Fuel Processing Technology (v.114, #C)
Editorial Board (IFC).
Beneficial effects of polycyclic aromatics on oxidative desulfurization of light cycle oil over phosphotungstic acid (PTA) catalyst by Gwang-Nam Yun; Yong-Kul Lee (1-5).
The amphiphilic phosphotungstic acid catalyst (A-PTA) was prepared with quaternary ammonium salt to apply for the oxidative desulfurization (ODS) of light cycle oil (LCO), resulting in high activity of the ODS conversion of 95%, at H2O2/S ratio of 10 and 353 K. The model reaction tests for the ODS of refractory sulfur compounds in n-octane demonstrated that the addition of indole drastically reduced overall ODS conversion, while the introduction of 1-methylnaphthalene fully recovered the ODS activity, which were attributed to the high solubility of the oxidized S or N compounds in the 2-ring aromatics.Display Omitted
Keywords: Light cycle oil; Phosphotungstic acid; Oxidative desulfurization; 2-ring aromatics;
Thermal behavior of renewable diesel from sugar cane, biodiesel, fossil diesel and their blends by Charles C. Conconi; Paula Manoel Crnkovic (6-11).
Biofuels and their blends with fossil fuel are important energy resources, whose production and application have been largely increased internationally. This study focuses on the evaluation of the activation energy of the thermal decomposition of three pure fuels: farnesane (renewable diesel from sugar cane), biodiesel and fossil diesel and their blends (20% farnesene and 80% of fossil diesel — 20F80D and 20% farnesane, 50% fossil diesel and 30% biodiesel — 20F50D30B). Activation energy has been determined from thermogravimetry and Model-Free Kinetics. Results showed that not only the cetane number is important to understand the behavior of the fuels regarding ignition delay, but also the profile of the activation energy versus conversion curves shows that the chemical reactions are responsible for the performance at the beginning of the process. In addition, activation energy seemed to be suitable in describing reactivity in the case of blends of renewable and fossil fuels.
Keywords: Biofuels; Activation energy; Ignition delay; Thermogravimetry;
Single-step esterification of crude karanj (Pongamia pinnata) oil to fatty acid methyl esters over mesostructured SBA-16 supported 12-molybdophosphoric acid catalyst by M.S. Khayoon; B.H. Hameed (12-20).
Fatty acid methyl esters (FAME) are synthesized via the single step esterification of non-edible feedstock, crude karanj oil (CKO), of high level of free fatty acids (FFAs about 20%) with methanol over series of solid acid catalysts prepared by anchoring molybdophosphoric acid (MP, 5 to 25 wt.%) onto SBA-16 support. The prepared catalysts were intensively characterized for their intrinsic physicochemical and textural properties using BET surface area, NH3-TPD, XRD, SAXS, FT-IR, SEM and EDX. Characterization results revealed that the intact MP Keggin structure was preserved in the final catalyst after the thermal treatment at 220 °C. The catalyst with 15 wt.% MP (MP-S-16(15)) exhibited a peerless catalytic activity achieving 82% of FAME yield using a molar ratio of methanol to CKO of 1:8 at 140 °C and after 5 h. The effect of different operational parameters such as MP concentration in the final catalysts, reaction temperature, molar ratio of methanol to CKO, catalyst wt.% and reaction time were investigated over the MP-S-16(15) catalyst toward the maximum FAME yield. The stability of the catalytic activity was examined through leaching and reusability tests. As such, the MP-S-16(15) catalyst was recycled through four consecutive batch runs to understand its stability.
Keywords: SBA-16; Biodiesel; Karanj oil; FAME; TOF;
V–Ni–Mo sulfide supported on Al2O3: Preparation, characterization and LCO hydrotreating by Paulino Betancourt; Santiago Marrero; Susana Pinto-Castilla (21-25).
The effect of vanadium incorporation on the HDS, HDN, and HDA activities of LCO hydrotreating was investigated on NiMo supported hydrotreating catalysts. The catalysts were characterized by XRD, BET, XPS, NO-chemisorption and evaluated in fixed bed reactor using real LCO as feed. The vanadium promoted NiMo catalyst presented higher HDS and HDN activities, and surprisingly a relatively low activity toward the HDA. This behavior is probably due to a vanadium-mixed active phase, this has superior conversion as compared to NiMo catalyst.Display Omitted
Keywords: Hydrotreating; Light cycle oil; Nickel–molybdenum sulfides; Vanadium sulfide;
An experimental investigation of effect on diesel engine performance and exhaust emissions of addition at dual fuel mode of hydrogen by H. Köse; M. Ciniviz (26-34).
