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This study aims to research the implications of rubber powder utilisation, from tires recycling, in the deformability and strength properties of CPB. In the end, it will be concluded that mine paste backfill with recycled rubber materials contributes to the decrease of waste tire pollution and improve some mechanical properties of the filling body. For that purpose, tests were carried out to determine the uniaxial compressive strength, the elastic energy of deformation, Young's modulus, and Poisson's ratio in specimens made up of mine tailings, Portland cement, wastewater, rubber powder, and plasticisers. The analysis of experimental data determines that recycled rubber makes fresh slurry have better performance in flow characteristics. In the hardened state, recycled rubber reduces the uniaxial compressive strength of the specimens and Poisson's ratio, but other features like deformability increase (Young's modulus decrease) that enhance the ability to absorb elastic strain energy of the filling body. As a result, the study indicates that recycled rubber is applicable to rockburst prevention. The findings of this study provide both invaluable information and industrial applications for the efficient management of solid waste, based on sustainable development and circular economy. [ABSTRACT FROM AUTHOR]

In recent years, one of the environmental issues for human society has been discarded scrap tires. Environmental sustainability demands a solution to resolve the problem of this undesirable waste material; in addition, recycling scrap tires is another controversial issue. Utilizing scrap tires in either civil or geotechnical activities is increasingly recognized as a topic of interest among researchers. This paper investigates a series of large-scale pullout tests (i.e., 1.4 m × 0.8 m × 0.8 m) to evaluate the performance of the innovative suggested reinforcement of ladder geo scrap tire (LGST). The LGST reinforcement has been compared with double geo scrap tire (DGST), double steel strip (DSS), and double geosynthetic strip (DGS); moreover, it has been validated with theoretical values. The experimental pullout results revealed that LGST for a ratio of S/H = 11(S and H are space and height of transverse members) has the highest pullout resistance and the least interference. LGST with a ratio of S/H = 11 increased pullout resistance by more than 190, 377 and 217% compared to DGST, DSS, and DGS, respectively. Therefore, the use of LGST in addition to opening a new window to solve the problem of scrap tires, leads geotechnical engineers to achieve more economical designs. [ABSTRACT FROM AUTHOR]

As vehicles are on the rise globally, so is tire disposal when out of service. One potential recycling process is turning the waste tire into a useful composite by incorporating it with thermoplastic materials. In the present work, composite based on waste tire rubber (WTR) and polypropylene (PP) were developed using a single screw filament extruder for various concentrations of WTR (20, 40, 60, and 80% wt.). Physical and morphological characterization of WTR (425 µm) and WTR-PP composite was performed; furthermore, mechanical characterization of WTR-PP composites was also carried out under the tensile load. Morphological observation reveals that WTR-PP with low WTR content shows comparatively better distribution, maintaining the necessary strength and thermoplasticity of the composite compared to the higher WTR content in the composite. The tensile study shows that incorporating WTR with polypropylene decreased tensile strength but improved elongation at break. The macrofractography is carried out to study the failure origin and crack propagation in the WTR-PP composite. [ABSTRACT FROM AUTHOR]

In this study, the biomass of rubber seed pericarp was first treated with sulfuric acid and then its activated carbon was formed by the pyrolysis process. As produced acid-treated activated carbon of chosen biomass was then used for the adsorption of crystal violet (CV) and methylene green (MG) from the colored aqueous solution. The adsorbent was exposed to several characterization methods to know its structural and morphological behaviors before and after CV and MG adsorption. The adsorbent was found to be mesoporous having a surface area of 59.517 m2/g. The effect of pH, time, and concentration was assessed while various isotherm and kinetics models were employed to know the adsorption insight. The optimum conditions were at pH 8, within 30 min, 50 mg/L concentration, and 0.06 gm dose. The adsorption data (the maximum adsorption capacity for CV and MG were found to be 302.7 and 567.6 mg/g, respectively) was validated by fitting in a response surface statistical methodology and the positive interactions between the studied factors were found. The adsorption was mainly belonging to the electrostatic attraction of the dye molecules. The study proves that the used adsorbent is economical and an excellent source of treating wastewater. The novelty of this research work comes from the conversion of the abundant biomass waste namely rubber seed pericarp into sulfonated-rich carbon material by pyrolysis process to be an efficient adsorbent for two structurally different cationic dyes. Furthermore, statistical optimization by using response surface methodology was applied to optimize the adsorption key parameters. [ABSTRACT FROM AUTHOR]

