorption system were modeled by evaluating widely used kinetic and isotherm equations. The maximum adsorption capacity of BAC was determined as 752 mg/g for methylene blue, 911 for oxytetracycline, and 556 mg/g for lead (II) from the Langmuir isotherm model. The thermodynamic parameters determined showed that the adsorption processes were self-occurring and also endothermic for methylene blue and oxytetracycline and exothermic for lead(II). In addition, BAC showed stability and recyclability in adsorption-desorption cycles for the pollutants studied. These findings suggest that BAC can be used as an ultra-efficient adsorbent for larger-scale wastewater treatment.

Optoacoustic and optical coherence tomography guided lipid-selective ablation for atherosclerotic plaque

Atherosclerosis is a life-threatening disease of utmost clinical importance, which, despite recent progress in cardiovascular field, is still related to high morbidity and mortality. It is characterized by the accumulation of lipids within the arterial wall that is vulnerable and prone to rupture in pathological cardiovascular changes and acute events. In this paper, for the first time, we proposed a conceptually theranostics method to stabilize the atherosclerosis: Optoacoustic tomography (OAT)/optical coherence tomography (OCT) guided lipid-selective ablation for atherosclerotic plaque. To achieve this theranostics goal, the underlying pulsed laser-tissue interaction mechanisms of OA/OCT theranostics models was investigated for both OAT localization of lipid core as well as pulsed laser power titration for ablation. OCT was used to observe pre- and post-ablation result of fibrous caps and vessel wall, followed by histology validation. The feasibility of OA/OCT was first verified by plaque composition mimicking experiment. Furthermore, ex-vivo mouse aortas containing lipid-rich plaque were imaged and selectively ablated to show the intrinsically registered OA/OCT for targeting lipid core without causing adjacent tissue damage. Our results demonstrated the superiority of this theranostics technique for effective and precise removal of atherosclerotic plaque, which brings new capabilities and photonics insights to cardiovascular medicine.

MOF‐Heterostructure‐Mediated pH‐Responsive Adsorptive Removal of Ciprofloxacin: A Step towards Pharmaceutical Wastewater Treatment

AbstractOne of the biggest challenges of the modern world is the antibiotic pollution in the water resources owing to the lack of effective removal techniques in the conventional wastewater treatment processes. Importantly, very few commercially available adsorbents are at the same time porous, magnetic, and have the capacity to bind and remove particular antibiotic classes from the slurries in a selective manner. Herein we report CNS@ZIF67 heterostructure derived adsorbent for the pH‐dependent removal of ciprofloxacin (CIP). The materials can be synthesized via a simple two‐step wet chemical method followed by annealing in a controlled atmosphere. The material demonstrates an attractive surface‐to‐mass ratio of 203.02 m2 g−1. We have performed a detailed time dependent adsorption study indicating a high removal efficiency of 96% within 2 h. Experimental adsorption data matches the Langmuir isotherm model and the kinetics follows pseudo‐second‐order reaction kinetics suggesting a chemisorption pathway of adsorption kinetics. The adsorbent has an interesting pH dependent adsorption behavior towards CIP. The adsorbent has also demonstrated its value in being reusable for four cycles of adsorption and desorption without significantly changing the removal efficiency.

Recent advances in application of metal-organic frameworks (MOFs) as adsorbent and catalyst in removal of persistent organic pollutants (POPs).

The presence of persistent organic pollutants (POPs) in the aquatic environment is causing widespread concern due to their bioaccumulation, toxicity, and possible environmental risk. These contaminants are produced daily in large quantities and released into water bodies. Traditional wastewater treatment plants are ineffective at degrading these pollutants. As a result, the development of long-term and effective POP removal techniques is critical. In water, adsorption removal and photocatalytic degradation of POPs have been identified as energy and cost-efficient solutions. Both technologies have received a lot of attention for their efforts to treat the world's wastewater. Photocatalytic removal of POPs is a promising, effective, and long-lasting method, while adsorption removal of persistent POPs represents a simple, practical method, particularly in decentralized systems and isolated areas. It is critical to develop new adsorbents/photocatalysts with the desired structure, tunable chemistry, and maximum adsorption sites for highly efficient removal of POPs. As a class of recently created multifunctional porous materials, Metal-organic frameworks (MOFs) offer tremendous prospects in adsorptive removal and photocatalytic degradation of POPs for water remediation. This review defines POPs and discusses current research on adsorptive and photocatalytic POP removal using emerging MOFs for each type of POPs.

Laccase immobilization on hierarchical micro/nano porous chitin/graphene oxide beads prepared via Pickering emulsion template for dye decolorization

Nowadays, the removal of dye molecules from water sources is a major environmental concern and challenge. Enzymatic degradation (biological) and adsorptive (physical) dye removal are considered to be the most effective dye removal techniques. Laccase catalysis is a reliable method to remove synthetic dyes from water to reduce environmental pollution, but free laccase has the disadvantages of low stability and non-reusability. In this study, stable Pickering emulsions were prepared using chitin (Ch) and graphene oxide (GO) composite solutions. Ch/GO composite aerogel beads with hierarchical porous structure were obtained by emulsion template method combined with freeze-drying, and then used for laccase immobilization and dye decolorization experiments. The results showed that the immobilized laccase had better thermal stability compared to the free enzyme, and it was found that the optimum pH of the immobilized laccase was 3.4 and the optimum temperature was 55 °C. In the cyclic decolorization experiments of acid Big Red GR, the decolorization rate of CH/GO-30 was maintained at 100% after 5 cycles of ABTS (2,2-biazo-bis(3-ethyl-benzothiazole-6-sulfonic acid) diammonium salt) by enzyme catalysis and carrier adsorption synergistically. The preparation of Ch/GO composite aerogel beads by the Pickering emulsion template method is simple and green, without the use of surfactants, avoiding secondary pollution to the environment, and has potential industrial applications in the decolorization and biodegradation of dye wastewater.