Internal combustion engines are an indispensable part of our daily life, especially in transportation and agriculture sectors. However, the reduction of petroleum resources and environmental problems are leading to an increasing trend towards alternative energy sources. In this regard, hydrogen usage is expected to be a solution for previously mentioned problems as one of the renewable energy resources. In this concept, effects of hydrogen as an additional fuel used in a compression ignition engine performance and exhaust emissions parameters different engine speeds were investigated at full load. For this purpose, a compression ignition engine (CI) with 17/1 compression ratio, four cylinders, four stroke, turbocharger and 3.908 liters engine volume was used. While diesel fuel was injected directly to combustion chamber, hydrogen was added to inlet manifold at rates of 2.5%, 5% and 7.5% as volume.As a result, an increase in engine torque, power, thermal efficiency, nitrogen oxides (NOx) and exhaust gasses temperatures were acquired at every hydrogen addition ratio while a decrease in hydrocarbons (HC), carbon monoxide (CO) and oxygen (O2) emissions were attained. While engine torque exhibited an increase at a rate of 8.3% comparing with standard diesel operation at 1250 min− 1 and 7.5% hydrogen addition ratio, engine power increased 17% at 2250 min− 1 engine speed and 7.5% hydrogen addition ratio. Brake thermal efficiency of 2.5% was obtained as 40.4% comparing with 33% value of SDI at 1750 min− 1. The lowest CO, CO2, HC and NOx emission values were obtained at 2250 min− 1 engine speed and 2.5% hydrogen addition ratio as 0.013; 2500 min− 1 engine speed and 7.5% hydrogen addition ratio as 7.4%; 1250 min− 1 engine speed and 2.5% hydrogen addition ratio as 10 ppm and 1000 min− 1 engine speed and 7.5% hydrogen addition ratio as 1092 ppm respectively comparing with standard diesel operation.
Keywords: Alternative energy resource; Compression ignition engine; Exhaust emission; Hydrogen dual fuel;
Technoeconomic assessment of potential processes for bio-ethylene production by P. Haro; P. Ollero; F. Trippe (35-48).
The use of biomass in the production of plastics can contribute to the depletion of greenhouse gas (GHG) emissions and secondarily to partially fulfill the growing demand for plastics expected in the near future. The aim of this study is to assess the production of ethylene, one of the most important commodities in the petrochemical industry, via the dehydration of bioethanol and the conversion of bio-dimethyl ether (bio-DME) into olefins. Four case studies have been developed taking into account the different origins of bioethanol, and one for the conversion of bio-DME. The assessment includes current and promising processes for the production of bioethanol, i.e., 1st generation and 2nd generation bioethanol. The latter comprises biochemical processing (enzymatic hydrolysis), thermochemical processing (both direct and indirect syntheses from syngas) and hybrid processing (fermentation of syngas) of biomass. The results show that two of the considered case studies (Brazilian ethanol and ethanol via indirect synthesis from syngas) enable the cost-competitive production of ethylene at current market prices. If BECCS (Bioenergy with Carbon Capture and Storage) is taken into account for the case studies, the results would be substantially enhanced and all cases, except for the case of bioethanol from biochemical processing, would be profitable.
Keywords: Ethylene; Biomass; 1st generation bioethanol; 2nd generation bioethanol; Thermochemical processing; Technoeconomic assessment;
Process development and simulation of glycerol-free biofuel from canola oil and dimethyl carbonate by Yogesh M. Kurle; Mohammad R. Islam; Tracy J. Benson (49-57).
