Suchergebnisse

As a developing country, Bangladesh has to face numerous challenges. Self Independence in electricity, contributing to climate change by reducing carbon emission and bringing the backward population of society to the mainstream is more challenging for them. Therefore, it is essential to ensure recycled use of local products to the maximum level in every sector. Some private organizations have already worked alongside government to bring the backward population to the mainstream by developing their financial capacities. As rice husk is the largest single category of the total energy supply in Bangladesh. As part of this strategy, rice husk can play a great as a promising renewable energy source, which is readily available, has considerable environmental benefits and can produce electricity and ensure multiple uses of byproducts in construction technology. For the first time in Bangladesh, an experimental multidimensional project depending on Rice Husk Electricity and Rice Husk Ash (RHA) concrete brick/block under Green Eco-Tech Limited has already been started. Project analysis, opportunity, sustainability, the high monitoring component, limitations and finally evaluated data reflecting the viability of establishing more projects using rice husk are discussed in this paper. The by-product of rice husk from the production of green electricity, RHA, can be used for making, in particular, RHA concrete brick/block in Bangladeshi aspects is also discussed here.

The performance of a sustainable green concrete with fly ash (FA), rice husk ash (RHA), and stone dust (SD) as a partial replacement of cement and sand was experimentally explored. FA and RHA have a high silica content, are highly pozzolanic in nature and have a high surface area without any treatment. These by-products show filler effects, which enhance concrete's density. Results showed that the FA and RHA materials have good hydration behaviour and effectively develop strength at an early age of concrete. SD acts as a stress transferring medium within concrete, thereby allowing the concrete to be stronger in compression, and bending. Consequently, water absorption capacity of the sustainable concrete was lower than that of the ordinary one. However, a little reduction in strength was observed after the replacement of the binder and aggregate using the FA, RHA and SD, but the reduction was insignificant. The reinforced structure with sustainable concrete containing the FA, RHA, and SD generally fails in concrete crushing tests initiated by flexural cracking followed by shear cracks. The sustainable concrete could be categorized as a perfect material with no significant conciliation in strength properties and can be applied to design under-reinforced elements for a low-to-moderate service load.

AbstractA study on the removal of hexavalent chromium by adsorption of rice husk nanosilica was attempted. The usage of chromium causes immense pollution as it is used in the leather industry, metal finishing, electroplating, and chromate preparations. To understand the adsorption capacity and its behavior, as well as the adsorption potential of rice husk nanosilica, the effluent used in this experiment is tannery wastewater. The experiment was conducted in tannery industrial wastewater using nanosilica extracted from rice husks ash for various pH, contact time, and adsorbent dosages. The result shows 88.3% chromium removal using rice husk ash nanosilica (RHANS) at pH 4, 1.75 mg adsorbent dosage, and 50 min of contact time. Removal of chromium by this method was a more economical and alternative process. RHANS was selected due to its source availability and antimicrobial properties.

The commercial use of coffee (Coffea arabica) husks, one of the major solid residues obtained during the dry processing of coffee, has previously been considered unprofitable. However, coffee husks are an excellent source of stable anthocyanins that have antioxidative, anti-inflammatory, and cardioprotective properties. The present work identified two anthocyanins, cyanidin-3-glucoside and cyanidin-3-rutinoside, from coffee husks by high-performance liquid chromatography and liquid chromatography-mass spectrometry. The antioxidant capabilities were tested by quenching free radical scavenge assay, reducing power, and ORAC assay at 50, 100, 150, 200 mg/L of coffee husk anthocyanins (CHAs). Moreover, the effects of different concentrations of CHAs on superoxide dismutase (SOD) and lactate acid dehydrogenase (LDH), and the concentration of malondialdehyde (MDA) in human umbilical vein endothelial cells exposed to hydrogen peroxide were also evaluated. Human colon cancer (Caco-2) cell apoptosis induced by CHAs was examined by flow cytometry. Based on the results, CHAs showed strong dose-dependent antioxidant activities, and could increase SOD activity, and suppress indicators for oxidative injuries such as MDA and LDH. Furthermore, the proportion of apoptotic Caco-2 cells ranged from 4.12 to 41.3% in response to treatment with different concentrations of CHAs. These results suggest that CHAs exhibit antioxidant and pro-apoptosis activities.

