Oxidative Desulfurization Research Articles

Ultra-thin C/Si Shell Pieces as Amphiphilic Janus Materials for Efficient Oxidation Desulfurization.

Constructing favorable morphology is considered to be an effective strategy to enhance the amphiphilic performance of materials. The directional alignment of ultra-thin lamellar materials significantly facilitates utilization of active sites at the bi-phase interface. Herein, an ultra-thin amphiphilic C/Si shell pieces Janus material (d = 10.4nm) prepared by graphene oxide and SiO2 is reported. The outer SiO2 layer is associated with hydrophilicity, while the inner C layer exhibits hydrophobicity. A Pickering emulsion interface catalyst for fuel oil oxidative desulfurization is constructed by impregnating an amino-modified C/Si Janus material with keggin-type HPW. The results demonstrate that amphiphilic catalyst with an ultra-thin C/Si shell pieces exhibits superior performance in terms of emulsification rate (100%) and desulfurization rate (99.62%) in the O/W emulsion formed by n-octane/acetonitrile. The catalyst demonstrates the advantages of easy recovery and regeneration, maintains a higher activity after oxidative desulfurization (ODS) process, and has higher industrial application value.

Oxidative Desulfurization of Dibenzothiophene Using Catalyst of NiO Impregnated on Magnetic Silica Sand from Parangtritis Beach

Oxidative desulfurization of dibenzothiophene (ODS-DBT) using catalyst of NiO impregnated on magnetic silica sand from Parangtritis beach (Ps) had been evaluated. The NiO-Ps catalyst was prepared using wet impregnation method with Ps to Ni (NO3)2·6H2O weight ratio of 1:1. The catalyst was calcined at a temperature of 400 °C for 5 h under flow of 20 mL min-1 of N2 gas. The ODS-DBT process was carried out using NiO-Ps catalyst on solution of n-hexane with a sulfur content of 500 ppm under variations of temperature, time, and H2O2 volume. The results of XRD and FTIR indicated the main minerals of Ps were quartz, alumina, and magnetite. The Ps and NiO-Ps had crystallinities of 59.97 and 70.32% with crystal sizes of 16.32 and 10.95 nm. The SEM-EDX and TEM analysis showed the surface of Ps was flat and NiO-Ps was rough. The BET-nitrogen absorption-desorption indicated the Ps and NiO-Ps were mesoporous materials with average pore diameters of 11.98 and 24.01 nm, total pore volumes of 0.008 and 0.057 cm3 g-1, and specific surface areas of 2.611 and 9.502 m2 g-1. The Ps and NiO-Ps have acidity values of 1.14 and 1.74 mmol g-1. The optimum desulfurization using NiO-Ps catalyst in the ODS-DBT was 79.40% obtained at a temperature, time, and H2O2 volume of 60 °C, 30 min, and 0.42 mL.

Facile Construction of Supported Polyoxometalate Ionic Liquids for Deep Oxidative Desulfurization of Fuel

Facile Construction of Supported Polyoxometalate Ionic Liquids for Deep Oxidative Desulfurization of Fuel

Hydrophobic Modification of Halloysite Nanotubes Loaded with a Small Amount of Tungsten Oxide for Efficient Oxidative Desulfurization.

Transition metal oxides can be used as efficient multiphase catalysts in the field of catalysis. In this study, a hydrophobic halloysite nanotube (HNT) catalyst was designed and prepared with a low loading. Tungsten oxide was immobilized on the inner surface of the HNT, through electrostatic adsorption and calcination. Furthermore, a dual-functional W/HMT/M catalyst was prepared by hydrophobic modification of the outer surface of HNT through a harmless and nontoxic method. The catalyst was applied in the oxidative desulfurization (ODS) of dibenzothiophene (DBT), and characterized by inductively coupled plasma (ICP), contact angle tests, and other methods. Systematic characterization further confirmed that W/HNT/M has a low loading (0.48 wt %) and a relatively high contact angle of 92.6°. Oxidative desulfurization experiments demonstrated that the high contact angle corresponds to good hydrophobicity. The low loading and high activity of the catalyst enabled it to achieve a removal efficiency of 100% for DBT under conditions of 60 °C and an O/S = 4. The hydrophobic surface of HNT allowed better dispersion in the oil phase, while its hydrophilic inner cavity could adsorb H2O2 and the converted dibenzothiophene sulfoxide, thereby reducing the subsequent extraction steps after oxidative desulfurization and enhancing the reaction environment for reactants and active oxygen. W/HNT/M maintained high activity for at least 5 cycles. Additionally, the potential mechanism of the catalyst in the aqueous ODS reaction was proposed. This study demonstrates that HNT-supported metal oxides have desulfurization potential and provides ideas for improving ODS catalytic activity of the ODS through low loading, high activity, and unique hydrophobicity design.

