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This study investigates the influence of spent coffee (SC), and potassium hydroxide (KOH) modified spent coffee (ACT-SC) as fillers on the mechanical and thermal properties of epoxidized natural rubber (ENR) biocomposites. The results show the tensile strength, 100% modulus, elongation at break of the ACT-SC rubber biocomposites were enhanced, which was further confirmed by changes in the diffraction pattern for filler filled composite. The SEM micrograph indicates the biocomposite was substantially more homogenous with modified spent coffee. However, FTIR analysis revealed no significant differences between the modified and unmodified samples. In addition, the thermal analysis results show the thermal stability of ENR-ACT-SC is higher than that of ENR-SC but lower than that of ENR.

A stabilizing method for mercury vapor using compatible pellets containing immobilized-colloidal sulfur has been studied. The pellets were made of sawdust and subsequently coated by chitosan prior to immobilization of colloidal sulfur. The treated pellets were physically stable during rotating in dry conditions and did not decompose during 5 days of immersion either in water, in diluted acetic acid, in methanol or in hexane. The sulfur and water contents of the pellets were 2% and 16.25% respectively. The absorption capacity for mercury vapor released from burning amalgam was 0.12 g of Hg per gram pellets. The 20 gram of treated pellets absorbed and stabilized 93–96 wt% of 1.5 g mercury vapor source. At least 30% of HgS can be desorbed and separated from the pellets by washing it with diluted aqueous acetic acid.

Three adsorbents based on the metal–organic frameworks (MOFs), viz.; MIL-88(Fe), NH2-MIL-88(Fe), and mixed-MIL-88(Fe) were synthesized using a microwave-assisted solvothermal technique. The as-synthesized MOFs were characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), field emission scanning microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FTIR). The MOFs were shown to possess highly crystalline and porous structures with specific surface areas of 1240, 941, and 1025 m2 g−1 and pore volumes of 0.7, 0.6 and 0.6 m3 g−1 for MIL-88(Fe), NH2-MIL-88(Fe) and mixed-MIL-88(Fe), respectively. Faster removal of a model polycyclic aromatic hydrocarbon, anthracene (ANT) within 25 minutes, was achieved when these MOFs were used as adsorbents in water. The removal efficiency was 98.3, 92.4 and 95.8% for MIL-88(Fe), NH2-MIL-88(Fe) and mixed-MIL-88(Fe), respectively. The kinetics and isotherms of the process were best statistically described by pseudo-second-order and Langmuir models, respectively, while the thermodynamic studies revealed the exothermic and spontaneous nature of the process. Docking simulations were found to be consistent with the experimental results with MIL-88(Fe) showing the best binding capacity with the ANT molecule.

Water-borne emerging pollutants are among the greatest concern of our modern society. Many of these pollutants are categorized as endocrine disruptors due to their environmental toxicities. They are harmful to humans, aquatic animals, and plants, to the larger extent, destroying the ecosystem. Thus, effective environmental remediations of these pollutants became necessary. Among the various remediation techniques, adsorption and photocatalytic degradation have been single out as the most promising. This review is devoted to the compilations and analysis of the role of metal-organic frameworks (MOFs) and their composites as potential materials for such applications. Emerging organic pollutants, like dyes, herbicides, pesticides, pharmaceutical products, phenols, polycyclic aromatic hydrocarbons, and perfluorinated alkyl substances, have been extensively studied. Important parameters that affect these processes, such as surface area, bandgap, percentage removal, equilibrium time, adsorption capacity, and recyclability, are documented. Finally, we paint the current scenario and challenges that need to be addressed for MOFs and their composites to be exploited for commercial applications.

