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•Effect of pre-treatment on thermochemical characteristics of rice husk.•Acid and alkali treatment of rice husk.•Thermal degradation of chemically treated and raw rice husk.•Kinetic ...and thermodynamic parameters for pyrolysis of chemically treated and raw rice husk.•Reaction mechanism of pyrolysis for chemically treated and raw rice husk.
Pyrolysis of untreated, acid treated and alkali treated rice husk (URH, ARH and ALRH, respectively) was investigated. Pre-treatment resulted in change in values of proximate and ultimate analyses parameters, gross calorific values and cellulose, hemi-cellulose and lignin contents. Thermal degradation experiments were carried out from ambient to 800 °C at heating rates of 5, 10 and 15 °C/min in presence of nitrogen (flow rate 50 mL/min). Analysis of the pyrolysis data was carried out using, Flynn – Wall – Ozawa (FWO), Kissinger – Akahira – Sunose (KAS) and Starink iso-conversional models. The activation energy was estimated to be 219.67, 220.09 and 218.83 kJ/mol using FWO model; 222.18, 222.69 and 227.98 kJ/mol using KAS model and 222.19, 223.57 and 228.38 kJ/mol using Starink model for URH, ARH and ALRH, respectively. Thermodynamic parameters (ΔH, ΔG, ΔS) were also evaluated in each case. Effect of pre-treatment on the pyrolysis reaction mechanism was predicted using Criado method. The results indicated that pre-treatment of RH improved its thermal degradation process.
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•Detailed analysis of TGA-DTG and DSC results of sugar cane leaves.•Model free methods have been used to evaluate kinetic parameters for sugar cane leaves.•Uses Vyazovkin and ...Vyazovkin (AIC) kinetic model for sugar cane leaves.•Multiple linear regression method has also been successfully used.•A multi-step reaction mechanism through z(α) master plots has been ascertained.
Pyrolysis of sugarcane (Saccharum officinarum L) leaves (SCL) has been investigated using DTA/TGA and DSC techniques. Proximate and ultimate analyses and calorific value measurement have been carried out using standard protocols. The sugar cane leaves contain 44% cellulose, 22% hemicellulose and 17% lignin. The pyrolysis have been carried out at six heating rates varying from 5 to 40 °C/min. Analysis of the pyrolysis results has been carried using iso-conversional model free methods as well as multiple linear regression method. For the fractional conversion range of 0.05–0.95, the average apparent activation energy values evaluated from iso-conversional methods have ranged from 214.9 to 239.6 kJ/mol where as in the case of multiple linear regression analysis it has ranged from 25.06 to 57.23 kJ/mol. The multi-step reaction mechanism has been investigated using the Criado method. The results of this study are useful for the design of large scale biomass thermal conversion process.
Indiscriminate use of chemical fertilizers in the agricultural production systems to keep pace with the food and nutritional demand of the galloping population had an adverse impact on ecosystem ...services and environmental quality. Hence, an alternative mechanism is to be developed to enhance farm production and environmental sustainability. A nanohybrid construct like nanofertilizers (NFs) is an excellent alternative to overcome the negative impact of traditional chemical fertilizers. The NFs provide smart nutrient delivery to the plants and proves their efficacy in terms of crop productivity and environmental sustainability over bulky chemical fertilizers. Plants can absorb NFs by foliage or roots depending upon the application methods and properties of the particles. NFs enhance the biotic and abiotic stresses tolerance in plants. It reduces the production cost and mitigates the environmental footprint. Multitude benefits of the NFs open new vistas towards sustainable agriculture and climate change mitigation. Although supra-optimal doses of NFs have a detrimental effect on crop growth, soil health, and environmental outcomes. The extensive release of NFs into the environment and food chain may pose a risk to human health, hence, need careful assessment. Thus, a thorough review on the role of different NFs and their impact on crop growth, productivity, soil, and environmental quality is required, which would be helpful for the research of sustainable agriculture.
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•Nanofertilizers (NFs) are the best alternative to traditional chemical fertilizers.•Nutrients use efficiency of NFs is higher than the conventional chemical fertilizers.•NFs can increase the tolerance of plants against biotic and abiotic stresses.•Supra optimal dose of NFs had a negative impact on crops, soil, and the environment.
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The thermo-chemical characterization (proximate and ultimate analyses and higher heating value) of banana trunk biomass waste has been carried out. The thermo-gravimetric and ...differential scanning calorimetric (DSC) investigations have been made at heating rates of 10, 15, 20 and 25 °C/min. The TGA data have been used to carry out kinetic analysis and evaluate the kinetic and thermodynamic parameters using iso-conversional models. The values of activation energy increase with conversion (α) irrespective of the iso-conversional model used. The average values of activation energies (Eα) are found to be 386.21, 355.43, 385.77, 355.01, 379.67, and 292.78 kJ/mol for Flynn-Wall-Ozawa (FWO), Starink, Kissinger-Akahira-Sunose (KAS), Tang, Vyzovkin and Vyzovkin AIC model, respectively. The average values of change in enthalpy, Gibbs free energy, and entropy have been calculated. The reaction mechanisms of pyrolysis have been predicted using Criado’s method.
