Waste Composite Materials Research Articles

Insight into the photothermal boosted ofloxacin removal by magnetic CuFe2O4/pyrite waste catalyst: Mechanism, degradation pathways, and toxicity evaluation

The widespread distribution of antibiotics in natural waters has raised global concerns due to their potential threat to the aquatic environment. In this study, 40 %-CuFe2O4/pyrite waste composite material was constructed for the removal of ofloxacin (OFX) through activating H2O2 in photothermal Fenton processes. It had excellent photothermal conversion performance and could serve as a superior photothermal-Fenton catalyst. The removal efficiency of OFX was 96.13 % in the photothermal Fenton reaction, and the apparent first-order kinetics rate constant (k) was 4.33 and 12.15 times higher than in the traditional Fenton without light and 40 %-Fe/PW photothermal Fenton reaction. This could be attributed to the introduction of photothermal effect promoted collisions between substances, and expedited the reaction rate. The redox cycle of Fe(II)/Fe(III) and Cu(I)/Cu(II) in the Cu-Fe bimetal system also contributed to the removal of OFX. Besides, it exhibited excellent cycling stability, extensive adaptability for various pollutants and water properties. The order of contribution of active radicals to the removal of OFX was ∙ OH>h+ >∙O2-, and they attacked the active atoms of OFX molecule with high Fukui index. Hopefully, this study may encourage the utilization of the photothermal effect for contaminant removal and introduce a novel perspective for environmental remediation.

Modified rare earth waste composite material for simultaneous denitrification and recovery of phosphate in water

Nitrogen and phosphorus discharged into water bodies with sewage are the main causes of water eutrophication.Currently,the adsorption method is a cost-effective and efficient denitrification and phosphorus removal technology. In this study, waste polishing powder, manganese dioxide and sepiolite are used as raw materials, and a novel adsorbent of Sep-pp-MnO2 is prepared through co-precipitation and redox methods for simultaneous removal of ammonia nitrogen and recovery of phosphate in water.The physicochemical properties of the adsorbent are characterised, and the adsorption performances and denitrification and phosphorus removal mechanisms are determined. Results showed that,at a temperature of 25°C and pH of 8, the maximum removal of ammonia nitrogen reaches 11.47 mg/g, while the adsorption capacity for phosphates is 14.93 mg/g. Adsorption mechanisms indicated that the removal mechanism of phosphate is ligand exchange, while the removal mechanism of ammonia nitrogen involves electrostatic attraction and oxidation to nitrogen. Recycling experiments showed that after five desorption cycles, the material could achieve a removal of 4.7 mg/g for ammonia nitrogen, an adsorption capacity of 8.25 mg/g for phosphate and a phosphate recovery rate of 55 % after desorption with 0.1 M NaOH solution. Municipal wastewater validation experiments demonstrated that when the dosage of Sep-pp-MnO2 was 4 g/L,Treated water met the Class B requirements of the comprehensive emission standard for pollutants from urban sewage treatment plants in China (GB18918–2002). This study explores a new method for efficient simultaneous nitrogen and phosphorus removal in water and provides a feasible idea for alleviating the shortage of phosphate rock resources.

A comparative study of expanded and raw cork waste composite materials

The use of cork waste in the development of construction materials is an interesting alternative for saving energy and preserving the environment. Cork has excellent thermal and acoustic properties, making it a common choice for building applications. This article presents a comparative study of composites based on expanded and raw cork (L) mixed with cement in C/L ratios of 1/1, 1/2, and 1/3. The physical, mechanical, thermal, and acoustic absorption properties of these composites were investigated. The results show that composites with expanded cork exhibit better compressive strength than those with raw cork. Expanded and raw cork-based compositions in a 1/3 ratio showed compressive strengths of 2.39MPa and 2.00MPa, respectively. However, the composite containing raw cork presents higher thermal conductivity and more favorable acoustic absorption coefficients. The results highlight the potential for using these composite materials as structural or non-structural components, depending on the volume of cork used

INVESTIGATING CHRYSOTILE ASBESTOS WASTE AS A POTENTIAL MATERIAL FOR SYNTHETIC ADSORBENTS

Technological methods have been developed to acquire an active component with a high SiO2 content, which serves as a matrix foundation for synthetic adsorbents made from chrysotile asbestos production waste composite materials. Comparative analyses were conducted between the obtained adsorbent and a zeolite adsorbent of the NaX model. The physico-chemical analyses unveiled that the synthetic adsorbent obtained is not inferior in any aspect, and in certain instances, even outperforms in the demetallization process of heavy petroleum raw materials. The demetallization process exhibits an optimal temperature range of 380-410 °C, with a contact time of 60 minutes and a pressure range of 8-10 atm. Concurrently, the concentration of vanadium in heavy crude oil decreases significantly from 540 to 28 micrograms per kilogram, while nickel content diminishes from 50 to 26 micrograms per kilogram. Moreover, iron content experiences a reduction from 50 to 12 micrograms per kilogram, and sulfur content decreases from 3.50 % to 2.39 %.

