Optimum Pyrolysis Temperature Research Articles

Valorisation of microalgae residues after lipid extraction: Pyrolysis characteristics for biofuel production

As a promising source of renewable energy, biofuel from microalgae pyrolysis is seen as a competitive alternative to fossil fuels. However, currently, the widely applied pre-treatment process of lipid extraction results in large amounts of microalgae residues, which though with energy potential, being considered as process wastes and ignored of its re-utilization potential. In this study, a new workflow of biofuel generation from microalgae biomass through lipid extraction and pyrolysis of defatted microalgae residues was proposed and assessed. The effects of lipid extraction and pyrolysis temperature (350–750 ℃) on pyrolysis products were investigated, and pyrolysis pathways were postulated. To address the twin goals of lowering emission of pollutants and elevating energy products, an optimal pyrolysis temperature of 650 ℃ was suggested. After extraction of lipids, the relative contents of valuable products (aromatic, aliphatic hydrocarbons and fatty acids) and some harmful by-products, e.g., PAHs, significantly reduced, while other harmful substrates, e.g., nitrogen-compounds increased. Mechanistic investigations indicated that pyrolysis of proteins without the presence of lipids could promote higher production of nitrogen-containing organics and aromatics. These results reveal the effects of lipid extraction and variation of temperature on microalgal pyrolysis, and also provide a basis for full utilization of microalgae as an aid to alleviate many fossil energy problems.

Formation mechanism and structural characteristic of pore-networks in shale kerogen during in-situ conversion process

In-situ conversion process (ICP) appears to be a promising approach to enhance hydrocarbon recovery of shale reservoirs. During the ICP, the pore-networks gradually generate underground and serve as the conduits for the storage and transport of hydrocarbon, which finally decides the recovery ability of the reservoir. Reactive molecular dynamics simulations are used to study the pyrolysis behavior of kerogen under the reservoir conditions. The pyrolysis proceeds in four stages: energy accumulation, oil window, gas window, and steady stage. And during this process, the kerogen pyrolytic pore-networks form under the combined actions of chemical bond breaking and physical deformation. Further analysis demonstrates that the structural characteristic is dependent on the maturities of kerogen and pyrolysis temperature. Low-maturity kerogen creates high-quality pore-networks (∼15% porosity), while the pores in medium- and high-maturity kerogen are scarce and isolated (∼1% porosity). In the simulation, the optimal pyrolysis temperature of pyrolysis is about 2300 K to develop high-quality pore-networks. In addition, a conversion relationship between the simulation temperatures and ICP engineering temperatures is established using Arrhenius equations, and the optimal temperature for ICP engineering is suggested to be ∼730 K.

Microwave catalytic co-pyrolysis of waste cooking oil and low-density polyethylene to produce monocyclic aromatic hydrocarbons: Effect of different catalysts and pyrolysis parameters

It is promising to convert waste oil and plastics to renewable fuels and chemicals by microwave catalytic co-pyrolysis, enabling pollution reduction and resource recovery. The purpose of this study was to evaluate the effect of catalysts on the product selectivity of microwave-assisted co-pyrolysis of waste cooking oil and low-density polyethylene and optimize the pyrolysis process, including pyrolysis temperature, catalytic temperature, waste cooking oil to low-density polyethylene ratio, and catalyst to feedstocks ratio. The results indicated that catalysts had a great influence on the product distribution, and the yield of BTX (benzene, toluene, and xylenes), which increased in the following order: SAPO-34 < Hβ < HY < HZSM-5. HZSM-5 was more active for the formation of light aromatic hydrocarbons as compared to others, where the concentrations of toluene, benzene and xylenes reached 252.59 mg/mL, 114.7 mg/mL and 132.91 mg/mL, respectively. The optimum pyrolysis temperature, catalytic temperature, waste cooking oil to low-density polyethylene ratio and catalyst to feedstocks ratio could be 550 °C, 450 °C, 1:1 and 1:2, respectively, to maximize the formation of BTX and inhibit the formation of polycyclic aromatic hydrocarbons.

