Organics adsorption on novel amorphous silica and silica xerogels : microcolumn rapid breakthrough test coupled with sequential injection analysis

The adsorption capacities of a novel amorphous silica and silica xerogels for aromatic compounds were investigated using microcolumn rapid breakthrough tests coupled with sequential injection flow-based automated instrumentation in order to evaluate their operative feasibility under conditions typically used in water treatment facilities. Extraction columns were fabricated using stereolithographic 3D printing. Sorbent reusability was also investigated using automated flow-based techniques. Benzene was selected as the target dissolved organic compound usually present in produced waters from the oil and gas sector, continuously increasing. 3,4-Dichloroaniline (3,4-DCA) was selected as part of the endocrine disrupting chemicals, which are becoming a source of major concern for human and wildlife toxicity. Novel amorphous silicas were synthesized at low temperature and under ambient pressure from a sodium metasilicate precursor and were subjected to postsynthetic methylation. Silica xerogels were prepared via acid catalysis of a sodium metasilicate solution and functionalized with trimethylchlorosilane at low temperature and under ambient pressure. The removal efficiency of the silica xerogels tested was found to be equal to or greater than 22.62 mg/g for benzene at a flow rate of 0.6 mL/min, while the uptake of 3,4-DCA was found to be > 4.63 and > 7.17 mg/g, respectively, at flow rates of 1.8 and 0.6 mL/min

Characterization of a silica based nano/mesoporous material for adsorption application : A study of the relation between synthesis, structure and adsorption efficiency

During last years the interest in large scale production of nano/mesoporous materials has increased in the industry due to benefits that these materials can provide. Silica based nanomaterials are examples of such materials with large specific surface area and pore volume where the porous structure is the key for the resulting properties leading to efficiency in e.g. filtration applications. The aim of this research was to contribute knowledge on understanding the porous structure and its relation to the efficiency. For this approach, the porous structure of a nano/mesoporous silica-based material is characterized. The analysis of this material is a challenge as it has a wide range of pores in the structure from a few nanometres to several micrometres. Electron microscopy (EM) methods are used for the structural analysis of the materials as a complementary method to nitrogen adsorption (NA). The samples are analysed as powders and the relation between the structure and efficiency in the application is discussed. Through this research different synthesis pathways have been studied under the family name of Quartzene®, and the differences in the resulting structure is discussed. The synthesis and storage conditions have been varied in order to study the effect on the porous structure

Characterization of a silica based nano/mesoporous material for adsorption application : A study of the relation between synthesis, structure and adsorption efficiency

During last years the interest in large scale production of nano/mesoporous materials has increased in the industry due to benefits that these materials can provide. Silica based nanomaterials are examples of such materials with large specific surface area and pore volume where the porous structure is the key for the resulting properties leading to efficiency in e.g. filtration applications. The aim of this research was to contribute knowledge on understanding the porous structure and its relation to the efficiency. For this approach, the porous structure of a nano/mesoporous silica-based material is characterized. The analysis of this material is a challenge as it has a wide range of pores in the structure from a few nanometres to several micrometres. Electron microscopy (EM) methods are used for the structural analysis of the materials as a complementary method to nitrogen adsorption (NA). The samples are analysed as powders and the relation between the structure and efficiency in the application is discussed. Through this research different synthesis pathways have been studied under the family name of Quartzene®, and the differences in the resulting structure is discussed. The synthesis and storage conditions have been varied in order to study the effect on the porous structure

Nanostructured Ceramics - Synthesis and Understanding

During the last years, nanostructured ceramics have been favored for use in the industry due to their beneficial properties. For example, calcium phosphate ceramics with their biocompatible and bioactive characteristics are beneficial in biomedicine. On the other hand, silica-based nanoporous materials with large specific surface areas are efficient in adsorption applications. In such materials, the structure is the basis for efficiency in the mentioned applications. This investigation was conducted to understand the structure and its relation to the synthesis process. Two types of materials were investigated: silica-based nanoporous materials under the family name of Quartzene® and calcium phosphate ceramics. We have used different analysis methods, e.g., electron microscopy, nitrogen adsorption, and x-ray diffraction, to characterize the materials and understand the structure. We observed that similar synthesis processes could lead to different structures that were efficient for different applications, e.g., adsorption. The relation between the structure of Quartzene® and its efficiency in the adsorption application is discussed. Various factors (e.g., cleaning method and the storage time/conditions) influenced the resulting structures. Calcium phosphates were produced in aqueous solutions, and the effect of residual ions combined with various reaction temperatures and time was studied. We observed that the combination of residual ions and varying reaction temperature and time could influence the formation of the intermediate phase, octacalcium phosphate (OCP), and dicalcium phosphate dihydrate (DCPD), and particle size when the starting ion concentrations were fixed. High reaction temperature (60 °C) induced OCP and higher precipitation efficiency. For future investigation, fine-tuning the synthesis process is recommended to enhance the structure of the materials suitable for industrial use

