Recycling Strategies Research Articles

Application of UF and RO for power plant's wastewater treatment and recycling for environmental sustainability

Abstract Global indicators have warned of freshwater scarcity in Asia. However, the utilization of freshwater resources has skyrocketed for commercial and industrial purposes without any strategy for recycling and reuse. The power plant's wastewater/reject mainly consisted of cooling tower blowdown water and reverse osmosis (RO) plant reject water. Due to the high turbid nature of reject water, pretreatment was carried out to achieve SDI15 <3 by employing multimedia filters (MMF), activated carbon filters (ACF) and ultrafiltration (UF). Operational parameters of RO membranes were optimized (11.5 bar, 29 °C) to achieve maximum water recovery along with higher rejection rates of critical scale forming species such as 81% total dissolved solids (TDS), 73% calcium hardness and 72% silica (Si). After accounting for backwash water and other concentrate rejections, the membrane treatment plant has achieved an appreciable recovery rate of more than 44%. The RO membrane-treated water was then incorporated in the cooling tower and a 16% reduction in freshwater makeup was achieved. Reduction of microbial growth rate as well as corrosion and scaling in the cooling tower was observed due to the reuse of treated water. This is to confirm here that brackish water RO membranes can act as a strong contender for reject water reclamation and effective utilization.

Review on anti-corrosion properties of expired antihypertensive drugs as benign corrosion inhibitors for metallic materials in various environments

Discovering new classes of organic corrosion inhibitors, such as expired drugs, can provide cheaper, low-toxic, and highly efficient alternatives to the toxic organic counterparts that serve as an efficient recycling or disposal strategy. Antihypertensive drugs constitute one of the cheapest classes of drugs, globally, and have been reported as highly effective corrosion inhibitors for a variety of metallic materials in various corrosion environments. The corrosion inhibition mechanism of these drugs, generally, involves the adsorption on the metallic surfaces and the formation of a protective organic film that retards the attack of substrates by corrosive entities in the media. The drug molecular structure usually contains π-bonds, phenyl rings, and polar functional groups (such as –NH2, –OH, –CN, and −Cl) which influence the electron density within the inhibitor framework and also facilitate adsorption of the drug on the metal surface. Generally, most antihypertensive drugs act as mixed-type inhibitors and usually obey Langmuir adsorption isotherm revealing physisorption adsorption mechanisms except telmisartan, losartan potassium, and atenolol when used in nitric acid. The reported inhibition efficiency of the drugs is generally above 90% with spironolactone having the highest efficiency of 98.1% at 30 °C.

Recycling and Reuse Strategies for Ceramic Components of Solid Oxide Cells

The integration of solid oxide cells (SOCs) into circular economy is crucial to enable efficient preservation of critical and high-cost resources such as rare earth elements, cobalt, and nickel used in conventional SOC applications. Based on the fuel electrode-supported cell (FESC) design, a semi-closed loop recycling approach was applied for cell material from CeramTec/Forschungszentrum Jülich. We show that more than 85 wt% of the ceramic components can be successfully reprocessed to new fuel electrode-based substrate that can be further used in cell production. Reprocessing of sintered bodies requires a multi-stage procedure. Increasing the amount of recyclate in the substrate leads to changes in substrate properties such as higher porosities and reduced shrinkage.

The behavioural evolution of the smart electric vehicle battery reverse supply chain under government supervision