•Generation of RVEs for short fibre composites with periodic boundary conditions for material continuity.•Four different cases of fibre arrangements and different fibre volume fractions ...studied.•Mathematical theory of homogenization was used to predict the stiffness.•Efficient in predicting the overall behaviour with repetitiveness.
In this study an attempt is made to generate the microstructure of short fibre composites through representative volume element (RVE) approach and then analyzed using mathematical theory of homogenization with periodic boundary conditions to estimate the homogenized or effective material properties. An algorithm, based on random sequential adsorption technique (RSA), has been developed to generate the RVE for such materials. The goal of the present study is to demonstrate the methodology to generate RVEs which are effective in predicting the stiffness of the short fibre composites with repetitiveness. For this purpose, RVEs for four different scenarios of fibre orientations have been developed using this technique. These four different scenarios are: Fibres are aligned in a direction; fibres are oriented randomly in one plane; fibres are randomly oriented in one plane and partially random oriented in other plane and finally, fibres are completely random oriented. For each case three to four different fibre volume fractions are studied with five different RVEs for each volume fraction. These four cases presented different material behaviour at macroscale due to random location and orientation of fibres. The effective properties obtained from numerical technique are compared with popular non RVE methods like Halpin–Tsai and Mori–Tanaka methods for the case where fibres are aligned in a direction and were found to be in good agreement. The variation in the predicted properties for a given volume fraction of any of the four cases studied is less than 1%, which indicates the efficacy of the algorithm developed for RVE generations in repetitiveness of predicted effective properties. The four cases studied showed gradual change in macroscopic behaviour from transversely isotropic, with respect to a plane, to a nearly isotropic nature.
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•Thermal behaviour of paper mill waste (PMW).•Effect of Montmorillonite clay as a catalyst on the pyrolysis of PMW.•Thermal degradation behaviour of PMW and PMW and clay ...mixture.•Kinetic analysis using iso-conversional models of FWO, DAEM and Vyazovkin.
The thermal degradation of paper mill waste (PMW) has been investigated in presence and absence of Montmorillonite clay in the temperature range of ambient to 1000 °C and at the heating rates of 20 °C/min, 25 °C/min and 30 °C/min. Proximate and ultimate analyses and evaluation of calorific value (HHV) of PMW have been carried out using standard protocols. The thermo-gravimetric analysis (TGA) and differential thermogravimetric (DTG) data obtained under both situations have been used to evaluate the kinetic and thermodynamic parameters and elucidate the reaction mechanism. The clay has also been characterized using TGA/DTG analysis, Fourier Transform Infra-Red (FTIR) spectroscopic analysis and X-ray diffraction (XRD), Energy dispersive spectroscopy (EDS), and scanning electron microscopic (SEM) techniques. The activation energy, pre-exponential factor and thermodynamic parameters have been evaluated using the model-free iso-conversional method of Flynn-Wall-Ozawa (FWO) and Vyazovkin and the distributed activation energy model (DAEM). The Montmorillonite clay has influenced the degradation process appreciably through its catalytic action.
Biochar generated from pyrolyzed leftover green coconut was used to explore the impact of various experimental settings. The optimization of this biochar using response surface methodology (RSM), the ...Box-Behnken design, and statistical modelling led to the optimal parameters, such as pH 2.3 ± 0.1, solution temperature of 303 K, and the adsorbent weight of 6 g L
−1
, which resulted in approximately 99.99% expulsion of Cr(
vi
) from the aqueous solution. By using FESEM, EDAX, elemental mapping, FTIR spectroscopy, XRD, XPS, and pH
ZPC
, the surface characteristics of coconut biochar (CB) were evaluated. The functional groups C-O, C-H, C&z.dbd;O, and O-H were found to be present and were primarily in charge of controlling the adsorption mechanism. The change in Cr(
vi
) oxidation state was confirmed by XPS analysis, and the presence of Cr(
vi
) on CB after adsorption was confirmed by EDAX. With high
R
2
values, the pseudo-second-order rate was the best adsorption mechanism for Cr(
vi
). The ideal adsorption capacity of 9.75 mg g
−1
was obtained from the Langmuir isotherm. The thermodynamic study confirmed that the experiment was exothermic with spontaneous nature. According to the adsorption mechanism, electrostatic attraction, reduction, and complexation were the main causes of Cr(
vi
) adsorption on CB. The efficiency of CB as an adsorbent for extracting Cr(
vi
) from an aqueous solution was thus supported by all available studies.
