Nitrogen Adsorption Isotherms Research Articles

Novel carbon-ceramic composite membranes with high cation exchange properties for use in microbial fuel cell and electricity generation

Actually, there are different configurations used in microbial fuel cells (MFCs) with presence or absence of an ion exchange membrane between their electrodes. Specifically, MFCs that use membranes have the objective of avoiding the diffusion of oxygen and substrate between the anodic and cathodic compartment, and to achieve a correct transfer of protons from one chamber to another. In this regard, the current study seeks to prepare and characterize new composite membranes using as precursors three types of carbonaceous materials such as bone char, coconut shell activated carbon and bituminous activated carbon and natural clay. The composite membranes of bituminous activated carbon and clay showed more promising specific conductivity (42%) than the one made with pure clay. The physicochemical properties of the membranes and their precursors were elucidated by SEM/EDX analysis, IR spectroscopy, nitrogen adsorption isotherms at 77 K and optical microscopy. Further, membranes performance was assessed using microbial fuel cells (MFCs) where the composite membranes prepared with clay-bituminous carbon reached the highest voltage values (0.95–1.02 V) in open circuits, while that reached a maximum power density of 0.699 W/m3 at a current density of 4.012 A/m3 in closed circuit. This behavior is associated with the high content of silicon and aluminum in bituminous activated carbon, which favored the proper functioning of membranes in the MFCs. Specifically, with this type of cells, energy recovery of 0.0057 kWh/m3 and 0.1322 kWh/kg chemical oxygen demand (COD) removed, which indicates an extra economic income of the order of $0.0025/kg COD. Finally, the produced power was demonstrated in prototypes to power LED and four digital clocks. This novel clay-bituminous activated carbon showed promising cost-effectiveness and sustainable energy generation, which may be suitable for wastewater treatment.

2nd generation PLA; Lactide formation directly from aqueous lactic acid

In order to develop a 2nd generation polylactic acid (PLA) process, lactide (LD) was synthesized directly from a commercially available 90% aqueous lactic acid (LA) solution. Experiments were conducted in an ordinary continuous flow fixed bed reactor. The reaction was carried out over various zeolites and γ-Al2O3 catalysts. Furthermore, the influence of pressure, temperature and water content in the inlet was studied. The highest LD selectivity of 98.9% was obtained using 90% LA and γ-Al2O3 as catalyst. In addition, it is concluded that LD yield increases when using highly concentrated LA oligomer with a minor amount of water. The catalysts were characterized by inductively coupled plasma atomic emission spectroscopy (ICP-AES), X-ray powder diffraction (XRD), nitrogen adsorption isotherms (BET), temperature programmed desorption of ammonia (NH3-TPD) and pyridine Fourier transformed infrared spectroscopy (Py-FTIR).

Recycling of tobacco wastes in the development of ultra-high surface area activated carbon

Activated carbons are vital for remediation processes such as water treatment. Nevertheless, some commercial versions have poor characteristics, such as low surface area and efficacy in removing contaminants. This work accessed the production of highly developed surface area activated carbons for environmental purposes and the recycling of tobacco wastes as an alternative precursor. Important parameters were tested, such as activation temperature (700, 800, and 900 °C) and mass ratio of chemical agents (KOH and ZnCl2, 3:1, 4:1, and 5:1 m:m). Activated carbons were evaluated using mathematical models of nitrogen adsorption and desorption isotherms (BET and BJH) and infrared spectroscopy (FT-IR). KOH was more effective than ZnCl2 as a chemical modifier, resulting in products with a greater surface area. Activation with KOH at 900 °C and a mass ratio of 4:1 resulted in a surface area of 3294 m2 g −1 and functional groups OH, CH, CO, CC, and CO, i.e., resulting in a promising adsorbent for contaminant sorption/removal processes. The developed methodology results in tobacco-based activated carbon with an extremely high surface area. Thus, tobacco wastes are excellent alternatives for producing KOH-activated carbons, besides being an ecological alternative to tobacco wastes destination.

