Tài liệu miễn phí Hoá học
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Enhancing phenol removal from waste water by adding powder activated carbon to the lab scale activated sludge system
In this study, the commercial powder activated carbon (PAC) was added to a bench scale conventional activated sludge (CAS) system to enhance phenol removal. The mixed liquor suspended solid (MLSS) concentration of CAS with adding PAC was stable in all stages of operation, while MLSS concentrations in CAS without PAC addition sharply decreased as the Phenol loading reached 1.8 g phenol/L.day.
4/5/2023 2:24:54 PM +00:00
Graphitic carbon nitride quantum dots: Synthesis and applications
In this review, recent advances in synthesis and applications of g-CNQDs were summarized and the future challenges as well as opportunities of these g-CNQDs in the chemical and biomedical fields will be highlighted.
4/5/2023 2:24:43 PM +00:00
Xác định tỷ lệ các chất phụ gia kháng UV và oxy hóa cho hỗn hợp vật liệu polypropylen bằng phương pháp quy hoạch thực nghiệm trực giao và tối ưu hóa hàm đa mục tiêu
Bài viết này trình bày quá trình xác định tỷ lệ các chất phụ gia bằng phương pháp quy hoạch thực nghiệm trực giao và tối ưu hóa hàm đa mục tiêu. Kết quả thu được đã tìm ra tỷ lệ tối ưu bột than đen, chất kháng UV và chất chống ôxy hóa theo phần khối lượng tương ứng là 3:3,8:0,6.
4/5/2023 11:57:04 AM +00:00
Đánh giá khả năng xử lý chất hữu cơ và giảm thiểu bùn thải bằng bể sinh học giá thể cố định FBBR
Trong nghiên cứu này, bể sinh học có lớp đệm cố định (Fixed Bed Bio-Reactor - FBBR) được đề xuất để loại bỏ chất hữu cơ khỏi nước thải. Bể FBBR đã xuất hiện trong một số nghiên cứu cho thấy hiệu quả xử lý nước thải sữa cao trên 98% ở tải trọng 1,2 kgCOD/m3 ngày, đạt 98,41% ở tải trọng 1,5 kgCOD/m3 ngày.
4/5/2023 11:56:32 AM +00:00
Structure and properties of Ni0.7Zn0.3Fe2O4 ferrite nanoparticles synthesized by solid state reaction method
The main aim of this study is to determine the structure and properties of the Ni0.7Zn0.3Fe2O4 ferrite nanoparticles (FNP) synthesized by solid-state reaction method under the laboratory conditions of the unit and compare them with those of world publication.
4/5/2023 11:56:19 AM +00:00
Nghiên cứu ứng dụng công nghệ quang Fenton để xử lý nước thải phát sinh từ quá trình xì tháo bom mìn, vật nổ
Nghiên cứu này đã xây dựng mô hình thử nghiệm và đánh giá hiệu quả của công nghệ quang Fenton đối với nước thải có chứa TNT và các chất hữu cơ khác từ quá trình xì tháo bom mìn, vật nổ với mong muốn xử lý triệt để các chất ô nhiễm hữu cơ và giảm thiểu phát sinh chất thải thứ cấp.
4/5/2023 11:56:06 AM +00:00
Nghiên cứu đặc tính chống tạo cặn của cation Zn2+ trong môi trường dung dịch ethylene glycol nước
Bài viết này trình bày một số kết quả nghiên cứu khả năng chống tạo cặn của ion Zn2+ trong môi trường dung dịch ethylen glycol (EG). Nghiên cứu tiến hành với nồng độ ion Zn2+ từ 0 ppm đến 12 ppm. Kết quả nghiên cứu điện hóa cho thấy, sự ion Zn2+ với nồng độ 8 ppm cho hiệu quả ức chế sự tạo cặn tốt nhất. Phổ tổng trở điện hóa chỉ ra rằng sự có mặt của ion Zn2+ làm hạn chế sự tạo thành lớp cặn có độ dẫn kém trên bề mặt điện cực.