PurposeRecycling and reuse of the electric vehicle (EV) batteries are ways to extend their limited lives. If batteries can be traced from production to recycling, it is beneficial for battery recycling and reuse. Using blockchain technology to build a smart EV battery reverse supply chain can solve the difficulties of lack of trust and data. The purpose of this study is to discuss the behavioural evolution of a smart EV battery reverse supply chain under government supervision.Design/methodology/approachThis study adopts evolutionary game theory to examine the decision-making behaviours of the government, EV manufacturers with recycled used batteries and third-party EV battery recyclers lacking professional recycling qualification.FindingsOn the smart reverse supply chain integrated by blockchain technology, a cooperative recycling strategy of the third-party EV battery recycler is the optimal choice when the government tends to actively regulate. The probability of the EV manufacturer choosing the blockchain adoption strategy exceeds (below) the threshold, and the government prefers negative (positive) supervision. According to numerical analysis, in the mature stage in the EV battery recycling industry, when the investment cost of applying blockchain is high, EV manufacturers' willingness to apply blockchain slows down, the government accelerates adopting a negative supervision strategy and third-party EV battery recyclers prefer cooperative recycling.Practical implicationsThe results of this study provide opinions on the strength of government supervision and the conditions under which EV manufacturers and third-party EV battery recyclers should apply blockchain and cooperate. On the other hand, this study provides theoretical analysis for promoting the application of blockchain technology in smart reverse supply chain.Originality/valueCompared with previous research, this study reveals the relevance of government supervision, blockchain application and cooperation strategy in smart EV battery reverse supply chain. In the initial stage, even if the subsidy (subsidy reduction rate) and penalty are high and the penalty reduction rate is low, the EV manufacturer should rather give up the application of blockchain technology. In the middle stage in the EV battery recycling industry, the government can set a lower subsidy (subsidy reduction rate) combined with a penalty or a higher penalty (penalty reduction rate) combined with a subsidy to supervise it. The third-party EV battery recycler is advised to cooperate with the EV manufacturer when the subsidy is low or the penalty is high.

Towards Closed-Loop Recycling of Ceramic Particle-Reinforced Aluminium Alloys: Comparative Study of Resistance-Heating Sintered Primary and Solid-State Recycled Secondary SiCp/AlSi7Mg Composites

Particle-reinforced aluminium matrix composites (AMC) with a high-volume fraction of ceramic reinforcement (>30 vol.%) combine high specific strength and stiffness with good wear resistance and thermal stability, resulting in their increasing popularity in high-load applications, such as brake discs and bearings. It is hence assumed that AMC will accumulate as scrap in the near future. Appropriate recycling strategies must therefore be developed to maintain AMC’s inherent properties. Melt-metallurgical recycling routes bear the danger of dissolving the ceramic reinforcement in the liquid metallic matrix and contaminating primary melts or forming intermetallic phases in secondary melts. Here, a solid-state AMC recycling route with crushing and sintering is investigated, wherein all steps are carried out below the solidification temperature of the aluminium matrix. A sintered primary AMC is mechanically converted into a particulate/powdery secondary raw AMC in coarse, medium, and milled quality (i.e., with d ≈ 7–12 mm, d ≈ 3–7 mm, and d < 300 µm) and subsequently resistance heating sintered to a secondary AMC under a variation of the sintering pressure. The two AMC generations are analysed and discussed regarding their microstructure and mechanical properties. Since the secondary AMC show reduced the mechanical strength, the fracture surfaces are analysed, revealing iron contaminations from the mechanical processing.

Recycling of glass fibre reinforced polymer (GFRP) composite wastes in concrete: A critical review and cost benefit analysis

The application of fibre reinforced polymer (FRP) composites has increased substantially in recent years as a result of need for lighter and stronger materials. Currently, the reuse and/or recycling of composite wastes is very limited while most of wastes are disposed of in landfill or incinerated. Recently, mechanical recycling, fluidised bed, and pyrolysis has been developed to recycle FRP composites, but yet to be fully commercialised. As an alternative recycling strategy, incorporating glass fibre reinforced polymer (GFRP) into concrete has shown a great potential from both economic and environmental perspectives. This paper systematically reviews the performance of recycling of GFRP wastes into concrete with respect to fresh properties, mechanical properties, durability, environmental and financial aspects. Results show that the effect of recycled glass fibre reinforced polymer (rGFRP) on concrete mechanical strength is associated with the content of waste material (fibre or resin rich) and physical properties (shape, density, hydrophilicity) of GFRP recyclates, as well as the amount of recyclates. For rGFRP powder, the filler effect combined with the pozzolanic reaction can improve interfacial transition zone strength, increasing mechanical strength. Recycled glass fibre has reinforcing effect to restraint cracks and can provide extra slip resistance to strengthen the bond, resulting in improvement of flexural strength. Recycling of GFRP waste in concrete reduces water absorption of the concrete, improving durability properties. Furthermore, this research presents outcomes of cost-benefit analysis and benefit-cost ratio on five common GFRP recycling methods. The results show that repurposing rGFRP in concrete can reduce the total required investment and increase net profit. Recommendations and future perspectives are also provided to allow a wider adoption of rGFRP repurposing from industrial waste and the development of a more sustainable life cycle.