Recycling of electrode materials from spent lithium-ion battery by pyrolysis-assisted flotation

In this study, the flotation technology is used for the separation and purification of cathode and anode material after removing organics by pyrolysis. Effects of surface microscopic properties on the flotation efficiency of spent electrode materials are investigated, and on this basis, surface analysis combined with flotation foundation tests are conducted to reveal pyrolysis-assisted surface modification mechanism. Residual electrolyte and organic binders decrease the difference in wettability of cathode and anode material, and hinder the interaction between electrode particles and collecting agent. Organics and their pyrolysis products can be adequately removed at the optimum pyrolysis temperature of 550 °C. After pyrolysis, the change of Zeta potential and surface free energy demonstrates that hydrophilic components of cathode material increase while the hydrophobic components of the anode material increase. The induction time of cathode material rises from 190 ms to 650 ms while the induction time of the anode material decrease from 145 ms to 37 ms. Collector adsorption capacity of anode material is obviously improved and anode material is easy to incorporate with bubbles and will be collected in the froth product. After one stage flotation, the recovery rate of cathode material is 83.75% with a high grade of 94.72%.

Coeffect of pyrolysis temperature and potassium phosphate impregnation on characteristics, stability, and adsorption mechanism of phosphorus-enriched biochar

Potassium phosphate (K3PO4)-impregnated bamboo was pyrolyzed at temperatures ranging from 350 to 950 °C to explore the coeffect of pyrolysis temperature and K3PO4 impregnation on biochar’s characteristics and adsorption behavior. The degree of aromatization and graphitization in phosphorus-enriched biochars (PRBCs) rose as temperature increased, whereas H/C and O/C ratios, pH value, and O-containing group content decreased. The pre-aging impact of K3PO4 impregnation results in increased stability and adsorption performance of PRBCs. Adsorption mechanism of PRBCs to heavy metal varies from pyrolysis temperature. Micropores dominate medium-temperature PRBCs (prepared at 550 ∼ 750 °C), possessing the highest P-containing group content (116 % that of PRBC-350) and maximal adsorption capacity (greater than289 mg/g). The medium-temperature PRBCs adsorb Cd (II) via the role of O-containing groups, PO43-, and P2O74-, mainly by reactions of organic complexation, precipitation and inorganic complexation, respectively. 550 °C is the optimal pyrolysis temperature for both energy saving and heavy metal adsorption.

Synthesis of Iron and Phosphorous‐Embedded Nitrogen‐Containing Porous Carbon as an Efficient Electrocatalyst for Microbial Fuel Cells

AbstractEfficient and stable electrocatalysts are required for microbial fuel cells (MFCs). They must be accessible to realize industrialization. Herein, a hierarchically porous phosphorus and iron‐embedded nitrogen‐containing carbon (P/Fe‐SS) was synthesized with shrimp shells as a carbon matrix via a facile oxidation pretreatment and pyrolysis process, where FeCl3 and H3PO4 were used as the catalyst and activator, respectively. Meanwhile, both of them acted as the doping sources to induce more active sites. The optimal pyrolysis temperature (900 °C) introduced a large specific surface area (857 m2/g) and hierarchical pores, facilitating the exposure of active sites. Furthermore, the presence of pyridinic‐N and Fe/P active sites endowed P/Fe‐SS 900 with excellent activity during the oxygen reduction reaction process. In particular, P/Fe‐SS 900 showed higher long‐term stability and poisoning resistance than those of Pt/C. When P/Fe‐SS 900 was applied as an air cathode in a MFC, its maximum power density reached 96.7 % of that of Pt/C. These results provide a promising alternative to Pt/C for MFC application due to their low cost, accessibility, and high stability.