Biofuels, especially biodiesel, have become commonplace over the last couple of decades. The conventional transesterification process used for biodiesel production leaves manufacturers with a byproduct, glycerol, that is of low value. Dimethyl carbonate has been studied as an alternate methylating agent to methanol and alters the chemistry such that glycerol is not formed. Triazabicyclodecene was chosen as the catalyst due to its ability to easily ionize the dimethyl carbonate and ease of separation post reaction.This paper reports on the development of specific processing steps to convert canola oil to FAMEs and fatty acid glycerol carbonate (FAGCs) compounds. The process flow diagram was developed using Aspen Plus simulation software and verified through laboratory testing. Process conditions were adjusted until a glycerol-free biofuel was produced that meets the ASTM D6751 standard for biodiesel. By utilizing the glycerol moiety within the final product, about 9.7% increase (by mass) of biofuel was obtained compared to the traditional methanol synthesis route. Glycerol carbonate and glycerol dicarbonate were formed as byproducts but were in low concentrations. These results reveal the potential of using dimethyl carbonate as a replacement for methanol to produce an acceptable, more environmentally friendly biofuel.
Keywords: Biodiesel; Glycerol; Dimethyl carbonate; Biofuel; Canola oil; Renewable energy;
Particulate emissions from the co-combustion of forest biomass and sewage sludge in a bubbling fluidised bed reactor by A.I. Calvo; L.A.C. Tarelho; E.R. Teixeira; C. Alves; T. Nunes; M. Duarte; E. Coz; D. Custodio; A. Castro; B. Artiñano; R. Fraile (58-68).
In the present study, particulate emissions from the co-combustion of forest biomass residues with sewage sludge in a pilot-scale bubbling fluidised bed combustor were characterised. The combustion flue gas was exhausted to the atmosphere after passing through a cyclone separator. Physical–chemical characteristics of the particles were studied: i) morphology and aerosol size, surface and volume distributions before the cyclone and ii) chemical composition (carbonates, water soluble-inorganic ions, organic and elemental carbon) before and after the cyclone. Chemical composition data were used to calculate aerosol density and refractive index. Aerosols showed a unimodal size distribution with a geometric mean diameter of 2.25 ± 0.02 μm and a geometric standard deviation of 1.27 ± 0.01. The surface and volume mean diameters were 2.64 ± 0.02 μm and 2.91 ± 0.05 μm, respectively. Water-soluble inorganic ions were predominant in the fine particle fraction (PM2.5). The filters were loaded of crystallised mineral particles. The analysis revealed a dominance of calcium carbonate/oxide and halide (NaCl or KCl), sulphate and aluminosilicate nanocrystals forming larger mixed aggregates.
Keywords: Aerosol; Biomass; Co-combustion; Fluidised bed; Sewage sludge;
Influence of pore distribution on catalytic performance over inverse CeO2/Co3O4 catalysts for CH4/CO2 reforming by Shanghong Zeng; Xiaojuan Fu; Tiezhuang Zhou; Xiaoman Wang; Haiquan Su (69-74).
A series of inverse CeO2/Co3O4 catalysts with different Ce loading was prepared via the hydrothermal process and microemulsion method, and characterized by XRD, BET, H2-TPR and TGA–DSC techniques. The catalysts exhibited high activity and moderate H2 and CO selectivity for CH4/CO2 reforming under atmospheric pressure and 750 °C. The results showed that the CeO2/Co3O4 catalysts with double pore distribution could provide more active sites as well as better gas circulation channels, which could reduce the internal diffusion resistance and improve the catalytic performance for CH4/CO2 reforming.The curves of CeO2/Co3O4 (1:1) and CeO2/Co3O4 (1:2) catalysts were single pore distribution (Fig. 3A), and the wide pore size was favorable for the gas diffusion. The curves of catalysts became double pore distribution when the Ce/Co molar ratio varying from 1:3 to 1:6 (Fig. 3B). The micropores could provide the more active sites, and the mesopores could offer the gas diffusion channels from the particle surface to the interior . Further decreasing the Ce/Co molar ratio to 1:8, the interaction between CeO2 and Co3O4 became weaker in compare with the other catalysts.Display Omitted
Keywords: CeO2/Co3O4; Molar ratio; Double pore distribution; CH4/CO2 reforming;
Improved reactivity of large coal particles by K2CO3 addition during steam gasification by Sansha Coetzee; Hein W.J.P. Neomagus; John R. Bunt; Raymond C. Everson (75-80).
