Attempts to use waster rubber powder as an adsorbent of pollutants in wastewater treatment applications is an environmentally friendly, efficient and novel method, especially in the tire industry wastewater treatment process. This study evaluated the efficiency of waste tire rubber powder in adsorbing the tire industry wastewater. The rubber and The wastewater were prepared from Kavir Qom Co. and Artawheel Tire Co., respectively. Comparison of UV-vis spectrophotometer results of the nontreated wastewater with the wastewater data after adsorption under various thermal and temporal conditions indicated that the tire powder adsorbent has the necessary efficiency for treating the tire industry wastewater. Examination of data with pseudo-first- and second-order kinetic models also confirmed the adsorbent’s efficiency and showed that the second-order kinetic model had a good correspondence with the obtained results.

Hypothesis: The primary method for recycling waste tires is grinding them into fine particles and then mixing them with various matrices to improve their properties. For example, ground tire rubber (GTR) can be used to enhance the impact resistance of brittle polymers such as polystyrene (PS). However, weak interactions between the two components may lead to a decline in mechanical properties. Polymer grafting onto GTR is a successful method for rubber modification. The unique advantage is the graft polymer can be selected based on the matrix polymer. Namely, polystyrene grafted onto the surface of GTR, PS-g-GTR, can be used as a compatibilizer for the PS/GTR blend. Methods: In this study, styrene monomer was in-situ polymerized in the presence of GTR to synthesize PS-g-GTR in bulk and solution environments. The variation in monomer conversion and grafting efficiency was investigated by increasing the temperature in bulk polymerization and increasing the initiator concentration in solution polymerization. Findings: The highest grafting efficiency (57%) and grafting degree (247%) were achieved in solution polymerization at 90 °C, with a molar ratio of initiator to monomer equal to 1% and a weight percentage of GTR to monomer equal to 13. A comparison of Fourier Transform Infrared Spectroscopy (FT-IR) spectra for GTR and PS-g-GTR clearly showed the appearance of peaks corresponding to benzene rings after grafting. Based on thermogravimetric analysis (TGA), the synthesized PS-g-GTR contained 56% polystyrene by weight. By calculating the cooperatively rearranging region (CRR) length scale at the glass transition temperature using differential scanning calorimetry (DSC), the molecular weight of the grafted chains was estimated to be greater than 104 g mol-1. This graft polymer appears to significantly improve the impact resistance of PS by enhancing compatibility between polystyrene and GTR.

The results on testing application of ground tire rubber (GTR), as potential filler for butyl rubber, are presented. The GTR content variation, within the range of 10-90 phr, was studied with respect to the vulcanization process, static mechanical properties (tensile strength, elongation-at-break, hardness and resilience), dynamic mechanical properties and the morphology of the obtained vulcanizates. Butyl rubber was characterized by its low compatibility to other elastomers [i.e., natural rubber and styrene–butadiene rubber (SBR) -the main ingredients of tires] and low degree of unsaturation. To evaluate the impact of these factors on curing characteristics and mechanical properties of butyl rubber vulcanizates filled with GTR, the same compositions of SBR compounds, cured under identical conditions, were used as reference samples. Based on the obtained data, it can be stated that butyl rubber vulcanizates containing 30 phr of GTR as filler revealed the highest tensile strength and elongation-at-break. The microstructural analysis of a sample containing 30 phr of GTR revealed strong interactions between the butyl rubber matrix and GTR. This phenomenon resulted mainly from two factors. First, the cross-link density of the butyl rubber matrix was affected by its competition against GTR for cross-linking agents. Secondly, the migration of carbon black particles from GTR into the butyl rubber matrix had a significant impact on properties of the obtained vulcanizates.

Some of the desirable properties of concrete include high impact resistance and great energy-sucking capacity to name a few. These properties can be improved through the use of sustainable materials. This study investigated the effects of partly replacing fine aggregate with linear low-density polyethylene (LLDPE) and waste rubber (WR) as fine aggregates on the efficiency of concrete under impact loading. Two water to binder ratio (W/B) percentages of (0.40 and 0.55) were selected, with six (LLDPE-R) replacement grades (0%, 5%, 10%, 15%, 20%, and 30%) and two silica fume (SF) replacement grades (0% and 15%). Six cylinders with 150 and 60 mm were subjected to an impact by a 4.45 kg hammer striking. Test results indicated that impact resistance for the first visible crack and the ultimate failure increased with LLDPE-R content, where it increased by 4.76 times. This study also demonstrated that the impact resistance for the first visible crack of LLDPE-R concrete was improved by an average of 295% for specimens without SF and 292% for specimens containing SF. This enhancement for the ultimate failure is 291% and 290% for specimens without SF and containing SF, respectively.

