Microwave pretreatment is a promising and unsophisticated technique for energy recovery in solid waste management. The present investigation was focused on microwave activated carbonization of mixed solid waste (MSW). The effect of process parameters such as size of particles, temperature and duration of carbonization, microwave output power for pretreatment, irradiation time and amount of additives added during microwave heating were studied. The most important factors that influenced MW drying (pre-treatment) were found to be the sample mass and the Microwave output power. Microwave induced carbonization not only overcomes the disadvantages of conventional heating method such as low heat transfer rate but also improves the quality of final carbonization products. © 2017 Elsevier Ltd.

Mahesh Ganesapillai

Department of Chemical Engineering

School of Chemical Engineering

Vellore Campus

Kumar V

Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

Materials Today: Proceedings

To highlight the shortcomings in conventional methods of extraction, this study investigates the efficacy of Microwave Assisted Extraction (MAE) toward bioactive compound recovery from pharmaceutically-significant medicinal plants, Adathoda vasica and Cymbopogon citratus. Initially, the microwave (MW) drying behavior of the plant leaves was investigated at different sample loadings, MW power and drying time. Kinetics was analyzed through empirical modeling of drying data against 10 conventional thin-layer drying equations that were further improvised through the incorporation of Arrhenius, exponential and linear-type expressions. 81 semi-empirical Midilli equations were derived and subjected to non-linear regression to arrive at the characteristic drying equations. Bioactive compounds recovery from the leaves was examined under various parameters through a comparative approach that studied MAE against Soxhlet extraction. MAE of A. vasica reported similar yields although drastic reduction in extraction time (210 s) as against the average time of 10 h in the Soxhlet apparatus. Extract yield for MAE of C. citratus was higher than the conventional process with optimal parameters determined to be 20 g sample load, 1:20 sample/solvent ratio, extraction time of 150 s and 300 W output power. Scanning Electron Microscopy and Fourier Transform Infrared Spectroscopy were performed to depict changes in internal leaf morphology. © 2015 Faculty of Engineering, Alexandria University.

Fulltext

Alexandria Engineering Journal

Empirical modeling of drying kinetics and microwave assisted extraction of bioactive compounds from Adathoda vasica and Cymbopogon citratus

Pyrolysis is considered to be a sustainable energy technology and is practiced widely in waste management. In this study, three issues were explored: (a) the implication of crude glycerol addition to lignocellulosic biomass in pyrolysis, (b) the effect of microwave pretreatment on the pyrolysis product yields and (c) study of pyrolysis parameters and assessment of products quality. Characterization of the above glycerol-biomass mixtures along with pyrolysis products was performed by ICP-OES, SEM, EDX and GC techniques. It was resulted that higher liquid yield (max 59.53% v/v) obtained by pyrolysis of pretreated mixtures at 500 °C, compared to pyrolysis yields of non-pretreated mixtures, due to the prevalence of recombination reactions in pyrolysis of the microwave-pretreated mixtures. The gas produced from the microwave pretreated feedstock-based pyrolysis showed an enriched syngas (H2 + CO) concentration (84.9% v/v), compared to the non-microwave pretreated samples (79.1% v/v), at 720 °C. No significant effect, either on the char yields or on the char structural characteristics were observed. Consequently, microwave pretreatment before pyrolysis, can serve as a potential pretreatment for enhanced production of fuels via post-pyrolysis. © 2015 Elsevier Ltd. All rights reserved.

Energy Conversion and Management

Effect of microwave pretreatment on pyrolysis of crude glycerol–olive kernel alternative fuels