Preparation, mechanism, and application of silica fume–steel slag composite cementitious material based on the D-optimal mixture method

Steel slag and silica fume as cementitious materials to replace cement have been subjected to many recent investigations. However, the optimization of the mix ratio of silica fume–steel slag composite cementitious materials has rarely been reported. This study aims to design and optimize a novel composite cementitious material of the steel slag–silica fume–ordinary Portland cement (SSP) using the D-optimal mixture design (DOD) method. A DOD model was developed to determine the optimal mix ratio of SSP. Microscopic tests were conducted to investigate the synergistic effect of SSP. The mechanical properties of SSP-stabilized macadam and stone chips were evaluated using unconfined compressive strength (UCS), water stability, and split strength tests. The results indicate that the optimal content of steel slag in SSP was determined to be 16.238%, and that of silica fume was 1.917%. Silica fume consumes the Ca(OH)2 generated during hydration, and as a filler, it also provides nucleation sites for hydration reactions, promoting the secondary reaction to generate calcium silicate hydrate (C–S–H) gels wrapped around the steel slag particles, optimizing the pore structure and reducing the porosity of SSP. The SSP promoted the development of mechanical strength in the later stages. The greatest growth observed in SSP-stabilized stone chips, from 7 days to 28 days of curing, the UCS, water stability coefficient, and split strength increased by 62.6%, 9.9%, and 71% respectively. A significant correlation was observed between UCS and split strength, with UCS being approximately 9.0 to 9.8 times higher than the split strength. This study contributes to the optimal design of similar solid waste composite materials and provides a reference for the use of silica fume and steel slag in road construction.

Enhancing interfacial adhesion through coupling agent incorporation in plywood/ plastic waste composite materials

The objective this study was to fabricate 5-ply boards using virgin and recycled high-density polyethylene (vHDPE and rHDPE) films as formaldehyde-free adhesives, respectively. To enhance the interfacial adhesion between the wood veneer and HDPE film, various loadings (0, 3, 6, 8, and 11 wt%) of polyethylene grafted maleic anhydride (PE-g-MA) were applied as a coupling agent. The physical and mechanical performance of the resulting plywood boards was evaluated using standard test methods, with a UF resin-bonded plywood used as a control for comparison. All materials used were for commercial-scale plywood production. Fourier transform infrared spectroscopy (FT-IR) results provided valuable information about chemical interactions that occurred during the coupling of poplar fibers with HDPE using PE-g-MA. The experimental results showed that the mechanical and physical properties of the plywood boards improved as the amount of coupling agent increased from 0 to 11 wt%. PE-g-MA played a crucial role in the properties of plywood boards made with rHDPE and vHDPE by enhancing the interfacial bonding ability between the HDPE and adjacent veneers, leading to good stress propagation and improved mechanical properties. The properties of samples bonded with vHDPE were significantly more improved than those made with rHDPE, likely due to the presence of color pigments, additives, fillers, and impurities in the rHDPE, which made the coupling agent less effective. In addition, the results demonstrated that the samples made with rHDPE and vHDPE were superior to the plywood bonded with UF resin (control), and the optimal content of the coupling agent was found to be 8 and 11 wt%. These findings suggest that incorporating recycled HDPE films and using coupling agents, such as PE-g-MA, can produce high-quality plywood composite materials with improved mechanical and physical properties, providing an eco-friendly alternative to traditional UF resin-bonded plywood.