Recycling Strategies in a Collector-Led Remanufacturing Supply Chain under Blockchain and Uncertain Demand

Remanufacturing has been regarded as a key to the sustainable development of enterprises. However, collection strategies affect the remanufacturing and recycling of used products. Blockchain can ensure the authenticity of disclosed information and improve the consumer’s trust in remanufactured products. Inspired by this, this paper develops a game-theoretic model to examine the selection of different recycling strategies in the remanufacturing supply chain considering blockchain adoption and uncertain demand. Incumbent collector 1 provides the manufacturer with used product 1 for remanufacturing product 1. For product 2, the manufacturer has two different collection strategies: in-house collection by the manufacturer or external collection by collector 2. The collectors act as the channel leader, and the manufacturer, who has private demand information, is the follower. Results show that collectors are incentivized to participate in the blockchain. If there is no blockchain, collector 1 prefers external collection. In the case of blockchain, the manufacturer prefers external collection when the demand variance is low. The manufacturer’s decision on the in-house collection and external collection depends on the coefficient of collection investment costs.

Treatment and recycling of arsenic slag by hydrothermal reduction of As2S3 to As(0)

Arsenic existed concomitantly with minerals containing precious or non-ferrous metals, in which arsenic-containing wastewater (ACW) is inevitably generated during the process of smelting. In the treatment of ACW, the precipitation method using sulphide is widely used, but the resulting arsenic sulphide slag poses a risk of secondary pollution. In this work, a reduction strategy was developed to transform arsenic sulphide slag into elementary arsenic under hydrothermal conditions by using sodium formate as the reductant, with the aim to treat the slag and recycle As. The experimental results show that As(0) can be obtained by one-step hydrothermal reduction by sodium formate at temperature of 200 ℃ and pH 4, and the purity of elementary arsenic produced under the optimum conditions is higher than 90%. Mechanism analyses reveal that the reduction process of As2S3 to As(0) experiences two steps, where amorphous As2S3 primary particles first transform and crystallize into partially reductive AsS in a bulk size, and then AsS is further reduced into As(0) through a collapse process to form small particles. This work provides a recycling strategy for the efficient conversion of arsenic sulphide slag to As(0) for potential applications.

Marketing strategies for waste recycling: a bibliometric analysis towards the circular economy.

Companies have adopted green marketing and marketing strategies to position themselves in consumer preferences and combat the problem of accelerated consumption of resources that has compromised the planet's regenerative capacity, where the circular economy emerges as a solution to move towards responsible production and consumption patterns. From waste recycling marketing strategies, a descriptive analysis of 120 documents from the SCOPUS database was carried out using bibliometric techniques to know the existing state of the art for the period 1977-2021. The results indicate that the annual scientific production increased in the last ten years by over 200% for 2019, highlighting the USA, China, UK, Germany, and India, and Mexico is in position 22. The conceptual and trend analysis points out the relationship between marketing, waste management, commercialization, recycling, sustainable development, and circular economy, topics that have deepened research in the last 5 years due to the SDGs. Through intellectual analysis, schools of thought were identified, highlighting Chen, Wang, Zhang and Liu, Lu, and White as the most influential and connected with other authors. The results show no link between the study areas, but rather that they are developed in isolation, evidencing an area of opportunity to work on marketing strategies for waste recycling, where companies adopt circular economy objectives, obtaining an advantage. Competitive position and position in the market by offering products from a valorization that the consumer prefers.

