Cleaning Methods Research Articles

Heat-activated persulfate for chemical cleaning of ceramic MBR

Irreversible membrane fouling is a major concern in the application of membrane bioreactors (MBRs), and periodic chemical cleaning is required to sustain MBR operation. However, conventional NaClO cleaning exhibited limited efficacy and caused secondary environmental risks (e.g. disinfection by-products). Therefore, it is necessary to develop safe and efficient chlorine-free cleaning methods. Here, we proposed a heat-activated persulfate (peroxymonosulfate PMS and peroxydisulfate PDS) process for efficient cleaning of fouled ceramic membrane in MBR. Results showed much higher chemical cleaning efficiency in heat-activated persulfate process (79–81%) than that in NaClO (34–52%). A medium solution temperature of 60 °C was enough to efficiently activate PMS and PDS, with the optimal persulfate concentration of 1 mM and solution pH of 7. Both SO4•− and •OH were identified as the main reactive oxygen species for membrane cleaning. Compared with PDS, PMS was easier to be activated, and thus more free radicals were generated in heat/PMS system. Further investigations demonstrated radicals degraded polymers and broke microbial cell structure, thereby effectively removing foulants from membrane. This work provides a new idea for developing safe and efficient chemical cleaning method for ceramic MBR.

Synergistic reductive catalytic effects of an organic and inorganic hybrid covalent organic framework for hydrogen fuel production.

Electrocatalytic hydrogen generation in alkaline medium has become widely used in a variety of sectors. However, the possibility for additional performance improvement is hampered by slow kinetics. Because of this restriction, careful control over processes such as water dissociation, hydroxyl desorption and hydrogen recombination is required. Covalent organic frameworks (COFs) based on porphyrin and polyoxometalates (POMs) show encouraging electrocatalytic performance, offering a viable route for effective and sustainable hydrogen generation. Their specific architectures lead to increased electrocatalytic activity, which makes them excellent choices for developing water electrolysis as a clean energy conversion method in the alkaline medium. In this regard, TTris@ZnPor and Lindqvist POM were coordinated to create a new eco-friendly and highly active covalent organic framework (TP@VL-COF). In order to describe TP@VL-COF, extensive structural and morphological investigations were carried out through FTIR, 1H NMR, elemental analysis, SEM, fluorescence, UV-visible, PXRD, CV, N2-adsorption isotherm, TGA and DSC analyses. In an alkaline medium, the electrocatalytic capability of 20%C/Pt, TTris@ZnPor, Lindqvist POM and TP@VL-COF was explored and compared for the hydrogen evolution reaction (HER). The TP@VL-COF showed the best catalytic efficiency for HER in an alkaline electrolyte, requiring just a 75 mV overpotential to drive 10 mA cm-2 and outperforming 20%C/Pt, TTris@ZnPor, Lindqvist POM and other reported catalysts. The Tafel slope value also indicates faster kinetics for TP@VL-COF (114 mV dec-1) than for 20%C/Pt (182 mV dec-1) TTris@ZnPor (116 mV dec-1) and Lindqvist POM (125 mV dec-1).

Improved N2 photo-fixation performance of nanocrystalline TiO2 films by photon localization effects and Fe doping

The development of clean and sustainable nitrogen-fixing methods has always attracted significant attention for decades.

Catalytic Synthesis of Carbon Nanotubes and Hydrogen Gas from Waste Plastics Using LaNiO3 Perovskite Catalyst

Using waste plastic syngas to prepare carbon nanotubes (CNTs) and hydrogen-rich gas is a clean and efficient recycling method for waste plastics, and it is very important to find out how to improve its yield and quality. In this work, CNTs and hydrogen-rich gas were prepared by LaNiO3 perovskitetype catalysts from waste plastic syngas model compound in laboratory. The LaNiO3 catalysts, carbon nanotubes and gas fractions produced at different temperatures were characterized and compared with the supported catalyst Ni/ZSM-5. The main conclusions were as follows: 650 °C catalytic temperature had maximum carbon nanotubes yield of 5.84 gCNTs/gCatalyst and H2 content of 44 Vol.%, which was 4.44 times the carbon nanotubes yield from the Ni/ZSM-5 catalyst at the same temperature case. A bottom growth pattern of carbon nanotubes produced on the LaNiO3 catalyst was observed by high resolution transmission electron microscopy (HRTEM). The X-ray crystal diffractometer (XRD) analysis revealed that the interaction force between Ni and the carrier was stronger in LaNiO3 than that of the Ni/ZSM-5 catalyst, resulting in two different growth patterns of carbon nanotubes. The present experiments probe that the LaNiO3 catalysts have a greater prospect of application in the preparation of CNTs and hydrogen-rich gas from waste plastic syngas.