Photocatalytic Degradation of Organic Dyes from Clinical Laboratory Wastewater

Clinical laboratory wastewaters are of important environmental concern due to the highly complex chemical reagents and dyes used to identify various pathologies, which are difficult to degrade by conventional treatment methods. The present research aimed to assess the effects of ilmenite use in the discoloration process of clinical laboratory wastewater. The wastewater originates from a Gram staining process used to identify pathogenic microorganisms present in biological samples. The active ingredient is crystal violet, a triphenylmethane dye derivative, highly toxic and non-biodegradable that causes a shiny purple color in the wastewater. The ilmenite was characterized by X-ray Fluorescence, X-ray Diffraction, Scanning Electron Microscopy, energy-dispersive spectroscopy and Nitrogen adsorption isotherm, while the discoloration process of the wastewater was measured by UV–Vis spectrophotometry and pH change trough the reaction time, evaluating different ilmenite loads, particle size and stability under light sources with different energies. Chemical oxygen demand analysis confirmed that acid formation and discoloration were associated with organic substance mineralization. Type C ultraviolet light and 0.7 g/L load were identified as the best operating conditions for the discoloration process. It was possible to establish that ilmenite is stable after four uses in the discoloration process, obtaining, in all cases, discoloration percentages higher than 90% after 3 h of irradiation.

Reduced Graphene Oxide Aerogels Cartridges for Solid Phase Extraction of Benzotriazoles

UV-benzotriazoles have been identified as water micropollutants that cause serious problems for human health and the environment. Their low concentration in water bodies complicates their detection by direct water analysis, slowing the corrective actions to avoid bioaccumulation. In this regard, the use of graphene-based materials with a high affinity for non-polar molecules has been demonstrated to be a potential tool for the optimal separation and concentration of this type of molecules in solid phase extraction (SPE) processes. This work evaluates the potential of novel reduced graphene oxide aerogels (rGO) as extractants of mixtures of three UV-benzotriazoles in water at low concentrations. These rGO aerogels incorporate graphenic domains into a tough structure of polymeric chains by adding graphene oxide during the synthesis of resorcinol-formaldehyde gels. Aerogels with a different content and ordering of graphenic domains were obtained and characterized using Raman, XRD, SEM and nitrogen adsorption isotherms (-196 °C). The rGO aerogels that performed better as solid phase extractants were those containing 60% rGO. Aerogels with lower rGO contents (40%) required a high-temperature (2000 °C) treatment to render competitive results. The SPE methodology using selected rGO aerogels was optimized by varying the elution solvent, elution time and volume. The best performances, i.e., recoveries of 80-100% and enrichment factors of 12.5-50, were accomplished when using 0.8 mL of tetrahydrofuran (THF) as an elution solvent. As a result, a fast (10 min) and simple extraction method of UV-benzotriazoles in water was attained, achieving a detection limit of 1 ng mL-1. Selected aerogels were finally tested for the SPE of spiked samples of river waters, showing a similar performance to that observed with synthetic mixtures.

One-Step Fabrication of the ZnO/g-C3N4 Composite for Visible Light-Responsive Photocatalytic Degradation of Bisphenol E in Aqueous Solution.

The ZnO/g-C3N4 composite was successfully synthesized by a simple one-step calcination of a urea and zinc acetate mixture. The photocatalytic activity of the synthesized composite was evaluated in the degradation of bisphenol E (BPE). The morphology, crystallinity, optical properties, and composition of the synthesized composite were characterized by using various analytical techniques such as scanning electron microscopy (SEM), transmitted electron microscopy (TEM), field emission-electron probe microanalysis (FE-EPMA), nitrogen adsorption and desorption isotherm measurement, Fourier-transform infrared (FTIR) spectroscopy, X-ray powder diffraction (XRD), diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy, electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). The degradation rate of BPE with the ZnO/g-C3N4 composite was 8 times larger than that obtained with pure g-C3N4 at the optimal conditions. The excellent photocatalytic activity was attributed to the synergistic effect between the g-C3N4 and ZnO, which enhanced the efficiency of charge separations, reduced the e-/h+ pairs recombination, and increased the visible light absorption ability. The radical scavenger studies indicated that the •O2 - and h+ species were mainly responsible for the degradation of BPE. The stability test suggested the chemical and photostability of the synthesized composite. Two possible photocatalytical mechanisms have been suggested.