Adopting GRI Standards for the Circular Economy strategies disclosure: the case of Italy

PurposeCircular economy (CE) disclosure is becoming urgent for firms, but an accepted and recognized approach to address it is still missing, especially at small and medium enterprises (SMEs) level. This study aims to contribute to this issue by exploring the potential of the adoption of Global Reporting Initiative (GRI) Standards as a standardized approach for CE disclosure. The paper proposes a framework that identifies the existence of specific relationships between the topics included in GRI 300 Standards and CE strategies, which can be considered as managerial guidelines for CE strategy disclosure by companies.Design/methodology/approachThe paper uses an explorative research methodology based on the content analysis of secondary data taken from the sustainability reports of the SMEs listed in STAR segment of Borsa Italiana.FindingsThe analysis shows that GRI Standards are currently adopted to disclose the CE strategies by Italian SMEs across different economic sectors including construction, food, automotive, retail, personal and household goods, industrial goods and services, electronics, media and technology. In particular, GRI 301 is used for the disclosure about Recycling, Reuse, Reverse logistics, Industrial Symbiosis, Eco-Design, Product as a Service and Refurbishing/Reconditioning/Remanufacturing. GRI 302 is suited to disclose CE strategies about Eco-Design, Renewable Energy and Industrial Symbiosis. GRI 303 can be useful to disclose about Reuse and Industrial Symbiosis. GRI 305 is appropriate for Eco-Design, Renewable Energy, Product as a Service, Industrial Symbiosis and Recycling. Finally, GRI 306 is useful to communicate the CE strategies of Recycling, Reuse, Reverse Logistics, Eco-Design, Industrial Symbiosis, Maintenance/Repair, Refurbishing/Reconditioning/Remanufacturing.Practical implicationsThe paper includes implications concerning how to report the implementation of a wide range of CE practices, mainly using GRI 301, 302, 303, 305 and 306. These implications are mainly addressed to SMEs in different economic sectors.Social implicationsThe use of the proposed framework, by improving the transparency and communication of the CE strategies used by companies, may contribute to accelerate the consumer awareness on CE practices fostering the CE transition, especially of SMEs, with a positive effect on society and environment.Originality/valueThis study extends the literature on CE by developing one among the few standardized approaches using the GRI Standards for the disclosure of CE strategies, a topic mainly investigated in the literature with reference to large companies in a few industries. The framework is also useful to explore the implementation of CE strategies across SMEs in different industrial sectors.

Catalytic disconnection of C–O bonds in epoxy resins and composites

Fibre-reinforced epoxy composites are well established in regard to load-bearing applications in the aerospace, automotive and wind power industries, owing to their light weight and high durability. These composites are based on thermoset resins embedding glass or carbon fibres1. In lieu of viable recycling strategies, end-of-use composite-based structures such as wind turbine blades are commonly landfilled1–4. Because of the negative environmental impact of plastic waste5,6, the need for circular economies of plastics has become more pressing7,8. However, recycling thermoset plastics is no trivial matter1–4. Here we report a transition-metal-catalysed protocol for recovery of the polymer building block bisphenol A and intact fibres from epoxy composites. A Ru-catalysed, dehydrogenation/bond, cleavage/reduction cascade disconnects the C(alkyl)–O bonds of the most common linkages of the polymer. We showcase the application of this methodology to relevant unmodified amine-cured epoxy resins as well as commercial composites, including the shell of a wind turbine blade. Our results demonstrate that chemical recycling approaches for thermoset epoxy resins and composites are achievable.