Here, we report the extracellular biosynthesis of silver nanoparticles (AgNPs) and determination of their antibacterial and anticancer properties. We also explore the efficacy of bioAgNPs incorporated in cellulose nanocrystals (CNCs) and alginate (Alg) for the formation of an antibacterial hydrogel film. Streptomyces sp. PBD-311B was used for the biosynthesis of AgNPs. The synthesized bioAgNPs were characterized using UV-Vis spectroscopy, TEM, XRD, and FTIR analysis. Then, the bioAgNPs’ antibacterial and anticancer properties were determined using TEMA and cytotoxicity analysis. To form the antibacterial hydrogel film, bioAgNPs were mixed with a CNC and Alg solution and further characterized using FTIR analysis and a disc diffusion test. The average size of the synthesized bioAgNPs is around 69 ± 2 nm with a spherical shape. XRD analysis confirmed the formation of silver nanocrystals. FTIR analysis showed the presence of protein capping at the bioAgNP surface and could be attributed to the extracellular protein binding to bioAgNPs. The MIC value of bioAgNPs against P. aeruginosa USM-AR2 and MRSA was 6.25 mg/mL and 3.13 mg/mL, respectively. In addition, the bioAgNPs displayed cytotoxicity effects against cancer cells (DBTRG-0.5MG and MCF-7) and showed minimal effects against normal cells (SVG-p12 and MCF-10A), conferring selective toxicity. Interestingly, the bioAgNPs still exhibited inhibition activity when incorporated into CNC/Alg, which implies that the hydrogel film has antibacterial properties. It was also found that bioAgNP-CNC/Alg displayed a minimal or slow release of bioAgNPs owing to the intermolecular interaction and the hydrogel’s properties. Overall, bioAgNP-CNC/Alg is a promising antibacterial hydrogel film that showed inhibition against the pathogenic bacteria P. aeruginosa and MRSA and its application can be further evaluated for the inhibition of cancer cells. It showed benefits for surgical resection of a tumor to avoid post-operative wound infection and tumor recurrence at the surgical site.

The photocatalytic degradation of the vapor odor of skim natural rubber latex, which is composed of volatile organic compounds (VOCs-NR), was conducted using iron-doped zinc oxide (Fe-ZnO) photocatalyst nanoparticles. The research objectives were to study the photocatalyst, to develop the photocatalytic reactor used for the photodegradation of VOCs-NR, and to analyze the odor reduction of the degraded VOCs-NR. Fe-ZnO was prepared by the sol-gel method and immobilized onto fiberglass cloth as the support material, followed by annealing. The Fe-ZnO nanoparticles were dispersed on the fiberglass surface. A photocatalytic reactor was developed for the gas phase. The research findings showed that gas chromatography-mass spectroscopy detected 24 dominant chemical components in the VOC-NR stock before photocatalytic degradation. The components decreased to 11 after 30 min, only 3 components remained after 40 min of the photocatalytic process, and no component was observed after 80 min of photoirradiation. An organoleptic test was conducted to validate that the odor degraded to a very low level.

An environmental friendly, low cost composite for the photo-assisted degradation of methyl orange (MO) is proposed. Here, natural rubber–silver (NR–Ag) composites are formed through soft thermal reduction. The characteristics of the NR–Ag composites were investigated using UV–vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The deposition of Ag on the surface of natural rubber was proven by the XRD diffraction peaks, attributed to metallic Ag and the appearance of the surface plasmon resonance of Ag, at ~ 420–460 nm in the UV–vis spectrum. The degradation of MO dye by NR–Ag composite under UV light source showed positive results for the degradation of dye even with minute amounts of Ag content. The degradation mechanism of MO involved the generation of hydroxyl radicals from the UV-irradiated NR–Ag composite by the formation of superoxide species as the important radical intermediate. Several parameters such as the Ag salt concentration and pH of the MO dye were investigated. Complete degradation of MO was achieved when the composites containing 2 × 10−3 wt% of Ag (NR–Ag4) were employed at pH 3. Under this condition, complete degradation occurred within 30 min. Kinetic studies were conducted to understand the degradation phenomenon.

Halloysite nanotubes (HNTs) were modified with CuO to form CuO-HNT composites. Results revealed that the CuO particles deposited on the HNT have higher specific surface area (SBET) and pore volume ...

Three adsorbents based on the metal-organic frameworks (MOFs)

Optimization studies was conducted for the pyrene (PYR) adsorption onto Zr-based metal organic frameworks (MOFs), UiO-66(Zr) and NH2-UiO-66(Zr) in aqueous medium. Central composite design (CCD) model has shown good fittings of the coefficient of determination (R2) with non-significant lack of fit for both UiO-66(Zr) and NH2-UiO-66(Zr) MOFs. The optimized adsorption efficiency achieved by the UiO-66(Zr) and NH2-UiO-66(Zr) were 99.22 and 95.67% respectively. Artificial neural network (ANN) model was able to predict the experimental findings with high precision at topographic node of 5-4-2 structural layer. The kinetics and isotherms of the process was best described by pseudo-second-order Langmuir models respectively. The process was exothermic and spontaneous with the good reusability of the MOFs.