ADSORPTION PURIFICATION OF UNREFINED VEGETABLE OILS WITH BENTONITE CLAY OF ZYRYANSK DEPOSIT

Magnesium ions predominate in the exchange complex of bentonite clay from the Zyryanskoye deposit. The amount of exchange cations varies within 76–95 mmol equivalents. The main rock-forming mineral of Zyryansk bentonite is montmorillonite. The adsorption and desorption isotherm of nitrogen by bentonite clay from the Zyryanskoe deposit has the form of a hysteresis loop, which is typical for bentonite clays from other deposits and corresponds to adsorption in mesoporous solids.
 The dynamics of the content of free fatty acids ((FFA (acid number (AN)) and peroxide compounds ((PC (peroxide number (PN)) in samples of unrefined vegetable oils: sunflower oil “Sloboda” and linseed oil “Yeleya” was studied. Six months later the AN and the PN in unrefined linseed oil, and the AN in unrefined sunflower oil increased, but the numbers did not exceed the maximum permissible values. The PN in unrefined sunflower oil increased by 6.4 times and exceeded the maximum permissible values.
 Isotherms of sorption of FFA and PC by native bentonite clay (NG) of the Zyryansk deposit have been obtained. The kinetics of sorption of FFA and PC of sunflower and linseed oil has been studied. The equilibration time is 90–120 min. The optimum operation of sorption of FFA and PC has been determined (static operation with stirring for 2 h at a ratio of m(clay) : V(oil)=1 g : 40 ml.
 The maximum degree of extraction of FFA from sunflower oil by bentonite clay was 31%; from linseed – 9%. The degree of extraction of PC from sunflower oil by bentonite clay was 48%, from linseed oil – 33%.

Organic solvent reverse osmosis characteristics of TiO2-ZrO2-organic chelating ligand (OCL) composite membranes using OCLs with different molecular sizes

In this study, organic chelating ligand (OCL) composite membranes (TiO2-ZrO2-OCL) were fabricated for application to organic solvent reverse osmosis (OSRO). Although it is difficult to control the pore structures of TiO2 and ZrO2 at the RO level, we attempted to control the dense pore structure of the TiO2-ZrO2-OCL membranes by using three different molecular sizes of OCLs: Acetylacetone (ACA), Methyl-2,4-heptanedione (ACAiB), and 2,6-Dimethyl-3,5-heptanedione (ACA2iP). The bonding state, amorphous structure, and pore structure of TiO2-ZrO2-OCL powder samples were investigated. Pair distribution function (PDF) analysis of TiO2-ZrO2-OCL powders suggested that the TiO2-ZrO2 network was changed with the molecular sizes of the OCLs. Nitrogen adsorption isotherms showed that OCLs with a larger molecular size had a larger BET specific surface area. TiO2-ZrO2-ACAiB and TiO2-ZrO2-ACA2iP membranes exhibited excellent methanol selective permeability for methanol (90 wt%) and toluene (10 wt%) at a transmembrane pressure of 5 MPa, and OSRO membranes with total flux that ranged from 0.072 to 0.968 kg m-2h−1 were fabricated with separation factors that ranged from 3.2 to 180. The molecular weight cut-off (MWCO) of TiO2-ZrO2-OCL membranes was evaluated based on the rejection of ethanol or isopropyl alcohol in methanol and methyl orange in methanol, and it was ranged from 80 to 200 g/mol. In addition, TiO2-ZrO2-OCL membranes showed high selectivity at low pressure with relatively low levels of methanol flux.

Determining the Geometric Surface Area of Mesoporous Materials

Specific surface area is an important property of porous materials and a crucial index in multiple disciplines, which is mainly measured using nitrogen isotherms and the Brunauer–Emmett-Teller (BET) equation. The BET surface area is remarkably higher than the geometric surface area, which is defined as the surface area of the crystal geometry structure. However, many studies directly use the BET surface area as the geometric surface area. We proposed a simple, general, and accurate method that only needs the nitrogen adsorption isotherm as the input to calculate the geometric surface area of mesoporous materials. The proposed method considers the adsorptive potential influences and the physical state of adsorbed nitrogen in estimating the surface area. We utilized 18 isotherms generated by molecular simulations and actual experiments to cover a wide range of materials, including minerals, catalysts, and carbon-based tubes, and validate the effectiveness of the proposed method. Our results showed that the surface area determined by the proposed method is almost identical to the referenced geometric area. The surface area obtained by the proposed method can be typically considered a geometric surface area.

