Waste Recovery through Thermochemical Conversion Technologies: A Case Study with Several Portuguese Agroforestry By-Products

Agroforestry waste stores a considerable amount of energy that can be used. Portugal has great potential to produce bioenergy. The waste generated during agricultural production and forestry operation processes can be used for energy generation, and it can be used either in the form in which it is collected, or it can be processed using thermochemical conversion technologies, such as torrefaction. This work aimed to characterize the properties of a set of residues from agroforestry activities, namely rice husk, almond husk, kiwi pruning, vine pruning, olive pomace, and pine woodchips. To characterize the different materials, both as-collected and after being subjected to a torrefaction process at 300 °C, thermogravimetric analyses were carried out to determine the moisture content, ash content, fixed carbon content, and the content of volatile substances; elementary analyses were performed to determine the levels of carbon, nitrogen, hydrogen, and oxygen, and the high and low heating values were determined. With these assumptions, it was observed that each form of residual biomass had different characteristics, which are important to know when adapting to conversion technology, and they also had different degrees of efficiency, that is, the amount of energy generated and potentially used when analyzing all factors.

Liquefaction of almond husk for assessment as feedstock to obtain valuable bio-oils

Almond husk liquefaction can be envisaged as an alternative to fossil sources which are becoming exhausted. Lately, the polyols obtain from the lignocellulosic biomass have been under investigation for the production of sustainable chemicals, fuel, materials or other commodities. Within this context, acid-catalyzed liquefaction of such lignocellulosic biomass has been successfully used to access highly functionalized compounds that can be used to replace those produced from petroleum. Almond shells waste can be considered to be part of the lignocellulosic biomass. Its main constituents of are cellulose, hemicellulose, and lignin. In this assay, the biochemical composition of almond husk was estimated based on atomic mass balances, and at the same time, the pyrolysis outcome was also estimated using a kinetic model using some reference compounds. In order to evaluate the use of almond waste as a substrate for acid-catalyzed liquefaction, the most favorable conditions of the liquefaction process were investigated. To better understand the liquefaction process, response surface methodology, in particular, central composite face-centered factorial design was used to set an array of 17 experiments including three replications at the center point leading to the development of a reaction model for further prediction and optimization of the liquefaction outcome. The effect of temperature (120–150 °C), time (20–200 min) and catalyst amount (0.5–5 wt. %) was investigated and a predictive model established.

Study of Adsorption Phenomena by Using Almond Husk for Removal of Aqueous Dyes

Among air and soil, water pollution is considered as an important one. Deterioration of water resources by the addition of various pollutants leads to the major threat to water quality and use of water for domestic purpose which leads to unaesthetic. For the plants, animals and human beings dyes are considered as most hazardous among various water pollutants. The present paper describes the adsorption behaviour of adsorbent almond husk with respect to dyes of Crystal violet, Bromocresol green, Pararosaniline and Victoria blue was investigated. The batch method was used and parameters like pH, adsorbent dosage, contact time and initial and final concentration of dyes were studied. Adsorbent used to be effective, with total removal of all dyes of 90%, with higher percentage removal from bromocresol green 97.5%, Crystal violet 96.9%, Pararosaniline 95.6% and Victoria blue 95%. Almond husk was an effective adsorbent with maximum percentage removal of 97.5% bromocresol green. Adsorbent was analysed by the instrument of scanning electron microscopy and Fourier infrared spectroscopy. In the present study almond husk almond husk was studied as a very good adsorbent for the removal of dyes from the aqueous media. Isotherm model of Langmuir, Freundlich and Dubinin-Radushkevich were considered to be favourable.

Aprovechamiento de residuos orgánicos (cáscara de almendra) para sustitución de árido grueso en la elaboración de hormigón convencional = Use of organic waste (almond shell) to replace coarse aggregate in conventional concrete processing

ResumenEl presente trabajo, busca conocer el posible aprovechamiento de residuos orgánicos, como es la cáscara de almendra, como sustitución de una parte de la fracción granulométrica del árido grueso para la fabricación de hormigones convencionales. Para ello, primero, caracterizamos los materiales, árido y cascara de almendra. Posteriormente, fabricamos las probetas de hormigón con distintas sustituciones (10%, 20% y 30%) de cáscara de almendra sobre la fracción gruesa del árido y procedemos a la realización de los ensayos marcados por las normas UNE, evaluando su comportamiento a compresión, tracción, flexión, penetración de agua, absorción de agua, hielo y deshielo y térmico.AbstractThe present work seeks to know the possible use of organic residues, such as the almond husk, as a substitution of a part of the granulometric fraction of the coarse aggregate for the manufacture of conventional concretes. For this, first, we characterize the materials, arid and almond husk. Subsequently, we made the concrete samples with different substitutions (10%, 20% and 30%) of almond shell on the coarse fraction of the aggregate and proceed to the tests marked by UNE standards, evaluating their behavior to compression, Traction, flexion, water penetration, water absorption, ice and melt and thermal.

Efficient Removal of Dyes Using Almond Husk as a Natural Adsorbent

<div><p><em>Industrialization and urbanization is considered as, one of major threat to pollution of air, soil and water systems. Among these, water pollution is considered as important one. The addition of various pollutants to water resources is considered as major threat for deterioration of water quality and makes it unsuitable for domestic purposes. Out of many water pollutants, dyes are considered as most hazardous for the plants, animals and human beings. So, it is very important to conserve water due to limited availability. In the present study, almond husk was neutraceutical spent used as adsorbent for the removal of dyes from aqueous solutions in batch mode experiments. Parameters like contact time, pH, adsorbent concentration, adsorbent dose were studied. The results show that, almond husk is a very good adsorbent for the removal of dyes from the aqueous medium. The adsorption isotherms like Freudlich and Langmuir model were calculated and found to be favorable. </em></p></div>

Temperature dependent, shape variant synthesis of photoluminescent and biocompatible carbon nanostructures from almond husk for applications in dye removal

The effect of the carbonization temperature on the morphology and properties of synthesized water soluble photoluminescent carbon nanostructures from almond husks have been investigated.