Policy Analysis on Clean Cooking in Malawi: Case of Improved Cookstoves

Transition from cooking with traditional biomass to clean cooking is a persistent challenge in Malawi. The underlying technologies in clean cooking are improved cookstove. Improved cook stoves are designed to reduce fuel consumption per meal and to curb smoke emissions experienced in traditional three-stone cookstove. However, promotion adoption and utilisation of clean cooking requires coordinated policy and regulatory framework. This study analysed the Malawi policy regulatory framework on clean cooking by benchmarking with relevant literature. The following policy gaps were identified: (i) the lack of clear cookstove rating by Malawi Bureau of Standards; (ii) uncomplimentary policies and regulations in the energy and forestry sectors on clean cooking fuels and technologies; (iii) the lack of empirical data on adoption and utilisation of clean cooking technologies and fuels in Malawi; (iv) predicaments in adopting and using international standards for testing cookstoves; and (v) the value chain of improved cookstoves and other forms of clean cooking fuels and technologies that is not adequately analysed. Coordinated development and harmonious implementation of clean cooking regulations in the key sectors of energy and forestry can promote adoption and utilisation of clean cooking methods and technologies in Malawi.

Recent advances in photoelectrochemical hydrogen production using I-III-VI quantum dots.

Photoelectrochemical (PEC) water splitting, recognized for its potential in producing solar hydrogen through clean and sustainable methods, has gained considerable interest, particularly with the utilization of semiconductor nanocrystal quantum dots (QDs). This minireview focuses on recent advances in PEC hydrogen production using I-III-VI semiconductor QDs. The outstanding optical and electrical properties of I-III-VI QDs, which can be readily tuned by modifying their size, composition, and shape, along with an inherent non-toxic nature, make them highly promising for PEC applications. The performance of PEC devices using these QDs can be enhanced by various strategies, including ligand modification, defect engineering, doping, alloying, and core/shell heterostructure engineering. These approaches have notably improved the photocurrent densities for hydrogen production, achieving levels comparable to those of conventional heavy-metal-based counterparts. Finally, this review concludes by addressing the present challenges and future prospects of these QDs, underlining crucial steps for their practical applications in solar hydrogen production.

Pediatric Uropathogens and their Antimicrobial Susceptibility Pattern: Experience from an Impoverished District of Karachi, Pakistan.

Urinary tract infection (UTI) is the most common infection of the pediatric age group. Several factors linked to higher prevalence include poor personal hygiene, improper sanitation, lower socioeconomic status, and malnourishment. In addition to having a worse quality of life, the 1.8 million children who live in Karachi's Korangi district are routinely exposed to such factors. The study aims to evaluate the frequency of UTI and distribution of uropathogens along with their antimicrobial susceptibility pattern in patients presenting to a pediatric tertiary care center in the Korangi district of Karachi, Pakistan. The study employed an observational cross-sectional design. The study was conducted at the Microbiology laboratory of Sindh Institute of Child Health and Neonatology, Karachi, Pakistan from 1st January to 15th August 2023. Urine samples of patients 1 to 16 years of age were collected via midstream clean catch method and of patients from birth up to 1 year were collected in urine collection bags. The samples were cultured on Cystine Lactose Electrolyte Deficient (CLED) agar and antibiotic susceptibility testing was performed using the Kirby-Bauer Disc Diffusion method. A total of 457 urine samples were collected, of which 90 (19.7%) were positive for significant uropathogens. With a mean age of 4.6 years, majority of the culture-positive patients were female (n = 72; 80%). Enterobacterales were the most frequently isolated (n = 88; 95.6%), of which Escherichia coli was the most common (73.9%; n = 68). Citrobacter (n = 7; 7.6%), Klebsiella (n = 6; 6.5%), Serratia (n = 4; 4.3%), Proteus (n = 2; 2.2%), Salmonella (n = 2; 2.2%), and Enterobacter (n = 1; 1.1%) were among the other Enterobacterales isolated. Meropenem and imipenem were the most effective in isolates from Enterobacterales (n = 88) followed by amikacin (n = 84), ciprofloxacin (n = 75), and piperacillin-tazobactam (n = 70). Ceftriaxone and cefixime exhibited moderate susceptibility (n = 69 and 52) whereas, amoxicillin-clavulanate was the least susceptible (n = 3). We report high frequency of UTI in our pediatric population with uropathogens and associated antimicrobial susceptibility pattern confirming to the existing trends of pediatric UTIs in Pakistan. In addition to valuable insights for treating patients under similar conditions, our study serves as a catalyst for further multi-center research in this area.