Polycyclic aromatic hydrocarbons (PAHs) and phenolic compounds had been widely recognized as priority organic pollutants in wastewater with toxic effects on both plants and animals. Thus, the remediation of these pollutants has been an active area of research in the field of environmental science and engineering. This review highlighted the advantage of adsorption technology in the removal of PAHs and phenols in wastewater. The literature presented on the applications of various porous carbon materials such as biochar, activated carbon (AC), carbon nanotubes (CNTs), and graphene as potential adsorbents for these pollutants has been critically reviewed and analyzed. Under similar conditions, the use of porous polymers such as Chitosan and molecularly imprinted polymers (MIPs) have been well presented. The high adsorption capacities of advanced porous materials such as mesoporous silica and metal-organic frameworks have been considered and evaluated. The preference of these materials, higher adsorption efficiencies, mechanism of adsorptions, and possible challenges have been discussed. Recommendations have been proposed for commercialization, pilot, and industrial-scale applications of the studied adsorbents towards persistent organic pollutants (POPs) removal from wastewater.

Metal-organic frameworks (MOFs), MIL-88(Fe) and NH2-MIL-88(Fe) were synthesized using microwave-assisted solvothermal technique. BET analysis has shown the porous nature of the MOFs, possessing surface areas with corresponding pore volumes of 1240 m2g−1 and 0.7 m3 g−1, 941 m2 g−1 and 0.6 m3 g−1 for MIL-88(Fe) and NH2-MIL-88(Fe), respectively. Other characterizations were also conducted using scanning electron microscopy (SEM), powdered X-ray diffraction (XRD) and Fourier transformed infrared (FTIR) spectroscopy. The MOFs were evaluated for application as adsorbents for the removal of pyrene (PYR) in aqueous solution. The removal efficiency achieved by MIL-88(Fe) was 99.7% while for NH2-MIL-88(Fe) was 96.0% within 40 minutes. Both MOFs has shown good removal of the PYR even after 5 consecutive uses. The adsorption isotherm was studied and favoured more by the Langmuir model, while the kinetics was found to follow pseudo-second-order model. The process was thermodynamically exothermic and spontaneous. Thus, the MOFs studied exhibited favourable features as potential adsorbents for the removal of PYR in wastewater.

Metal-organic frameworks UiO-66(Zr) and NH2-UiO-66(Zr) were characterized by x-ray diffraction (XRD), fourier transformed infrared spectroscopy (FTIR), field emission scanning electron microscopy (SEM), thermogravimetry (TG) and N2 adsorption–desorption measurements. The porous nature of the materials was revealed by the higher Brunauer-Emmett-Teller (BET) surface area of 1420 m2 g−1, 985 m2 g−1 and particles size of 7.56 nm, 3.56 nm for UiO-66(Zr) and NH2-UiO-66(Zr) respectively. Enhanced adsorption capacity and recyclability of the MOFs towards anthracene (ANT) and chrysene (CRY) removal in aqueous medium was achieved. 98.6 and 96.4% of ANT was removed within 25 mins, while 97.9 and 95.7% of CRY was removed within 30 mins for the UiO-66(Zr) and NH2-UiO-66(Zr) respectively. Molecular docking was employed to model the surface interactions of the synthesized MOFs with the pollutants and the simulated binding energies were in good agreement with the experimental results.

MIL-88(Fe) and NH2-MIL-88(Fe) metal-organic frameworks were synthesized using the microwave-assisted solvothermal method and were characterized using scanning electron microscopy (SEM), Brunauer Emmett Teller (BET), powdered X-ray diffraction (XRD) and Fourier transformed infrared (FTIR) spectroscopy. Relatively high surface areas with corresponding pore volumes of 1240 m2 g−1 and 0.7 m3 g−1, 941 m2 g−1 and 0.6 m3 g−1 were found for MIL-88(Fe) and NH2-MIL-88(Fe), respectively. The MOFs were evaluated as adsorbent for the removal of chrysene (CRY) in water. Important parameters that affect the adsorption such as contact time, initial concentration of CRY, pH and temperature were systematically studied. Adsorption isotherms using Langmuir, Freundlich and Temkin models were investigated. Other details of the adsorption process were also studied using kinetics and thermodynamics approaches. Additionally, molecular docking was used to unravel the nature of the adsorption between the MOFs and CRY. The reusability of the adsorbents was evaluated using regeneration studies. In conclusion, these MOFs exhibit favorable characteristics to be used for the removal of CRY from water.