PHYSICAL CHARACTERIZATION OF STARCH-COTTON FIBER COMPOSITE SHEETS

Biobased materials had been identified as replacements for materials produced with chemical binders. Panels made from starch-cotton fiber waste composite materials fit perfectly into the category of biobased materials. The aim of this study was to measure the physical properties of starch-cotton fiber composite sheets. For sheets manufactured in 300x300x100mm3, the density and dimensional stability properties (water content, absorption rate, dimensional and volumetric swelling) were calculated. Density was determined in accordance with NF EN 323. Swellings were determined in accordance with EN 317. Water content was measured in accordance with EN 322. The sheets were manufactured with starch/water and starch/cotton fiber mass ratios respectfully equal to 0.25 and 1. We obtained an average water content of 4.27% and an absolute densityγs =1.13g/cm3. The average absorption coefficient measured was 62.88%. The measurement of dimensional variations showed that the panels underwent little deformation in the length and width directions. The average was 2%. In the thickness direction, on the other hand, dimensional variation was very high. This averaged 44%. The latter reflects the porosity of the material.

Recycling of both resin and fibre from wind turbine blade waste via small molecule-assisted dissolution

Wind energy has significant growth potential and applicability on a global scale, but approximately 2.4% of wind turbine blades must be decommissioned annually. The majority of blade components can be recycled; however, wind blades are rarely recycled. In the present study, an alternative method was presented involving a small molecule-assisted technique based on a dynamic reaction that dissolves waste composite materials containing ester groups to recycle end-of-life wind turbine blades. This effective process requires temperatures below 200 °C, and the major component, i.e., resin, can be easily dissolved. This method can be applied to recycle composite materials, such as wind turbine blades and carbon fibre composites comprising fibres and resins. Depending on the waste, up to 100% of the resin degradation yield can be achieved. The solution used for the recycling process may be reused multiple times and can be reused to obtain resin-based components and create a closed loop for this type of material.

HIGH STRENGTH MANGO LEAF WASTE/POLYURETHANE COMPOSITE REINFORCEMENT USING QUARTZ MATERIAL

Quartz stone contains silica components (SiO2) which have the ability as a reinforcement material for composite materials. Quartz SEM-EDX testing shows that the quartz silica comonent is 69%. Other components contained in quartz are 34% MgO and 2% CaO. Therefore, quartz stone is used as a reinforcing material in mango leaf waste composite materials. Meanwhile, compressive strength testing of composite materials was carried out with variations of Polyurethane (PU) polymers, namely 1, 2, 3, 4, 5, 6, and 7 grams, obtaining the highest maximum pressure at 6 grams polymer mass, which is 38.91 grams. Testing of composite materials that have been given a mixture of quartz stone with a mass of Polyurethane (PU) 6 grams and a quartz stone variation of 0.03; 0,06; 0,09; 0,12; 0,15; and 0.18 grams obtained the maximum power most optimally there is a quartz mass of 0.06 grams of 40.47 grams. The strength of mango leaf composite meets the strength standard for building materials, namely concrete with a value of 20-150 MPa. This shows that quartz stone can be a composite reinforcement comprehenent for mango leaf waste.

Analysis and prediction of plastic waste composite construction material properties using machine learning techniques

AbstractThe use of plastic‐based composites as building materials may be one method of recycling plastic waste. Plastic pollution has emerged as a global issue since our planet is becoming increasingly engulfed in plastic waste. In order to preserve a long‐term sustainable ecosystem, alternative methods of recycling this plastic trash would be extremely beneficial. In this study, the six attributes, which are ingredients used to make plastic composite construction material, are used to predict five target variables or properties of plastic composite construction material, such as compressive strength, flexural strength, split tensile strength, density, and water absorption. Five machine learning techniques random forest, Decision Tree, Ridge, Lasso, and Linear regression have been used to get the best prediction model for the properties of plastic composite construction material. The correlation method has been used to analyze the relationships among the properties and ingredients of plastic composite construction material. Analytical results for K‐fold cross‐validation show that random forest and decision tree form the best predictive models, having greater prediction accuracy than the rest of the machine learning algorithms. This pioneering work provides a simple and convenient method for predicting various properties of plastic‐based composite construction material and finding the impact of each composition mix on various properties.

Water-Soluble Poly(vinyl alcohol)/Biomass Waste Composites: A New Route toward Ecofriendly Materials.