4/5/2023 11:55:54 AM +00:00
Nghiên cứu chế tạo cảm biến phát hiện khí cháy nổ NO2 trên cơ sở vật liệu Zn2SnO4 ứng dụng trong quân sự
Bài viết trình bày các kết quả nghiên cứu chế tạo cảm biến khí phát hiện cháy nổ NO2 nhằm ứng dụng trong lĩnh vực quân sự. Cảm biến khí được chế tạo dựa trên vật liệu ôxít kim loại bán dẫn Zn2SnO4. Các kết quả phân tích vật liệu, chế tạo cảm biến và đo tính chất nhạy khí NO2 đã được tiến hành.
4/5/2023 11:55:28 AM +00:00
Tổng hợp và đánh giá đặc trưng của kẽm undecylenat có độ tinh khiết cao
Bài viết này giới thiệu phương pháp tổng hợp, phân tích muối kẽm undecylenat thu được dựa trên phản ứng hệ lỏng-lỏng giữa dung dịch kẽm axetat và dung dịch axit undecylenic với nguyên liệu ban đầu là kẽm oxit, axit axetic, axit undecylenic và etanol.
4/5/2023 11:55:14 AM +00:00
Phương pháp phân tích khí hồng ngoại buồng tĩnh kín và ứng dụng trong việc xác định lượng carbon phát thải qua hô hấp đất tại rừng ngập mặn Cần Giờ
Trong nghiên cứu này, hô hấp đất của hệ sinh thái tự nhiên rừng ngập mặn Cần Giờ (Thành phố Hồ Chí Minh) được đo bằng phương pháp buồng kín di động (DC-Dynamic chamber method) tại 12 sinh cảnh rừng tự nhiên với kích thước ô mẫu 20 m x 20 m.
4/5/2023 11:54:59 AM +00:00
Nghiên cứu ảnh hưởng của nhiệt độ và hàm lượng của hệ phụ gia ức chế ăn mòn đa kim loại lên hiệu quả chống ăn mòn trong môi trường ethylene glycol
Bài viết này trình bày kết quả nghiên cứu khả năng chống ăn mòn của hệ phụ gia phức hợp (AC-2HM) gồm các phụ gia truyền thống kết hợp các axit hữu cơ lên hệ đa kim loại gồm thép, đồng, nhôm trong môi trường nước ăn mòn.
4/5/2023 11:54:47 AM +00:00
Nghiên cứu khả năng kháng UV của lớp phủ trên cở sở chất tạo màng họ fluoropolyme và định hướng chế tạo lớp phủ độ bền cao bảo vệ vũ khí
Nghiên cứu nhằm mục đích chế tạo lớp phủ bền UV với Fluoropolyme và các loại bột màu, phụ gia đặc biệt. Khảo sát độ bền UV được tiến hành giữa Fluoroethylene vinyl ether (FEVE) so với Polyurethane, Epoxy, Acrylic, Alkyd.
4/5/2023 11:54:33 AM +00:00
So sánh phương pháp phân tích 2,4,6 – Trinitrotoluen trong nền mẫu đất bằng phương pháp sắc ký khí và sắc ký lỏng ghép nối đầu dò khối phổ
Hợp chất 2,4,6 – Trinitrotoluen (TNT) trong nền mẫu đất được chiết siêu âm trong dung môi acetonitril, sau đó, được phân tách và xác định trên hệ thống sắc ký khí với đầu dò khối phổ (GC-MS) và sắc ký lỏng ghép nối đầu dò khối phổ (LC-MS). Kết quả cho thấy phương pháp phân tích TNT bằng phương pháp GC-MS có khoảng tuyến tính từ 5,0 đến 500 ng/mL, độ đúng đạt 80,5%, độ lệch chuẩn tương đối (RSD) nhỏ hơn 7,1%, giới hạn phát hiện (LOD) là 16 ng/g.
4/5/2023 11:54:04 AM +00:00
Preparation of black-TiO2 and its application in photocatalytic removal of methyl orange dye
For a few decades, Titanium Dioxide (TiO2) has been the most studied photocatalyst due to its significant optical property. In the paper, TiO2 pigment powder (Anatase form) was selected as a precursor to prepare a variety of Black-TiO2 samples, and the typical material was then evaluated for its photocatalytic activity in organic pollutant treatment.
