Vittorio Boffa

Microporous Niobia-Silica Membrane with Very Low CO2 Permeability

A sol-gel-derived microporous ceramic membrane with an exceptionally low permeability for CO(2) from gaseous streams was developed and characterized. The sols were prepared from a mixture of niobium and silicon alkoxide precursors by acid-catalyzed synthesis. Microporous films were formed by coating asymmetric gamma-alumina disks with the polymeric sol (Si/Nb=3:1), followed by calcination at 500 degrees C. The membrane consists of a 150-nm-thick layer with a Si/Nb atomic ratio of about 1.5. The single-gas permeance of small gas molecules such as H(2), CH(4), N(2), and SF(6) decreases steadily with kinetic diameter. Hydrogen, helium, and carbon dioxide follow an activated transport mechanism through the membrane. The permeance of CO(2) in this membrane is much lower than that in pure silica, and its behavior deviates strongly from the general trend observed with the other gases. This is attributed to a relatively strong interaction between CO(2) and adsorption sites in the niobia-silica membrane.

Biochemenergy: a project to turn an urban wastes treatment plant into biorefinery for the production of energy, chemicals and consumer’s products with friendly environmental impact

Urban bio-wastes (UBW) contain soluble bio-organics (SBO) with excellent surfactant properties are proven or expected to perform as bio-based products for use in chemical and environmental technology, in agriculture and in animal husbandry as well as or better than commercial synthetic products. On these basis, UBW are proposed as renewable sources of a wide number of products with potential sale value ranging from one to several tens € kg?1. The expected economical and environmental impacts of scaling up the laboratory result to production and commercial level are evaluated based on a virtual scenario which comprises integration of SBO production technology into a waste management plant treating UBW by aerobic and anaerobic microbial digestion according to the current technology. The results point out that the integrated plant selling biogas and SBO is likely to yield six times higher earnings than the current plant whose revenue comes from biogas and compost.

Cat‐in‐a‐Cup: Facile Separation of Large Homogeneous Catalysts

A cat with nine lives: Catalyst separation and recycling is the bane of homogeneous catalysis. This problem is addressed by a two-layered ceramic membrane cylinder that allows the diffusion of reactants and products in and out, but keeps the catalyst trapped. The concept is demonstrated for the enantioselective transfer hydrogenation of acetophenone to (S)-phenylethyl alcohol with large molecular catalysts anchored on Frechet-type dendrimers.

Use of biosurfactants from urban wastes compost in textile dyeing and soil remediation

A compost isolated humic acid-like (cHAL) material was pointed out in previous work for its potential as auxiliary in chemical technology. Its potential is based on its relatively low 0.4gL(-1) critical micellar concentration (cmc) in water, which enables cHAL to enhance the water solubility of hydrophobic substances, like phenanthrene, when used at higher concentrations than 0.4gL(-1). This material could be obtained from a 1:1 v/v mixture of municipal solid and lignocellulosic wastes composted for 15 days. The compost, containing 69.3% volatile solids, 39.6% total organic C and 21C/N ratio, was extracted for 24h at 65 degrees C under N2 with aqueous 0.1molL(-1) NaOH and 0.1molL(-1) Na4P2O7, and the solution was acidified to separate the precipitated cHAL in 12% yield from soluble carbohydrates and other humic and non-humic substances. In this work two typical applications of surfactants, i.e., textile dyeing (TD) and soil remediation by washing (SW), were chosen as grounds for testing the performance of the cHAL biosurfactant against the one of sodium dodecylsulfate (SDS), which is a well established commercial synthetic surfactant. The TD trials were carried out with nylon 6 microfiber and a water insoluble dye, while the SW tests were performed with two soils contaminated by polycyclic aromatic hydrocarbons (PAH) for several decades. Performances were rated in the TD experiments based on the fabric colour intensity (DeltaE) and uniformity (sigmaDeltaE), and in the SW experiments based on the total hydrocarbons concentration (CWPAH) and on the residual surfactant (Cre) concentrations in the washing solution equilibrated with the contaminated soils. The results show that both cHAL and SDS exhibit enhanced performance when applied above their cmc values. However, while in the TD case a significant performance effect was observed at the surfactants cmc value, in the SW case the required surfactants concentration values were equivalent to 25-125xcmc for cHAL and to 4-22xcmc for SDS. The vis-a-vis comparison of the two surfactants gave the following results: in the TD case the cHAL biosurfactant at 0.4gL(-1) yields good colour intensity and equal colour uniformity as SDS at 5gL(-1), in the SW case cHAL was found to enhance CWPAH by a factor of 2-4 relative to SDS with one soil, whereas with the other soil the two surfactants behaved similarly. The Cre data, however, showed that both soils absorbed by far more SDS (68-95%) than cHAL (12-54%). The results point out intriguing technological and environmental perspectives deriving from the use of compost isolated biosurfactants in the place of synthetic surfactants.

