In this work, it is reported a scalable and systematic protocol for the preparation of xerogels based on the use of green, highly available, and low‐cost materials, i.e. halloysite nanoclay and chitosan, without the need for any expensive equipment or operational/energetic demands. Starting from colloidal dispersions, rheological studies demonstrate the formation of hydrogels with zero‐shear viscosities enhanced by ≈9 orders of magnitude and higher storage moduli. Hence, the corresponding self‐standing xerogels are prepared by a simple solvent casting method and their properties depend on the concentration of halloysite, possessing enhanced thermal stability and outstanding mechanical performances (elastic modulus and ultimate elongation of 165 MPa and 43%, respectively). The resulting biohybrid materials can be exploited for environmental remediation. High removal efficiencies are reached for the capture of organic molecules from aqueous media and the CO ₂ capture from the atmosphere is also investigated. Most importantly, the presence of an inorganic skeleton within the xerogels prevents the structure from collapsing upon drying and it allows for the control over their morphology and shape. Therefore, taking advantage of the overall features, the designed xerogels offer an attractive strategy for sustainably tackling pollution and for environmental remediation in a plethora of different domains.

A scalable protocol is proposed for the fabrication of hollow spherical capsules by geopolymerization of halloysite clay nanotubes (HNTs) incorporated within alginate gel beads. Alginate/HNTs composite beads have been geopolymerized by alkaline treatment through their immersion in highly concentrated NaOH solution. The influence of the immersion time on the structure and mesoscopic properties of the beads has been studied to optimize the geopolymerization efficacy as well as the mechanical resistance and adsorption performances of the capsules. SEM images demonstrate that the alkaline treatment is efficient in the conversion of compact beads to hollow spherical capsules, which possess improved water uptake capacity and enhance flexibility under compressive forces as evidenced by the relevant increase (in the range ca. 55–75%) of the elastic modulus. Due to their internal cavity and surface porosities, geopolymerized capsules exhibit better adsorption performances toward hydrocarbons with respect to the untreated alginate/HNTs beads. Moreover, geopolymerization of alginate/HNTs beads significantly improves the CO ₂ capture efficiency. The CO ₂ amount adsorbed by the composites bead has been doubled after 5 seconds of alkaline treatment. This study highlights that the geopolymerization of halloysite loaded in biopolymeric beads can be exploited to obtain sustainable materials suitable for CO ₂ storage and removal of contaminants.

The effect of the preparation protocol of chitosan (CHI) based films filled with wax microparticles stabilized by halloysite nanotubes (HNTs) in Pickering emulsions (PE) is investigated. The obtained results show that the addition of acetic acid (before or after the preparation of wax/HNT microspheres) affects the properties of the composite films as well as the colloidal stability of PE. The colloidal behavior of CHI/HNT/wax PE by optical microscopy and sedimentation tests are studied. On the other hand, the corresponding composite films (prepared by solvent casting method) are characterized through several techniques, including Scanning Electron Microscopy, UV–vis spectrometer, water permeability, and contact angle measurements. Dynamic Mechanical Analysis allows this to estimate the effect of wax microparticles on the tensile performances of CHI‐based films. As a general consideration, the filling of the CHI matrix with wax/HNT improves the physicochemical properties of the films. Finally, the efficacy of the films as adsorbents of n‐dodecane vapors is explored. Due to the presence of hydrophobic domains (wax embedded in CHI), the composite films possess higher adsorption efficiencies compared to pristine CHI. Accordingly, it can be stated that the combination of CHI with wax/HNT microparticles is promising to obtain biocompatible composite films useful for remediation purposes.

This work deals with the influence of zinc on cement hydration. The amount of zinc in cement has increased over recent years. This is mainly due to the utilization of solid waste and tires, which are widely used as a fuel in a rotary kiln. Zinc can also be introduced to cement through such secondary raw materials as slag, due to increased recycling of galvanized materials. The aim of this work was to determine the effect of zinc on the hydration of Portland cement, blended with ground blast furnace slag (GBFS). This effect was studied by isothermal and isoperibolic calorimetry. Both calorimetry methods are suitable for measurements during the first days of hydration. Isoperibolic calorimetry monitors the hydration process in real-life conditions, while isothermal calorimetry does so at a defined chosen temperature. Zinc was added to the cement in the form of two soluble salts, namely Zn(NO₃)₂, ZnCl₂, and a poorly soluble compound, ZnO. The concentration of added zinc was chosen to be 0.05, 0.1, 0.5, and 1mass percent. The amount of GBFS replacement was 15% of cement dosage. The newly formed hydration products were identified by X-ray diffraction method (XRD).