Experience of application of chemical cleaning of oil heat exchanger in conditions of Turkmenistan

This paper presents the results of research on the application of chemical cleaning for oil/oil heat exchangers. The aim of the research is to develop a safe and effective chemical cleaning method for these exchangers, using the model HJ2300-H/1.6-Q (H-2001A) as the object of the research. The results showed that after 48 hours of chemical cleaning, all oil fouling and scale were completely removed. Additionally, the pressure drop across the oil/oil heat exchanger decreased to 1.85 kgf/cm² after 12 hours, 1.38 kgf/cm² after 24 hours, 0.75 kgf/cm² after 36 hours, and finally reached the nameplate value of 0.3 kgf/cm² after 48 hours.

Expression of concern: Sonochemistry: a good, fast and clean method to promote the removal of Cu(ii) and Cr(vi) by MWCNT/CoFe2O4@PEI nanocomposites: optimization study

Expression of concern for ‘Sonochemistry: a good, fast and clean method to promote the removal of Cu(ii) and Cr(vi) by MWCNT/CoFe2O4@PEI nanocomposites: optimization study’ by Mohammad Hassan Omidi et al., New J. Chem., 2018, 42, 16307–16328, https://doi.org/10.1039/C8NJ03277G.

Optimization of the deodorization process of cotton oil with the participation of floating plants

The quality of vegetable oils intended for consumption depends on the complete and perfect deodorization process. Unpleasant taste and odor volatile substances contained in vegetable oils are composed of a complex complex of substances with different composition in terms of quality and quantity. They have more vapor elasticity compared to triglycerides, that is, they create volatility. In the process of deodorization, the odorous substances in the liquid layer move to the evaporation layer, and the molecules of the evaporated substances are lost. Based on the scientific results obtained on the improvement of the deodorization technology of oils on the basis of the computer model of the deodorization process in the liquid-steam-floating nozzle system: in a short time and using modern cleaning methods, it is possible to recommend the optimal conditions for the preparation of high-quality, harmless cottonseed oil for the human body.

Research, design and manufacture a prototype of solar panel cleaning system via WiFi

This paper presents research of design and manufacturing a prototype of solar panel cleaning system in Vietnam. The 2D and 3D design of this prototype is also shown in this study. The device is used to clean dust accumulated in the face of solar panels so that it can help for enhancing power efficiency of solar panels. The prototype can be controlled manually or automatically via WiFi based on options of control system. An ESP8266 NODEMCU board is used in the hardware of the controller so that it can connect to WiFi, control motors and traveling of the device. An app is set based on Blynk app to control the system via WiFi. Operators can control the system everywhere with WiFi or 5G connection. The device can help to remove dust on solar panels and enhance the power generation efficiency, reduce time, labor, keep safety for cleaning solar panels compared with manual cleaning method.

Preserving Normal Power Curve Data with Sparse Density via Wind Speed-Power Correlation Trend Cleaning Method

Preserving Normal Power Curve Data with Sparse Density via Wind Speed-Power Correlation Trend Cleaning Method

