Evaluation of the CH4/CO2 separation by adsorption on coconut shell activated carbon: Impact of the gas moisture on equilibrium selectivity and adsorption capacity.

Upgrading biogas to biomethane is of great interest to change the energy matrix by feeding the renewable fuel produced from biomass waste into natural gas grids or directly using it to replace fossil fuels. The study aimed to assess the adsorption equilibrium of CH4, CO2, and H2O on a coconut-shell activated carbon (CAC 8X30) to provide data for further studies on its efficiency in upgrading biogas by Pressure Swing Adsorption (PSA). The adsorbent was characterized, and equilibrium parameters were estimated from monocomponent CH4, CO2, and H2O equilibrium isotherms. Binary and ternary equilibrium isotherms were simulated, and the selectivity and adsorption capacity of the CAC 8X30 were calculated in dry and wet conditions and then compared with zeolite 13X as a reference material. Regarding characterization, Nitrogen and Hydrogen Physisorption results indicated that 94 % of the pore volume is concentrated in the region of micropores. The adsorption affinity with CAC 8X30 estimated from monocomponent isotherms was in the order KH20>KCO2>KCH4. IAST-Langmuir model simulations presented good agreement with experimental binary equilibrium data. Further simulations indicated equilibrium selectivity for CO2 over CH4 (e.g., 4.7 at 1 bar and 298 K for a mixture of CH4/CO2, 60/40 vol%), which increased in the presence of moisture, indicating its suitability for upgrading humid biogas. Simulations for zeolite 13X suggested that the material is unsuitable in the presence of water vapor but presents higher selectivity than the CAC 8X30 in dry conditions. Hence, the integration of both materials might be helpful for biogas upgrading.

Green synthesis of silver nanoparticles with Euphorbia tirucalli extract and its protection against microbial decay of strawberries during storage.

Silver nanoparticles (AgNPs) can be produced through an easy and safe process called green synthesis and have been considered an efficient antimicrobial agent. The antimicrobial effect of silver nanoparticles green synthesized with E. tirucalli (aveloz) can be a promising technique for preserving stored strawberries. The objective of this work was to perform a green synthesis of AgNPs with aveloz extract (Av) and evaluate its effect on the physiology and preservation of stored strawberries. Silver nitrate was reduced with Av to produce Av-AgNPs. The Av-AgNPs were characterized by Scanning Electron Microscope, Energy Dispersive X-ray Spectrometry, and laser diffraction. The in vitro antifungal activity of Av-AgNPs was evaluated against Botrytis cinerea and Rhizopus stolonifer. Strawberries were treated with Av-AgNPs and stored (5 °C) for 12 days. Respiratory rate, decay, fresh mass loss, firmness, total phenolics and antioxidant activity of the strawberries were evaluated. According to the results, Av-AgNPs synthesis was performed, and it presented sizes between 40 and 90 nm. Av-AgNPs inhibited B. cinerea but was less effective for R. stolonifer. Total phenolic compounds, antioxidant activity, fresh mass loss and firmness of strawberries were not influenced by Av-AgNPs. Treated strawberries had a lower respiratory rate than the control and showed no symptoms of microbiological deterioration until 9 days of storage, while in the control the deterioration symptoms started after 3 days. This study showed that the green synthesis of AgNPs with Av produced nanoparticles smaller than 100 nm, and that they were effective against strawberries decay during storage, indicating to be a promising protection technique against decay.

Valorization of poultry slaughterhouse sludge oil: a strategy to reduce Brazil's dependency on soybean oil in the biodiesel industry.