Surface characteristics of coconut biochar before and after adsorption.
Peanut shell biomass was selected and utilized to produce biochar through pyrolysis under N2 atmosphere at 923 K. After studying various effects of experimental parameters and by statistical modeling ...and optimization by RSM using Box-Benken design, optimized conditions of pH 2.0 ± 0.1, temperature 303 K, and adsorbent dose used of 2.5 g L−1 were obtained giving almost 99.99% removal for Cr(VI) from the solution. FESEM, FTIR, XRD, XPS, EDX, elemental mapping, and pHzpc were used for the evaluation of the surface characteristics of peanut shell biochar (PSB). Studies revealed C–O, C–H, CO, and O–H functional groups’ presence with the help of FTIR, majorly in control of adsorption mechanism and the EDX confirmed the presence of Cr(VI) onto peanut shell biochar (PSB). Further adsorption mechanism for Cr(VI) adsorption followed the pseudo-second-order rate with adsorption capacity of 29.38 mg g−1 given by the Langmuir isotherm. The thermodynamic study confirmed the exothermic and spontaneous nature of the process for Cr(VI) adsorption onto PSB. The adsorption mechanism showed electrostatic attraction, reduction, and complexation mainly responsible for Cr(VI) adsorption by PSB. Thus, PSB effectively removes Cr(VI) is confirmed by the present study.
•Waste peanut shell pyrolyzed biochar used as adsorbent for Cr(VI) removal.•Multivariable modeling and optimization were done by RSM using Box-Benken design.•Adsorption followed pseudo-second-order rate with adsorption capacity of 29.38 mg g−1 suggested by Langmuir isotherm.•Redox process with electrostatic attraction was the adsorption mechanism and film diffusion majorly controlling the rate.
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•Cyanobacterial hydrolysate is a good source of fermentable sugar for biobutanol.•Addition of glucose (10.0 g/L) increased biobutanol production by 55.0%.•Use of L. limnetica biomass ...(from two-stage growth) improves productivity by 37.0%.•Use of 1.0L agitated bioreactor improves biobutanol production by 9.0%.
The potential of hydrolysates of cyanobacteria Lyngbya limnetica and Oscillatoria obscura for biobutanol production was evaluated under varying operating conditions using Clostridium beijerinckii ATCC 35702 culture as the fermenting microrganism. Effects of various process parameters affecting the biobutanol production were investigated using glucose as the C-source. The maximum biobutanol productivity of 1.565 g/L/d was obtained with L. limnetica biomass hydrolysate supplemented with 10.0 g/L of glucose under the best conditions in batch mode. The large biobutanol production (8.873 g/L) was obtained with glucose supplemented hydrolysate while the highest yield (0.421 g/g sugar) was found with pure cyanobacterial hydrolysate indicating its industrial feasibility. The hydrolysates prepared from biomass of L. limnetica and O. obscura grown following a two-stage protocol, were utilized for the first time for biobutanol fermentation and nearly 33.0 and 31.0% increased biobutanol productivities, respectively, were obtained under the best operating conditions. Results of the agitated bioreactor studies were analysed by fitting the data into the Mercier’s kinetic model and the high value of regression coefficients (≥0.93) indicated excellent agreement between the experimental values and model predictions. The results were also used to present a metabolic pathway and carry out a mass balance analysis for biobutanol fermentation.
Human beings have been using fossil fuels for their energy needs since long. Reducing availability of these non-renewable energy sources due to increasing consumption and resultant adverse effects on ...the environment has led researchers to focus on renewable and cleaner energy alternatives. Hydrogen is one such promising option which can serve as a renewable and cleaner alternative to conventional fossil fuels. Water-gas shift (WGS) reaction is currently widely employed to produce hydrogen from fossil carbonaceous as well as renewable biomass feed-stocks. WGS reaction involves reaction between CO and water over a suitable catalyst to enrich the gaseous mixture with H2. Traditionally, iron-chromium (Fe-Cr) and copper-zinc (Cu-Zn) catalysts have been used to facilitate the reaction at high and low temperatures, respectively. But over the years, WGS reaction catalyst technology has advanced dramatically and has been suitably modified to assist the reaction even in the medium temperature range and achieve higher CO conversion. Most of the current research is focused on ceria (CeO2) based WGS catalysts because of their unique favorable properties. Furthermore, there have been an ever-increasing number of recent studies which deal with fabricating nano-structured catalysts for WGS reaction because of the advantages offered by nano-materials over conventional materials. This review gives a progressive account of the evolution of WGS catalysts over the years with focus on those that are currently being investigated for better performances.
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