Acid soluble bio-organic substances isolated from urban bio-waste. Chemical composition and properties of products

As previous work proposed commercial expectations for soluble bio-organic substances (SBO) isolated from compost of urban food, gardening and park trimming residues as chemical auxiliaries, nine urban bio-wastes (BW) treated by aerobic and anaerobic digestion for 0-360 days were used to extract SBO and investigate source variability effects on product chemical composition and properties. The bio-wastes were collected over a 13732 km(2) area populated by 2.9 millions from 565 municipalities. The SBO were characterized by their content of different C types and functional groups and by their distribution coefficient (K(PEGW)) between polyethylene glycol and water. A significant linear correlation was found between K(PEGW) and the lipophilic/hydrophilic C ratio. The investigated SBO exhibited up to sixfold change of K(PEGW) demonstrating that BW available from densely populated urban areas are an interesting exploitable source of a wide variety of potential products for the chemical market.

Waste-derived bioorganic substances for light-induced generation of reactive oxygenated species.

Urban waste-derived bioorganic substances (UW-BOS) have shown promise as chemical auxiliaries for a number of technological applications in the chemical industry and in environmental remediation. In this study, the application of these substances in the photodegradation of organic pollutants is addressed. The experimental work is specifically focused on the photolysis mechanism promoted by AC8, a UW-BOS isolated from a 2:1 w/w mixture of food and green residues, composted for 110 days, using 4-chlorophenol (4-CP) as probe molecule. The production of (⋅)OH and the ¹O₂ is monitored by EPR spectroscopy. The correlation between radical species evolution and photodegradation of 4-CP is investigated. The effect of ¹O₂ and (⋅)OH scavengers on the 4-CP degradation process is also checked. The results suggest that the role of these species in the photodegradation of 4-CP depends on AC8 concentration. AC8 is thereby proven to be a photosensitizer for applications in environmental remediation. The results on AC8 further support the use of urban bio-waste as a versatile source of chemical auxiliaries of biological origin for use in diversified applications.

Biosurfactants from Urban Green Waste

From waste came forth surfactants: Humic acid like substances isolated from 0-60 day-old compost display excellent surface activity and solvent properties. These biosurfactants were used to solubilize a dye in water below and above their critical micellar concentration. The biosurfactant unimers appear to have higher dye-solubilizing power than the corresponding micelles.Humic acid like substances isolated from compost show potential as chemical auxiliaries. In the present study, three surfactant samples were obtained from green waste composted for 0-60 days to assess aging effects of the source on the properties of the products. The surface activity, dye solubility enhancement, and chemical nature of these substances were compared. No differences in performance were established among the samples. They lower water surface tension and enhance the dye solubility upon increasing their concentration. However, the ratio of soluble dye to added surfactant is higher in the premicellar than in the postmicellar concentration region. Structural investigations indicated the humic acid like substances to be amphiphiles with molecular weights in the range of 1-3 x 10(5) g mol(-1). The surfactant samples were also compared to sodium dodecylbenzenesulfonate, polyacrylic acid, and soil and water humic substances. The results encourage the application of compost as a source of low-cost biosurfactant.