Wastewater from textile industries commonly produce large amount of water often rich in colour containing residues of dyes and toxicity. In order to degrade dyes from the effluent before releasing to the environment, the natural rubber incorporated with silver nanoparticles (NR-Ag) were studied. In this work, the dye that used as a model of dye was methylene blue (MB) and the NR-Ag ball membranes have been prepared using fishing float ball coated with NR-Ag. The NR-Ag ball membranes were formed using mild heat treatments and characterized using UV-Vis Spectrophotometer and Atomic Absorption Spectroscopy (AAS). Catalytic activity of the NR-Ag ball membranes for the degradation of MB dye was studies using potassium borohydride (KBH4) as reducing agent. The report emphasizes the effect of quantity of NR-Ag balls, the effect of air pressure and the effect of KBH4 concentration on decolourization rate of MB by KBH4. The rate of decolourization was found to increase with increasing amount of NR-Ag balls and with increasing of air pressure. The optimum amount of NR-Ag ball was 10 and the best air pressure rate was 0.6 bar. Furthermore, the process of decolourization increased with higher concentration of KBH4.

Multi-component nanohybrids comprising of organo-modified montmorillonite (MMT) and immiscible biopolymer blends of poly(3-hydroxybutyrate) (PHB) and epoxidized natural rubber (ENR-50) were prepared by solvent casting technique. The one and three dimensional morphology of PHB/ENR-50/MMT systems were studied using Polarizing Optical Microscopy (POM) and Scanning Electron Microscopy (SEM). Differential scanning calorimetry (DSC) technique was used to evaluate the thermal properties of the nanohybrids. The melting temperature (Tm) and enthalpy of melting (ΔHm) of PHB decrease with respect to the increase in ENR-50 as well as MMT content. The non-isothermal decomposition of the nanohybrids was studied using thermogravimetric (TG-DTG) analysis. FTIR-ATR spectra supported ring opening of the epoxide group via reaction with carboxyl group of PHB and amines of organic modifier. The reaction mechanism towards the formation of the nanohybrids is proposed.

A growing demand for biofuels as the alternative for fossil fuels’ extinction has produced abundance amount of crude glycerol as by-product in biofuel industries. Utilization of crude glycerol into a value-added product such as monoolein has been the focus for this present work. Instead of using free catalyst, the enzyme (lipase) used for this study was immobilized onto the halloysite nanotubes. The immobilized enzyme was characterized using TEM, BET and FTIR analysis. Further, the effect of time, temperature, agitation rate, and substrate molar ratio on monoolein production and fatty acid conversion were studied between free lipase and immobilized lipase using GC analysis. The best working conditions for immobilized lipase to produce monoolein was at 50oC, with 8 to 1 ratio of glycerol to oleic acid, agitated at 250 rpm for 18h. The amount of monoolein produced using immobilized lipase was highly comparable with free lipase, with ability to be reused and thermally stable at higher temperature.

Graft copolymers of natural rubber (NR) and poly-3-hydroxybutyrate (PHB) with 60:40 ratio were synthesized in chlorobenzene. Two types of initiators namely azoisobutyronitrile (AIBN) and benzoyl peroxide (BPO) AIBN and BPO were employed to initiate the free radical grafting of the two polymers. The influence of the various types of initiator loadings was also investigated. Estimation of the grafted NR was performed using FTIR. The thermal stability and crystallization behavior of NR-g-PHB was studied using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) TGA as well as DSC respectively. The absence of the C=C peak of NR in the FTIR spectra confirmed that PHB grafted on this site after the breakage of the C=C bond. The increase in initiator loading, improved the smoothness of the NR-g-PHB. Moreover, single Tg were observed for NR-g-PHB which indicate that no phase separation occurs and the thermal stability of pristine NR after grafting was improved compared with that of NR alone.

