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This study explores the depollution activity of a photocatalytic cementitious composite comprising various compositions of n-TiO2 and CaCO3. The photocatalytic activity of the CaCO3–TiO2 composite material is assessed for the aqueous photodegradation efficiency of MB dye solution and NOx under UV light exposure. The catalyst CaCO3–TiO2 exhibits the importance of an optimal balance between CaCO3 and n-TiO2 for the highest NOx removal of 60% and MB dye removal of 74.6%. The observed trends in the photodegradation of NOx removal efficiencies suggest a complex interplay between CaCO3 and TiO2 content in the CaCO3–n-TiO2 composite catalysts. This pollutant removal efficiency is attributed to the synergistic effect between CaCO3 and n-TiO2, where a higher percentage of n-TiO2 appeared to enhance the photocatalytic activity. It is recommended that CaCO3–TiO2 photocatalysts are effectiveness in water and air purification, as well as for being cost-effective construction materials.

A facile and cost-effective approach assisted by ball milling (BM) of commercial titanium dioxide (TiO2), has been utilized to develop cheaper and efficient construction materials. At least three of the commercial and cheaper TiO2 samples (BA01-01, BA01-01+ and R996, designated as A1, A4 and R1, respectively) were selected and subjected to BM treatment to enhance their photocatalytic efficiencies, if possible. It was noted, that the samples A1, A4 and R1 were typical composites of TiO2 and calcium carbonate (CaCO3) and contained varying proportions of anatase, and rutile phases of TiO2 and CaCO3. Two of the highly efficient commercial TiO2 samples, Degussa P25 (simply designated as P25) and ST01 (Ishihara Ind.) were selected for making benchmark comparisons of photocatalytic efficiencies. The BM treated TiO2 samples (designated as TiO2-BM with respect to A1, A4 and R1) were evaluated for photocatalytic efficiencies both in both aqueous (methylene blue (MB)) and gaseous (NOx) photodegradation reactions. Based on detailed comparative investigations, it was observed that A1-BM photocatalyst exhibited superior photocatalytic performances over A4-BM and R1-BM, towards both MB and NOx photodegradation reactions. The difference of NOx photodegradation efficiency between the mortar mixed with A1-BM and that mixed with ST01, and P-25 at 15% were 16.6%, and 32.4%, respectively. Even though the mortar mixed with A1-BM at 15% composition exhibited a slightly lower NOx photodegradation efficiency as compared to mortar mixed with the expensive ST01 and P-25 photocatalysts, the present work promises an economic application in the eco-friendly construction materials for air purification considering the far lower cost of A1. The reasons for the superior performance of A1-BM were deduced through characterization of optical properties, surface characteristics, phase composition, morphology, microstructure and particle size distribution between pristine and BM treated A1 using characterization techniques such as diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction analysis, field emission scanning electron microscopy and particle size analysis.

Abstract Amorphous micro-steel (AMS) fibre made by cooling of liquid pig iron is flexible, light and durable to corrosion, then to be compatible with high flowable and disperable states of mixing as well as high ductile post-cracked performances to apply in fibre-reinforced cementitious composites. In the current research, AMS fibre-reinforced cementitious composites based on cement and alkali-activated ground granulated blast furnace slag mortars were newly manufactured and evaluated for the strength and ductile characteristics mainly by direct tensile and shear transfer tests in the variation in the volume of AMS fibres with two different lengths of 15.0 and 30.0 mm. As a result, it was found that 1.0–1.25% fibre volume fractions were recommendable for AMS fibre-reinforced cementitious composites to maximize direct tensile strength, ductile tensile strain, and shear strength of the composites. However, a further fraction of AMS fibre lowered these mechanical characteristics. Simultaneously, it could be said that AMS fibre-reinforced cementitious composites exhibited up to about 3.7 times higher in direct tensile strength and up to 2.3 times higher in shear strength, compared to AMS fibre-free specimens.