Constructing frustrated Lewis pairs on Mo-doped Fe2O3 catalyst to enhance oxidative desulfurization efficiency

The emission of sulfur oxides will not only cause a series of environmental pollution but also threaten human health. At present, oxidative desulfurization is considered one of the technologies to achieve high-efficiency conversion of sulfur-containing compounds. Herein, the special frustrated Lewis pairs (FLPs) for efficient oxidative desulfurization are created by regulating surface doping in a redox iron-based oxide. According to experimental results, the Lewis acidic sites can be considered as the iron atoms adjacent to the molybdenum dopant, while the doped metal proximal to the oxygen vacancies serves as Lewis basic sites to create FLPs in redox iron-based oxide. This reactivity of FLPs is further adapted to the chemical activation of molecular oxygen and aromatic sulfur-containing compounds. The Fe2O3-FLP catalyst can achieve 100 % sulfur removal at 3 h and maintains 96.9 % after seven cycles, higher than other previously reported iron-based oxidative desulfurization catalysts. In addition, the design of FLPs offers a promising approach for developing high-efficiency catalysts in the oxidative desulfurization process.

Uncovering structure-activity relationships in Brønsted acidic deep eutectic solvents for extractive and oxidative desulfurization

Modeling the structure-activity relationships (SARs) of deep eutectic solvents (DESs) is crucial for upgrading their catalytic performance in targeted reactions. Herein, a series of Brønsted acidic DESs are developed for the SARs research at molecular and atomic levels. Experimental and theoretical results suggest that the catalytic activity increases with the decreasing distances between O atom of active sites in DESs and S atom in sulfur compounds, and the R2 between EODS efficiency and the valid distances of O···S is above 0.9. Such geometric configuration can be optimized by altering the composition of DESs, which in turn substantially triggers the reaction acceleration between active intermediates and substrates. The resulting DES (TEAC/2BSA) achieved deep desulfurization for various sulfur compounds based on the optimal valid distances of O···S. This work contributes to a deep understanding of the reaction mechanism and enables the effective screening of task-specific DESs.

Metal-based Ionic Liquids and Solid-loaded Catalysts in Fuel Oil Desulfurization: A Review

Abstract: Metal-based ionic liquids (MILs) have the advantages of designability, efficiency, stability, and regenerative cycle and can efficiently convert thiophene and its derivatives, which are important for the production of "ultra-low sulfur" oils. This paper provides an overview of the research progress of MILs in the field of fuel desulfurization, focusing on the current status of MILs and solid-loaded MILs catalysts in extractive desulfurization, oxidative desulfurization, extraction-catalyzed oxidative desulfurization, and catalytic-adsorption desulfurization processes. For MILs, the anion and cation can be altered by design so as to impart specific functions. Loading is one of the effective ways to solidify MILs, and the combination of MILs with different carriers can not only reduce the usage while ensuring the catalytic activity but also improve the reusability of the catalyst. The combination of MILs with specially structured carriers also allows solution-free adsorption and removal of oxidation products. Compared with conventional MILs, polymetallic-based ionic liquids (PMILs) exhibit ultrahigh catalytic activity and are one of the most promising materials available, but are still in their infancy in the field of fuel catalysis, and researchers are needed to enrich the gap in this field. Finally, some problems faced by various types of MILs are pointed out in order to design new functional MILs catalysts with better properties in the future and promote the further development of MILs in the field of fuel catalysis.