Mechanistic insights into the ultra-deep desulfurization of liquid fuel on date-seed derived hierarchical porous carbon

This study described the synthesis of activated carbon and its application in the removal of DBT and DMDBT from isooctane using both experimental and DFT calculations. The effect of synthesis conditions (pyrolysis temperature, precursor-activator ratio and ramping rate) on the properties of activated carbon were also presented. Activated carbon (AC) of high surface area and porosity was synthesized from an agricultural waste material (date seeds) using Zn-acetate as an activator. Thorough study of the characteristic activity and selectivity of this adsorbent in the removal of organosulfur compounds; dibenzothiophene (DBT) and dimethyldibenzothiophene (DMDBT) at room temperature were carried out. DFT simulations predicted the selectivity of AC towards DMDBT promoted by the charge donation and the positive inductive (+ I) effects of the methyl groups resulting in strong van der Waals interactions and theoretical adsorption energy of – 12.3 kcal/mol. It was observed that surface area, porosity, and surface chemistry of the adsorbent highly depends on the process parameters. The adsorbent pyrolyzed at 1000 °C and 10 °C/min performs better and shows exceptional capability to remove DBT and DMDBT (200 ppmw-S) in model fuel to almost sulfur-free fuel at minimum adsorbent weight (200 mg). However, the precursor-activator ratios at optimum pyrolysis temperature and ramping rate had little effect on the adsorbents’ performance. DMDBT was found to preferentially adsorb on the adsorbents with increasing pore size and volume than DBT. The kinetics and isotherms studies confirmed that the obtained data fitted more to pseudo-second order and Langmuir model.

A new nanocomposite assembled with metal organic framework and magnetic biochar derived from pomelo peels: A highly efficient adsorbent for ketamine in wastewater

A new nanocomposite, magnetically modified metal-organic framework ZIF-8/biochar (MZBC), was synthesized and used for removal of emerging contaminant ketamine (KET). Here, ZIF-8 was used as a sacrificial template and magnetic biochar was derived from pomelo peels. The influence of different pyrolysis temperatures (400, 500, 600 and 700 ºС) on adsorption performance was investigated in detail. The optimal pyrolysis temperature for the preparation of MZBC was obtained at 600 ºС. The maximum adsorption capacity of MZBC-600 for KET was 32.50 mg·g−1, which was 24.8 times higher than that of a single magnetic biochar (MBC-600). MZBC-600 exhibited a high stable adsorption capacity for KET over a wide pH (3−12) range and even high ionic strength in water. The pseudo-second-order kinetic model and Freundlich isotherm model were more suitable to analyze the adsorption process of MZBC-600 to KET, with R2 of 0.996 and 0.998, respectively. Adsorption kinetics, isotherms, pH effect, ionic effect and series of characterization analysis suggested that the adsorption process was dominated by pore filling, π-π interaction, hydrogen bonding and chelation. The sustainable adsorption capacity (>90% of the initial adsorption capacity) of MZBC-600 was well maintained even after five reuse cycles. In a word, this novel nanocomposite (MZBC-600) contributed a high adsorption efficiency, environment-friendliness and good sustainability.

ANALISIS PENGARUH TEMPERATUR PIROLISIS LIMBAH PLASTIK HIGH DENSITY POLYETHILENE (HDPE) TERHADAP LAJU REAKSI HASIL BIO OIL SEBAGAI BAHAN BAKAR ALTERNATIF

Plastics are synthetic polymer compounds formed from the polymerization of small molecules(monomers) composed of hydrocarbon bonds. The use of plastic waste as a material to produce fueloil is an alternative that can increase the economic value of plastic waste, besides that it can alsosolve one of the environmental problems. This study aims to analyze the characteristics of fuel oilproduced from plastic waste type High Density Poly Ethylene (HDPE) with the pyrolysis process. Theresearch methodology variables include; the pyrolysis time was 120 minutes and the pyrolysistemperatures were 390oC, 410oC, 430oC, and 450oC. The test of the pyrolysis oil is based on theflash point. Furthermore, the calculation of the reaction kinetics using the Arrhenius Equationmethod. The optimum temperature for HDPE plastic pyrolysis is at a temperature of 450°C with aconversion efficiency of 59.3% wt. The value of the reaction rate constant obtained is k = 7.3 x 109 .e(117.013/R.T).