Magnetic nanoparticles (MNPs) are widely used materials for biomedical applications owing to their intriguing chemical, biological and magnetic properties. The evolution of MNP based biomedical applications (such as hyperthermia treatment and drug delivery) could be advanced using magnetic nanofluids (MNFs) designed with a biocompatible surface coating strategy. This study presents the first report on the drug loading/release capability of MNF formulated with methoxy polyethylene glycol (referred to as PEG) coated MNP in aqueous (phosphate buffer) fluid. We have selected MNPs (NiFe2O4, CoFe2O4 and Fe3O4) coated with PEG for MNF formulation and evaluated the loading/release efficacy of doxorubicin (DOX), an anticancer drug. We have presented in detail the drug loading capacity and the time-dependent cumulative drug release of DOX from PEG-coated MNPs based MNFs. Specifically, we have selected three different MNPs (NiFe2O4, CoFe2O4 and Fe3O4) coated with PEG for the MNFs and compared their variance in the loading/release efficacy of DOX, through experimental results fitting into mathematical models. DOX loading takes the order in the MNFs as CoFe2O4 > NiFe2O4 > Fe3O4. Various drug release models were suggested and evaluated for the individual MNP based NFs. While the non-Fickian diffusion (anomalous) model fits for DOX release from PEG coated CoFe2O4, PEG coated NiFe2O4 NF follows zero-order kinetics with a slow drug release rate of 1.33% of DOX per minute. On the other hand, PEG coated NiFe2O4 follows zero-order DOX release. Besides, several thermophysical properties and magnetic susceptibility of the MNFs of different concentrations have been studied by dispersing the MNPs (NiFe2O4, CoFe2O4 and Fe3O4) in the base fluid at 300 K under ultrasonication. This report on the DOX loading/release capability of MNF will set a new paradigm in view that MNF can resolve problems related to the self-heating of drug carriers during mild laser treatment with its thermal conducting properties.

Titanium dioxide (TiO2), the golden standard among the photocatalysts, exhibits a varying level of photocatalytic activities (PCA) amongst the synthetically prepared and commercially available products. For commercial applications, superior photoactivity and cost-effectiveness are the two main factors to be reckoned with. This study presents the development of simple, cost-effective post-treatment processes for a less costly TiO2 to significantly enhance the PCA to the level of expensive commercial TiO2 having demonstrated superior photoactivities. We have utilized sequential calcination and ball milling (BM) post-treatment processes on a less-costlier KA100 TiO2 and demonstrated multi-fold (nearly 90 times) enhancement in PCA. The post-treated KA100 samples along with reference commercial samples (P25, NP400, and ST01) were well-characterized by appropriate instrumentation and evaluated for the PCA considering acetaldehyde photodegradation as the model reaction. Lattice parameters, phase composition, crystallite size, surface functionalities, titanium, and oxygen electronic environments were evaluated. Among post-treated KA100, the sample that is subjected to sequential 700 °C calcination and BM (KA7-BM) processes exhibited 90-fold PCA enhancement over pristine KA100 and the PCA-like commercial NP400 (pure anatase-based TiO2). Based on our results, we attribute the superior PCA for KA7-BM due to the smaller crystallite size, the co-existence of mixed anatase-srilankite-rutile phases, and the consequent multiphase heterojunction formation, higher surface area, lattice disorder/strain generation, and surface oxygen environment. The present work demonstrates a feasible potential for the developed post-treatment strategy towards commercial prospects.

Titanium dioxide (TiO2) has been extensively investigated in interdisciplinary research (such as catalysis, energy, environment, health, etc.) owing to its attractive physico-chemical properties, abundant nature, chemical/environmental stability, low-cost manufacturing, low toxicity, etc. Over time, TiO2-incorporated building/construction materials have been utilized for mitigating potential problems related to the environment and human health issues. However, there are challenges with regards to photocatalytic efficiency improvements, lab to industrial scaling up, and commercial product production. Several innovative approaches/strategies have been evolved towards TiO2 modification with the focus of improving its photocatalytic efficiency. Taking these aspects into consideration, research has focused on the utilization of many of these advanced TiO2 materials towards the development of construction materials such as concrete, mortar, pavements, paints, etc. This topical review focuses explicitly on capturing and highlighting research advancements in the last five years (mainly) (2014–2019) on the utilization of various modified TiO2 materials for the development of practical photocatalytic building materials (PBM). We briefly summarize the prospective applications of TiO2-based building materials (cement, mortar, concretes, paints, coating, etc.) with relevance to the removal of outdoor/indoor NOx and volatile organic compounds, self-cleaning of the surfaces, etc. As a concluding remark, we outline the challenges and make recommendations for the future outlook of further investigations and developments in this prosperous area.

