Cleaner Materials最新文献

The main objective of this study is to review the applicability of rapeseed straw (RSS) as a sustainable filler material in polylactic acid (PLA)-based biocomposites. The effect of different RSS particle sizes and concentrations (0–20 wt%) on the mechanical, morphological, thermal, and water absorption properties was investigated. The composites were fabricated by melt compounding using a twin-screw extruder followed by injection molding. The mechanical properties were analyzed through tensile and flexural tests and Charpy impact tests. The morphology of the samples was investigated by scanning electron microscopy (SEM). The thermal properties and the crystallinity of the composites were determined through differential scanning calorimetry (DSC). Mechanical properties revealed an increasing stiffness of PLA as a function of RSS loading, albeit at the cost of strength. SEM images have shown a limited interfacial adhesion between PLA and the straw, which was suggested to be responsible for the decreased strength values. Based on the DSC measurements, the RSS fibers facilitated the nucleation in the composites, thereby decreasing the cold crystallization temperature of PLA. The conducted experiments demonstrated that environmentally friendly and economically attractive biocomposites can be fabricated by substituting part of the PLA with RSS as a lignocellulosic by-product.

Se nanoparticles (NPs) with smaller size often exhibit higher antibacterial activity, thus size control of Se NPs is important to develop its application in the antibacterial field. In this study, Se NPs loaded attapulgite (APT) nanocomposites (Se/APT) were successfully prepared by a one-pot green method mediated by Aloe vera leaf extract, for which APT acts as a support to anchor Se NPs leading to the formation of small-sized and dispersed Se NPs. Structure characterization showed that the well-crystalline Se NPs with a size range of 1 ∼ 3 nm were uniformly distributed on the surface of APT nanorods. Antibacterial activities of the Se/APT nanocomposites were examined against S. aureus, and the result showed that the higher the Se loadings, the better the antibacterial activities of the nanocomposites, and the minimum inhibitory concentration of Se/APT-40% nanocomposite was up to 0.5 mg/mL. In addition, the green-synthesized nanocomposites have little cytotoxicity on mouse fibroblast cell L-929, and conversely promoted the growth and proliferation of the cells. The nanocomposites are expected to be candidates used in various antibacterial fields for preventing infections induced by S. aureus, such as suppuration of the wound.

The Government of Mauritius has come up with new regulations in an attempt to ban the use of petroleum based plastics bags so as to protect the environment. Hence it is important to find substitute materials to achieve this goal set by the government. Interestingly though, Mauritius being an island with a large Exclusive Economic Zone (EEZ), there is an abundancy of seaweeds, which is an interesting avenue to explore. The unexploited seaweed in the waters surrounding Mauritius remains a remarkably potential raw material for the manufacture of an alternative to petro-plastics, especially polypropylene non-woven bags, in the form of reusable and fully biodegradable bioplastic bags. This research attempts to investigate the use of algae, mainly Gracilaria Salicornia and Ulva lactuca as a potential; raw material for the production of reusable bioplastic bags through Taguchi optimisation method for the culling of optimum constituent wt.%. For the preparation of the biofilm to be solution casted, cassava starch, algae powder, glycerol and acetic acid were selected as controllable factors. The Taguchi L9 orthogonal array experimental design plan was considered for carrying out the experiments. The responses analysed were the tensile strength, water absorption, biodegradation and water vapour permeability. A maximum tensile strength and degradation of 7.325 MPa and 91.32% respectively were achieved from Taguchi optimal conditions. A maximum water absorption and minimum water vapour permeability of 60.3 % and 3.0181 g/h.m² respectively were evaluated from the experiments. Contribution of factors to the responses were determined through analysis of variance. Furthermore, regression models and contour plots were developed for predicting the best combination which was determined to be 8 % (w/v) starch, 3 % (w/v) algae, 1 % (w/v) glycerol and 8 % (w/v) acetic. An Ulva lactuca blend was experimented to act as substitute for cassava starch, achieving a tensile strength and water absorption of 3.578 MPa and 175.0 % respectively. Compared to other materials, used for bag production, available on the market, the mechanical properties of the developed algae-based material showed its potential as a replacement with some having much higher tensile strength confirming its successful usage.