4/5/2023 11:53:50 AM +00:00
Green synthesis of MIL-100(Fe) metal-organic frameworks as a carrier for chloroquine delivery
The metal-organic framework MIL-100(Fe) was synthesized by the green process using the ultrasonic method and water. By using this approach, the energy consumption was reduced by 100 times compared to the hydrothermal method. The prepared MIL-100(Fe) was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and BET surface area measurements.
4/5/2023 11:53:37 AM +00:00
In-situ synthesis of phthalocyanines on electrospun TiO2 nanofiber by solvothermal process for photocatalytic degradation of methylene blue
Titanium dioxide/phthalocyanine (TiO2/Pc), TiO2/fluor containing phthalocyanine (TiO2/FPc), and TiO2/fluor containing cobalt phthalocyanine (TiO2/FCoPc) had been successfully fabricated by a simple combination of phthalocyanines obtained by insitu synthesis on the surface of TiO2 nanofibers prepared by electrospinning. Scanning electron microscopy micrographs and X-ray diffraction analysis indicated that the phthalocyanines uniformly immobilized on the surface of TiO2 nanofibers. Photocatalytic activity of TiO2, TiO2/Pc, TiO2/FPc, TiO2/FCoPc nanofibers for methylene blue in water was comparatively investigated firstly by ultravioletvisible absorption measurements with time, and kinetic parameters were calculated.
4/5/2023 5:53:23 AM +00:00
A fluorescent sensor-based tripodal-Bodipy for Cu (II) ions: bio-imaging on cells
A general synthetic method was improved to synthesize a chemosensor based on a tripodal Bodipy (t-BODIPY) structure. The product and its intermediate products were successfully prepared and fully characterized. The metal ion sensing performance of the tripodal compound was evaluated by UV/Vis and fluorescence spectroscopies. According to the obtained data, t-BODIPY is a selective and sensitive fluorescence probe for detection of Cu2+ ions in the presence and in the absence of competing ions. This chemosensor presents relatively a low detection limit of 5.4 x10–7 M for Cu2+. Bio-imaging studies on living yeast cells suggest that tBODIPY has some advantages over other chemosensors to recognize copper (II) ions.
4/5/2023 5:53:16 AM +00:00
Polyethylene glycol/silica and carbon black/silica xerogel composites as an adsorbent for CO2 capture
Mesoporous polyethylene glycol (PEG)/silica and carbon black (CB)/silica xerogel composites were prepared by the solgel method as an adsorbent for CO2 adsorption. The CO2 adsorption process was carried out under pure CO2 atmosphere at room temperature in addition to ambient air. The xerogel composites with high surface area and pore volume showed better CO2 adsorption capacity than the pure silica xerogel. After modifying samples with propylene diamine using the wet impregnation method, an increase in CO2 adsorption capacity was observed for the samples except CB/silica xerogel composite.
4/5/2023 5:53:09 AM +00:00
Poly(N-vinylimidazole): A biocompatible and biodegradable functional polymer, metal-free, and highly recyclable heterogeneous catalyst for the mechanochemical synthesis of oximes
The catalytic activity of poly(N-vinylimidazole), a biocompatible and biodegradable synthetic functional polymer, was investigated for the synthesis of oximes as an efficient, halogen-free, and reusable heterogeneous catalyst. The corresponding oximes were afforded in high to excellent yields at room temperature and in short times using the planetary ball mill technique. Some merits, such as the short reaction times and good yields for poorly active carbonyl compounds, and avoiding toxic, expensive, metal-containing catalysts, and hazardous and flammable solvents, can be mentioned for the current catalytic synthesis of the oximes. Furthermore, the heterogeneous organocatalyst could be easily separated after the reaction, and the regenerated catalyst was reused several times with no significant loss of its catalytic activity.
4/5/2023 5:53:02 AM +00:00
Silk fiber-based composite nanofiber tissue scaffold produced with electrospinning method
Wound dressings are one of the most rapidly expanding areas in medical textiles. In recent years, a large number of functional wound dressing has been developed. The aims of these products are to speed up the wound healing process and to provide maximum comfort for patients. Today, the multidisciplinary studies are required to improve further existed wound dressings. The results of such research studies are also promised new hopes for the Turkish textile industry weakened by the global competition.