With the remarkable increase in the number of vehicles worldwide, the disposal of scrap tire is a pressing issue. Pyrolysis is one treatment option to recover resources from the scrap tire, by which pyrolytic char with a high ash and sulfur content is generated, restricting its utilization value. The focus of this study was to improve the quality of the solid product obtained from scrap tire pyrolysis. In this paper, a feasible and effective approach is presented to remove ash from the char using a bench-scale unit. Unlike direct co-pyrolysis of the mixture of scrap tire and other materials, in the study, prior to pyrolysis, the scrap tire was soaked in waste coal tar for a few hours, and then, char was obtained from pyrolysis of the as-prepared scrap tire. According to the comparative analysis of thermogravimetric kinetics of the scrap tire and the as-prepared scrap tire, it revealed that the as-prepared scrap tire was more easily pyrolyzed under relatively low temperature with activation energy of 45.65 kJ/mol and at higher temperature with activation energy of 142.12 kJ/mol. With three kinds of acid (HCl, HNO3, and H2SO4) as the demineralization agent, comparative experiments on the removal of ash from the chars arising from pyrolysis of the as-prepared scrap tire (Char1) and the scrap tire (Char2) were carried out. The results showed that there were the highest efficiencies of ash removal from chars soaked in HCl solution, at 84.9% for Char1 and 59.6% for Char2. With HCl as the demineralization agent, a series of experiments on the removal of ash from Char1 and Char2 was conducted in which the effects of parameters, such as the mass ratio of the acid to the char (L/S), acid concentration, heating temperature, reaction time, stirring rate, particle size of the char, and the number of filtrate cycles, were systematically performed. Under the optimum conditions, the ash removal efficiencies for Char1 and Char2 reached 87.5% and 77.2%, respectively. The kinetics of the char demineralization process was also performed, conforming to a quasi-first-order rate equation. The results obtained indicated that the process of soaking scrap tire in waste coal tar is very useful for removing ash from the char. [ABSTRACT FROM AUTHOR]

In this research work, the role of a pyrolitic oil (PO) produced by pyrolysis of used car tires in coal flotation was evaluated using an extended full factorial design. Effects of operating parameters including pulp solid content and the concentration of pine oil, diesel oil, and pyrolitic oil on ash content and yield of final concentrate as process responses were assessed using experimental and statistical analyses. Fourier Transform Infrared Spectroscopy (FTIR) technique revealed that PO consists of hydrocarbons and their hydrophilic oxides. Analysis of variance (ANOVA) results indicated that the main effect of all parameters on flotation responses was significant. Experimental results showed that pyrolitic oil increased both the ash content and total yield through a nonlinear trend in ranges of 5% and 40%, respectively. Nonselective interaction between pyrolitic oil and pine oil molecules, and competitive adsorption of PO and diesel oil on the surface of coal particles were found to be the chief reasons behind the observed curved behavior of flotation measures. The negative effect of PO on ash content of final concentrate was also ascribed to the interaction between hydrophilic groups in PO structure and the oxide nature of noncombustible materials in coal particles. [ABSTRACT FROM AUTHOR]

Waste tyre generation in South Africa is one of the issues that have not found a sustainable solution. Approximately 1.5 billion tyres are produced annually around the world, and South Africa contributes about 11 million tyres accounting to about 177 835 tons of waste annually. Numerous technologies have been used as possible pathways to recycle waste tyres. This review analyzes the main advances in waste tyre pyrolysis and gasification technologies and lists challenges and successes. For waste tyre pyrolysis, recovering high-value products such as limonene, benzene, xylene, and activated carbon can make the process profitable. For gasification, the objective of new studies is for the producer gas to have a desirable composition for further application in the production of chemicals, heat and power and synthesis of liquid fuels. Also, more research is required to fill the gap in the optimum conditions for solar integrated pyrolysis and gasification of waste tyres. A comprehensive comparative techno-economic analysis of chemicals production from waste tyre via gasification is required to determine the most commercially viable route for tyres. [ABSTRACT FROM AUTHOR]