Development of silver dichromate-geopolymer composite: An innovative catalyst for simultaneous desulfurization and denitrogenation for cleaner petroleum fuel

Rising global energy demands necessitate cleaner fuel technologies due to stringent environmental regulations. Emerging techniques like oxidative desulfurization and denitrogenation offer advantages over traditional hydrotreatment, selectively oxidizing sulfur and nitrogen compounds without damaging hydrocarbon structures. This research employs nano-crystalline silver dichromate-geopolymer composites catalysts prepared by direct precipitation, sonochemical, surfactant-assisted and surfactant assisted sonochemical routes for oxidizing sulfur and nitrogen compounds in fuel oil. Surfactant assisted preparation aided in generating catalysts with controlled size, while sonochemical synthesis facilitated uniform dispersion of the particles. The uniform dispersion, controlled particle size, and low agglomeration along with unclogged pores aided the sonochemically prepared catalyst in demonstrating superior catalytic performance over other counterparts in individual sulfur oxidation tests. In contrast, due to the high rate of oxidation and high affinity to occupy active sites, the catalyst prepared by surfactant assisted sonochemical route performed better than its sonochemical counterpart in individual nitrogen compound oxidation tests. The prepared catalysts were thoroughly characterized by different analytical characterization techniques. Single component oxidation resulted in 80.86 and 98.94% conversion of sulfur and nitrogen, while simultaneous oxidation resulted in 58.41% sulfur oxidation and 95.69% nitrogen conversion. Due to the cavitation effect, efficient mixing and a high local temperature and pressure created due to the introduction of ultrasound, the conversion rose to 88.02 and 98.02% for sulfur and nitrogen, respectively. Post oxidation, the oxidation products were removed by extraction, leading to 100% removal of nitrogen and 85% removal of sulfur. The proposed mechanism suggested the oxidation of both the compounds to occur through the formation of active Cr(VI)-peroxo species.

Comb-grafted poly(vinyl phosphate)-based molybdovanadate heteropoly acid for efficient deep oxidative desulfurization using ionic liquid extractants under mild conditions

Comb-grafted poly(vinyl phosphate)-based molybdovanadate heteropoly acid for efficient deep oxidative desulfurization using ionic liquid extractants under mild conditions

Achieving Ultra-Low-Sulfur Model Diesel Through Defective Keggin-Type Heteropolyoxometalate Catalysts

Various Keggin-type heteropolyoxometalate catalysts with structural defects and surface acidity were synthesized by immobilizing 12-phosphotungstic acid (HPW) on mesoporous SBA−15, to produce near-zero-sulfur diesel fuel. As the calcination temperature increased, the W=O and the corner-shared W–O–W bonds in the Keggin unit partially broke, creating oxygen defects, as evidenced by the Rietveld refinement and in situ FTIR characterization. All the catalysts contained Lewis (L) and Brønsted (B) acid sites, with L acidity predominant. The relative intensity of the IR band (I980) of W=O bond inversely correlated with the number of L acid sites as the calcination temperature varied, suggesting that oxygen defects contributed to the Lewis acid sites formation. In the oxidation of dibenzothiophene (DBT) in a model diesel within a biphasic system, DBT conversion exceeded 99% under the optimal reaction conditions (reaction temperature 70 °C, reaction time 60 min, H2O2/sulfur molar ratio 8, H2O2/formic acid molar ratio 1.5, catalyst concentration 2 mg/mL). The influence of fuel composition and addition of indole and 4,6-DMDBT on DBT oxidation were also evaluated. Indole and cyclohexene negatively impacted the DBT oxidative removal. Oxygen defects served as active centers for competitive adsorption of sulfur compound and oxidant. Both L and B acid sites were involved in transferring O atom from peroxophosphotungstate complex to sulfur in DBT, resulting in DBTO2 sulfone, which was immediately extracted by polar acetonitrile. This study confirms that structural defects and surface acidity are crucial in the deep oxidative desulfurization (ODS) reaction, and in enabling the simultaneous oxidation and separation of refractory organosulfur compounds in a highly efficient model diesel.

Mesoporous Silica Supported Hydrophilic Ionic Liquid Gel Microspheres for Solvent-Free Deep Oxidative Desulfurization.

Solvent-free oxidative desulfurization can avoid environmental pollution caused by organic solvents as well as prevent loss of fuel during the oil-water separation process. In this work, first, hydrophilic ionic liquid gel microspheres with [BMIM]BF4 and PHEMA as the dispersion medium and gel network, respectively, were successfully prepared by using mesoporous silica microspheres as a supporting skeleton capable of stabilizing the gel through an anchoring effect, and then the catalyst [BMIM]PW and oxidant H2O2 were incorporated into the gel microspheres to construct a liquid compartment microreactor for deep desulfurization. The prepared microreactor (SiO2@[BMIM]PW/ILG-microspheres) has excellent extraction-catalytic capacity and exhibited ∼100% desulfurization ratio for a model oil of n-heptane with 500 ppm of DBT at 60 °C for 3 h without solvents. Additionally, the prepared microreactor can absorb hydrophilic desulfurization products after the reaction and has advantages of reusability and simple recovery without polluting the fuel oil, which is beneficial for potential petroleum industrial application.

