In-situ monitoring of the thermal desorption of alkanethiols with surface plasmon resonance spectroscopy (SPRS)

Fuzzy Coordination Control Strategy and Thermohydraulic Dynamics Modeling of a Natural Gas Heating System for in Situ Soil Thermal Remediation

Soil contamination remains a global problem. Among the different kinds of remediation technologies, in situ soil thermal remediation has attracted great attention in the environmental field, representing a potential remedial alternative for contaminated soils. Soils need to be heated to a high temperature in thermal remediation, which requires a large amount of energy. For the natural gas heating system in thermal remediation, a fuzzy coordination control strategy and thermohydraulic dynamics model have been proposed in this paper. In order to demonstrate the superiority of the strategy, the other three traditional control strategies are introduced. Analysis of the temperature rise and energy consumption of soils under different control strategies were conducted. The results showed that the energy consumption of fuzzy coordination control strategy is reduced by 33.9% compared to that of the traditional control strategy I, constant natural gas flow and excess air ratio. Further, compared to the traditional control strategy II, constant excess air ratio and desired outlet temperature of wells, the strategy proposed can reduce energy consumption by 48.7%. The results illustrate the superiority of the fuzzy coordination control strategy, and the strategy can greatly reduce energy consumption, thereby reducing the cost of in situ soil thermal remediation.

Nanoscale lithography mediated by surface self-assembly of 16-[3,5-bis(mercaptomethyl)phenoxy]hexadecanoic acid on Au(111) investigated by scanning probe microscopy

The solution-phase self-assembly of bidentate 16-[3,5-bis(mercapto-methyl)phenoxy]hexadecanoic acid (BMPHA) on Au(111) was studied using nano-fabrication protocols with scanning probe nanolithography and immersion particle lithography. Molecularly thin films of BMPHA prepared by surface self-assembly have potential application as spatially selective layers in sensor designs. Either monolayer or bilayer films of BMPHA can be formed under ambient conditions, depending on the parameters of concentration and immersion intervals. Experiments with scanning probe-based lithography (nanoshaving and nanografting) were applied to measure the thickness of BMPHA films. The thickness of a monolayer and bilayer film of BMPHA on Au(111) were measured in situ with atomic force microscopy using n-octadecanethiol as an internal reference. Scanning probe-based nanofabrication provides a way to insert nanopatterns of a reference molecule of known dimensions within a matrix film of unknown thickness to enable a direct comparison of heights and surface morphology. Immersion particle lithography was used to prepare a periodic arrangement of nanoholes within films of BMPHA. The nanoholes could be backfilled by immersion in a SAM solution to produce nanodots of n-octadecanethiol surrounded by a film of BMPHA. Test platforms prepared by immersion particle lithography enables control of the dimensions of surface sites to construct supramolecular assemblies.

Surface assembly and nanofabrication of 1,1,1-tris(mercaptomethyl)heptadecane on Au(111) studied with time-lapse atomic force microscopy

The solution self-assembly of multidentate organothiols onto Au(111) was studied in situ using scanning probe nanolithography and time-lapse atomic force microscopy (AFM). Self-assembled monolayers (SAMs) prepared from dilute solutions of multidentate thiols were found to assemble slowly, requiring more than six hours to generate films. A clean gold substrate was first imaged in ethanolic media using liquid AFM. Next, a 0.01 mM solution of multidentate thiol was injected into the liquid cell. As time progressed, molecular-level details of the surface changes at different time intervals were captured by successive AFM images. Scanning probe based nanofabrication was accomplished using protocols of nanografting and nanoshaving with n-alkanethiols and a tridentate molecule, 1,1,1-tris(mercaptomethyl)heptadecane (TMMH). Nanografted patterns of TMMH could be inscribed within n-alkanethiol SAMs; however, the molecular packing of the nanopatterns was less homogeneous compared to nanopatterns produced with monothiolates. The multidentate molecules have a more complex assembly pathway than monothiol counterparts, mediated by sequential steps of forming S-Au bonds to the substrate.