With the intention to abate the pollution arising from the improper handling of petroleum-based plastic, green composites consisting of biodegradable plastics and biomass wastes have received widespread attention. However, the balance between mechanical performance and biodegradability still has not been reconciled and evaluated. Herein, a concept for water-soluble poly(vinyl alcohol) (PVA)/biomass waste composite materials is proposed. Instead of degrading to small molecules, the PVA matrix can dissolve in water within the soil. Moreover, after PVA was composited with waste cottonseed shell (CTS) using solid-state shearing milling (S3M) technology, considerable mechanical and thermal performance was achieved, with the maximum tensile strength and degradation temperature of the PVA/CTS composites reaching 10.3 MPa and ∼250 °C, respectively. Moreover, the soil burial test demonstrated that even if PVA cannot degraded in environment within a short term, its water-soluble nature ensures its environmental friendliness, as the PVA matrix can dissolve in soil in 10 days without imposing any adverse effects on either plants (wheat) or animals (earthworm). This work not only describes the preparation a series of ecofriendly PVA/biomass composites but also provides new insight into the environmental friendliness of PVA-based materials.

Material innovation and performance optimization of multi-solid waste-based composite grouting materials for semi-flexible pavements

With the increasing power generation capacity of circulating fluidized bed boilers and electrolytic aluminum production worldwide, the emissions of fluidized bed coal combustion fly ash (FBCF) and bayer red mud (BRM) have increased dramatically, resulting in extremely severe environmental issues as it is difficult to utilize these as resources. To address this issue, this study uses industrial solid wastes such as BRM, FBCF, and silica fume as mineral admixtures to develop a green and low-carbon early strength multi-solid waste composite grouting material (ESMSWCGM) for semi-flexible pavements (SFPs). According to the findings of this study, 18 % of the cement in the ESMSWCGM could be replaced with the three solid waste mineral admixtures. With the optimal ratio, the developed ESMSWCGM exhibits initial and 20-min flow-cone fluidities of 12 s and 14 s, respectively, and initial and final setting times of 66 min and 69 min, respectively. The compressive strengths at 3 h, 1 d, 7 d, and 28 d are 17.05 MPa, 22.95 MPa, 29.55 MPa, and 30.72 MPa, respectively, and the dry shrinkage rate at 28 d is 0.12 %. The performance of the SFP material obtained through grouting is excellent. When the grouting saturation is 95 %, the SFP has a dynamic stability of 28911, a rutting depth of 1.19 mm, and a splitting strength of 1.91 MPa.

Comparative Study on Mechanical Properties of Waste Composite Materials for Bricks Application

This study discusses mechanical properties and analysis of composite materials to develop building bricks for structural lightweight concrete replacement applications made from three different waste materials, i.e. sawdust, polyethylene terephthalate (PET) plastic bottle, and used diaper. All waste materials are used to mixture composite, as cement replacement, with a mixture of 0, 5, 10, 15, and 20 percent of the total weight. This study uses a quantitative method with the sample used as cylindrical tube with 20 mm of diameter and 40 mm of height. Tests were carried out in the form of compressive and specific gravity tests to determine the mechanical and physical properties of the composite material. The use of waste materials as mixtures for composite manufacture with a water per cement ratio of 0.4 at the age of 28 days results in the best compressive strength of 20.70 MPa (5 percent of sawdust), 33.04 MPa (5 percent of PET), and 18.05 MPa (5 percent of used diaper). The density value shows that the addition of waste materials tends to decrease the weight of the composite result. Based on these results, it can be concluded that the use of waste composite materials is a potential replacement for lightweight structural concrete as an effort to reduce the cement requirement for building material applications. DOI: 10.17977/um024v7i22022p092

Waste eggshell-derived CaO-Ag composite and Ca(II) Curcumin Complex antimicrobial materials

Waste eggshell-derived CaO-Ag composite and Ca(II) Curcumin Complex antimicrobial materials

Development of a continuous PET depolymerization process as a basis for a back-to-monomer recycling method

AbstractThis study presents a new approach for the recycling of bilayered PET waste in an efficient, continuous process with a depolymerization degree >97%. The complex PET waste was converted by chemolysis into its monomers ethylene glycol (EG) and the corresponding salt of terephthalic acid (TA) in a twin-screw extruder (TSE). Via this method, the starting materials for PET production were recovered, and highly contaminated PET waste and PET composite materials were transformed into valuable starting materials. The PE layer of the composite PET/PE material remained inert under depolymerization conditions and could be separated by filtration. An increase in the rotational speed by 200 rpm in the TSE reduced the residence time, but the degree of depolymerization was not affected in a proportional manner. Thus, the results indicate that a shorter residence time can be compensated with intensified mechanical agitation due to higher rotational speeds to obtain a similar degree of depolymerization. These results support the potential of this recycling concept to substantially contribute to the implementation of a circular PET economy.