Ammonia capture by adsorption on doped and undoped activated carbon: Isotherm and breakthrough curve measurements

Doped and undoped activated carbons were characterized by scanning electron microscopy, energy dispersive spectrometry, helium pycnometry, mercury intrusion porosimetry, and adsorption isotherms of nitrogen and carbon dioxide. The adsorption isotherms of ammonia were measured at 278, 293, 303, and 318 K and pressures up to 105 kPa using a manometric system on both activated carbons. These measurements showed that the doped activated carbon had the highest ammonia adsorption capacity, especially at low ammonia partial pressures. The Toth isotherm model was used to correlate the adsorption isotherms and estimate the isosteric heats of adsorption at 278 K and at zero fractional loading that were 25.6 and 41.9 kJ.mol−1 for undoped and doped activated carbon, respectively. Ammonia breakthrough curves were measured with both activated carbons in a pilot column. The behavior of doped and undoped activated carbon during adsorption/desorption cycles shows that despite the possibility of regeneration and enhancement of undoped activated carbon, the doped activated carbon provides better single use performance. A study of the operating parameters of doped activated carbon was conducted to evaluate the effects of ammonia concentration, gas flow rate, operating temperature, and relative humidity. The occurrence of two independent ammonia adsorption mechanisms (chemical and physical) on the doped activated was demonstrated.

Fabrication of High Surface Area TiO2-MoO3 Nanocomposite as a Photocatalyst for Organic Pollutants Removal from Water Bodies

A nanocomposite (NC) of titanium (IV) oxide (TiO2) and molybdenum (VI) oxide (MoO3) was synthesized using a hydrothermal route. Detailed analyses using transmission electron microscopy, X-ray diffraction, X-ray fluorescence (XRF), Brunauer–Emmett–Teller (BET) isotherms, X-ray photoelectron spectroscopy, Raman, and diffuse reflectance infrared Fourier transform spectroscopy were carried out and confirmed the successful formation of pure TiO2-MoO3 (Ti-Mo) NC. The Ti-Mo NC possesses sizes in the range of 150–500 nm. XPS, Raman, and DRIFT shift measurements confirmed the formation of mixed oxide linkage in the form of Ti-O-Mo. Sorption of nitrogen isotherms revealed a significant increase in the number and pore widths of mesopores in the NC. Water sorption isotherms revealed enhanced affinity of the nanocomposites for water relative to the pure metal oxides. The BET surface area for Ti-Mo NC from the nitrogen adsorption isotherm was 129.3 m2/g which is much higher than the pure metal oxides (i.e., 37.56 m2/g for TiO2 and 2.21 m2/g for MoO3). The Ti-Mo NC provided suitable adsorption sites that captured the studied carbamates from the solution and promoted their photodegradation process. The photocatalytic degradation of MB in the presence of the catalyst was enhanced by 2.9 and 5.5 folds upon irradiation with white LED and 302 nm UV light sources, respectively.

Periodic mesoporous organosilicas containing naphthalenediimides as organic sensitizers for sulfadiazine photodegradation.

In this work, periodic mesoporous organosilicas (PMO) functionalized with the organic sentisizer naphthalenediimide (NDI) were employed as heterogeneous catalysts for the photodegradation of the antibiotic sulfadiazine (SDZ), taken as a model for contaminants of emerging concern (CECs). The catalysts, designated as PMONDI, were prepared by surfactant-directed co-condensation of the precursor N,N'-bis(3-triethoxysilylpropyl)-1,4,5,8-naphthalenediimide with tetraethoxysilane. The synthesized PMONDI were characterized using transmission electron microscopy, nitrogen adsorption isotherms and small and large angle x-ray scattering. The performance of PMONDI catalysts in the photodegradation of SDZ was compared to that of TiO2 nanoparticles impregnated into SBA-15 mesoporous silica (TiO2/SBA-15), under irradiation with a Hg lamp with a bandpass filter of 320-500nm. Under optimal conditions, PMONDI degraded 100% of the SDZ in 45min, while the total degradation of SDZ was achieved only after 150min with TiO2/SBA-15. PMONDI also performed better than TiO2/SBA-15 in reuse tests. The mechanism of photodegradation with PMONDI involves the formation of excited triplet states of NDI (3NDI*) upon irradiation, which can then react with molecular oxygen to form reactive oxygen species, which degrade SDZ. Analysis of the SDZ degradation products indicated two main pathways: (1) hydroxylation of the aniline ring and (2) SO2 extrusion and rearrangement, followed by oxidation of the aniline ring to nitrobenzene. In conclusion, the great potential of the PMONDI materials as photocatalysts for CECs degradation was demonstrated in this work, encouraging further research on these materials for the degradation of pollutants.