During the poultry industrialization process the so-called sludge oil, a residual chicken fat, is recovered in the wastewater treatment plant and its use presents potential as raw material for biodiesel production. Thus, the aim of the study was to prepare blends of sludge oil with soybean oil to obtain fatty acid methyl esters (FAME) through the homogeneous alkaline transesterification reaction. To perform this study, a simple pre-treatment process - heating and subsequent filtration - was used, allowing sludge oil to be mixed with soybean oil to compose blends, without the need to use more sophisticated pre-treatment processes. After this step, blends ranging from 5% to 90% (m/m) of sludge oil mixed with soybean oil were prepared. The results showed that the molar ratio (1:6 oil blend:methanol), catalyst concentration 0.5% NaOH (mcat/moil), at 65 °C for 60 min yielded FAME above 99.0 and 90.0% (m/m) for blends with up to 5 and 15% sludge oil, respectively. By increasing the temperature to 70 °C, under the same selected parameters, the blend with 10% sludge oil provided yield above 99.0% (m/m), presenting appropriate physicochemical properties, within the parameters required by National Agency of Petroleum, Natural Gas and Biofuels (ANP). These findings show the great potential sludge oil provides to reduce Brazil's dependency on soybean oil for biodiesel production.Highlights Sludge oil, a waste raw material for biodiesel production, is not yet explored in Brazil.A procedure for biodiesel production using soybean oil and sludge oil blends was proposed.The best reaction condition was 1:6 oil blend:MeOH molar ratio; 0.5% NaOH (mcat/moil), at 70 °C for 60 min.Biodiesel yield was higher than 99% (m/m) under optimal reaction conditions.Sludge oil represents a promising waste raw material for biodiesel production.

Alternative methods for the pilot-scale production and characterization of chitosan nanoparticles.

This work describes the production/characterization of low molar mass chitosan nanoparticles derived from waste shrimp shells (SSC), as well as from a commercial chitosan (CC). The production of low molar mass nanochitosan employed thermal shock, alternating between 100 °C and ambient temperature, followed by grinding the dry material (SSC and CC) in a ball mill, producing around 500 g of nanochitosan per batch. A highlight of the methodology employed is that it enables nanochitosan to be obtained even from a low quality commercial raw material. All particles had diameters smaller than 223 nm, with an average diameter below 25 nm (determined by DLS), while reductions of molar mass were between 8.4-fold and 13.5-fold. The depolymerization process resulted in a reduction in crystallinity of 38.1 to 25.4% and 55.6 to 25.9% in the CC and SSC samples, respectively. The production of nanochitosans was also confirmed by TEM through the observation of crystalline domains with diameters between 5 and 10 nm. This work perfectly reproduces the results on bench scale from previous research. The simple and inexpensive processes enable easy scale-up, representing an important advance in the production chain of biopolymers. Graphical abstract.

High performance on the moisture reduction in waste oils by a bentonite-based adsorption process.

In this work, the reduction of the moisture content from waste oils by a bentonite-based adsorption process was investigated as an alternative for reuse in energy production. Waste cooking oil (WCO) and waste poultry fat (WPF) were characterised (moisture and viscosity, values of acidity, saponification, and peroxide), as well as bentonite clay adsorbent. The response surface methodology (RSM) was applied to define the best moisture adsorption condition by bentonite-based adsorbent regarding a full factorial experimental design (FFED). In the framework of RSM, the adsorbent mass, oil acidity, and agitation speed were varied in three levels in the range of 1.5-3.0 g, 1-38 mgKOH goil-1, and 50-150 rpm, respectively, while the adsorption time was fixed in 24 h. Under the best moisture adsorption condition, kinetic tests were performed in a 1-24 h contact time range, besides performing equilibrium adsorption tests at 5 h contact time. Around 90% moisture removal was attained with 1.5 g adsorbent, acidity value of 1 mgKOH goil-1, and 50 rpm agitation speed, achieving the equilibrium in 5 h. A multilayer adsorption process, as described by the BET isotherm model, was acting in dried bentonite clay, allowing getting excellent moisture adsorption capacity (∼200 mgwater gBent-1). Therefore, moisture removal from waste oils by a bentonite clay-based adsorption process has provided results that are suitable and recommendable for economically viable biodiesel production.

Two-Stage anaerobic digestion in agroindustrial waste treatment: A review.