4/5/2023 5:52:55 AM +00:00
Tunable aryl alkyl pyrazolium tetrafluoroborate ionic liquids/salts: synthesis, characterization, and applications for removal of methyl orange from aqueous solution
In this work, new tunable aryl alkyl pyrazolium tetrafluoroborate ionic liquids/salts, 2-ethyl-1-(p-X-phenyl)-3,5- dimethylpyrazolium tetrafluoroborate [X: -Br (4a), -OCH3 (4b), -NO2 (4c)] and 2-butyl-1-(p-X-phenyl)-3,5-dimethylpyrazolium tetrafluoroborate [X: -Br (5a), -OCH3 (5b), -NO2 (5c)], were synthesized by following halide-free synthetic route. Their chemical structures were identified through NMR (1 H, 13C, 19F), IR, elemental analysis, and HRMS data. The synthesized 4a-4c and 5a-5c salts were used for the removal studies of methyl orange dye from aqueous solutions. The effects of specific parameters such as nature of the solvent, pH, contact time, amount and structure of the salts, and concentration of potassium chloride on the removal efficiencies were investigated.
4/5/2023 5:52:45 AM +00:00
A four-component modified Biginelli reaction: A novel approach for C-2 functionalized dihydropyrimidines
A novel four component modified Biginelli reaction for the synthesis of C-2 functionalized dihydropyrimidines has been established. The approach uses assembly of less explored acetyl acetone with aromatic aldehyde, thiourea, and dimethyl sulphate to construct a novel 5-acetyl 2-methylthio dihydropyrimidine system, which works as an efficient well-designed intermediate for generating C-2 modified Biginelli libraries with nitrogen nucleophiles. Phenyl hydrazine, semicarbazide, and aryl semicarbazides are successfully used as N-nucleophiles to generate C-2 functionalized dihydropyrimidine derivatives, which fulfil the demands of active pharmacophore. Time economy, step economy, and a single pot reaction with moderate to excellent yield are the major advantages of this novel method.
4/5/2023 5:52:34 AM +00:00
Reductant free green synthesis of magnetically recyclable MnFe2O4@SiO2-Ag coreshell nanocatalyst for the direct reduction of organic dye pollutants
The present paper describes in situ green immobilization of silver nanoparticles on MnFe2O4@SiO2 nanospheres using Epilobium parviflorum (EP) without using any other toxic chemicals and reducing or stabilizing agents. The morphology, composition, and magnetic properties of the resulting MnFe2O4@SiO2-Ag core-shell nanocatalyst were characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR). The catalytic performance of the synthesized MnFe2O4@SiO2-Ag was employed on the organic pollutants dyes such as rhodamine B (RhB) and methylene blue (MB).
4/5/2023 5:52:28 AM +00:00
Volatile constituents of three Thymus sipyleus Boiss. subspecies from different sites in Turkey
This study was designed to reveal the chemical diversity of some Thymus sipyleus subspecies growing wild in Turkey and to compare the volatile compound profiles by using micro(hydro)distillation technique. For this purpose, volatile compounds isolated by microdistillation from nine samples (three plant samples collected from different regions in Antalya) of Thymus sipyleus Boiss. subsp. sipyleus var. sipyleus, T. sipyleus Boiss. subsp. sipyleus var. davisianus Ronniger, and T. sipyleus Boiss. subsp. rosulans (Borbas) Jalas were analyzed by GC and GC-MS systems. 1,8-Cineole, p-cymene, α-terpineol and carvacrol were identified as major compounds in T. sipyleus subsp. sipyleus var. sipyleus samples.
4/5/2023 5:52:19 AM +00:00
Synthesis and application of colloidal CdS quantum dots as interface modification material in perovskite solar cells
In this study, colloidal CdS quantum dots were synthesized, structurally characterized, and their effect on performance of perovskite solar cells was observed by using them as interface modification agent between TiO2 /perovskite. Colloidal CdS quantum dots were synthesized based on two-phase method and characterized by X-ray diffraction and Transmission Electron Microscopy techniques. The average particle size of CdS quantum dots have found to be around 5 nm. Oleic acid was used as capping agent during synthesis to lead solubility in organic solvents.