In this study, the excess solution impregnation method was used to impregnate large coal particles (5 and 10 mm) with K2CO3, and the effect of the additive on steam gasification reactivity was investigated. A washed bituminous, medium rank-C Highveld coal, with an ash content of 12.6 wt.% (air-dried basis), was used for experimentation. The excess solution method was used to impregnate coal particles with the selected additive, K2CO3, and results from XRF analysis indicated that the potassium loading increased from 0.05 wt.% (raw coal) up to 0.83 wt.% (impregnated coal), on a coal basis. The potassium-impregnated large coal particles were used for low temperature (800–875 °C) steam gasification experiments. Results obtained for the reactivity of the parent coal were compared to that of the impregnated coal, which indicated that the addition of K2CO3 increased the reaction rate of large coal particles by up to 40%. It was also found that the addition of K2CO3 decreased the activation energy, from 191 kJ/mol (raw coal) to 179 kJ/mol (impregnated coal).
Keywords: Potassium carbonate; Large coal particles; Impregnation; Catalytic steam gasification;
Adsorption of SOx by oxide materials: A review by Yannick Mathieu; Lydie Tzanis; Michel Soulard; Joël Patarin; Matthieu Vierling; Michel Molière (81-100).
This paper is an attempt to provide a review — as extensive as feasible — of the literature devoted to the wide variety of sorbent systems that are currently either in use or under laboratory investigation for the removal of the SOx (SO2 + SO3) from flue gases. From an industrial perspective and besides any economic consideration, “the ideal” SOx sorbent candidate must ally four essential qualities some of which may appear contradictory to some extent: a strong affinity of the sorbent towards SOx along with fast kinetics; a large specific surface; a high physical/thermal/chemical stability and the capability for multiple regenerations at a reasonable temperature and with performance recoveries close to 100%.In this paper, the sorbent are classified in four categories which are: (i) single oxides; (ii) mixed oxides (including spinels and alumina supported oxides); (iii) oxides supported on carbonaceous materials and (iv) oxides supported on zeolites and mesoporous materials. A noteworthy outcome of this review lies in the promising prospects offered by porous silica-based materials as desulfurization (“DeSOx”) candidates and the interest of elaborating in this direction.
Keywords: SO2 adsorption; Single oxides; CuO/γ-Al2O3; Zeolites; Carbonaceous materials; Regeneration;
Optimization of base-catalyzed ethanolysis of sunflower oil by regression and artificial neural network models by Olivera S. Stamenković; Katarina Rajković; Ana V. Veličković; Petar S. Milić; Vlada B. Veljković (101-108).
The present work combines a 34 full factorial design with two replications with both a second-order polynomial equation and an ANN model for the case of the sunflower oil ethanolysis reaction catalyzed by sodium hydroxide. RSM and ANN models were developed and compared for their predictive, generalization and optimization abilities. The results obtained showed that both models work well, but the MRPD values for RSM and ANN models of ± 3.1% and ± 0.6%, respectively, indicated the superiority of the latter in capturing the nonlinear behavior of the system. These results show that the ANN is a better choice over the least squares method from modeling prospective. However, having the ability of sensitivity analysis and optimization, the RSM model has advantages over the ANN model. The effects of individual process variables and their interactions are obvious from the coded regression equation, while the ANN is a black box model that does not give directly such an insight into the ethanolysis reaction system. A maximum predicted value of FAEE content of 98.9% was found by the RSM model under the following optimum reaction conditions: reaction temperature between 50 and 59 °C, ethanol-to-oil molar ratio of 12:1, catalyst loading of 0.75% (based on the oil weight) and reaction time of 15 min, which absolutely agree with the experimental value (98.6%).
Keywords: ANN modeling; Biodiesel; Ethanolysis; Optimization; RSM modeling;
Flue gas cleanup using the Moving-Bed Copper Oxide Process by Henry W. Pennline; James S. Hoffman (109-117).
