scholarly journals Remediation of Soils Contaminated by Pesticides Using Physicochemical Processes: a Brief Review

2019 ◽  
Vol 37 ◽  
Author(s):  
D.P. BALDISSARELLI ◽  
G.D.L.P. VARGAS ◽  
E.P. KORF ◽  
L. GALON ◽  
C. KAUFMANN ◽  
...  
Keyword(s):  
High Efficiency ◽  
Uv Light ◽  
Soil Washing ◽  
Ultrasound Irradiation ◽  
Degradation Process ◽  
Physicochemical Processes ◽  
Agronomic Crops ◽  
Treatment Techniques ◽  
Agricultural Contaminants ◽  
Soil Recovery

ABSTRACT: After years of pesticide application, often indiscriminately, damage has been caused to the environment, as well as to agronomic crops grown in contaminated areas. In water treatment, techniques based on physical and/or physicochemical processes are used, being formed secondary oxidizing agents responsible for the mineralization of contaminants present in the herbicides, thus causing the degradation process. However, few studies have demonstrated the effectiveness of these techniques in soils. The aim of this study was to review the existing studies, presenting the main techniques used for remediation of soils contaminated with pesticides. Emphasis was placed on electrokinetics, advanced oxidative processes, soil washing, chemical or solvent extraction, and combinations of these methods. According to the results of several studies, the combination of techniques, such as electrokinetics and soil washing processes, allows achieving a high efficiency when it is applied for the degradation of agricultural contaminants. The combination of electrolysis with other methods, such as the Fenton’s reagent, ultrasound irradiation, and UV light, also present satisfactory results in removing pesticides in soil treatment. However, Fenton technology used alone is the most promising of the assessed techniques since it can be used for the remediation of several contaminants, especially pesticides, not harming the environment and allowing soil recovery.

scholarly journals Awareness of aerosol-related transmission of COVID-19 among the dentists of Nepal

BDJ Open ◽  
2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Nashib Pandey ◽  
Buddha Bahadur Basnet ◽  
Sushmit Koju ◽  
Anju Khapung ◽  
Alka Gupta
Keyword(s):  
Social Sciences ◽  
Particle Size ◽  
High Efficiency ◽  
Emergency Services ◽  
Uv Light ◽  
Ventilation System ◽  
Age Groups ◽  
Air Filtration ◽  
Online Questionnaire ◽  
Dental Practitioners

Abstract Objective To access the awareness of dental practitioners of Nepal towards COVID-19 transmission through aerosols. Materials and methods The study involved 384 dentists from all over Nepal and was conducted for a period of 3 months. A self-reported online questionnaire was developed using Google forms and the link was shared. It emphasized the awareness related to the aerosol and ventilation system in their daily practices was prepared. The data were analyzed in Statistical Package for Social Sciences version 20.0 software. Results The majority of participants were female 52.9% (n = 203) and within the age groups of <30 years 57% (n = 219). Participants from Bagmati Province were 60.4% (n = 232), with least from Sudurpaschim Province 0.5% (n = 2). 60% of participants provided only emergency services during the COVID-19 pandemic and few (7%) provided consultations via telephone. The current ventilation system used was a well-ventilated room with open windows 65.4% (n = 251). However, 52.8% (n = 203) preferred specialized operatory incorporating high-efficiency particulate air (HEPA) filters and ultraviolet (UV) light. More than 60% of respondents were unaware of the particle size of the aerosol. Conclusions The obtained results signify the need for the proper ventilation system with appropriate air filtration systems in dental clinical setups.

scholarly journals Superior Degradation Performance of Nanoporous Copper Catalysts on Methyl Orange

Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 913
Author(s):  
Jinyi Wang ◽  
Sen Yang
Keyword(s):  
Activation Energy ◽  
Methyl Orange ◽  
High Efficiency ◽  
Low Cost ◽  
Degradation Process ◽  
Copper Catalysts ◽  
Reaction Rate Constant ◽  
Nanoporous Structure ◽  
Intra Particle Diffusion ◽  
Different Temperatures

The development of low-cost and high-efficiency catalysts for wastewater treatment is of great significance. Herein, nanoporous Cu/Cu2O catalysts were synthesized from MnCu, MnCuNi, and MnCuAl with similar ligament size through one-step dealloying. Meanwhile, the comparisons of three catalysts in performing methyl orange degradation were investigated. One of the catalysts possessed a degradation efficiency as high as 7.67 mg·g−1·min−1. With good linear fitting by the pseudo-first-order model, the reaction rate constant was evaluated. In order to better understand the degradation process, the adsorption behavior was considered, and it was divided into three stages based on the intra-particle diffusion model. Three different temperatures were applied to explore the activation energy of the degradation. As a photocatalytic agent, the nanoporous structure of Cu/Cu2O possessed a large surface area and it also had low activation energy, which were beneficial to the excellent degradation performance.