Universal Langmuir and Fractal Analysis of High-Resolution Adsorption Isotherms of Argon and Nitrogen on Macroporous Silica.

High-resolution isotherms of argon and nitrogen adsorption on macroporous silica have been simulated with universal Langmuir and fractal models. A four-parameter, fractal universal Langmuir equation is a good fit to the data at low pressures. Standard Gibbs energy changes calculated from equilibrium adsorption coefficients show a series of broad peaks that indicate adsorbate structural transformations as a function of pressure and coverage. The Freundlich equation or mean fractal model is also a good fit to isotherms at low pressures. Pressure-varying fractals are accurate fits to the data. Fractal exponents provide information on adsorbate coverage and surface access. Broad peaks in pressure-varying exponents are indicators of adsorbate structure. From adsorptive gas amounts, mean and pressure-varying fractal exponents provide details of adsorbate fractal dimensions and surface roughness. Both Ar and N2 adsorption cause increases in mean surface roughness when compared with pure silica. Surface roughness fluctuations from pressure-dependent adsorptive gas fractal dimensions are associated with adsorbate structure. At one trough, the surface is smooth and is linked to close-packed Ar or N2. For Ar adsorption at 87 K, this structure is a complete monolayer (1.00(4)), while for Ar (77 K), 1.15(4) layers and for N2 (87 K), 2.02(10) layers. The universal Langmuir specific area of the silica is 10.1(4) m2 g-1. Pressure- and coverage-dependent adsorbate structures range from filling defects and holes on the surface to cluster formation to adsorbed Ar or N2 evenly distributed or packed across the surface. The Ar (87 K) isotherm is most sensitive to adsorbate structural transformations.

Composite of α-FeOOH and Mesoporous Carbon Derived from Indian Blackberry Seeds as Low-Cost and Recyclable Photocatalyst for Degradation of Ciprofloxacin

This study aims to analyse the use of biowaste-derived carbon in enhancing the photocatalytic effect of Earth-abundant visible light active goethite (α−FeOOH). The biowaste material used in this case is seeds of the Indian blackberry fruit. The FeOOH/C composite has been synthesized using an assisted sonochemical technique. The photocatalysts have been characterized using powder x-ray diffraction, nitrogen adsorption isotherms and scanning electron microscopy technique. FTIR and Raman studies have been carried out to understand the structure bonding correlation. The band gap has been ascertained using Tauc plots. The adsorption and consequent photodegradation of CIP have been studied via UV-visible spectroscopy and the mechanism has been ascertained by using radical quenching techniques. The charge separation efficiency has been ascertained through photoluminescence (PL) studies and electrochemical impedance studies (EIS). The pivotal role played by photogenerated holes (h+) in the photocatalytic degradation of CIP has been highlighted. The low cost biowaste-derived carbon as a constituent of the FeOOH/C composite shows great promise as a supporting material for enhancing the photocatalytic properties of such semiconductor materials.

Development of MOF Based Recyclable Photocatalyst for the Removal of Different Organic Dye Pollutants