This paper presents an experimental study of the strength and suction development of cemented paste backfill (CPB), which is an innovative cementitious construction material for mining (made by recycling mine waste into a construction material), and modified with nanoparticle (NP) additives. The effects of different amounts of four types of NP additives, including nano-silica (SiO₂), nano-calcium carbonate (CaCO₃), nano-iron oxide (Fe₂O₃), and nano-aluminum oxide (Al₂O₃), on the key engineering properties of CPB are investigated. An ether-based polycarboxylate superplasticizer (SP) is added to the backfill to help the NPs to better disperse in the mixture. Ordinary Portland cement is used as the binder in the CPB mixture. Uniaxial compressive tests (UCS) are conducted to determine the strength of the CPB, while suction monitoring experiments are performed to evaluate changes in suction with time. To understand the effects of the NP additives, different microstructural analyses and tests, including thermal analyses (thermogravimetry (TG), differential thermogravimetry (DTG)), mercury intrusion porosimetry (MIP), and X-ray diffraction (XRD) are conducted on the nano-CPB and the cement paste of nano-CPB. The results indicate that the addition of NP additives in the absence of SP results in lower strength due to high likelihood of agglomeration. In contrast, samples with SP and NP additives show a higher UCS and more suction than the control sample at the early ages of curing. It has been observed that the addition of NP additives results in the generation of more hydration products which enhance the interparticle friction and packing density of the CPB structure. Higher strength is obtained by increasing the SP content (0.25%) with the same NP content (1%). Enhancement of the strength of CPB and increase in suction, particularly at early ages, can have great importance in speeding up the mining cycle and thus increasing mining productivity, which is obviously associated with financial benefits to the mine.

Waste management is becoming increasingly important around the world, and incorporating agro-waste into the pavement industry represents a promising strategy for achieving sustainability while improving mixture properties. In this study, we optimize and determine the optimum asphalt binder content of asphalt concrete mixtures modified with waste palm oil clinker powder (WPOCP) and waste rice straw ash (WRSA) to improve their engineering properties. To optimize the interactions between three independent variables (asphalt binder, WPOCP, and WRSA content) on mixture bulk unit weight (BUW), void in the total mix (VTM), Marshall stability, and flow values, the Marshall mix design approach and response surface methodology (RSM) with a Box-Behnken design were used. WPOCP samples containing 2%, 4%, 6%, and 8% by weight of asphalt mixtures were prepared, as were WRSA samples containing 25%, 50%, 75%, and 100% by weight of filler, with asphalt binder content ranging from 4 to 6% by weight of the mix. The statistical model results show that all responses were significant, with high coefficients of correlation (R2) of 0.9840, 0.9971, 0.9920, and 0.9891 for the BUW, VTM, Marshall stability, and flow, respectively. Individual effects of the input variables and synergistic interactions between the three variables were observed to influence all of the responses. Numerical optimization produced optimum WPOCP, WRSA, and asphalt content values of 8%, 74%, and 5%, respectively. The mean error for all responses was less than 5%, indicating that predicted values agree well with experimental data and that generated models accurately reflect experimental results. Based on the findings of the study, it can be concluded that RSM is an effective method for determining the optimal asphalt binder and modifier content in asphalt mixtures. It enables the identification of the most important variables influencing the response of the asphalt mixture and enables mixture optimization for improved performance. Furthermore, incorporating WPOCP and WRSA into asphalt mixtures was found to improve both volumetric and Marshall properties, resulting in a more sustainable approach in the pavement industry.

The high cost and recycling issues of common separators as the main components of Microbial fuel cells (MFCs) have slowed down the development of MFCs recently. In this paper, a polypropylene membrane is proposed as an inexpensive membrane that can be recycled with lower environmental impacts. An experiment is performed in a dual-chamber microbial fuel cell to investigate and compare the proposed membrane effectiveness to Nafion117. The dual-chamber MFC was used because of its ease of use. A mixture of microbes and glucose was fed to the cell during the experiment. The internal resistance and coulombic efficiency are calculated by measuring the circuit voltage, power density, and open-circuit voltage to monitor the performance. The maximum output voltage of 500 mV was attained at a resistance of 380 kΩ. Furthermore, the maximum output power density was 0.7 mW.m⁻², which occurred for 3.3 mA.m⁻².