scholarly journals Degradasi Tirosina Menggunakan Mangkinfoto Berasaskan TiO2

2012 ◽  
Author(s):  
Rusmidah Ali ◽  
Siti Salamah Maisoan @ Selamat
Keyword(s):  
Amino Acid ◽  
Metal Ions ◽  
Uv Light ◽  
Degradation Process ◽  
Aqueous System ◽  
Visible Spectroscopy ◽  
Photo Degradation ◽  
Efficient System ◽  
Catalyst Powder ◽  
Uv Visible

Asid amino merupakan bahan asas dalam tisu tumbuhan dan haiwan. Tirosina (Tr) salah satu jenis asid amino yang mengandungi gelang aromatik, telah dipilih sebagai sampel untuk proses degradasi dalam medium akueus. Ini bertujuan melihat kesan penggunaan mangkinfoto dalam sinaran ultralembayung (λ < 400 nm) atau cahaya matahari ke atas molekul tirosina. Kajian telah dijalankan menggunakan sistem cahaya, mangkin serbuk TiO2, hidrogen peroksida, H2O2 dan ion logam. Penambahan ion logam seperti Ni2+, Cu2+, Ag+, Mn2+, Co2+, Fe2+ dan Cd2+ dan agen pengoksidaan, iaitu hidrogen peroksida adalah untuk mendapatkan kaedah yang paling cekap. Keputusan menunjukkan penambahan H2O2 dan ion Fe2+ dan Ni2+ berjaya meningkatkan kecekapan proses degradasifoto tirosina. Ion Ni2+ memberikan keputusan terbaik berbanding ion-ion lain. Ion Cu2+, Ag+, Mn2+ dan Cd2+ merencat proses degradasi. Keputusan juga menunjukkan cahaya matahari adalah setanding dengan cahaya ultralembayung. Kepekatan H2O2 terbaik adalah 5.0 x 10-2M dan semakin banyak TiO2 digunakan semakin baik peratus degradasi tirosina. Oleh itu kaedah optimum untuk proses degradasifoto ialah Tr 2.5 x 10-4 M + TiO2 + H2O25.0 x 10-3 M + Mn+ 1.0 x 10-2 M. Proses degradasifoto dikaji menggunakan spektroskopi ultralembayung-nampak pada julat panjang gelombang 400-200 nm. Kata kunci: Tirosina; degradasifoto; serbuk TiO; akueus Amino acid is a basic component in plant or animal tissue. Tyrosine (Tr), an amino acid which contains aromatic ring, was chosen as a sample for a photodegradation process in an aqueous system. The purpose of the experiment is to study the effect of photocatalysis under UV (λ < 400 nm) or sunlight on tyrosine. The experiment was carried out by using UV light, catalyst powder (TiO2), hidrogen peroxide H2O2 and metal ions system. The addition of oxidising agent H2O2 and metal ions such as Ni2+, Cu2+, Ag+, Mn2+, Co2+, Fe2+ and Cd2+ were used in order to achieve the most efficient system. Results showed that the system with added H2O2 and metal ions such as Ni2+ and Fe2+ had successfully enhanced the process of the tyrosine photodegradation. Other metal ions system such as Cu2+, Ag+, Mn2+ and Cd2+ were found to inhibit the degradation process. The results also showed that sunlight was comparable to ultraviolet light. The best H2O2 concentration was 5.0 x 10-2 M and the percentage of tyrosine degradation increased with the addition of more TiO2) by mass. Therefore, the optimum condition for tyrosine photodegradation process was in Tr 2.5 x 10-4 M + TiO2 + H2O2 5.0 x 10-3 M + H2O2 1.0 x 10-2 M. The dissappearance of tyrosine in the photo degradation process was monitored by UV-visible spectroscopy between 400-200 nm. Key words: Tyrosine; photodegradation; TiO2 powder; akueus

Degradation of Pharmaceutical Pollutants under UV Light using TiO2 Nanomaterial Synthesized through Reverse Micelle Nanodomains

2021 ◽  
pp. 87-110
Keyword(s):  
Wastewater Treatment ◽  
Reverse Micelle ◽  
Uv Light ◽  
Sol Gel ◽  
Bet Surface Area ◽  
Tio2 Photocatalyst ◽  
Gel Method ◽  
Sol Gel Method ◽  
Treatment Techniques ◽  
Pharmaceutical Pollutants