Sustainable recovery of lithium from spent LiFePO4 via proton circulation

Excessive chemical consumption and its concomitant secondary pollution have become persistent issues in the wet chemical recycling process of spent LiFePO4 batteries (sLFP). In this study, a prospective recycling strategy is proposed based on sustainable proton circulation between organic leachants, extractants, and strippants, whereby expensive organic leachants can be regenerated and secondary pollutants are reduced. The leaching dependence of the sLFP powder on the structure of the organic leachants is determined. Monocarboxylic acids with low pKa and short carbon chains exhibit preferable lithium leaching performance (98.7 % for formic acid), and the leaching behavior of metal impurities (Al, Cu) are coupled with organic acid complexation and solution pH. The direct separation of lithium from organic leachates is explored with acidic extractants for the first time. Benefitting from the buffering capacity toward protons and the salt-out effect of organic acid anions, Li element could be successfully extracted with di-(2-ethylhexyl) phosphoric acid and the organic acids can be significantly regenerated by proton exchange equilibrium. Dilute H3PO4 is employed to selectively strip Li and contribute protons to regenerate the extractant, where the separation factors of Li/Cu and Li/Al are 148.9 and 54.1, respectively. Through two-stage counter-current extraction and stripping processes, the extraction and stripping efficiency of Li could enhance to 98.62 % and 99.38 %, respectively. Thus, the Li overall yield in the leaching-extraction-stripping processes is calculated as 96.73 %, exhibiting promising prospects for proposed proton circulation strategy.

Investigation on the recovery of thorium and rare earth from radioactive waste residue by functionalized ionic liquids

Thorium (Th) containing radioactive waste generated by ion-adsorbed rare earth ore (IATREO) separation plants poses a threat to the environment. The waste residue contains a much higher content of rare earth (RE) than the original IATREO. This study describes novel ionic liquids (ILs) containing cationic functionalization and evaluates their effectiveness in recovering Th and RE from the waste residue leaching solution (WRLS). Di-functionalization of the cation in ILs is more advantageous than mono-functionalization and non-functionalization, providing more coordination sites and achieving higher extraction and separation performance. In the simulated solution at an initial pH of 3, [OB2DTA][CA12] is able to extract 99.0% of Th and only 0.4% of RE, the Th/RE separation factor reaches 22114. The extraction reaction is carried out by an ion association mechanism. After 5 cycles of extraction-stripping-regeneration, the extraction and separation abilities of ILs remain stable. For the HCl leaching solution of waste residue, 99.5% of Th is separated in two extraction stages, while the total loss of RE is only about 15 mg/L. The recyclable separation strategy based on ILs simplifies the separation process of Th and RE, reduces chemical consumption, and provides a new idea for the treatment of IATREO waste residue.

A Critical Review on the Recycling Strategy of Lithium Iron Phosphate from Electric Vehicles.

Electric vehicles (EVs) are one of the most promising decarbonization solutions to develop a carbon-negative economy. The increasing global storage of EVs brings out a large number of power batteries requiring recycling. Lithium iron phosphate (LFP) is one of the first commercialized cathodes used in early EVs, and now gravimetric energy density improvement makes LFP with low cost and robustness popular again in the market. Developments in LFP recycling techniques are in demand to manage a large portion of the EV batteries retired both today and around ten years later. In this review, first the operation and degradation mechanisms of LFP are revisited aiming to identify entry points for LFP recycling. Then, the current LFP recycling methods, from the pretreatment of the retired batteries to the regeneration and recovery of the LFP cathode are summarized. The emerging direct recovery technology is highlighted, through which both raw material and the production cost of LFP can be recovered. In addition, the current issues limiting the development of the LIBs recycling industry are presented and some ideas for future research are proposed. This review provides the theoretical basis and insightful perspectives on developing new recycling strategies by outlining the whole-life process of LFP.