The anaerobic digestion is a process widely recognized as an interesting alternative for the treatment and stabilization of residual organic substrates. However, several technical limitations were observed based on the characteristics of the organic matter submitted to the process, such as the presence of high concentrations of soluble sugars or fats. The technology of anaerobic digestion in multiple stages is described as a viable option in the control of variables, optimizing the environmental conditions of the main microorganisms involved in the process, assuring high solid removal and methane production, besides allowing a higher energy yield through the generation of molecular fuel hydrogen. Several studies reviewed the process of anaerobic digestion in multiple stages in the treatment of food waste, although few report its use applied directly to agroindustrial residues. Thus, the present work aims to review the literature evaluating the scenario and viability of the multi-stage anaerobic digestion process applied to agroindustrial effluents. Effluents such as manipueira, vinasse, and dairy wastewater are substrates that present high yields when treated by AD processes with stage separation. The high concentration of easily fermentable sugars results in a high production of molecular hydrogen (co-product of the production of volatile acids in the acid phase) and methane (methanogenic phase). The great challenges related to the development of the sector are focused on the stability of the composition and yield of hydrogen in the acid phase, besides the problems resulting from the treatment of complex residues. Thus, the present study suggests that future works should focus on the technologies of new microorganisms and optimization of process parameters, providing maturation and scale-up of the two-stage anaerobic digestion technique.

Catalytic efficiency of the eggshell calcined and enriched with glycerin in the synthesis of biodiesel from frying residual oil.

Currently, there are several studies using calcium oxide, calcium alkoxide, and calcium hydroxide for biodiesel production. However, there is still a lack of studies highlighting the use of calcium diglyceroxide (calcium oxide enriched with glycerin in the presence of methanol) as a catalyst in the transesterification process. Therefore, the present work aimed to investigate the catalytic efficiency and reutilization of the eggshell calcined and enriched with glycerin and methanol (ECEG), in the synthesis of methylic esters from frying residual oil. As a result, thermochemically modified eggshells showed catalytic efficiency during methylic transesterification of residual oils in mass concentrations of 15%, 5%, 3%, and 1% due to the presence of a high level of esters (97.39, 96.97, 97.75, and 92.96%, respectively). The initial concentration of the enriched eggshell used in methanolysis had a direct effect on the final ester mixture. A 15% increase in the water content of the frying oil contributed to an increase in the ester content. The ECEG was reactive and efficient for four reaction cycles (without reactivation of the catalytic sites) due to the evidence of a high ester content (97.85%, 98.67%, 98.89%, 98.46%), reaching the standard quality of worldwide biodiesel regulations. Graphical abstract.

Poultry slaughterhouse anaerobic ponds as a source of inoculum for biohydrogen production.

Several waste sources have been studied as substrate sources for the production of biogas rich in hydrogen and for the isolation of bacteria capable of fermenting several substrates for the same purpose. Nonetheless, to simplify the process and minimize production costs, it is important to seek alternatives both for the use of microbial consortia using crude waste and for the use of substrates also in their crude form, without the need for purification. The aim of this study was to use only waste as inoculum and substrate for the biological production of hydrogen. Thus, samples from anaerobic ponds of a poultry slaughterhouse were used as inoculum. Sucrose, pure glycerol (in initial tests) and crude glycerol (inserted in blends with pure glycerol) were used as substrates. H2 production experiments were conducted in batches, using a reactor kept in an anaerobic environment for 11 days, at 35°C, under orbital agitation at 150 rpm. To analyse the composition of the biogas and the presence of soluble metabolic products (SMPs), samples of the headspace gases generated and of the reaction medium were collected. The results using sucrose as substrate indicated that the inoculum under study has potential for bio-H2 production, as it produced CH4-free biogas containing 50-60% H2. The inoculum was also shown to be adaptable to the use of glycerine as a substrate, producing biogas with similar characteristics to those obtained from sucrose degradation; however, it required a longer acclimatization period, and thus more in-depth study is required.