Behavior and Properties in Aqueous Solution of Biopolymers Isolated from Urban Refuse

Acid soluble biopolymeric substances (SBP) were isolated from different urban biowastes comprised of a range of materials available from metropolitan areas. These biowastes provided products with a chemical nature and solubility properties changing over a wide range and, thus, allowed to assess the effect of the variability of the chemical nature on molecular conformation and surface activity in water solution. For this scope, the SBP were characterized for chemical composition and molecular weight (MW) by microanalysis, potentiometric titration, (13)C NMR spectroscopy, and size exclusion chromatography (SEC) coupled with an online multiangle light scattering (MALS) detector. These materials were found to have 67-463 kg mol(-1) MW and 6-53 polydispersity index and to contain carboxylic acid and phenol groups bonded to aromatic and aliphatic C chains. An empirical parameter (LH) was calculated for use as an index of the lipophilic/hydrophilic C atoms ratio. The products solubility properties in solvents of different polarity, surface activity, power to enhance the water solubility of hydrophobic compounds, and particle size in water solution were also investigated by measurements of the products partition coefficient between polyethylene glycol and water (KPEGW) and of air-water surface tension (γ), water-hexane interfacial tension (IFT), disperse red orange dye solubility (DS), and dynamic light scattering (DLS) versus added SBP concentration (Cs). The results indicate that LH correlates well with KPEGW and with the products surface activity properties. Both γ and DS are shown to depend on Cs, although in opposite ways, that is, higher Cs values yield lower γ and higher DS values. Both DS-Cs and γ-Cs plots showed a significant slope change at approximately the same 1.8-2.5 g L(-1) Cs value. This suggested a change of molecular conformation taking place at the above Cs values. Hydrodynamic diameter values for SBP in solution at Cs ≤ 10 g L(-1) were found to range from 130 to 300 nm, consistent with their macromolecular nature. The DLS coupled to the γ data were consistent with molecules at the water-air interphase and in the bulk water phase having different conformations, but not significantly different molecular sizes. Molecular aggregates more likely form at 50-100 g L(-1) Cs. The results confirm that urban biowastes are a sustainable source of biobased products that may have real commercial perspectives.

A Waste‐Derived Biosurfactant for the Preparation of Templated Silica Powders

A polymeric anionic biosurfactant isolated from urban bio-wastes was used as a template for fabricating silica powders of pore size ranging from 4 to 30 nm by the sol-gel reaction of tetraethylorthosilicate and 3-aminopropyltriethoxysilane at pH 5. The morphology of the synthesized silica powders was found to depend on the size and the conformation of the biosurfactant molecules or aggregates in solution. The use of waste-derived biosurfactants as templating agents reduces the fabrication costs and the environmental impact of mesoporous materials. At the same time, it encourages the upgrade of bio-wastes from a costly disposal matter to a source of chemicals and therefore, of revenue.

Protein helical structure enhancement in biocompatible fluoro-phosphonate-based nanoporous silica glasses assessed by circular dichroism spectroscopy

The role of fluorine and phosphonate groups on protein structure and biocompatibility has been probed by protein encapsulation in tetramethoxysilane (TMOS)-based sol-gel glass and assessed by circular dichroism spectroscopy (CD). Apomyoglobin (apoMb) is known as a model protein for the study of protein folding. Thus, we demonstrated the increase of apoMb helicity in phosphonate and fluorinated phosphonate-based sol-gel glasses via the addition of methane diphosphonic acid (MDPA) and difluoromethane diphosphonic acid (DFMDPA) during the hydrolysis/polycondensation of TMOS precursor forming a nanoporous sol-gel glass host matrix for the protein. Alternatively to silica surface functionalisation using organosilane modifiers, functional organic molecules or nano-agents can be doped directly during the sol-gel process. Since TMOS is not functionalised, we can probe the role of some organic molecules as intermediates as well as their surface hydration effect contributing to the protein folding process. The presence of both fluorine and phosphonate groups in TMOS glass folded the protein to its native state as function of its molar content. The protein ellipticity has been enlightened by CD with signals observable at 222 nm characterising the secondary protein structure at the far UV. The incorporation of these groups to the sol-gel glass systems to mimic the behaviour and conformation of protein as function of its surrounding environment brings both steric and hydrophobic properties to enhance the protein folding. These results are important from the point of view of potential applications in bio-nanotechnology with the design of efficient biomaterials but also to probe the role of fluorine and phosphonate groups in protein folding for the human healthcare.