Water contamination by pathogens and diseases induced by these pathogens is a major water quality issue all over the world. Poor public health has been linked to tap water polluted with DNA harboring antibiotic resistance genes sequence. According to HSAB concept, surface modification of rubber seed shell waste with alumina (AIRSS) as novel agro-waste adsorbent creates more active surface constituents for DNA adsorption. The proximate, ultimate and EDAX analysis provides the percentage levels of ash concentration, volatile, moisture and fixed carbon content, elemental composition present in the adsorbent. The structural features of AIRSS were determined using FT-IR, SEM and XRD. In order to improve reaction conditions, the effect of pH, temperature, adsorbent amount, and reaction time is also examined. The highest percent of DNA removal (92.5%) was achieved at the optimum conditions: 2 g/L at pH 4, contact time 120 minutes as compared to the conventional methods. The DNA adsorbs onto the surface of AIRSS through physical (vander Waals force) and chemical interactions, as demonstrated by kinetics and spectroscopic analyses. Changes in enthalpy (H), free energy (G), and entropy (S) indicate that adsorption is a spontaneous and exothermic process, according to thermodynamic parameters. The results of the experiments showed that the prepared AIRSP adsorbent could be used to remove DNA from water. The efficacy of AIRSS for the removal of DNA has decreased after nine months of storage and use. Low pH and the presence of AIRSS improved DNA-AIRSS adsorption, according to our findings. [ABSTRACT FROM AUTHOR]

The two-stage technology of porous carbonaceous material obtained via pyrolysis in inert medium with subsequent activation by steam is well known. While steam could be a suitable substance for pyrolysis as well, single-staged technology for waste tire recycling is yet to be developed. A comparative analysis of the characteristics of the carbonaceous materials obtained by the single-staged steam pyrolysis of waste tires was carried out, which could provide a theoretical background for the development of such technology. The steam pyrolysis was performed in a tubular reactor in an overheated steam medium (500°C with 5 kg/h mass flow rate). The technical characteristics of the obtained samples were evaluated in the context of their potential for further application as absorbent and raw material for rubber production according to Chemical Abstracts Service No. 1333–86-4. The composition and physico-chemical properties of the obtained samples were studied using BET and thermogravimetric analysis, atomic emission, transmission and scanning electron microscopies, Raman, X-ray diffraction, and photoelectron spectroscopies. The results revealed that the structure and properties of all obtained carbonaceous material samples were similar. The samples consisted of amorphous carbon (with a disordered graphite lattice) and contained a significant amount of metal oxides. According to experimental data, zinc was present in the form of ZnO with a binding energy of 1022.4 eV, while sulfur was observed in the form of sulfide and oxysulfide with binding energies of 161.8 and 163.2 eV, respectively. According to electron microscopy, the morphology of samples was represented by a set of spherical agglomerates comprising nanosized particles. According to the BET analysis of the samples, the specific surface area varied in the range between 52.0 and 66.0 m2/g and the pore volume values were within a range of 0.53–0.87 cm3/g, while the average pore size varied from 412 to 527 Å. Implications: Our paper presents original research in the field of characterization of solid material obtained by single-staged steam gasification of waste tires, which were produced and exploited in conditions of Russia. Modern technology allows thermal utilization of waste tires by obtaining powders of carbonaceous material, which could be used as fuel, adsorbent, etc., but this process usually consists of two stages – pyrolysis in inert medium and activation in steam or carbon dioxide. One of the most promising directions of technological development is simplifying this process into single step, ensuring that the obtained material could be used as carbon black or adsorbent for gas steam cleansing. No data on suitability of carbonaceous material obtained by single-step steam pyrolysis of all-season waste tires to be adsorbent and/or carbon black is present in the literature. In order to evaluate the suitability of the obtained material to be adsorbent, the high specific surface area should be determined, while CAS technical standards specify many chemical and physical properties of industrial carbon black. The aim of the current article is to study the properties of carbonaceous material obtained during single-staged steam gasification of four different all-season tires (due to their widespread application worldwide) and evaluate its fitness as industrial-scale carbon black or adsorbent. The additional problem addressed was the evaluation of the variation in characteristics of carbonaceous material obtained due to different origins of tires. Experiments were conducted in a tubular lab reactor in order to simplify the experimental procedure while ensuring the applicability of the obtained results to practical conditions. The obtained results could be used for the development of the technology for closed-cycle tire processing (because black carbon is used for tire production) and adsorbent production. The characteristics of the materials obtained allow us to choose optimal parameters for such treatment and develop special policies and programs, which will integrate and regulate waste tire utilization via steam gasification. [ABSTRACT FROM AUTHOR]