Controlling water pollution are huge challenges throughout the world especially concerning pharmaceutical pollutants. Common practices at industrial wastewater treatment facilities need to be upgraded with advanced wastewater treatment techniques. TiO2 based photocatalytic processes have shown great potential for removal of these aqueous pharmaceutical pollutants. Reverse micelle based modified sol-gel method is utilized for the synthesis of TiO2 nanomaterial. Generated reverse micelle nanodomains have controlled size and particle size distribution (PSD) of synthesized TiO2 nanomaterial, as revealed by SEM and DLS analysis. Thermal behaviour of synthesized sample is characterized by TGA analysis. TiO2 photocatalyst is also characterized through XRD, BET surface area, and UV-Vis spectroscopy. TiO2 photocatalyst is used for degradation of three model pharmaceutical pollutants viz. Levofloxacin hemihydrate (LFX), Metronidazole (MNZ) and Ketorolac tromethamine (KRL) under a UV light source. Reverse micelle mediated modified sol-gel method synthesized TiO2 nanomaterial has shown excellent photocatalytical performance, where degradation efficiency of LFX, KRL and MNZ were found to be 99.6%, 98% and 91.4% respectively within a little as 60 minutes.

High-efficiency near-UV light-emitting diodes on Si substrates with InGaN/GaN/AlGaN/GaN multiple quantum wells

2020 ◽  
Vol 8 (3) ◽  
pp. 883-888 ◽  
Author(s):  
Yuan Li ◽  
Zhiheng Xing ◽  
Yulin Zheng ◽  
Xin Tang ◽  
Wentong Xie ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Quantum Efficiency ◽  
High Efficiency ◽  
Light Emitting Diodes ◽  
Uv Light ◽  
Multiple Quantum ◽  
High Quantum Efficiency ◽  
Light Emitting ◽  
Si Substrates

High quantum efficiency LEDs with InGaN/GaN/AlGaN/GaN MQWs have been demonstrated. The proposed GaN interlayer barrier can not only increase the concentration and the spatial overlap of carriers, but also improve the quality of the MQWs.

Study on Preparation of Microstructured Optical Membrane

2020 ◽  
Vol 861 ◽  
pp. 159-164
Author(s):  
Chang Song Zhao ◽  
Jun Yong Wu ◽  
Fan Zhong Chu ◽  
Kai Rui Zhao ◽  
Lei Yu
Keyword(s):  
High Efficiency ◽  
Uv Light ◽  
Light Transmittance ◽  
Manufacturing Cost ◽  
Market Demand ◽  
Direct Writing ◽  
Forming Process ◽  
Optical Elements ◽  
Optical Film ◽  
Warpage Deformation

Micro-structured optical film is one of the micro-optical elements and has a great market demand. This article studies the microstructured optical film formed by UV imprinting: The influence of embossing pressure on microstructure replication accuracy was explored. The larger the pressure, the better the material filling. When the pressure is 5N, the microstructure replication is complete; The relationship between the radiation intensity and warpage deformation was explored, and the decrease in the intensity of the UV light source can effectively reduce the warpage deformation; The influence of the material formula on the optical properties of the product was explored. When the oligomer content was 55%, the film had a high light transmittance. At the same time, the prepared film was subjected to an apparent inspection with good microstructure replication accuracy.Microstructured optical elements are widely used in optical fields such as semiconductors, lasers, beam shaping [1-2] and solar energy [3-5] due to their unique advantages such as small size and high performance. As a key component in many industries, it has a high market demand rate. However, the microstructure forming process is complicated, the manufacturing cost is high, and the accuracy is difficult to guarantee, which has restricted its development. With the advancement of science and technology and the increase in market demand, more and more researchers and enterprises have put their eyes on the research of preparing micro-structured optical elements.At present, the commonly used microstructures are mainly icrolens array [6-8], and the processing methods include micro-imprinting [9-10], etching [11], electron beam direct writing, and micro-injection [12], etc. This article studies the UV-curing embossing process in micro-embossing. This processing method has the advantages of fast molding, high efficiency, and environmental protection. And this process is conducive to mass production and has a broad market application prospect.In this paper, the forming process and material formulation of microstructured optical film prepared by light-cured micro-imprinting were investigated, and the microstructure morphology of the preparation was analyzed apparently.

scholarly journals Ultrasonic-Assisted Synthesis, Characterization, and Photocatalytic Application of SiO2@TiO2 Core-Shell Nanocomposite Particles

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Newaz Mohammed Bahadur ◽  
Farhana Chowdhury ◽  
Md. Obaidullah ◽  
Md. Shahadat Hossain ◽  
Rumana Rashid ◽  
...  
Keyword(s):  
Zeta Potential ◽  
Metal Oxide ◽  
Uv Light ◽  
Water Solution ◽  
Ultrasound Irradiation ◽  
Blue Dye ◽  
Core Shell ◽  
Nanocomposite Particles ◽  
Ultrasonic Assisted ◽  
Shell Particles