Water recycling system based on adsorption by activated carbon synthesised from c. verum for space exploration; an estimated design

Water recycling is a crucial component of space flights. In this study, c.verum, a low-cost agricultural by-product abundant in Egypt, which was not utilized before for the preparation of porous carbons, and its ability for recycling water in space stations was estimated. The prepared samples show high porosity and surface area by physical activation. The influences of the pyrolysis temperature and activation hold-up time on the activated carbon’s porosity were studied. The BET surface area and the total pore volume of the prepared carbon were used as the criteria for selecting the optimum preparation parameters. The optimum temperature for pyrolysis was found to be at a temperature of 900°C, hold-up time of two-hour, a nitrogen flow rate of 150 cm3/min, and a heating rate of 10°C/min. However, the optimum activation conditions were at a temperature of 900°C, a CO2 flow rate of 150 cm3/min, a heating rate of 200C/min, and a hold-up time of 120 min. Equilibrium data is used for fitting to Freundlich, Langmuir, and Temkin isotherms models. The result revealed that the Langmuir model was the finest match for the equilibrium data, with an extreme monolayer adsorption capability of 12.37 mg/g at 25°C. The maximum monolayer adsorption capacity decreased with increasing temperature confirmed the exothermic character of the adsorption interaction.

Development of biocarbon sorbent from corn waste with increased destructive activity in relation to oil

The object of research is the created bioactive sorbent based on biochar from corn waste for the purification of oil-contaminated natural environments. The expediency of using biochar from corn cobs as a matrix – a carrier of microorganisms-destructors of petroleum hydrocarbons in the production of biosorbent – has been substantiated. Biochar meets the requirements for oil sorbents – environmental friendliness, oil resistance (6–8 g of oil per 1 g of sorbent), manufacturability and biocompatibility. The porous structure and chemical nature of the surface partly determines the absorbency of the material, but the dominant factor is the interaction of the hydrophobic surface with petroleum hydrocarbons. A universal oil oxidizer – a microbial complex isolated from oil-polluted natural objects, in combination with a carbon carrier, is capable of neutralizing oil pollution of various types and concentrations. It has been established that microorganisms – oil-destructors, immobilized on the surface of the sorbent, are capable of decomposing almost all oil hydrocarbons. Microorganisms immobilized on a carbon material have a great potential for destructive action. During immobilization, the viability of microbial cells is maintained, and the effect of their use is significantly increased. The use of a bioactive carbon sorbent based on biochar and immobilized natural oil-oxidizing microorganisms of a wide spectrum of action allows one to localize oil pollution and neutralize it through biodegradation. The optimal parameters for obtaining an oleophilic sorption matrix based on biochar from corn waste and for growing microbial biomass with a high destructive activity for oil hydrocarbons have been established. The optimum pyrolysis temperature is 300–350 °С, the pyrolysis time is 25–30 minutes. In this case, the sorption of oil obtained biochar reaches maximum values (6–8 g oil/gsorbent). Sufficient number of immobilized microorganisms – oil destructors 120–200·104 cells for active decomposition of oil localized on the sorbent surface. The operational characteristics of the obtained bioactive sorbents, technological features and methods of their use in cleaning the environment from oil pollution have been studied. The biosorbent does not require removal from the places of use and disposal. Cleaning of soils contaminated with oil and oil products has specific features and requires the use of agricultural techniques (loosening, moistening). The studies carried out have shown a change in the concentration of oil pollution in the soil from 40 % to 1–5 % of oil in the process of biodegradation after 3 months at positive temperatures.

