Magnetite nanoparticles (Fe3O4) represent the most promising materials in medical applications. To favor high-drug or enzyme loading on the nanoparticles, they are incorporated into mesoporous materials to form a hybrid support with the consequent reduction of magnetization saturation. The direct synthesis of mesoporous structures appears to be of interest. To this end, magnetite nanoparticles have been synthesized using a one pot co-precipitation reaction at room temperature in the presence of different bases, such as NaOH, KOH or (C2H5)4NOH. Magnetite shows characteristics of superparamagnetism at room temperature and a saturation magnetization (Ms) value depending on both the crystal size and the degree of agglomeration of individual nanoparticles. Such agglomeration appears to be responsible for the formation of mesoporous structures, which are affected by the pH, the nature of alkali, the slow or fast addition of alkaline solution and the drying modality of synthesized powders.
This review presents "a state of the art" report on sustainability in construction materials. The authors propose different solutions to make the concrete industry more environmentally friendly in order to reduce greenhouse gases emissions and consumption of non-renewable resources. Part 1-the present paper-focuses on the use of binders alternative to
The thermal transformation of a sample of Ba-exchanged zeolite A, containing a residual
Na content of 0.20 meq/g, into monoclinic celsian is thoroughly investigated. The samples
were thermally treated at temperatures ranging from 200 to 1500 °C for times up to 40 h
and subsequently were characterized by room-temperature X-ray diffraction. The following
are the main results of this investigation:(1) Above 500 °C, the presence of small crystalline
aggregates of monoclinic celsian dispersed in the amorphous phase arising from the thermal
collapse of Ba-exchanged zeolite A is recorded.(2) Above 900 °C, crystallization of hexacelsian
occurs.(3) Above 1100 °C, hexacelsian converts into monoclinic celsian. The conversion is
complete with thermal treatments at 1300, 1400, and 1500 °C within 22, 15, and 22 h,
respectively.The presence of monoclinic celsian nuclei above 500 °C appears to favor the
conversion of hexacelsian into monoclinic celsian at temperatures higher than 1100 °C. The
residual Na content of Ba-exchanged zeolite A was found to strongly affect the temperatures
and times at which the transformations of amorphous phase → hexacelsian and hexacelsian
→ monoclinic celsian occur. Actually a higher Na residual content results in lower
temperatures and times, ceteris paribus.
The paper represents the "state of the art" on sustainability in construction materials. In Part 1 of the paper, issues related to production, microstructures, chemical nature, engineering properties, and durability of mixtures based on binders alternative to Portland cement were presented. This second part of the paper concerns the use of traditional and innovative Portland-free lime-based mortars in the conservation of cultural heritage, and the recycling and management of wastes to reduce consumption of natural resources in the production of construction materials. The latter is one of the main concerns in terms of sustainability since nowadays more than 75% of wastes are disposed of in landfills.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.