The preparation of metal organic frameworks (MOFs) has come to the forefront in recent years because of their outstanding physical and chemical properties. Many MOFs such as Zn, Co, Ni, Fe, and Ag, etc., have been successfully synthesized. In this work, we followed the solvothermal assisted route to synthesize Ag-MOF (abbreviated as AMOF) nanosheets and then applied them as a photocatalyst to remove different organic pollutants, namely methyl orange (MO), crystal violet (CV), and methylene blue (MB). Chemical composition, optical properties, morphology, and microstructural analysis were analyzed using XPS, UV-visible spectrophotometer, FESEM, TEM, and EDS, respectively. The structural properties of AMOF nanosheets were studied by X-ray diffraction (XRD). Nitrogen adsorption and desorption isotherm analysis were utilized to evaluate the specific surface area and pore size of the AMOF nanosheets. Further, AMOF nanosheets showed notable photocatalytic performance for various dye pollutants degradation. The results confirmed 74.5, 85.5, and 90.7% of MO, CV, and MB dye pollutants removal after 120 min of irradiation with the rate constants (k) of 0.0123, 0.0153, and 0.0158 min-1, respectively. The effect of superoxide radicals (O2-) and photogenerated holes (h+) on the organic dye pollutants removal was investigated using radical scavenger trapping studies. Moreover, the stability study also confirmed the recyclability of the photocatalyst. Therefore, the findings of this research present a realizable method to grow AMOF photocatalyst for successful degradation of various dye pollutants.

Effective Removal of Metal ion and Organic Compounds by Non-Functionalized rGO.

Effective removal of heavy metals from water is critical for environmental safety and public health. This work presents a reduced graphene oxide (rGO) obtained simply by using gallic acid and sodium ascorbate, without any high thermal process or complex functionalization, for effective removal of heavy metals. FTIR and Raman analysis show the effective conversion of graphene oxide (GO) into rGO and a large presence of defects in rGO. Nitrogen adsorption isotherms show a specific surface area of 83.5 m2/g. We also measure the zeta-potential of the material showing a value of -52 mV, which is lower compared to the -32 mV of GO. We use our rGO to test adsorption of several ion metals (Ag (I), Cu (II), Fe (II), Mn (II), and Pb(II)), and two organic contaminants, methylene blue and hydroquinone. In general, our rGO shows strong adsorption capacity of metals and methylene blue, with adsorption capacity of qmax = 243.9 mg/g for Pb(II), which is higher than several previous reports on non-functionalized rGO. Our adsorption capacity is still lower compared to functionalized graphene oxide compounds, such as chitosan, but at the expense of more complex synthesis. To prove the effectiveness of our rGO, we show cleaning of waste water from a paper photography processing operation that contains large residual amounts of hydroquinone, sulfites, and AgBr. We achieve 100% contaminants removal for 20% contaminant concentration and 63% removal for 60% contaminant concentration. Our work shows that our simple synthesis of rGO can be a simple and low-cost route to clean residual waters, especially in disadvantaged communities with low economical resources and limited manufacturing infrastructure.

A facile method for synthesizing MOF derived ZnCo2O4 particles on MXene nanosheets as a novel anode material for high performance hybrid supercapacitors

MXene (MX) is a capable material for future generation supercapacitor devices. But, the attraction between active functional groups and hydrogen bonds on the surface of MX make the interlayer agglomerate obviously. In this work, we present a ZnCo-MOF (ZCM) derived ZnCo2O4 (ZCO) particles to adsorb on the (MX) nanosheets and form a mesoporous structure which may provide the flexible ion diffusion pathways. The as obtained MXene@ZnCo2O4 (MX@ZCO) composite is investigated using XRD, XPS, HRTEM, FESEM, and nitrogen adsorption and desorption isotherm analysis. The ZCO particles not only provide activation sites for free movement of charges but also help to avoid the agglomeration of MX nanosheets. Benefitted from this novel composite structure, MX@ZCO holds a great specific capacity of 260 mAh g−1 at the current density of 1 mA g−1. Further, the MX@ZCO electrode exhibits a good cyclic stability of 78.9% even after 5000 cycles at the current density of 10 mA g−1, which can be ascribed to excellent electronic conductivity and short ion transport path. Furthermore, the fabricated aqueous HSC device with MX@ZCO/NF as a positive electrode and AC/NF as a negative electrode revealed a high energy density of 63.8 Wh kg−1 at power density of 3512.2 W kg−1, along with the outstanding capacitance retention of 91.3% even after 15,000 GCD cycles. This work offers an excellent approach for the preparation of MX and ZCO composite material as an electrode for hybrid supercapacitors.