Walnut (Julgans regia L.) shells, an agro-forestry waste, are a rich source of phytochemicals with anti-oxidative and medicinal properties. Whilst recent research efforts focus on waste valorization, the present investigation demonstrates a process to extract and characterize bio-components from physically pretreated walnut shells. Pretreatment was undertaken using microwave irradiation and ultra-sonication with two different solvents (methanol and acetone). The extract obtained was optimized using Response Surface Methodology (RSM). Further, the bio-components in the extract were identified using GCMS and FTIR analyses. Through the experimental runs, it was observed that pretreatment enhanced the total extract yield from the process relative to conventional Soxhlet extraction. As a method of pretreatment, microwave irradiation was found to suit the extraction better than ultra-sonication. In addition, acetone performed better as a solvent than methanol in the bio-components recovery. Relative to conventional Soxhlet extraction, microwave pretreatment allowed for enhanced separation by 4.06 folds for methanol and 5.25 for acetone. The yield was found to be the highest (46 mg/g) while using acetone, when pretreated with microwaves at 180 W for 4 min. © 2016, Technical University of Budapest. All rights reserved.

Periodica Polytechnica Chemical Engineering

Influence of Microwave and Ultrasound pretreatment on Solvent Extraction of Bio-components from Walnut (Julgans regia L.) Shells

As a solution to the drawbacks of modern sanitation systems and to shift towards a recycling society, source separation of human wastes coupled with resource recovery could be seen as a potential solution. In this research, microwave activated coconut shells were utilized to recover urea from human urine. Batch adsorption studies were carried out to determine the effect of initial concentration, adsorption temperature, microwave output power and irradiation time on the urea uptake capacity of the tailored activated carbon. The shells pretreated with microwave irradiation of 360 W, for 15 min (MACCS-360W-15) shown to be promising adsorbents with BET surface area &gt;1000 m2 g-1. The sorption data were tested against different isotherm models and found to closely follow Langmuir isotherm with a maximum monolayer sorption capacity of 312 mg g-1. Kinetic data over temperature range of 30-60 °C was found to closely follow pseudo-first-order at all adsorbate concentrations. Gibbs free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) indicated the spontaneity and physical nature of the sorption; sorption experiments indicated a urea recovery of ~95% from urine. Finally, the application of urea adsorbed carbon as a soil conditioner in field trials resulted in significant improvement in the number of seed germination and plant biomass (132%) with a substantial increase in the soil nitrogen and cation exchange capacity. Results also indicated that nearly all the urea was desorbed within the soil during irrigation becoming readily available to the plants. This study demonstrates a closed-loop sanitation cycle that channels nutrients from human beings back to agricultural fields. © 2015 The Institution of Chemical Engineers.

Sustainable Production and Consumption

Closed-loop fertility cycle: Realizing sustainability in sanitation and agricultural production through the design and implementation of nutrient recovery systems for human urine

Microwave Activated Carbonized Coconut Shell (MACCS) was used to recover urea from human urine. Batch adsorption studies were conducted to evaluate the effect of initial adsorbate concentration (25%-100%), contact time, carbon loading (1-3 g) and shaking speed (150-200 rpm) on the removal of urea at 30 C. Microwave activation was performed at 180 W (microwave output power) for 10 min. The sorption data were fitted to Langmuir, Freundlich, Tempkin, Flory-Huggins and Dubinin-Radushkevich isotherm models. Results showed that the maximum monolayer adsorption capacity of the MACCS powder was 256.41 mg g-1. The Flory-Huggins model was found to best describe the urea uptake process since it demonstrated the minimum deviations from the experimental data. The kinetic data was fitted to pseudo-first-order, pseudo-second-order and intra-particle diffusion models, and was found to follow closely the pseudo-first order kinetic model. Based on the Central Composite Rotary Design, a five factor interaction model and a quadratic model were respectively developed to correlate the adsorption variables to the adsorption capacity. Field studies were conducted to determine the percentage biomass increase and relative agronomic effectiveness for soil treated with the urea adsorbed MACCS powder. Microwave activated carbonized coconut shell was shown to be a promising adsorbent for recovery and removal of urea from human urine solutions. © 2013 Elsevier Ltd.

Journal of Environmental Chemical Engineering

Recovering urea from human urine by bio-sorption onto Microwave Activated Carbonized Coconut Shells: Equilibrium, kinetics, optimization and field studies

Journal	Data powered by TypesetMaterials Today: Proceedings
Publisher	Data powered by TypesetElsevier BV
ISSN	2214-7853
Open Access	0