Duplex-specific nuclease powered 3D DNA walker and quantum dots barcodes for homogeneous electrochemical detection of microRNAs

Multiplex microRNAs (miRNAs) detection is beneficial for early diagnosis and prognosis of cancer. Herein, duplex-specific nuclease (DSN) powered 3D DNA walker and quantum dots (QDs) barcodes were designed for the simultaneous detection of miRNAs in a homogeneous electrochemical sensor. In the proof-of-concept experiment, the effective active area of the as-prepared graphene aerogel-modified carbon paper (CP-GAs) electrode was ∼14.30 times larger than that of the traditional glassy carbon electrode (GCE), endowing the enhanced capability of loading more metal ions for ultrasensitive detection of miRNAs. In addition, DSN-powered target recycling and DNA walking strategy assured the sensitive detection of miRNAs. After the introduction of magnetic beads (MNs) and electrochemical double enrichment strategies, the integration of triple signal amplification methods yielded good detection results. Under optimal conditions, towards simultaneous detection of microRNA-21 (miR-21) and miRNA-155 (miR-155), a linear range of 10−16–10−7 M and a sensitivity of 10 aM (miR-21) and 2.18 aM (miR-155) were achieved, respectively. It was worth mentioning that the prepared sensor can detect miR-155 down to 0.17 aM, which was also extremely advantageous among the sensors reported so far. What's more, through verification, the prepared sensor had good selectivity and reproducibility, and exhibited good detection ability in complex serum environments, showing great potential in early clinical diagnosis and screening.

Batch Production of Lead Sulfate from Spent Lead–Acid Batteries via an Oxygen-Free Roasting Route: A Negative-Carbon Strategy

Multicomponent lead compounds, including lead (Pb), lead oxide (PbO), lead dioxide (PbO2), and lead sulfate (PbSO4), in spent lead–acid batteries (LABs), if not properly disposed of and recycled, will cause serious pollution and damage to the ecological environment. Pyrometallurgical smelting performed above 1000 °C often incurs high energy consumption and lead pollution. In this study, a low-temperature (300 °C), oxygen-free roasting process was proposed. With potassium bisulfate (KHSO4) as the roasting reagent, the uniform conversion of multicomponent lead compounds from spent lead paste (SLP) to PbSO4 was successfully realized in one step. We observed that PbO2 species were relatively chemically stable, during the oxygen-free roasting. However, the decomposition of PbO2 into PbO can be achieved by heating to 300 °C, resulting in an effective conversion to PbSO4. The optimal conditions for PbSO4 production were a heating temperature of 300 °C, an SLP/KHSO4 mass ratio of 1:1, and a holding time of 10.0 min. Life cycle assessment results show that the recycling of 1.0 t spent LABs can reduce carbon emissions of 2.45 t CO2 and smog of 0.13 t. Our research provides an emission-free, low-temperature, and negative-carbon strategy for facile and cost-effective recycling of spent LABs, as an alternative to traditional pyrometallurgical smelting.

Converting waste expanded polystyrene into higher-value-added hyper-crosslinked porous polymer for rapid and high-efficient adsorption of aflatoxins

White pollution caused by the massive discharges of waste expanded polystyrene (WEPS) has become a critical global issue, so the effective conversion of WEPS is of great significance to reduce white pollution. Herein, adopting WEPS as raw material, three high-value-added hyper-crosslinked polymers (WEPS-HCPs) with high surface areas and abundant micro/mesoporous structures were synthesized via Friedel-Crafts alkylation reaction using dimethoxymethane, dichloroxylene and 4,4′-bis(chloromethyl)-1,1′-biphenyl (BCB) as cross-linker, respectively. The WEPS-HCPs were used as sorbent to extract aflatoxins (AFs) and all the HCPs exhibited high adsorption capacity. For the fast separation and recovery of the sorbent, WEPS-BCB was chosen as a model HCP to be magnetically functionalized to obtain a magnetic HCP (mWEPS-BCB) for the first time. Based on magnetic solid phase extraction with the mWEPS-BCB as sorbent, a fast and sensitive method was developed to determine trace level of AFs in grain food. Under the optimal conditions, the proposed method presented wide linear range (0.008–10.0 ng g−1), low detection limit (0.002–0.015 ng g−1) and satisfactory precision (relative standard deviation < 7%). Converting WEPS into a high-value-added sorbent not only provided a facile strategy for effective recycling of WEPS, but also developed a sensitive method for accurate determination of AFs in grain food, achieving significant economic and environmental benefits.