Four model tests were performed to examine the load-displacement behavior of a mechanically stabilised earth wall, where uniaxial geogrids and waste tires were adopted as the reinforcement materials. The effects of reinforcement length, reinforcement layer spacing and material type of reinforcement on the load-displacement response of the earth wall were investigated. The experimental results suggest that the vertical earth pressures measured at the observation points are location-dependent and generally increase with the increasing load applied at the top of the wall; the horizontal displacement of the wall also has an increasing trend for the applied load less than a critical value, beyond which the trend can be reversed. Besides, increasing the layers and length of reinforcement can reduce the vertical earth pressure, decrease the horizontal displacement of earth wall, and alleviate the strain of the reinforcement. The results also indicate that waste tires are desirable reinforcement materials to be applied to a mechanically stabilised earth wall, which is beneficial to the recycling of rubber resources and environmental protection. [ABSTRACT FROM AUTHOR]

Waste tires (WTs) are becoming a significant environmental, economic, and technological challenge due to their high contents of combustible composition and potential for valuable materials and energy resources. Few studies in developing and even developed countries have been carried out to assess the challenges regarding waste tire management and to suggest the best alternative solutions for managing this waste stream. Although developed countries made progress in waste tire management needs by implementing more efficient innovative recovery and recycling methods, and restrictive regulations regarding the management of used tires, in many developing countries, the management of waste tires has not received adequate interest, and the processing, treatment, and disposal of waste tire is still nascent. In recent years, worldwide, several methods for managing used tires, including other principal alternatives for managing end-of-life tires defined in the 4Rs: reduction, reuse, recovery, and recycling, have been adopted and applied to minimize serious threats to both the natural environment and humans. This paper attempted to establish stakeholders' action that has the responsibility in waste tire management in Botswana. This study also analyzed important aspects on waste tire management in Botswana. A synthesis of approaches was employed in the present investigation to determine the factors influencing effective performance of waste tire management practice in Botswana. Data for the present study were obtained using relevant published literature, scientific journals, other third-sector sources, academic sources, and research derived from governments and other agencies and field observations. Group discussions with the participants and semistructured interviews with professionals were carried out. The outcomes of this investigation are a wide-ranging outline concerning the participants that are important in waste tire management, and a set of aspects affecting the management of waste tires. The information provided by this study is very critical for reviewing and updating the methods and tools to update waste tire data and trends to improve waste tire management efficiency, suggesting innovative methods of recovering and recycling this waste stream in Botswana. Implications: Waste tire management in Botswana demonstrates challenges that epitomize many developing and transitioning countries due to inadequate knowledge to implement integrated programs that incorporate environmental sustainability, stockpiling of whole tires at landfills, lack of consistent and systemic approaches to tire regulation, lack of methods and tools to update tire data and trends, limited application of technology to process and treat WTs, and lack of societal acceptance. To improve WT management efficiency in Botswana, it is critical to implement efficient and well-functioning approaches, including the circular economy; encourage the harmonization of policies; implement recovery and recycling methods of waste tires; prohibit stockpiling of WTs at landfilling and unofficial dumpsites; and promote economic instruments such as the tax system and the extended producer responsibility. [ABSTRACT FROM AUTHOR]

Recycling of waste tire has great practical significance. This paper reports results from studies carried out to determine the time effectiveness of the low-temperature plasma surface modification of ground tire rubber (GTR). Attenuated total reflectance Fourier transform infrared spectroscopy showed that plasma treatment activated the powder surface. The X-ray photoelectron spectroscopy analysis showed an increase in oxygen and carbon element ratio. Meanwhile, the scanning electron microscopy analysis indicated a slight increase in the surface roughness of the treated powder. Testing its hydrophilic property in water indicated that the GTR powder showed decreased dispersive capacity as the time lengthened. Mechanical tests showed that the strength and toughness of the cement stone reduced slightly as a result of increased storage time. [ABSTRACT FROM AUTHOR]