In this study, we report the synthesis of SiO2@TiO2 core-shell nanocomposite particles by ultrasound irradiation of a mixture of dispersed SiO2 nanoparticles, titanium-tetra-n-butoxide (TBOT), and ammonia in an ethanol-water solution medium. The resulting core-shell nanocomposite particles were characterized by SEM, TEM, FT-IR, XPS, XRF, zeta potential measurements, XRD, and UV-visible spectroscopy. Results showed that TiO2 nanoparticles coated on the surface of SiO2 were 6–10 nm in size and retained an anatase crystalline phase. Zeta potential measurements confirmed that the surface property of the SiO2 changed after TiO2 coating. SiO2@TiO2 core-shell particles demonstrated better decolorization of methylene blue dye compared to commercial TiO2 in aqueous solution under UV light. After treatment, the catalysts were separated with low-speed centrifugation and successfully reused four times without loss of activity. This study may provide some inspiration for the synthesis of other metal oxide-metal oxide core-shell nanocomposite materials through ultrasound irradiation.

Effect of Cyclodextrins on Photodegradation of 4,4-Bis(4-Hydroxyphenyl)Pentanoic Acid under UV Irradiation

2014 ◽  
Vol 665 ◽  
pp. 455-458
Author(s):  
Li Guo ◽  
Jin Huang ◽  
Jun Wu ◽  
Lei Lei Luo
Keyword(s):  
Aqueous Solutions ◽  
Fluorescence Spectra ◽  
High Efficiency ◽  
Uv Light ◽  
Order Reaction ◽  
Pentanoic Acid ◽  
Pseudo First Order Reaction ◽  
First Order ◽  
Inclusion Interaction ◽  
Pseudo First Order

The photodegradation of 4,4-bis (4-hydroxyphenyl) pentanoic acid (DPA) with two cyclodextrins (α-CD and β-CD ) in aqueous solutions induced by UV-light was studied in this paper by means of fluorescence spectra and high efficiency liquid chromatography. The result suggested that DPA with α-CD or β-CD formed inclusion compound in aqueous solutions. The photodegradation of DPA with two cyclodextrins or without cyclodextrin was pseudo-first order reaction. The photodegradation of DPA was accelerated by the addition of β-CD in aqueous solutions, but the that of DPA was inhibited in case of adding α-CD. These differences were due to the differences in inclusion interaction of DPA with α-CD or β-CD.

Studies on Effect Factors of Porous Titanium Dioxide Film Degrading Azo Dyes

2012 ◽  
Vol 531 ◽  
pp. 403-406 ◽  
Author(s):  
Sheng Min Sun
Keyword(s):  
Titanium Dioxide ◽  
Ph Value ◽  
Uv Light ◽  
Pure Titanium ◽  
Degradation Process ◽  
Porous Titanium ◽  
Titanium Dioxide Film ◽  
Effect Factors ◽  
Micro Arc Oxidation ◽  
Dioxide Film

In pure titanium body, through the method of micro-arc oxidation (MAO) on the surface of porous titanium dioxide film and study on factors of methyl orange in the light influence of catalytic degradation process, the results show that: with uv light for the source, pH value of 5, micro-arc oxidation voltage is 400 V, the catalytic activity of porous titanium dioxide film was the highest.

Spreading of SARS-CoV-2 via Heating, Ventilation, and Air Conditioning Systems—An Overview of Energy Perspective and Potential Solutions

2020 ◽  
Vol 143 (8) ◽  
Author(s):  
Ahmad K. Sleiti ◽  
Samer F. Ahmed ◽  
Saud A. Ghani
Keyword(s):  
Air Conditioning ◽  
High Performance ◽  
Public Perception ◽  
High Efficiency ◽  
Uv Light ◽  
Experimental Studies ◽  
High Energy ◽  
Penalty Cost ◽  
Energy Penalty ◽  
Air Conditioning Systems

Abstract The role of heating, ventilation, and air conditioning systems (HVAC) in spreading SARS-CoV-2 is a complex topic and has not been studied thoroughly. There are some existing strategies and technologies for health and high performance buildings; however, applications to other types of buildings come at large energy penalty: cost; design, regulations and standards changes, and varied public perception. In the present work, different factors and strategies are reviewed and discussed and suggested mitigations and solutions are provided including the required air flowrates with the presence of infectors with and without mask and disinfection techniques including ultraviolet (UV) light. Experimental and numerical research in open literature suggests that the airborne transmission of SARS-CoV-2 is sufficiently likely. However, in situ detailed experimental studies are still needed to understand the different scenarios of the virus spread. Displacement ventilation, underfloor air distribution, chilled beams, radiant ceiling panels, and laminar flow systems have varied effectiveness. High-efficiency particulate arrestance (HEPA) filters and UV light can clean viruses but at high energy cost. Suggested solutions to reduce the infection probability include recommended levels of ventilation and a combination of virus sampling technologies including cyclones, liquid impinger, filters, electrostatic precipitators, and water-based condensation.

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