Photocatalytic Degradation of Textile dye Orange-122 Via Electrospray Mass Spectrometry

Abstract This work reports the study of the potential application of Zn/TiO2 catalysts, obtained by the sol-gel method, in processes of environmental decontamination through the reactions of photodegradation of textile dye, followed by electrospray mass spectrometry. The catalysts synthesis was performed according to a 2² factorial design with repetition at the central point. The characterization techniques used were: N2 adsorption measurements (BET method), scanning electron microscopy with energy dispersive X-ray (MEV/EDS), X-ray diffraction and point of zero charge (PZC). The photocatalytic tests were performed in batch in the presence of sunlight, and to evaluate the degradation kinetics study, a rapid direct injection electrospray mass spectrometry (DI-ESI-MS) method has been developed. By the photocatalytic tests, the calcination temperature of 400 °C has shown the best results of discoloration for the reactive Orange-122 dye (99.76%) in a reaction time of 2h. The discoloration kinetics were a pseudo-first order, and a statistical analysis was performed to investigate the effects of the variables and to optimize the conditions of discoloration to the dye. After the reactional time of 2 h, an ion of m/z 441.5 was detected by ESI-MS, indicating that the photocatalytic process was effective for the degradation of the dye to secondary compounds.

Evaluation of the effect of different treatment methods on sugarcane vinasse remediation.

Sugarcane vinasse is a by-product obtained during ethanol production in sugar-ethanol plants. For each 1 L of ethanol produced approximately 11 L of vinasse are generated. As this residue is obtained in high amounts, it is used as fertilizer in sugarcane crops. However, despite being rich in nutrients, sugarcane vinasse is approximately one hundred times more polluting than domestic sewage, making it an environmental problem. Thus, the aim of the present study was to propose a treatment sequence for sugarcane vinasse and evaluate the possibility of energetic use of the generated sludge in the coagulation/flocculation stage. pH, conductivity, turbidity and decreases in UV/Vis absorption spectra were determined for each treatment step. In addition, the upper calorific value of the generated sludge was also determined, while ash (adsorption treatment) and catalyst (heterogeneous photocatalysis) characterizations were also carried out. At the end of the treatment, initial vinasse turbidity was reduced by 100% and pH and conductivity values were stabilized. The sludge presented a higher calorific value of approximately 3,000 kcal kg-1 and the ash and catalyst displayed favorable characteristics to be applied to the sugarcane vinasse treatment stages.

Evaluation of different adsorbents for acidity reduction in residual oils.

This work aims to evaluate the adsorption potential of bentonite and sugarcane bagasse clay for the reduction of free fatty acids in cooking oil through batch technique, experimental planning with different operating conditions (temperature, adsorbent mass and agitation). After were carried out kinetic studies and thermodynamic studies. Thus, both adsorbents were characterized by nitrogen dispersion, scanning electron microscopy with coupled energy dispersion spectroscopy. The sugarcane bagasse provided higher reductions compared to the bentonite clay, 58 and 50%, respectively. In the kinetic studies, it was observed that the pseudo-secunda model for both materials. Among the isotherms studied, the Langmuir model was better adjusted for sugarcane bagasse and Freundlich for bentonite clay. Thermodynamic parameters indicated spontaneous and endothermic adsorption at temperatures of 18°C, 20°C and 25°C. Both materials showed an advantageous result with the reduction to the adsorption of free fatty acids in the residual oil, considering that they are low-cost materials, their pre-treatment is simple from the operational point of view and their physical and chemical characteristics are favorable to the adsorption process, sugarcane bagasse contains about 42% hemicellulose, which is a hydroxyl-rich material that attracts the H+ ions from the medium.

Use of rice husk in waste cooking oil pretreatment.

Since industrial wastes are increasing, the development of studies to find ways for their use is urgent. Waste cooking oil is an important source for the production of biodiesel, one of the main biofuels in Brazil. However, during cooking, the oil undergoes conditions that change its properties and decrease its quality, such as its acidity value. Current research treats waste cooking oil by the adsorption process using rice husk, an agro-industrial waste, and activated carbon to compare results. The potential of the adsorbents to remove free fatty acids in waste cooking oil has been investigated by the batch technique, evaluating different operating conditions of temperature, adsorbent mass and agitation. Adsorbents were characterized by nitrogen physisorption, scanning electron microscope, energy-dispersive spectroscopy and X-ray diffraction. The maximum result obtained for activated carbon at acidity reduction was 63%, using 22.4°C, 169.64 rpm and 3.39 g of adsorbent mass. Already, using the rice husk the percentage of removal was the same, 63% using 22.4°C, 80.36 rpm and 1.61 g of adsorbent, however in shorter times. The results prove that the application of the rice husk for this purpose is advantageous, for being a low-cost material, available on a large scale and that provide results similar to activated carbon.