There have recently been several initiatives to develop eco-sustainable materials because of the growing concern over ecological contamination caused by the overuse of synthetic materials. Previous studies in literature have explored the development of rice straw waste-based epoxy composites. Another waste hazard of concern in the current times is that of waste tire rubber. The present study investigates the physico-mechanical properties of a unique hybrid composite consisting of recycled waste tire rubber and rice straw reinforced composite, which has not been investigated in the literature. Their density, water absorption, hardness, tensile and flexural strengths were examined with variations in the proportion of rubber particles and rice husk. Increase in the rubber content resulted in proportional rise in the water uptake, hardness, tensile strength, and flexural strength. The composite with 25 wt.% of rubber and 5 wt.% of rubber showed the highest tensile strength and strain of 12.5 MPa and 0.015, respectively. The composite with 15% RS and WTR showed a 14.26% increase in flexural strength, with the neat composite exhibiting the highest strength. The composite material can be used as structural panels for instruments or devices in low load bearing applications. The developed sustainable material with waste generated from used tires and rice husk can aid in decreasing the harmful effects caused on the environment and human health during their disposal.

Background and Objectives: Some of heavy metals such as copper (Cu) and manganese (Mn) are toxic and represent as hazardous pollutants due to their persistence in the environment. Heavy metals can be introduced into soils and aqueous environments by natural processes or anthropogenic activities. They are non-degradable in nature and highly toxic to plants, animals and human beings. Various methods exist for the removal of heavy metal ions from solution, such as filtration, chemical precipitation, ion exchange and sorption by activated carbon and others. Discarded tires are an interesting and inexpensive medium for the sorption of heavy metals. There has been little research on heavy metal sorption into tire rubber in competitive systems. Therefore the present study was conducted to assess the sorption behavior of Cu and Mn on different sizes of tire rubber in a competitive system.Materials and Methods: The finely ground discarded tire rubber with three sizes including 0.088-0.125, 0.177-0.250 and 0.353-0.500 mm were prepared from Yazd Tire Company in Iran. A batch experiment was conducted by adding of 200 mg of ground tire to 10 ml of Cu+Mn aqueous solution of the desired concentration (10 to 50 mg L-1). After 24h, supernatant was separated by filtration and analyzed for remaining Cu and Mn by atomic absorption spectroscopy technique.Results: Sorption of Cu and Mn on tire rubber increased with increasing metal concentration from 0 to 50 mg L-1. The greatest sorption of Cu (1088.9 mg Kg-1) was found at the smallest tire rubber size (0.088-0.125 mm) and decreased by 35% when the largest size (0.353-0.500 mm) was used. At the highest concentration, sorption of Cu was restricted by Mn competition. In the whole range of studied metal concentrations, Mn occupied the least sorption sites of tire rubber. The sorption of Mn was not affected by tire rubber size and was restricted by Cu competition. Based on average, the experimental data were fitted in Langmuire (R2=0.94) better than Freundlich one (R2=0.87), showing monolayer sorption of Cu and Mn on discarded tire rubber. The values of maximum sorption capacities calculated from the fitted Langmuir equation showed that Cu sorption was higher than Mn. There was an increase in the qm values of Mn when the tire rubber diameter decreased. In this study, separation factor (RL) was used to predict if an adsorption system is favorable or unfavorable. In all cases, the values of RL were between 0 and 1, pointing to the favorable sorption of Cu and Mn on three size of rubber.Conclusion: Results clearly showed that ground discarded tire rubber (especially, the smallest size) are an effective adsorbent for the removal of Cu and Mn in competitive system. The equilibrium sorption isotherm of Cu and Mn onto discarded tire rubber is well described by the Langmuir and Freundlich models, but the Langmuir model fits the experimental data better than the Freundlich model.

It is essential to keep the balance among rolling resistance, wet skid resistance and wear resistance (the so-called devil's triangle) of tire treads so as to ensure the reliability and safety of the vehicles. For this purpose, hexamethyl-disiloxane (HMDS) and carboxylated polyethylene vinyl acetate copolymer (EVA, emulsion polymer latex) were used to modify nanosilica by in situ surface-modification method, thereby obtaining surface-capped nanosilica possessing good compatibility and strong interfacial interactions with rubber matrix. The surface-capped nanosilica of the above both modifications were introduced into the blend of solution polymerized styrene butadiene rubber (SSBR) and butadiene rubber (BR), and its effect on the mechanical properties and wear resistance of the SSBR/BR-matrix nanocomposites was investigated. The results indicated that both HMDS and EVA contribute to enhancing the compatibility and interfacial interactions of nanosilica with the rubber matrix, which is favorable for improving the mechanical properties and wear resistance of SSBR/BR-matrix nanocomposites. Particularly, HMDS can endow the rubber-matrix nanocomposites with increased wet skid resistance, and EVA can ensure the low rolling resistance of the nanocomposites. Therefore, the SSBR/BR blend filled with HMDS–, SiO2–, EVA possesses the desired mechanical properties and wear resistance and shows promising prospective as a candidate material for fabricating high-performance tire tread.