The effect of reagents on the production of highly nanocomposite bentonite sorbents using zol-gel technology

In this study, the analysis of the study of the effect of reagents upon receipt of cargo was highlighted—nanocomposite bentonite sorbents using Sol–gel technology and the results obtained were highlighted. The comparative surface surface was calculated at 77 K using a nitrogen adsorption isotherm. The size and pore size of the catalysts were determined from data on desorption and adsorption isotherms, respectively, at a relative pressure R/ro=0.99 in accordance with the BJH (Barette–Joyner–Halend) model. Bentonite in Navoi region of Navahor district is a light gray powder, odorless, practically insoluble in water and organic solvents, the pH value of the suspension is 7.1–8.7. The weak alkalinity of the suspension is explained by the presence of hydroxide soil and hydroxide metals in the clay. According to its adsorption properties, it is a combined meso–macromicrobial adsorbent, its specific surface area is 54.5 m2/g, the porosity volume is 0.065 cm3/g, the average porosity is 4.8 nm, the adsorption activity for blue methylene is 62.0 bentonite/g.

Production of Nanocarbon from Local Raw Materials

This research aims at extraction of nanocarbon from local raw materials through a detailed study of its characteristics. The research involves study of thermal properties of fruit kernels (apricots) and walnut kernels, determining the optimal modes of the carbonization process for each type of raw material, developing a method for the synthesis of spherical granules by liquid granulation and determining the optimum concentration of the sulfuric acid solution used in granulation. Analysis of the results on the dynamic sorption of petroleum products showed that maximum sorption is achieved when using a sorbent obtained at 400∘C for 30 minutes. Temperature regimes have been optimized for obtaining sorbent from walnut shells with different carbon content. The hydrophobicity and oleophilic of their surface are common to all these materials. The dynamic conditions of the adsorption capacity processes under the sorbents were studied. Sorption efficiency and the specific capacity of sorbents were determined. It has been shown that the technological cycle of the studied sorbents can be repeated by repeated purification. When activated charcoal is used to purify water from petroleum products, the process of leaching with colloidal and finely dispersed mixtures – it was found that deaeration is necessary. The individual composition of the ether fraction OV-1 has a fixed liquid phase, Connected to Finuigan 4023 Automated GC/MS System mass spectrometer, It was determined by chromato-mass spectrometry in a capillary column 40 m long and 0.25 mm in internal diameter. The results of the Fure-IR spectroscopy study of samples based on the apricot peel, walnut peel, and walnut peel showed that winning symmetrical bands (2920 and 2851 cm−1) were observed in them, these bands belong to the C-H-valence oscillation belonging to the methyl and methylene groups. In the spectrum taken from a sample of apricot peel, absorption bands belonging to cellulose (1377 cm−1 and 1069 cm−1 ) were observed.
 Thermogravimetric studies were performed on an STA 449C Jupiter synchronous thermal analysis instrument in the inert environment at a heating rate of 10∘ C/min in the temperature range of 25–1000∘C. Analysis of the porous structure parameters of carbon sorbents were carried out using the high-speed analyzer of gas sorption NOVA-1200e by the method of imaging nitrogen adsorption isotherms at a temperature of 77K.

Sulfur Vacancy-Rich CuS for Improved Surface-Enhanced Raman Spectroscopy and Full-Spectrum Photocatalysis.

There are growing interests in the development of bifunctional semiconducting nanostructures for photocatalysis and real-time monitoring of degradation process on catalysts. Defect engineering is a low-cost approach to manipulating the properties of semiconductors. Herein, we prepared CuS nanoplates by a hydrothermal method at increasing amounts of thioacetamide (CS-1, CS-2, and CS-3) and investigated the influence of sulfur vacancy (Vs) on surface-enhanced Raman spectroscopy (SERS) and photocatalysis performance. SERS intensity of 4-nitrobenzenethiol on CS-3 is 346 and 17 times that of CS-1 and CS-2, respectively, and enhancement factor is 1.34 × 104. Moreover, SERS is successfully applied to monitor the photodegradation of methyl orange. In addition, CS-3 also exhibited higher efficiency of Cr(VI) photoreduction than CS-1 and CS-2, and removal rate is 88%, 96%, and 73% under 2 h UV, 4 h visible, and 4 h near-infrared illumination, respectively. A systematic study including electron paramagnetic resonance spectra, photoelectrochemical measurements, and nitrogen adsorption isotherms were conducted to investigate the underlying mechanism. This work may help to understand the impact of vacancy defect on SERS and photocatalysis, and provide an effective and low-cost approach for the design of multifunctional materials.