We report the detailed microstructural, morphological, optical and photocatalytic studies of graphene (G) and manganese (Mn) co-doped titanium dioxide nanowires (TiO2(G−Mn) NWs) prepared through facile combined electrospinning−hydrothermal processes. The as-prepared samples were thoroughly characterized using X-ray diffraction (XRD), transmission electron microscopy, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and diffuse reflectance spectroscopy (DRS). XRD studies reveal the formation of mixed anatase-rutile phases or rutile phase depending on the dopant (Mn) precursor concentrations in the electrospinning dope and calcination temperature. The evaluation of lattice parameters revealed that the incorporation of Mn species and carbon atoms in to the lattice of anatase or rutile TiO2 could occur through substituting the sites of oxygen atoms. XPS results confirm the existence of Mn2+/Mn3+ within the TiO2 NW. Raman spectroscopy provides the evidence for structural modification because of the graphene inclusion in TiO2 NW. The optical band gap of G−Mn including TiO2 is much lower than pristine TiO2 as confirmed through UV-vis DRS. The photocatalytic activities were evaluated by nitric oxide (NOx) degradation tests under visible light irradiation. Superior catalytic activity was witnessed for rutile G−Mn-co-doped TiO2 NW over their anatase counterparts. The enhanced photocatalytic property was discussed based on the synergistic effects of doped G and Mn atoms and explained by plausible mechanisms.

Copper oxide (CuO) and cerium oxide (CeO2) of various concentrations have been prepared through an ultrasonically assisted dispersion of CuO and CeO2 nanoparticles (NPs) in which water and nanofluids (NFs) were formulated. The morphological properties of the CuO and CeO2 NPs are reported. Few of the physicochemical properties that can influence the photocatalytic activities of the NFs are evaluated, such as viscosity, activation energy, density, thermal conductivity, electrical conductivity, alternating current (AC) conductivity, pH, stability, refractive index and optical band gap of the CuO and CeO2 NFs. Viscosity studies have been made at four different temperatures (303 K, 308 K, 313 K and 318 K) and the activation energy is calculated and compared between the CuO and CeO2 NFs. The thermal conductivity of the two NFs is calculated and compared. Electrical conductivity is measured for CuO and CeO2 NFs using an impedance analyzer at different frequencies at 303 K. The dielectric constant and AC conductivity were studied. The electrical conductivity and pH of the prepared NFs are measured and the results are compared. The stability of the NFs is determined from Zeta potential values obtained from dynamic light scattering measurements. UV-Visible diffuse reflectance measurements were used to deduce the optical bandgap of the respective metal oxide NPs in the NFs. The photocatalytic efficiencies of the CuO NFs and CeO2 NFs were evaluated using methylene blue (MB) as the model dye. The rate constant for the photodegradation of MB was higher for CuO NF as compared CeO2 NF and also higher than simple NPs-based photocatalysts. A plausible explanation for the role of NFs over the simple NPs-based photocatalytic solution is presented.

The quest for developing highly efficient TiO2-based photocatalysts is continuing and, in particular, evolving a new strategy is an important aspect in this regard. In general, much effort has been devoted to the anatase TiO2 modifications, despite there being only a few recent studies on rutile TiO2 (rTiO2). To the best of our knowledge, studies on the preparation and characterization of the photocatalysts based on the intentional inclusion of graphene (G) into rTiO2 nanostructures have not been reported yet. Herein, we develop a new type of TiO2-based photocatalyst comprising of G included pure rTiO2 nanowire (abbreviated as rTiO2(G) NW) with enhanced visible light absorption capability. To prepare rTiO2(G) NW, the G incorporated titanate electrospun fibers were obtained by electrospinning and subsequently heat treated at various temperatures (500 to 800 °C). Electrospinning conditions were optimized for producing good quality rTiO2(G) NW. The rTiO2(G) NW and their corresponding samples were characterized by appropriate techniques such as X-ray diffraction (XRD), scanning electron microscopy, high-resolution transmission electron microscopy and UV-vis diffuse reflectance spectroscopy to ascertain their material characteristics. XRD results show that the lattice strain occurs upon inclusion of G. We present here the first observation of an apparent bandgap lowering because of the G inclusion into TiO2 NW. While anatase TiO2 NW exhibited poor visible light photocatalysis towards NOx removal, the rTiO2(G) NW photocatalyst witnessed a significantly enhanced (~67%) photocatalytic performance as compared to anatase TiO2(G) NW. We concluded that the inclusion of G into rTiO2 nanostructures enhances the visible light photoactivity. A plausible mechanism for photocatalysis is suggested.

Measuring crack length in concrete fracture test is not a trivial problem due to high speed crack propagation. In this study, mechanoluminascent (ML) material, which emits visible light under stress condition, was employed to visualize crack propagation during concrete fracture test. Three-point bending test was conducted with a notched concrete beam specimen. The cracking images due to ML phenomenon were recorded by using a high speed camera as a function of time and external loadings. The experimental results successfully demonstrated the capability of ML material as a promising visualization tool for concrete crack propagation. In addition, an interesting cracking behavior of concrete bending fracture was observed in which the crack propagated fast while the load decreased slowly at early fracture stage. [ABSTRACT FROM AUTHOR]