Natural composites as green membranes have shown great potential in water remediation. These membranes combine merits from both natural polymer and inorganic or organic additives. Natural polymers are biodegradable, non-toxic and offer flexibility for design purposes. Incorporation of additives can enhance the mechanical and thermal properties or impart antibacterial and catalytic properties to the composite. This chapter provides an overview of the different types of natural polymer composite membranes and their functions. It also highlights the recent development of cellulose, chitosan, and natural rubber composite-based membranes in water treatment technologies between 2010 and 2015.

A convenient and effective method of dispersing gold (Au), silver (Ag) and copper (Cu) particles in epoxy is described. Particles were synthesized in aqueous phase and subsequently dispersed in toluene-epoxy with or without the presence of curing agent. Sodium borohydride and 2-propanol were used as reducing and phase transfer agents respectively. The surface plasmon resonance (SPR) at ~ 540-620 nm, ~ 525 nm and ~450 nm confirms the presence of Cu, Au and Ag nanoparticles in the composites. No chemical interaction occurred between the metal particles and the epoxy or cured epoxy. Increase in epoxy content caused the size of the particles to decrease for all metals. The average particle size for Au, Ag and Cu in 1% and 10% epoxy are 3.9 nm and 2.5 nm, 10.1 nm and 3.2 nm as well as 8.1 nm and 5.9 nm respectively. Similar decreasing trend was also observed upon addition of curing agent. In all cases, metal nanoparticles exhibit self-assembly with inter-particle spacing of

Porous structured silicon or porous silicon (PS) powder was prepared by chemical etching of silicon powder in an etchant solution of HF: HNO3: H2O (1:3:5 v/v). An immersion time of 4 min was sufficient for depositing Cu metal from an aqueous solution of CuSO4 in the presence of HF. Scanning electron microscopy (SEM) analysis revealed that the Cu particles aggregated upon an increase in metal content from 3.3 wt% to 9.8 wt%. H2-temperature programmed reduction (H2-TPR) profiles reveal that re-oxidation of the Cu particles occurs after deposition. Furthermore, the profiles denote the existence of various sizes of Cu metal on the PS. The Cu-PS powders show excellent catalytic reduction on the p-nitrophenol regardless of the Cu loadings.

2nd International Conference on Materials and Products Manufacturing Technology (ICMPMT 2012), Guangzhou, PEOPLES R CHINA, SEP 22-23, 2012; International audience; A series of Pt-100 and bimetallic PtNi catalysts were prepared on various supports namely amorphous silica (Degussa), crystalline silica (Chempure) and cerium oxide (CeO2). The samples were prepared via precipitation method using NaBH4 as a reducing agent. H-2-TPR analysis revealed that total reduction of the metal salts to metal particles occurred during this stage. All catalysts were tested for the hydrogenation of benzene to cyclohexane. It was found that the catalysts exhibited a decrease in the catalytic reactivity in the order of amorphous silica, crystalline silica and CeO2. This is mainly due to the surface area and acidity of the support. Comparison of the PtNi catalysts with their respective monometallic catalyst showed that only the PtNi prepared on Chempure exhibited an enhanced reactivity. This is due to alloying of PtNi. For catalysts prepared on Degussa, the low H-2-chemisorption properties as well as lack in Pt peak shift in the XRD profiles leads to the believe that Ni and Pt may exist separately. H-2-TPD analysis supports these findings.

Citrate-stabilized gold and platinum particles were prepared in aqueous phase and transferred to toluene phase by employing 2-propanol as the transfer agent. It was found that the modified natural rubber (ENR) induced the phase transfer and assisted the dispersion of the citrate-free metal particles into the organic phase. The amounts of gold and platinum transferred are 93.4% and 86.1%, respectively. This phase transfer technique produced organosols of smaller particle sizes and narrower size distribution with self-assembly arrangements when compared to those prepared via the previous in situ preparations. The respective average particle size and standard deviation of gold before and after phase transfer were6.3±1.7 nm and7.2±1.3 nm, while for platinum they were4.0±0.7 nm and4.2±0.8 nm. The slight increase in the average sizes and overall size distributions in both metals after transfer was attributed to multiparticle aggregation in the organic phase.