The objective of this study was to evaluate the efficacy of replacing oat hay with coffee husk for the feeding of confined lambs. In this study, 24 male Texel lambs of approximately 60 days of age and with a mean ± standard error weight of 21.95 ± 5.81 kg were examined. Their diet was composed of 30% oat hay and 70% concentrated feed per kilogram of dry matter. The experimental design was randomized and included four treatments (0, 7.5, 15, and 22.5% of coffee husk in the total dry matter), with six replicates of each treatment. The animals were slaughtered when they reached a mean live weight of 32 kg. There was no significant difference in dry matter intake and mean daily weight gain (which were 197 g day-1) among treatments. The mean daily weight gain (DWG) was not significantly affected (P > 0.05) by the replacement of oat hay with coffee husk in the diet, with the overall mean DWG being 215.05 g day-1. There were no significant differences (P > 0.05) among treatments in any of the studied carcass variables, and the mean true carcass yield was 53.9%. The lambs presented a mean finishing score of 2.96 (on a scale of 1 to 5) and a conformation of 4.21 (on a scale of 1 to 6), characterizing them as good carcasses. In terms of economic viability, the 7.5% diet stood out as the one that had the highest profitability, generating a profit of $ 3.25 USD per kg of carcass produced. Coffee husk can therefore replace oat hay in the feed of finishing lambs in concentrations of 0.075 to 0.225 kg kg-¹ of total dry matter with biological and economical efficacy and generating good commercial carcasses.

Geopolymers simultaneously containing two waste materials have been developed: fluid catalytic cracking catalyst (FCC) as mineral admixture and rice husk ash (RHA) for preparing an alkaline activator. Alkaline activators were prepared by refluxing aqueous mixtures of ground or original RHA with NaOH. All mortars with alkaline activator containing RHA show compressive strength (cured at 65 °C for 1 day) in the range of 31 41 MPa, which is similar to control mortar prepared using an equivalent mixture of NaOH and water glass. Refluxing times between 30 and 240 min yielded good performance mortars. This new way of valorisation would imply economic and environmental benefits in geopolymer production. ; GEOCEDEM Project BIA 2011-26947 was financed by Spanish Government, Project 3018/2009 was financed by Generalitat Valenciana, Project AP/35235/11 was financed by AECID, COMBURES Project was financed by Centro de Cooperacion al Desarrollo de la Universitat Politecnica de Valencia ADSIDEO COOPERACIO and OMYA Clariana S.A. and Maicerias Espanolas DACSA S.A. supplied FCC and RHA samples respectively. ; Bouzón, N.; Paya Bernabeu, JJ.; Borrachero Rosado, MV.; Soriano Martínez, L.; Mitsuuchi Tashima, M.; Monzó Balbuena, JM. (2014). Refluxed rice husk ash/NaOH suspension for preparing alkali activated binders. Materials Letters. 115:72-74. https://doi.org/10.1016/j.matlet.2013.10.001 ; S ; 72 ; 74 ; 115

This study investigated the geotechnical and microstructural properties of cement-treated laterites stabilized with rice husk ash and bamboo leaf ash. In going about the tests, the soil sample was subjected to compaction, California Bearing Ratio (CBR) and preliminary tests; such as specific gravity, particle size distribution and Atterbergs limits to determine its index properties. Thereafter, the soil sample was mixed with cement at varying proportions of 0–12% at 2% intervals and also, separately mixed with bamboo leaf ash (BLA) and rice husk ash (RHA) in proportions of 0–16% at 2% intervals. The mixes at each stage were subjected to compaction, Atterberg limits and CBR tests. The highest values were 66.7% and 54.8% for unsoaked and soaked CBR at 6% cement+8% BLA and 78.5% and 63.8% for unsoaked and soaked CBR at 8% cement+8% RHA. Samples at these optimal CBR values were subjected into Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD) tests. Results showed that new compounds were formed and there were changes in the microstructural arrangements. It can therefore be concluded that pozzolanic and cement hydration reactions actually took place in the course of stabilization.

Thermal characterization of coffee husk (Coffea arabica) from Colombian coffee has been studied. Different products, mostly volatile and semivolatile compounds, were analyzed, paying special attention to 16 polycyclic aromatic hydrocarbons (PAHs) classified by the United States Environmental Protection Agency (U.S. EPA) as priority pollutants, frequently used for checking toxicity in environmental samples. A fixed amount of raw material was exposed to different excess air ratios (λ = 0–2.33) and nominal temperature of 1123 K in a horizontal quartz reactor. The results show that coffee husk is a promising biomass for energetic exploitation with reduced formation of PAHs in a low air excess ratio. This implies reduction of carcinogenic potential in the limited presence of oxygen, demonstrated by calculating the carcinogenic potential (KE) for each experimental condition. Most volatile and semivolatile compounds followed different trends, with the oxygen presence prevailing their decomposition with increasing the air excess ratio. ; Nazly E. Sánchez acknowledges the Colombian Government, Project InnovAcción Cauca, and Corporación Universitaria Autónoma del Cauca for her financial support of the research stay in Alicante, Spain. Financial support for this experimental work was provided by the CTQ2013-41006-R Project from the Ministry of Economy and Competitiveness (Spain) and the PROMETEOII/2014/007 Project from the Valencian Community Government (Spain).