Preparation and characterization of new adsorbent from Cinnamon waste by physical activation for removal of Chlorpyrifos

In this study, Cinnamon sticks, a low-cost farming by-product abundant in Egypt, were tested as a precursor for the production of porous carbons with high surface area and large pore volume using a two-step preparation method carbonization followed by physical activation in the presence of carbon dioxide. The influences of the pyrolysis temperature and activation hold-up time on the porosity of the activated carbon were studied. The BET surface area and the total pore volume of the prepared carbon were utilized as the criteria for selecting the optimum preparation parameters. The optimum temperature for pyrolysis was found to be at a temperature of 900 °C, hold-up time of two-hour, a nitrogen flow rate of 150 cm3/min, and a heating rate of 10 °C/min. However, the optimum activation conditions were at a temperature of 900 °C, a CO2 flow rate of 150 cm3/min, a heating rate of 20 °C/min. and hold-up time of 120 min. Steadiness data were tailored to Langmuir, Freundlich, and Temkin isotherms, and the equilibrium data were best described by the Langmuir isotherm model, with a maximum monolayer adsorption capacity of 12.37 mg/g at 25 °C. The extreme monolayer adsorption capacity declined with rising temperature confirming the exothermic character of the adsorption interaction.

Facile preparation of N-doped hierarchically porous carbon derived from pitch-based hyper-cross-linked polymers as an efficient metal-free catalyst for oxygen-reduction

Pitch, as a by-product of the petroleum and coal chemical industry, is in great need of improving its potential value by expanding its application areas. Using low-cost and available carbon precursors and facile preparation to design and prepare metal-free electrocatalysts with preeminent performance and high stability for oxygen reduction reaction (ORR) have become a research trend. Herein, we combine the above-mentioned requirements to prepare a kind of N-doped hierarchical porous carbon materials as ORR electrocatalysts using pitch-based hyper-cross-linked polymers (PHCPs) as carbon precursors by a simple ammonia activation process. Under the optimized pyrolysis temperature (900 °C), the optimal N-PHCP-900 owns high specific surface area of 999 m2 g−1, hierarchical pore structure, plentiful accessible active N and high density of defects. Benefitting from these special advantages, the N-PHCP-900 exhibits an outstanding ORR property with a positive half-wave potential (0.883 V vs. RHE) and robust durability in alkaline electrolyte, which surpass those for commercial Pt/C and the majority of non-noble metal electrocatalysts. Therefore, this work not only offers a novel paradigm in the development of affordable and efficient metal-free ORR electrocatalysts as the hopeful candidate, but also explores a feasible method for realizing the high value-added application of pitch.

Prediction of three-phase product distribution and bio-oil heating value of biomass fast pyrolysis based on machine learning

In this work, by mining the experimental data of fast pyrolysis of lignocellulosic biomass in bubbling fluidized bed in previous literature, regression prediction models were established for three-phase product distribution and bio-oil heating value (HHV) based on gradient boosting, random forest, support vector machine, and multilayer perceptron algorithms. Comprehensive feedstock characteristics and pyrolysis conditions were considered and compared as input features. Among the several algorithms, random forest is most suitable for the prediction of three-phase product yields and bio-oil HHV with the benefits of high accuracy and good generalization ability. Visual analysis of the model shows that pyrolysis temperature is the most critical factor affecting three-phase product distribution, while bio-oil HHV is more affected by the feedstock characteristics such as the contents of C and H. The highest yield and HHV of bio-oil is obtained at about 480 °C, suggesting 480 °C as the optimum pyrolysis temperature of fast pyrolysis of biomass in a bubbling fluidized bed. As for the feedstock characteristics, high contents of C and H and low content of O are favorable to the enhancement of bio-oil HHV, indicating the crucial importance of feedstock pretreatment such as torrefaction to the quality improvement of bio-oil.

Porous carbon materials derived from waste cotton stalk with ultra-high surface area for high performance supercapacitors

In recent years, porous carbon materials have gained attention as excellent electrode materials owing to their large specific surface area and good electrical conductivity to promote ion transport and electron transfer. Therefore, to realize their widespread application, it is of great significance to reduce the production cost of carbon materials. Hence, the preparation of carbon materials using cotton stalk has been proposed. In this study, we carried out the carbonization and activation of cotton stalk to prepare high-performance energy storage materials with different KOH/carbon mass ratios (0:1, 2:1, 3:1, and 4:1) at 600 and 800 °C. The cotton stalk-based carbon materials (CSCMs) prepared at the optimum pyrolysis temperature exhibited large specific surface area and good electrochemical properties. Therefore, the all-solid supercapacitor device assembled with gel electrolyte exhibited high rate capability (an energy density of 12.5 Wh/kg and a power density of 900 W/kg) and excellent stability. Thus, the proposed porous carbon materials derived from waste biomass cotton stalk for the preparation of high-performance supercapacitors have huge application prospects.