4/5/2023 5:52:12 AM +00:00
Crystal structure and vibrational spectra of bis(2‒isobutyrylamidophenyl)amine: a redox noninnocent ligand
The molecular structure of bis(2‒isobutyrylamidophenyl)amine (H3 LNNN) has been determined from single‒crystal X-ray diffraction data. The crystal packing of H3 LNNN is governed by the N–H⋯O and C–H⋯O hydrogen-bonding and C–H⋯π stacking interactions between the vicinal molecules. The intermolecular interactions in the crystal structure of H3 LNNN have been also examined via Hirshfeld surface analysis and fingerprint plots. The Hirshfeld surface analysis showed that the important role of N–H⋯O and C– H⋯π interactions in the solid‒state structure of H3 LNNN. The molecular structure, vibrational frequencies, and infrared intensities of H3 LNNN were computed by ab initio HF and DFT (B3LYP, B3PW91, and BLYP) methods using the 6–31G(d,p) basis set.
4/5/2023 5:52:00 AM +00:00
A facile approach for the synthesis of porous hematite and magnetite nanoparticles through sol-gel self-combustion
: Porous magnetite (Fe3 O4 ) and hematite (α-Fe2 O3 ) nanoparticles were prepared via the sol-gel auto-combustion method. The gels were prepared by reacting ferric nitrates (as oxidants) with starch (as fuel) at an elevated temperature of 200 °C. Different ratios (Φ) of ferric nitrates to starch were used for the synthesis (Φ = fuel/oxidant). The synthesized iron oxides were characterized by Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy, X-ray diffraction (XRD) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmet–Teller (BET) and vibrating sample magnetometer (VSM) analysis techniques.
4/5/2023 5:51:49 AM +00:00
Investigation of electrochemical behavior of potassium ferricyanide/ferrocyanide redox probes on screen printed carbon electrode through cyclic voltammetry and electrochemical impedance spectroscopy
Potassium ferricyanide, potassium ferrocyanide, and their combination system are widely used redox probes for electrochemical impedance spectroscopy (EIS) characterization. In this work, electrochemical behavior of K3 Fe(CN)6 , K4 Fe(CN)6 , and K3 Fe(CN)6 / K4 Fe(CN)6 redox probes at five different concentrations using a screen printed carbon electrode (SPCE) by cyclic voltammetry (CV) and EIS methods was analyzed. Redox potentials were observed as a result of anodic and cathodic peak with CV analysis with determination 10 mM appropriate concentration through 0.01 mM, 0.1 mM, 1 mM, and 100 mM. In addition, with EIS analysis, each redox probe was simulated according to two different Randles circuit models and fitting equivalent model with varying concentration was determined and examined in detail.
4/5/2023 5:51:35 AM +00:00
Preparation and characterization of nano MnO-CaLs as a green catalyst for oxidation of styrene
Hydrophilic nano MnO is shown to have significant stability in aqueous media for oxidation of styrene. Different catalysts have been used to synthesis styrene oxide, but MnO-CaL is considered the efficient and selective catalyst to produce styrene oxide. In general, this paper reported especial strategy for synthesis of novel nano MnO that stabilized with oleic acid in chloroform and changing nature of its stabilizer by exchanging oleic acid with lignosulfunate and displays its catalytic activity towards selective oxidation of styrene. The catalyst has shown good selectivity in oxidation of styrene by changing temperature.
4/5/2023 5:51:25 AM +00:00
Novel vic-dioximes: synthesis, structure characterization, and antimicrobial activity
The vic-dioximes are compounds with various industrial uses and scientific applications. Many coordination compounds have been synthesized based on vic-dioximes. This study presents the synthesis and full characterization of two vic-dioximes based on dichloroglyoxime, p-aminobenzoic acid, and p-aminotoluene. Their structures were proved by IR, 1 H, 13C and 15N NMR spectral analysis, and single crystal X-ray diffraction. One of the reported vic-dioximes, bis(di-p-aminotoluene)glyoxime mono-p-aminotoluene trihydrate showed good to moderate antimicrobial activity against both nonpathogenic gram-positive and gram-negative bacteria (Bacillus subtilis and Pseudomonas fluorescens), phytopathogenic (Xanthomonas campestris, Erwinia amylovora, E. carotovora) and the fungi (Candida utilis and Saccharomyces cerevisiae) at MIC – 70–150 μg/mL.
4/5/2023 5:51:17 AM +00:00