Adsorption of aquaculture pollutants using a sustainable biopolymer.

Intensive aquaculture needs to adopt techniques that are able to contribute towards sustainability. Closed systems that employ water recirculation can combine intensive production with environmental sustainability, since there is no exchange of water or discharge of effluents into the environment. In order to achieve this, effective filtration systems are required to ensure that the water quality is satisfactory for the cultivation of aquatic organisms. Chitosan, an industrial waste material derived from crustacean farming, is a renewable natural material that is biodegradable and possesses adsorbent characteristics. In this work, chitosan foam was incorporated in filters and was evaluated as an adsorbent of aquaculture pollutants, adding value to the material and at the same time providing a use for industrial waste. The foam was characterized by scanning electron microscopy and energy dispersive spectroscopy, apparent density, and water absorption capacity. It was used to remove ammonia, nitrite, orthophosphate, and turbidity from aquaculture effluents. The foam consisted of a bilayer with smooth and porous sides, which presented low density, flexibility, and high water absorption capacity. The best proportion of the foam, in terms of the mass of foam per volume of solution (% m v-1), was 0.10, which resulted in removal of 32.8, 57.2, 89.5, and 99.9% of ammonia, nitrite, orthophosphate, and turbidity, respectively. This biopolymer produced is biodegradable, and when saturated with organic compounds from aquaculture, and no longer suitable for reuse as a filter material, it can be employed as a fertilizer, hence closing the sustainability cycle of the aquaculture production chain.

Physicochemical Characteristics of Oil Obtained from the Treatment of Poultry Abattoir Effluents and its Potential for Biodiesel Production

ABSTRACT Sludge oil derived from the effluent generated in poultry abattoirs offers a promising biomass for the production of biodiesel. In this work, determination was made of its physicochemical characteristics, including acidity, density at 20ºC, peroxide index, moisture content, and saponification index, together with evaluation of a route for its conversion to biodiesel.

Environmental, economic and social impact of aviation biofuel production in Brazil.

The Brazilian aviation industry is currently developing biofuel technologies that can maintain the operational and energy demands of the sector, while reducing the dependence on fossil fuels (mainly kerosene) and greenhouse gas emissions. The aim of the current research was to identify the major environmental, economic and social impacts arising from the production of aviation biofuels in Brazil. Despite the great potential of these fuels, there is a significant need for improved routes of production and specifically for lower production costs of these materials. In addition, the productive chains of raw materials for obtaining these bioenergetics can be linked to environmental impacts by NOx emissions, extensive use of agricultural land, loss of wildlife and intensive water use, as well as economic, social and political impacts.

Infarto cerebelar. Considerações sobre 12 casos / Cerebellar infarction. Considerations about 12 cases

Trata-se de estudo retrospectivo sobre 12 casos de infarto cerebelar. Sete pacientes eram do sexo masculino e cinco, do feminino. A idade variou entre 46 e 76 anos, com média de 54 anos. As causas foram hipertensão arterial sistêmica em seis, endocardite bacteriana em três e desconhecida em outros três. A cefaléia foi sintoma presente em dez pacientes, vômitos em oito, tonteira em oito, ataxia da marcha em sete e vertigem em quatro. A tomografia do crânio foi útil no diagnóstico e conduta. Onze pacientes foram submetidos a tratamento conservador. Derivação ventricular externa e craniectomia suboccipital foram realizadas em um paciente. Houve quatro óbitos. O prognóstico esteve diretamente relacionado ao nível de consciência por ocasião da admissão, da extensão do infarto e da idade do paciente.