Migration and Environmental Effects of Heavy Metals in the Pyrolysis of Municipal Sludge

Migration characteristics of the heavy metals Fe, Zn, Mn, and Ni during the preparation of biochar from municipal sludge were studied, and the optimal pyrolysis temperature for the preparation of biochar was determined based on potential environmental risks. Four heavy metals (Fe, Zn, Mn, and Ni) with high total contents in the biochar were selected to determine their species and content changes under different pyrolysis temperatures using the BCR extraction method. An environmental risk assessment for sludge-based biochar was also carried out using the potential ecological risk index (PERI) and risk assessment code (RAC). The results showed that the volatility of the four metals is ranked as follows:Zn>Mn>Fe>Ni. The distribution and transformation of the four metal species were different, but their migration paths shared similar characteristics. In the pyrolysis stage at low temperatures (<500℃), unstable fractions gradually changed into more stable species; under high temperatures (>500℃), some of the oxidizable and residual fractions were broken, which transformed into reducible fractions, and other fractions escaped into the atmosphere. In the environmental risk assessment, biochar prepared under high pyrolysis temperatures (>500℃) showed lower environmental risks, with the best outcomes at 500℃.

Co-production of upgraded bio-oils and H2-rich gas from microalgae via chemical looping pyrolysis

In order to produce high-quality bio-oils and syngas from biomass, a novel pyrolysis approach based on the chemical looping concept, namely chemical looping pyrolysis (CLPy), was proposed. In the current work, thermodynamic feasibility study and experimental investigations of the proposed CLPy with calcium-ferrite oxygen carriers and Nannochloropsis sp. microalgal biomass were conducted. The results suggested that the reduced calcium-ferrite oxygen carrier facilitated the denitrification, ketonization, and hydrodeoxygenation (HDO) of bio-oils during the pyrolysis stage. Since large amounts of oxygen in bio-oils were transferred to the reduced oxygen carrier, the heating value of bio-oils was remarkably increased up to 34.2 MJ/kg and 36.0 MJ/kg by employing the reduced CaFe2O4 and Ca2Fe2O5 oxygen carrier, respectively. In addition, a high H2 content of 50% in the pyrolysis gas was observed at the optimal pyrolysis temperature. In the gasification stage, the production of high-quality syngas was achieved. The content of H2 accounted for up to 70% of the gasification products when taking steam as gasifying agent, while that of CO was composed of 66% without the use of a gasifying agent. Moreover, the oxygen carrier was reduced to its reduction state, available for the next loop. In summary, CLPy proposed in this work involves the continuous transference of the oxygen from bio-oils to syngas by an oxygen carrier and provides a brand-new approach for the comprehensive utilization of biomass.

Immobilized redox mediators on modified biochar and their role on azo dye biotransformation in anaerobic biological systems: Mechanisms, biodegradation pathway and theoretical calculation

In this study, a novel solid-phase redox mediator (RM) was manufactured via immobilizing anthraquinone-2-sulfonate (AQS) onto modified biochar (BC). The RM was used to enhance the anaerobic granular sludge (AGS) driven anaerobic biodegradation of azo dyes. Prepared at the optimal pyrolysis temperature of 550 ℃, the AQS modified BC550 exhibits a higher adsorption capacity of about 12.81% toward AQS compared to that of commercial granular activated carbon (GAC). X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy analyses showed that BC550-AQS contained more redox moieties (quinone and C = O) than GAC-AQS, indicating that the BC550 is suitable as a carrier of immobilized AQS. During the 36-h reaction, incubation of BC550-AQS as the solid-phase RM obviously enhanced the capacity of AGS (BC550-AQS + AGS), evidenced by the maximum percentage of Reactive Red 2 (RR2) decolorization (92.27%), which increased up by 80.55% and 14.48% compared to the controls (BC550-AQS, 17.95%) and (GAC-AQS + AGS, 78.61%). Besides, BC550-AQS exhibits good reusability and a higher RR2 decolorization rate (per AQS dosage) over 15 consecutive cycles. The mechanism of biodegradation pathway of RR2 initiated by BC550-AQS was studied using liquid chromatography-mass spectrometry and chemical computation. Density-functional theory calculations successfully predict that the RR2 biodegradation pathway mainly includes azo bond cleavage and electron attraction with a stronger electron affinity. This work not only proposes a deep insight into the biodegradation pathway of RR2 by employing BC550-AQS in an anaerobic biological system but also develops effective solid-phase RMs for efficient removal of contaminants from wastewaters by biological treatment.