COMPARATIVE ASSESSMENT OF THE ROOT CANAL IRRIGATION QUALITY WITH EXPERIMENTAL INTRA-ROOT RESORPTION IN VITRO

Introduction. To date, intra-root resorption of teeth is poorly understood, although it is often encountered in dental clinics. This study aimed on assess and comparison of different methods of irrigation and antiseptic solutions activation used for root canal treatment, and focus on cleaning the area of simulated intra-root resorption. Methods. 24 extracted teeth were used, which the simulation of internal resorption was reproduced by dissection the inside of the root canal under the control of an electron microscope (Karl Kaps, Germany) in. Distilled water, sodium hypochlorite 5.25 %, sodium hypochlorite 3 %, chlorhexidine 2 % were used for comparative assessment of irrigation quality by staining with Indian Ink dye. Results. When using an endodontic needle and passive irrigation with the studied irrigation solutions, the dye remained on the inner surfaces of the root canal walls, which indicated their insufficient cleaning. The use of auxiliary cleaning methods - sound and ultrasonic irrigation nozzles - showed better cleaning of the root canal resorption zone. When using the sound activation of the irrigator with the EndoActivator device, the dye partially remained in the simulated resorption zone, while a significant part of the root canal system was cleaned. The use of ultrasonic activation of the irrigator with the P5 XS device showed that all dye-stained root canals of the samples were cleaned. Zones of simulated root resorption did not show any dye residues visually and under electron microscope control. Conclusions. The quality of root canal cleaning in case of intra-root resorption in terms of visual assessment of their transparency and under the control of an electron microscope was more pronounced when using methods of activating irrigation solutions with sound and ultrasonic activators.

CONDITIONS FOR THE FORMATION OF WATER QUALITY WITH THE BIOLOGICAL CLEANING METHOD

Many organizations, especially the IMO (International Maritime Organization), began to conduct research on the dangerous impact of polluted waters on public health. Therefore, these waters undergo purification, after regeneration they are returned to circulation, and only after the impossibility of regeneration has been determined, they are averaged and transferred to factory treatment facilities and disposed of. Methods of cleaning polluted industrial waters can be combined into the following groups: mechanical, physical, physico-mechanical, chemical, physico-chemical, biological, complex. The method of purifying sewage and reservoir water from toxicants using the eichhornia plant differs in that, before water purification, the toxicant that limits the purification process is first determined, and then, before planting in the water to be purified, the eichhornia plant is moved into a solution of the toxicant, which is administered in small doses with by adding a plant growth stimulator and/or an oxidation catalyst that limits toxicants, and the cleaning is carried out in a state of rest of water, movement or bubbling with water vapor and/or air with a temperature from 2 to 50°.

Investigation of a Cleaning Method to Improve the Cleaning Rate of a Duct Cleaning Robot using a Planetary Gear Mechanism

Investigation of a Cleaning Method to Improve the Cleaning Rate of a Duct Cleaning Robot using a Planetary Gear Mechanism

Physicochemical Properties of Raw Cleaned Edible Bird’s Nest After Different Primary Processing Including a New Cleaning Method

Physicochemical Properties of Raw Cleaned Edible Bird’s Nest After Different Primary Processing Including a New Cleaning Method

Influence of Galvanic Interaction between the Iron Grinding Medium and Chalcopyrite on Collectorless Flotation Behavior of Chalcopyrite: Experimental and Density Functional Theory Study.

The eco-friendly flotation process for chalcopyrite is economically significant and promotes sustainable development in mining. Collectorless flotation is a green and clean method for chalcopyrite utilization, but galvanic interactions during the grinding process can affect the surface structure, chemical composition, and electrochemical properties, impacting collectorless flotation recovery. This article uses a self-made device and flotation experiments to study galvanic interactions and their effects on surface oxidation and collectorless flotation behavior under different grinding conditions (including mineral particle size, slurry water content, pressure, and galvanic interaction time). The impact of galvanic interaction on the surface chemical composition and electrochemical properties of chalcopyrite is studied using high-performance liquid chromatography (HPLC), X-ray photoelectron spectroscopy (XPS), and electrochemical tests. Additionally, the effect of the galvanic interaction on the surface structure is analyzed with density functional theory. XPS and HPLC results show that iron grinding media contact with chalcopyrite, reducing elemental sulfur content of the chalcopyrite surface, improving hydrophilicity, and decreasing chalcopyrite collectorless flotation recovery. Grinding conditions, such as mineral particle size, slurry water content, and galvanic interaction time, significantly impact collectorless flotation and can be regulated to optimize results.