Preparation and oxidative desulfurization performances of modified SBA-15 supported polyacid metal oxolates

In this study, eight composite catalysts were prepared by loading (CTAB)3H3[PW9V3O40] (active components) onto amino-functionalized mesoporous titanium silicate Ti-SBA-15(supports). In order to study the effects of different Ti contents and different active components on the catalytic performances of the catalysts, 30 %(CTAB)3H3[PW9V3O40]/NH2–Ti-SBA-X (X = 0, 25, 50, 75, 100) and X%(CTAB)3H3[PW9V3O40]/NH2–Ti-SBA-50 (X = 20, 40, 50) were obtained and characterized. The oxidative desulfurization performances of the composite catalysts were explored. It was found that catalyst 40 %(CTAB)3H3[PW9V3O40]/NH2–Ti-SBA-50 exhibits the optimal oxidative desulfurization performance. This is because the incorporation of SBA-15 with an appropriate amount of Ti (n(Si)/n(Ti) = 50) can improve the acidity and stability of mesoporous silica. The successful substitution of CTAB (n(CTAB)/n(H6PW9V3O40) = 3) in the active component can reduce the mass transfer resistance and speed up the reaction rate. 3-Aminopropyltriethyl silane (APTES) acts as a silane coupling agent to graft amino groups onto mesoporous molecular sieve SBA-15, which can enhance the interaction between heteropolyacids and carriers. Under the synergistic effect of the active component and the support, the total removal rate of the optimal catalyst with a total concentration of 1000 ppm sulfur compounds in the simulated fuel was 94.44 %. After four cycles, the total desulfurization rate of the catalyst can reach 91.28 %.

Sandwich structured Zn–W–Bi–O catalysts with low activation energy for highly effective oxidative desulfurization of oil

Sandwich structured Zn–W–Bi–O catalysts with low activation energy for highly effective oxidative desulfurization of oil

Synergistic Palladium Single Sites and Nanoparticles Implanted Into a Novel Zr‐Based Metal–Organic Framework via Solvent‐Free Processing for Upgrading Oxidative Desulfurization Performance

AbstractDesulfurization is a significant approach to producing clean fuel. The design of novel host–guest catalysts with multiple active sites at atomic‐ and nano‐scales, opens a new door to gain an ultrahigh synergistic performance for targeted applications. Herein, an in situ solvent‐free approach is conducted for synchronously implanting Pd single sites (PdSS) and nanoparticles (PdNP) into a novel Zr‐based metal–organic framework (Zr‐MOF). The optimal catalyst exhibits ultrahigh oxidative desulfurization (ODS) performance that can oxidize 1 000 ppm sulfur with diluted oxidant at 40 °C within 5 min. The turnover frequency of the catalyst at 40 °C reaches 774.7 h−1 which is 47.4 times higher than host Zr‐MOF and surpasses the most reported ODS catalysts. A substantial synergistic effect between PdSS and PdNP is responsible for the upgradation of ODS performance. Experimental and theoretical results indicate that PdSS in Zr‐MOF can readily absorb H2O2, and synergistically decompose H2O2 with the assistance of PdNP for accelerated generation of •OH radicals that dominates the ODS performance. This work provides a new solvent‐free way for in situ implanting synergistic catalytic sites into MOFs to upgrade their catalytic performance in targeted reactions.