Nanostructured Ceramics - Synthesis and Understanding

During the last years, nanostructured ceramics have been favored for use in the industry due to their beneficial properties. For example, calcium phosphate ceramics with their biocompatible and bioactive characteristics are beneficial in biomedicine. On the other hand, silica-based nanoporous materials with large specific surface areas are efficient in adsorption applications. In such materials, the structure is the basis for efficiency in the mentioned applications. This investigation was conducted to understand the structure and its relation to the synthesis process. Two types of materials were investigated: silica-based nanoporous materials under the family name of Quartzene® and calcium phosphate ceramics. We have used different analysis methods, e.g., electron microscopy, nitrogen adsorption, and x-ray diffraction, to characterize the materials and understand the structure. We observed that similar synthesis processes could lead to different structures that were efficient for different applications, e.g., adsorption. The relation between the structure of Quartzene® and its efficiency in the adsorption application is discussed. Various factors (e.g., cleaning method and the storage time/conditions) influenced the resulting structures. Calcium phosphates were produced in aqueous solutions, and the effect of residual ions combined with various reaction temperatures and time was studied. We observed that the combination of residual ions and varying reaction temperature and time could influence the formation of the intermediate phase, octacalcium phosphate (OCP), and dicalcium phosphate dihydrate (DCPD), and particle size when the starting ion concentrations were fixed. High reaction temperature (60 °C) induced OCP and higher precipitation efficiency. For future investigation, fine-tuning the synthesis process is recommended to enhance the structure of the materials suitable for industrial use

Novel hydrophilic and hydrophobic amorphous silica : Characterization and adsorption of aqueous phase organic compounds

Very few studies have investigated the adsorption performance of hydrophobic and hydrophilic silicas with dissolved organics in water, which is a required final step during produced water treatment. The cost of functionalization also hinders the use of hydrophobic materials as sorbents. Novel hydrophilic silicas, prepared at low temperature and ambient pressure, were characterised by SEM, FTIR and BET analysis, and studied for the adsorption of aqueous phase organic compounds at concentrations below their solubility limits. Adsorption capacities were found to be up to 264 mg/g for benzene and 78.8 mg/g for toluene. Direct comparison is made with the analogous hydrophobic version of one of the silica materials, demonstrating comparable uptakes for benzene concentrations lower than 50 mg/L. This finding supports the hypothesis that, at very low aqueous phase organic concentrations, hydrophobicization has no discernible effect on access of the pollutants to the internal porosity of the material

The Influence of Residuals Combining Temperature and Reaction Time on Calcium Phosphate Transformation in a Precipitation Process

Precipitation is one of the most common processes to synthesize hydroxyapatite, which is the human body’s mineral forming bone and teeth, and the golden bioceramic material for bone repair. Generally, the washing step is important in the precipitation method to remove the residuals in solution and to stabilize the phase transformation. However, the influence of residuals in combination with the reaction temperature and time, on calcium phosphate formation, is not well studied. This could help us with a better understanding of the typical synthesis process. We used a fixed starting ion concentration and pH in our study and did not adjust it during the reaction. XRD, FTIR, ICP-OES, and SEM have been used to analyze the samples. The results showed that combining residuals with both reaction temperature and time can significantly influence calcium phosphate formation and transformation. Dicalcium phosphate dihydrate formation and transformation are sensitive to temperature. Increasing temperature (60◦C) can inhibit the formation of acidic calcium phosphate or transform it to other phases, and further the particle size. It was also observed that high reaction temperature (60◦C) results in higher precipitation efficiency than room temperature. A low ion concentration combining reaction temperature and time could still significantly influence the calcium phosphate transformation during the drying