Pore structure characteristics and performance of construction waste composite powder-modified concrete

The recycling of construction waste composite powder materials (CWCPM) conserves resources and protects the environment. To study the effect of CWCPM as a supplementary cementitious material (SCM) on concrete performance, the mechanical properties, permeability and pore structure characteristics of concrete with CWCPM were investigated at different water-cement ratios, CWCPM mixing amounts and curing ages. The pore axis fractal dimension Df was used to characterize the pore structure, and the inherent correlations among the compressive strength, permeability and pore structure were analyzed. Furthermore, the improvement mechanism of the CWCPM on concrete performance was revealed by scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) analyses. The results show that the incorporation of CWCPM enriched the quantity and types of hydration products and improve the pore structure, providing a complementary superposition effect on the cementitious material. The pore axis fractal dimension Df had a significant correlation with compressive strength and chloride ion permeability coefficients, and the correlation coefficients reached 0.936 and 0.901, respectively. The Df can characterize the pore structure of CWCPM-modified concrete. When the CWCPM mixing amount was 30%, the compressive strength and permeability of concrete were optimal.

Behaviour of concrete adding chicken feather as fibre with partial replacement of cement with Cashewnut shell powder

Cashewnut Shell Powder (CNSP) is an agro waste composite material that will allow the concrete industry to maximize the usage of resources, produce economic benefits and build strong, robust and environmentally sensitive structures. The future usage of CNSP could be an appropriate alternative to substitute cement binders because the quality of the reactivity improves due to the existence of lime. The effect of CNSP on strength along with chicken feather as fiber in concrete is presented in this experimental study. The study explored the cashew nutshell powder and replaced it with ordinary Portland Cement at 0%, 4%, 8% and 12% along with 1% of chicken feather been prepared using a mix design ratio of grade 30 MPa concrete (M 30). The cashew nutshell was sun-dried for 7 days and grinded. It is proposed that CNSP been used as a building material in the manufacture of concrete with an optimal substitution of 8% of OPC for structural use and showed improvement in Compressive strength, splitting tensile strength, impact strength & flexural strength compared with the conventional. In addition, the use of CNSP concrete is often useful in a highly sulphate-rich environment. Finally, a stronger refining of the current concrete mix design technique given that the chemical composition of the materials is known.

Research on wear resistance of polymeric composite materials based on microparticles from tyre recyclation process

A huge amount of waste comes into being from tyres which cannot already be used for their purpose. There are many ways how to utilize this waste but material recyclation is a priority. Waste tyre rubbers can be processed into a form of granulate which can be used into polymeric composite materials. This research deals with possibili-ties of tyre waste composite material utilization in areas distinguished for wear. The aim of the research was an assessment of a usage possibility of rubber powder (RP) coming into being from tyre recyclation process as a filler into a thermosetting matrix from firm Havel Composite applied into composite boards made by a vacuum infu-sion. The research focused on an evaluation of wear by friction against loosely fixed abrasive particles according to GOST 23.208-79, hardness and interaction of the matrix and the reinforcement by means of SEM analysis of the polymeric composite materials reinforced with waste microparticles arisen from tyre recyclation process. Research results proved a positive influence of the filler on the improvement of the wear resistance depending on the size of active rubber powder.

Deterioration of the Anti-Frost Performance of Concrete with Construction Waste Composite Powder Materials

The present study is focused on investigating the deterioration mechanism of the anti-frost performance of concrete mixed with construction waste composite powder material (CWCPM), taking into acco...

The environmental benefits of improving packaging waste collection in Europe

Collecting more waste via source separation waste collection systems is an essential part of increasing resource efficiency, achieving European recycling targets and closing the loop in a circular economy. Huge variation in the capture rates of packaging waste (paper, plastic, metal, composite material and glass) exists in Europe, even between municipalities with similar characteristics, which suggests there is great potential to increase the amount of these materials that can be recovered. In order to assess the environmental impacts linked to higher collection rates, a Life Cycle Assessment model was built that considers the reduced need for virgin materials as the system’s loops are closed. An extra 18 million tonnes of waste could be collected annually in Europe if best practice collection strategies were to be deployed, leading to a 13% reduction in greenhouse gas production associated with the packaging and packaging waste. Although high collection performance is crucial for efficient resource use, improving source separation waste collection systems alone will not be enough to achieve recycling targets; material losses must be reduced throughout the value chain, i.e. at the sorting and recycling stages. By evaluating the circularity and environmental implications of current waste management, it can be shown at which points in the system the most improvement needs to be made for each material in order to facilitate the transition towards a circular economy.