Metabolism and disposition of zamicastat in rats

The metabolism and disposition of zamicastat, a reversible dopamine β-hydroxylase (DβH) inhibitor, developed for treatment of Pulmonary Arterial Hypertension (PAH), were investigated in rats after oral and intravenous administration of [14C]-zamicastat. Zamicastat was rapidly absorbed and widely distributed to peripheral tissues, with total radioactivity almost completely recovered 168 h post-dose. Its main route of excretion was via faeces, whilst urine and expired air had minor roles. Maximum plasma concentration of zamicastat-related radioactivity occurred in the first hours, remaining quantifiable up to 144 h. The unchanged zamicastat plasma peak was 2 h post-dose and declined to low levels over 24 h. Zamicastat metabolism occurs largely during the first 8 h with only one metabolite identified in the latest time-point (96 h), the isocyanic acid/thiocyanic acid (tautomeric forms). Zamicastat metabolic pathway involved multiple reactions comprising desulphurisation, oxidative desulphurisation, N-debenzylation followed by further oxidation or N-acetylation, and the unexpected multistep metabolic pathway leading to isocyanic acid/thiocyanic acid.

Experimental and ANN modeling of kerosene fuel desulfurization using a manganese oxide-tin oxide catalyst

This research pioneered the use of a nanocatalyst composed of manganese oxide (MnO2) and stannic oxide (SnO2) to effectively remove dibenzothiophene (DBT) from kerosene fuel through the catalytic oxidative desulfurization (ODS) process, using hydrogen peroxide (H2O2) as the oxidant. Impregnating SnO2 with varying amounts of MnO2 was used to manufacture the catalyst. The oxidation experiment ran in a batch reactor with varying reaction times and temperatures to determine optimal conditions. High MnO2 dispersion over SnO2 was shown by catalyst characterization data. Under optimal operating parameters (catalyst type: 5 % MnO2/SnO2, reaction temperature: 75 °C, and reaction duration: 100 min), the results demonstrated a maximum DBT removal efficiency of 82.84 % from kerosene fuel. This research also provides the construction of Artificial Neural Network (ANN) model to simulate the upgrading of kerosene fuel via desulfurization process. There has been a growing trend toward the diversified use of ANN to represent steady state systems in chemical engineering. MATLAB's code was employed for matching the experimental data to the artificial neural network (ANN) model. The resulted data showed significant agreement between the experimental and predicted outcomes, with regression coefficients (R2) of 0.99902, 0.99986, and 0.99961 and mean square errors (MSE) of 0.266, 0.272, and 0.104 for 0 % MnO2/SnO2, 1 % MnO2/SnO2, and 5 % MnO2/SnO2 respectively. This interactive model provided a solid foundation for understanding the novel behavior of the oxidation process.

Enhancing oxidative desulfurization catalytic performance of metal–organic frameworks UiO-66 (Zr) by post-synthetic with the creation of active sites

It is being explored to utilize two types of Zr-based metal–organic frameworks, bimetallic V/Zr-UiO-66 and functionalized UiO-66 by Vanadium (Zr-UiO-66-V), as heterogeneous catalysts in oxidative desulfurization processes. The bimetallic MOFs’ inorganic nodes contain two distinct ions; compared to their monometallic counterparts, these MOFs have a synergistic impact and improved characteristics. Innovative bimetallic MOFs provide additional options for further customizing the attributes of MOFs, which have drawn significant interest for various applications. On the other hand, the functionalization of MOFs further enhances the MOFs’ catalytic activity where V ions replace H+ in the –OH group in the zirconium-based node. Compared to UiO-66 (Zr), these techniques may significantly improve the efficacy of oxidative desulfurization. For the synthesized V/Zr-UiO-66 and Zr-UiO-66-V, having essential properties such as surface area (1287, 1392 m2/gr), pore volume (0.89, 0.93 cm3/gr), removal of DBT in model oil could reach > 91.4 % and > 97.7 % within 2.5 h at 343 K, respectively, which is 1.41 and 1.5 times as much as for parent UiO-66 (Zr). Furthermore, the heterogeneous catalyst displayed excellent thermal and chemical stability, and the DBT conversion efficiency remained > 78.9 % after six recycling cycles. Performance improvement is primarily attributable to the incorporation of active V sites.