The use of copper oxide on a support had been envisioned as a gas cleanup technique to remove sulfur dioxide (SO2) and nitric oxides (NOx) from flue gas produced by the combustion of coal for electric power generation. In general, dry, regenerable flue gas cleanup techniques that use a sorbent can have various advantages, such as simultaneous removal of pollutants, production of a salable by-product, and low costs when compared to commercially available wet scrubbing technology. Due to the temperature of reaction, the placement of the process into an advanced power system could actually increase the thermal efficiency of the plant. The Moving-Bed Copper Oxide Process is capable of simultaneously removing sulfur oxides and nitric oxides within the reactor system. In this regenerable sorbent technique, the use of the copper oxide sorbent was originally in a fluidized bed, but the more recent effort developed the use of the sorbent in a moving-bed reactor design. A pilot facility or life-cycle test system was constructed so that an integrated testing of the sorbent over absorption/regeneration cycles could be conducted. A parametric study of the total process was then performed where all process steps, including absorption and regeneration, were continuously operated and experimentally evaluated. The parametric effects, including absorption temperature, sorbent and gas residence times, inlet SO2 and NOx concentration, and flyash loadings, on removal efficiencies and overall operational performance were determined. Although some of the research results have not been previously published because of previous collaborative restrictions, a summary of these past findings is presented in this communication. Additionally, the potential use of the process for criteria pollutant removal in oxy-firing of fossil fuel for carbon sequestration purposes is discussed.
Keywords: Flue gas cleanup; Copper oxide sorbent; Desulfurization; Oxy-firing;
Catalytic decomposition of toluene using a biomass derived catalyst by Sudhagar Mani; James R. Kastner; Ankita Juneja (118-125).
Pine bark biochar generated by slow pyrolysis (950 °C) was used as a low cost catalyst to decompose toluene (model tar compound) over a temperature range of 600–900 °C. Relative to thermal cracking, fractional toluene conversion increased from 13 to 94% when increasing temperatures from 600 to 900 °C (2500 ppmv, SV = 0.76 s− 1, 3.8 g catalyst) and Arrhenius analysis indicated an activation energy of 91 kJ/mol, comparable to that of synthetic catalysts (e.g., 80.24 kJ/mol for Ni/Mayenite and 196 kJ/mol for olivine) and lower than that of thermal cracking (356 kJ/mol). The reaction rate for toluene decomposition increased linearly from 550 to 700 °C with a concentration range of 1000–4600 ppmv indicating a first order rate law with respect to toluene. Benzene was detected as a potential intermediate in the decomposition of toluene with selectivity ranging from 0 to 28% at temperatures from 600 to 900 °C respectively, and its formation increased with increasing toluene conversion. Toluene conversion ranged between 40 and 95% with benzene selectivity from 0 to 20% at 800 °C during catalyst longevity studies of 6 days. These results indicate that biochar generated from slow pyrolysis of pine bark at high temperature can be used as a low cost catalyst for tar removal from syngas. However, the tar removal rates using the biochar catalyst were lower than that of olivine and nickel based catalysts indicating the need to increase catalytic activity.
Keywords: Biochar; Pine bark; Toluene; Tar; Catalyst; Kinetics;
CFD modeling of ash deposition for co-combustion of MBM with coal in a tangentially fired utility boiler by Taha J. Taha; Arthur F. Stam; Kurt Stam; Gerrit Brem (126-134).
Ash deposition is one of the main challenges that needs to be tackled in response to increased percentage of biomass co-firing in pulverized fuel boilers. In this study, a model has been developed to investigate the slagging behavior of meat and bone meal (MBM) at higher co-firing rates in the Maasvlakte boiler operated by E.ON Benelux. The model includes the combustion of solid fuels in a tangentially fired boiler and post-processing of ash deposition on the heat exchange surfaces. The deposition tendency of the impacting ash particles is predicted on the basis of ash viscosity, which is calculated with the Urbain viscosity model. Thermodynamic equilibrium is used to calculate the various fuel ash properties for both oxidizing and reducing conditions. On the basis of the thermal heat input, solid fuel combustion is modeled and evaluated for various co-firing rates which consists of 0%, 12.5%, 25% and 40% of MBM. The calculation results show that the deposition propensity is the highest for a co-firing ratio of 25% MBM. The preferred deposition locations in the boiler calculated by the CFD model are in line with observations in operational practice.
Keywords: Slagging; Biomass; Co-firing; MBM; CFD; Coal;
Natural resins and their application in antifouling fuel technology by Constantinos G. Tsanaktsidis; Evangelos P. Favvas; Athanasios A. Scaltsoyiannes; Stavros G. Christidis; Elissavet X. Katsidi; Apostolos V. Scaltsoyiannes (135-143).