Food-waste out of household consumption ends up in landfills resulting into huge waste of materials and energy enhancing greenhouse effect and threatening water supplies. Composting is common solution for solid organic waste management and can safely and effectively be employed in each household to produce quality compost materials. This study palpates the average composition of the Mediterranean dietary pattern food-wastes and investigates the efficiency of a novel home-composter in managing organic wastes from dish to composter to quality compost. Four different additives, low cost and easily found in the market, are addressed, (1) woodchip, (2) woodchips & zeolite, (3) woodchips & vermiculite and (4) perlite. C/N≈20 substrate’s composition is investigated.

Results indicate that the composting process effectively converts food-wastes to compost within 21 days. The monitored parameters show good aeration and humidity levels of the substrate and an aerobic process. The product exhibits minor alkalinity and requires further maturing. Mineral additives help reducing TOC with vermiculite and perlite be the most promising. Zeolite and vermiculite result in higher TKN values of the product with zeolite exhibiting better performance. All minerals enchance C/N reduction when woodchips is proven inadequate as an additive if employed alone. The product can safely be used in domestic applications.

The concrete industry is facing significant challenges in substantially reducing CO₂ emissions, recycling waste materials and limiting the use of resources. Using ultra-high-performance concrete (UHPC) is one of the many possible solutions to reduce the environmental impact of the concrete industry. Numerous approaches have been applied to meet the challenges of making and utilising UHPC more environmentally friendly; however, an overall approach is lacking. This study aims to fill this gap by constructing a strategy for more sustainable use of UHPC. The strategy is developed by first evaluating measures known from the conventional concrete industry concerning transferability to the UHPC industry. Subsequently, the approach is enrichened with measures targeting the special composition and properties of UHPC. The strategy suggested in the conclusion consists of the following tools: efficient use of cement, efficient use of steel fibres, circularity: utilise by-products, local production, and efficient use of UHPC in structures.

The use of scrap tyres in construction materials has been promoted to curb the environmental exploitation caused by the open disposal of non-biodegradable waste rubber. Tyre grinds as aggregates in geopolymer concrete (GPC) would increase its sustainability value by reducing the consumption of natural aggregates. Although there is limited literature addressing the damage to GPC characteristics caused by rubber aggregates, this investigation was designed to determine the extent of possible side effects of using crumb rubber (CR) in GPC. Additionally, this investigation aims to address any resulting reduction in strength and durability using additives such as cement and fibres. Geopolymer specimens with CR replacement of fine aggregates by volume (0, 5, 10 and 15%) showed a compressive strength reduction of up to 17% when tested according to ASTM standards. Substituting the total binder by weight with Ordinary Portland cement (OPC) (0%, 5%, 10%, 15%, and 20%) improved the microstructural integrity of the rubberised geopolymer mix with the highest percentage of OPC. Despite producing new and additional binding products (CSH and CASH gels), the GPC surface readily disintegrated under acid exposure. Optimum glass fibres (GF) reinforcement (0.30%) effectively disrupted the GPC pore network, consequently reducing the acid permeability of the matrix. Further addition of steel fibres (SF) enhanced the GPC specimen's compressive and flexural strength. To analyse the cumulative effect of these additives on GPC microstructure, supporting tests such as scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy were carried out. Although these additives enhanced the overall performance of rubberised geopolymer, it might somewhat reduce its green aspect.

Sorghum stalks and other agricultural residues in excess of farmers animal feed requirements are often burnt, contributing to environmental pollution. On the other hand, such residues could serve as useful sources of fibre with different applications. The aim of this study was to investigate agricultural residue-based fibres (ARFs), using sorghum stalks as a model, for use as reinforcements in recycled low-density polyethylene (rLDPE) for the manufacture of agricultural residue-based fibre reinforced polymer composites (ARFRPCs). Thermo-alkali and thermo-laccase fibre modification treatments were employed to improve the properties of the ARFRPCs. The thermal conductivity values of the ARFRPCs at 0.23 – 0.3 W/m‧k are higher than some commercially available insulators. Moreover, thermo-alkali reinforced ARFRPCs exhibited a tensile strength of 28.57 Mpa and improved microstructure/interfacial adhesion relative to intreated and thermo-laccase treated samples. The conclusion is that thermo-alkali reinforced ARFRPCs, which was treated for 10 days, be used for non-structural applications in buildings.