Promising technologies for pre-sterilization ultrasonic cleaning of medical devices for patient safety in physiotherapy and medical rehabilitation

Intensive introduction of innovative technologies into practice in order to improve the effectiveness of treatment and diagnostic measures and reduce the negative impact on the human body nevertheless contributes to the emergence of adverse events directly related to the provision of medical care. In the complex of anti-epidemic measures aimed at eliminating infection in medical organisations, a major role belongs to the correct organisation and performance of pre-sterilisation cleaning of medical devices. Technologies of processing of medical devices and pre-sterilisation cleaning should be convenient and safe to use, have no damaging effect on the processed items, be highly effective and at the same time not labour-intensive. Today cleaning with the use of ultrasonic units remains promising, with the help of which the standardisation of the treatment process is carried out, the influence of the human factor on the quality of cleaning is reduced, and the control of the main critical parameters of the process is carried out in automatic mode. The purpose of the work is to justify the need to maintain the safety of the patient and staff using the promising use of ultrasonic influences. The results of this literature review reflect information about the safety and effectiveness of the method of ultrasonic pre-sterilization cleaning of medical instruments used in physiotherapy and medical rehabilitation. Basic information is provided about the physical essence of the ultrasonic cleaning process, its effect on biological systems from the standpoint of physical, biological and chemical effects, which ensures the safety of manipulations and procedures in physiotherapy and medical rehabilitation.

Towards All-Extruded Custom-Shape Batteries

The rapid growth of flexible electronics for wearable devices, on-skin or environmental sensors, and flexible displays have resulted in intensive research in the field of free form-factor energy-storage systems. Since batteries must withstand bending, folding, or stretching while maintaining their electrochemical performance, the design and processing of battery components, must be reconsidered. Moreover, there is a clear tendency to shift battery technology to clean and cost-effective dry methods with no toxic solvents. Dry fabrication methods are environmentally friendly, involve lower energy consumption, shorter time and are cost-effective. Hot-pressing and melting-extrusion strategies are appropriate for the fabrication of flexible, solid-polymer electrolytes and electrodes with high contents of active materials and high mass loading.Here we present the progress towards the simple, one-step extrusion of a solid-state battery with a multi-shell and layered architecture. Such structures fundamentally minimize the ionic pathway for Li+. As in the conventional battery, high ionic conductivity of extruded electrolyte and compatibility with electrode materials, are the essential properties for enabling high performance of the battery. The electrolytes are composed of LiTFSI, polyethylene oxide (PEO), which is a known lithium-ion conductor, and thermoplastic recyclable and biodegradable polymer- polyurethane (TPU) - for enhanced mechanical properties and high-temperature durability. The extruded electrolytes of different PEO-to-TPU ratios and salt content were characterized by means of ESEM imaging, mass spectroscopy, differential-scanning calorimetry (DSC), electrochemical-impedance spectroscopy (EIS) and solid-state nuclear magnetic resonance (NMR) diffusion measurements. The structure and electrochemical properties of extruded electrolytes were compared with cast films. It was found that TPU, having in its structure, both soft segments from polyol regions and hard segments from isocyanate not only improves the mechanical properties of neat PEO-based polymer electrolyte, but also forms complexes with lithium salt and serves as a conducting medium. Bulk conductivity vs. temperature dependencies obey Arrhenius behavior. The highest conductivity values varying from 0.3 to 1mS/cm over a temperature range from RT to 90ºC were achieved for the extruded 1:15 (Li:EO) solid polymer electrolyte. The NMR tests show that lithium self-diffusion coefficients in extruded PE with alumina filler are close to that in cast PE, but the anion diffusion coefficients (accessible through 19F NMR) are lower in extruded filaments, indicating a correspondingly higher Li+ transference number induced by the extrusion. Lithium cells with extruded LFP cathode and solid extruded polymer electrolyte demonstrated 40 reversible cycles with close to 96% coulombic efficiency. The electrochemical performance of half-cells composed of extruded LFP-based cathode and extruded TPU-MWCNT-based current collector will be presented.

Valorization of Waste Plastics into Nanostructured Materials for LI-ION Storage Application

Every year, several million tons of plastics are wasted, resulting in significant environmental pollution. Polyethylene terephthalate (PET) is one of the most commonly used plastics, with approximately 400 billion drink bottles produced annually. The widespread availability and environmental concerns associated with the non-natural degradability of PET waste necessitate the development of clean, efficient, and low-cost recycling methods or valorization into high-value materials. In this presentation, the molten salt conversion of waste PET into carbonaceous nanostructures is discussed as a facile, scalable, and fast method for valorizing PET waste. For instance, this molten salt process can result in the preparation of terephthalic acid embedded with tin dioxide nanocrystals. The resulting nanocomposite material shows interesting performance as anode of high-performance lithium-ion batteries. The structural, morphological and electrochemical performance of the terephthalic acid- tin dioxide are discussed in this presentation.