Biochar production investigation from pyrolysis of lamtoro wood as a coal blend for fuel substitution in steam power plants

The biochar utilization reduces CO2 emissions. This study aims to investigate the optimum pyrolysis temperature of lamtoro wood (Leucaena leucocephala) to produce suitable biochar for coal blends as fuel in the steam power plant. The experiment was carried out in a batch process, applied to a fixed bed reactor, 10°C/minute heating rate, three different variables temperature (300, 450, 600°C), and 60 minutes residence time. The biochar yield for each pyrolysis temperature is 61.77%, 26.45%, and 24.89%. This shows that the pyrolysis is carried out at a temperature of 300 to 450 °C, then ramps up to 600 °C. The volatile matter was released during the pyrolysis and raise the fixed carbon content. The fixed carbon content for each pyrolysis temperature is 26.35%, 61.82%, and 65.66%. Fixed carbon content at 450 and 600 °C identical to bituminous coal. The increase in fixed carbon content in biochar leads the heating value to increase. The heating value of lamtoro wood was 19.15 MJ/kg (db), increasing to 22.92, 28.01, and 29.73 MJ/kg (db) for each pyrolysis temperature. The biochar heating value is close to bituminous coal. The biochar energy content of original lamtoro wood for each pyrolysis temperature is 81.72%, 42.77%, and 42.71%. Biochar reaches its optimal point at pyrolysis temperature 450 °C, which has a yield and heating value almost the same at pyrolysis temperature of 600 °C. The biochar characterization results indicate that it can be used as a coal blend for steam power plants.

Elemental Analysis of Pharmaceutical Products for Chronic Kidney Disease by High-Resolution Continuum Source Graphite Furnace Atomic Absorption Spectrometry (HR–CS GFAAS)

Here is reported the development of methods for the determination of Al, Cd, Cu, Mo, and Pb by high-resolution continuum source graphite furnace atomic absorption spectrometry (HR–CS GFAAS) after microwave-assisted acid digestion in pharmaceuticals for patients with chronic kidney disease. The measurements were performed at the primary lines of the analytes. The optimum pyrolysis and atomization temperatures were 1800 and 2700 °C for Al, 600 and 1600 °C for Cd, 1400 and 2200 °C for Cu, 1400 and 2600 °C for Mo and 900, and 2400 °C for Pb, respectively. Palladium was used as a chemical modifier for Pb, while Mg(NO3)2 was employed for Al, Cd, and Cu. The validation parameters (linearity, analytical range, accuracy, precision, limit of quantification, and specificity) were obtained according to the stipulations in the Chapter American Pharmacopeia <233>. The limit of detection was 1.63 μg L−1 for Al, 0.02 μg L−1 for Cd, 0.49 μg L−1 for Cu, 0.76 μg L−1 for Mo, and 0.59 μg L−1 for Pb. The precision was between 2.1% for Mo and 8.1% for Al. The recoveries were from 90.2% for Pb to 106.1% for Cd. The developed methods were successfully applied to determine the five analytes in 50 pharmaceutical formulations. Cadmium, Cu, and Mo concentrations were within the maximum limits recommended by the Brazilian Pharmacopeia in all medicines. However, six drug products had a Pb concentration higher than the limit for this element. All samples analyzed showed relatively high concentrations of Al.