Sulfur oxidation of ferrate synthesized from sludge in the aspect of desulfurization: A parametric study

Abstract The emission of sulfur in the atmosphere poses a significant threat to human health and the environment. To address this issue, stringent regulations have been implemented to limit the sulfur content in diesel, and novel desulfurization technologies are being developed. One notable technology is oxidative desulfurization (ODS), which employs oxidants to transform sulfur compounds into their corresponding sulfones, which are relatively easier to recover. The application of high-shear mixing in ODS has been studied to increase sulfur-to-sulfone conversion by creating smaller droplets and reducing mass transfer resistance. This research investigates the application of potassium ferrate derived from drinking water treatment sludge (DWTS), in the mixing-assisted oxidative desulfurization (MAOD) of a dibenzothiophene (DBT) model fuel. Potassium ferrate was synthesized using the wet oxidation method. The study evaluated the effects of ferrate concentration (400 to 600 ppm), agitation speed (4,400 to 10,800 rpm), and temperature (40 to 60 °C) on the efficiency of DBT conversion. The results revealed that 493.2 ppm DBT conversion was achieved at 550 ppm Fe(VI) concentration, 7,600 rpm agitation speed, and 50 °C temperature. Notably, increasing Fe(VI) concentration, agitation speed, and temperature had significant effects on sulfur reduction. This study demonstrates the potential of using potassium ferrate derived from DWTS in MAOD for effective desulfurization and discusses insights into the effects of operating conditions to enhance desulfurization efficiency. Ultimately, the study contributes to the development of environmentally friendly and cost-effective desulfurization technologies.

Biomimetic supported polyoxometalate structures designed and its applications for the ultra-deep oxidative desulfurization of fuels

Inspired by the fact that human nose cilia can effectively contact with particles to prevent their entry into our body, this kind novel biomimetic structures are designed and synthesized to enable the loading efficiency between the polyoxometalate catalytic species (POMs) and the carrier, thereby improving their loading rate and promoting their catalytic performance. The mullite whiskers-uniformed cordierite (CMW) is used as a carrier to support POMs, in which mullite whiskers regarding as the cilia in our nose, this kind catalyst could not only overcome the shortcomings of simple POMs with low specific surface and easy to self-agglomerate, but also could greatly increase their contact probability with the carrier. At the same time, the advantage of the cordierite block structure also greatly conducive to their actual application value on the reusing operation. A series of Keggin-type POM-loaded bulk materials, POM@CMW, [VimAm]Br@POM@CMW, [DVim]Br@POM@CMW, have been developed with various ionic liquid-based POMs (ionic liquid = ILs, chosen these two kinds of [VimAm]Br and [DVim]Br) to a comparative study. The oxidative desulfurization reaction (ODS) for fuels was performed using the obtained materials as catalysts and H2O2 as oxidant, without the additional extractants for the existing of ILs in catalyst. Through experimental evaluations, [DVim]Br@POM@CMW was found the excellent efficiency on the Sulfur removal, with an DBT removal of 96.34 % at 70 °C for 120 min. According to the FT-IR and SEM results after the reaction, the catalyst could retain their original structure and the dibenzothiophene (DBT) removal could still be maintained above 95 % after 7 reuses. Furthermore, the oxidation reactivity of different substrates was in the following order: DBT > 4,6-dimethyldibenzothiophene (4,6-DMDBT) > thiophene (BT) and the high activity in actual diesel oil could be also exhibited. The enhanced reaction activity, excellent structural stability, and recyclability can be attributed to the abundance of active sites and outstanding mechanical properties provided by cordierite/mullite whiskers as a carrier, indicating their potential in the novel biomimetic-structured POMs-loaded catalysts.

Synergistic Influence of Non-Thermal Plasma and Hydrogen Peroxide on Oxidative Desulfurization (ODS) of Model Fuel

تتضمن إزالة الكبريت إزالة مركبات الكبريت العضوية من زيوت الوقود. في هذه الدراسة، تم استخدام تقنية البلازما اللاحرارية وتقنية البلازما بمساعدة بيروكسيد الهيدروجين لاكسدة الوقود المحتوي على مركبات من benzothiophene و dibenzothiophene. تم إجراء تفاعل الأكسدة باستخدام منظومة dielectric barrier discharge لتوليد بلازما غير حرارية. النتائج أظهرت ان تقنية البلازما ومزيج من البلازما مع بيروكسيد الهيدروجين معًا لأكسدة BT و DBT. تتبعان pseudo-first-order reaction وأن كفاءة الإزالة للبلازما 93.78٪ مقارنة مع مزيج البلازما وبيروكسيد الهيدروجين معًا والتي بلغت 95.12٪. هذا الاختلاف في الكفاءة لا يشكل فارقا اذا ما اخذ بنظر الاعتبار الناحية الاقتصادية (استهلاك المواد الكيميائية) ، حيث يمكن الاكتفاء بتقنية البلازما.