Environmental impacts and optimization simulation of aerobic anaerobic combination treatment technology for food waste with life cycle assessment

After the implementation of waste sorting policy in Shanghai, the amount of food waste (FW) separation and treatment demand has increased significantly. It is necessary to establish the life cycle assessment (LCA) to assess the environmental impacts of various treatment technologies comprehensively, thus provide support for sorting, recycling, treatment and disposal strategies of FW. In this study, a local FW treatment plant in Shanghai, using typically aerobic anaerobic combination treatment technology was selected to analyze the environmental impacts with LCA. The process mainly included pretreatment, power, aerobic composting, anaerobic digestion, and further process systems. LCA results showed that the environmental impacts mainly came from the power and aerobic composting systems on the fine particulate matter formation and eutrophication, and freshwater ecotoxicity and terrestrial acidification, respectively. Considering the carbon footprint, the aerobic composting system contributed 3.61E + 02 kg CO2 eq and represented the largest source of carbon emission. The soil conditioner yielded both environmental benefits on eutrophication and terrestrial ecotoxicity, and ecological benefits of 75.33 million CNY per year being the major revenue for the treatment plant. It also suggested that the biogas generation capacity of anaerobic digestion could be increased to achieve electricity self-sufficiency, thus save about 7.12 million CNY per year in electricity costs, and avoid corresponding environmental impacts caused by coal-fired. In summary, the aerobic anaerobic combination treatment could be further optimized and applied in FW treatment to reduce the environmental impacts, and enhance resource recovery and secondary pollution control.

IR780-doped cobalt ferrite nanoparticles@poly(ethylene glycol) microgels as dual-enzyme immobilized micro-systems: Preparations, photothermal-responsive dual-enzyme release, and highly efficient recycling

To solve the problems of separating dual enzymes from the carriers of dual-enzyme immobilized micro-systems and greatly increase the carriers’ recycling times, photothermal-responsive micro-systems of IR780-doped cobalt ferrite nanoparticles@poly(ethylene glycol) microgels (CFNPs-IR780@MGs) are prepared. A novel two-step recycling strategy is proposed based on the CFNPs-IR780@MGs. First, the dual enzymes and the carriers are separated from the reaction system as a whole via magnetic separation. Second, the dual enzymes and the carriers are separated through photothermal-responsive dual-enzyme release so that the carriers can be reused. Results show that CFNPs-IR780@MGs is 281.4 ± 9.6 nm with a shell of 58.2 nm, and the low critical solution temperature is 42 °C, and the photothermal conversion efficiency increases from 14.04% to 58.41% by doping 1.6% of IR780 into the CFNPs-IR780 clusters. The dual-enzyme immobilized micro-systems and the carriers are recycled 12 and 72 times, respectively, and the enzyme activity remains above 70%. The micro-systems can realize whole recycling of the dual enzymes and carriers and further recycling of the carriers, thus providing a simple and convenient recycling method for dual-enzyme immobilized micro-systems. The findings reveal the micro-systems’ important application potential in biological detection and industrial production.

Antibacterial and Photocatalytic Activities of LDH-Based Sorbents of Different Compositions.

Layered double hydroxides (LDHs) play a fundamental role in the processes for the abatement of pollutants in water, with reference to heavy metal decontamination. The research on the topic is multiobjective target oriented, aiming at combining environmental remediation with the possibility of reusing a sorbent as many times as possible, turning it into a renewable resource. In this study, the antibacterial and catalytic properties of a ZnAl-SO4 LDH and its resulting product after being subjected to a Cr(VI) remediation process are compared. Both solid substrates have also been tested after undergoing a thermal annealing process. The sorbent (previously described and tested for remediation) has been investigated for its antibacterial activity in view of further surgery and drug delivery applications. Finally, its photocatalytic properties have been experimentally tested in the degradation of a model pollutant, i.e., Methyl Orange (MO), under solar-simulated light. Identifying the best recycling strategy for these materials requires an accurate knowledge of their physicochemical properties. The results show that both the antimicrobial activity and the photocatalytic performance may considerably improve after thermal annealing.