A simple method is proposed for the improvement of diesel fuel properties without the addition of surfactants, chemicals or other pollutants components. Natural resin, a natural product from Pinus halepensis trees was used in order to remove water residues from diesel fuels. A simple but highly effective method was used in order to improve the physicochemical properties of commercial diesel fuels. The main idea is based on the property of the resin to adsorb water, especially when the water amount is dissolved into hydrocarbon fluids. This phenomenon was investigated as a resin concentration effecting into diesel fuel samples as well as a process of the mixing time. To this end different mass of resin was mixed with diesel fuel and after several times of blending process the main physicochemical properties were measured and compared with those of the raw diesel fuel. Specifically, the density, the kinematic viscosity, the conductivity, the humidity, the flash point and the heat of combustion were measured according to the ASTM standard protocols. This water removal improved the physicochemical properties of diesel fuel, up to 633 J/g for the heat of combustion, 69% for humidity and up to 74% for conductivity. In addition the humidity adsorption phenomenon was confirmable by water adsorption isotherm at 293 K as well as by using independent techniques such as FTIR, DSC and TGA. Overall, the proposed method can be used in a simple fuel cleaning process.Display Omitted
Keywords: Resin; Diesel fuel; Natural products; Water removal; Heat of combustion; Antifouling fuel technology;
Rheological, structural and chemical evolution of bitumen under gamma irradiation by M. Mouazen; A. Poulesquen; F. Bart; J. Masson; M. Charlot; B. Vergnes (144-153).
Bitumen derived from crude oil by fractional distillation has been used in the nuclear industry as a radioactive waste encapsulation matrix. When subjected to α, β and γ self-irradiation, this organic matrix undergoes radiolysis, generating hydrogen bubbles and modifying the physical and chemical properties of the material. In this paper, the effects of irradiation on bitumen materials, especially in terms of its physical, chemical, structural and rheological properties, were characterized at radiation doses ranging from 1 to 7 MGy. An increase in the shear viscosity and melt yield stress was observed with increasing doses. Similarly, the elastic and viscous moduli (G′ and G″) increase with the dose, with a more pronounced increase for G′ that reflects enhanced elasticity arising from radiation-induced cross-linking. In addition, a low-frequency plateau is observed for G′, reflecting pseudo-solid behavior and leading to an increase of the complex viscosity. This behavior is due to increased interactions between asphaltene particles, and to aromatization of the bitumen by γ-radiations. Cross-linking of bitumen enhances its strength, as confirmed by various techniques (modulated DSC, DTA/TGA, SEC, FTIR and XRD).
Keywords: Bitumen; Rheology; γ-Radiations; Chemical evolution; FTIR;
Transesterification of canola oil catalyzed by nanopowder calcium oxide by Lina Zhao; Zheyan Qiu; Susan M. Stagg-Williams (154-162).
Two types of commercial nanopowder calcium oxides, a higher surface area (HSA nano-CaO) and moderate surface area (nano-CaO) were studied for the transesterification of canola oil. The effect of reaction temperature, catalyst/oil weight ratio, and methanol/oil molar ratio on the reaction performance was investigated. The results show that nanopowder CaOs possess high activity due to their larger BET surface areas. At 65 °C, 99.85% biodiesel yield was obtained at 2 h when 3 wt.% of the nano-CaO catalyst was used with 9:1 methanol/oil molar ratio. The required catalyst/oil weight ratio to achieve the same yield under the same conditions was 10 times less for the HSA-nano-CaO catalyst. In contrast, only 88.59% and 16.23% yield were obtained for calcium methoxide (Ca(OCH3)2) and laboratory-grade CaO, respectively. A Langmuir–Hinshelwood model-based reaction mechanism was proposed for nano-CaO catalyzed transesterification reaction. The reaction was assumed to be first order with respect to triglyceride. The apparent reaction constants, apparent activation energy and pre-exponential factors have been calculated based on experimental data. Nanopowder CaOs were capable of being used without significant deactivation for 10 cycles. A slight drop in activity was ascribed to a combination of surface area loss from particle aggregation, the formation of Ca(OCH3)2, CaCO3, a Ca-glycerin complex, and adsorbed CO2 on the catalyst surface. Particle size did not have any effect on the amount of Ca leaching but leaching did increase with longer reaction time especially at higher catalyst loadings. Increasing the methanol/oil molar ratio increased Ca leaching in the glycerol-rich phase and decreased Ca leaching in the biodiesel-rich phase.
Keywords: Transesterification; Biodiesel; Catalyst; Nanopowder calcium oxide; Kinetics;