Petroleum oil and products recovery from oily sludge: Characterization and analysis of pyrolysis products.

Oily sludge (OS) has attracted special interest because of its hazardous nature and high potential as an energy resource. This study investigated the oil recovery from OS by thermal cracking and catalytic pyrolysis. The oil yield increased when the temperature exceeded 450 °C and reached a maximum (76.84 wt%) at 750 °C. Catalysts significantly improved the quality of oil produced during catalytic pyrolysis. Aromatic hydrocarbons were dominant (10.01-52.69%) in pyrolysis oil (PO) from OS catalytic pyrolysis, and the catalysts significantly reduced the presence of oxygen heterocycles. In addition, KOH and CaO reduced the ID (D-band peak intensity)/IG (G-band peak intensity) of OS char (OC) and increased the degree of graphitization. Owing to its higher iodine adsorption value and methylene blue (MB) adsorption value, OC exhibits potential as an adsorbent. The environmental assessment and potential applications of OC, along with possible reaction mechanisms and kinetic characteristics, are also discussed.

High-density silicon nanowires prepared via a two-step template method.

High density ordered Si nanowire arrays can be fabricated from a Fe2O3 template annealed from polystyrene (PS) microsphere layers via a metal-assisted chemical etching method. The metal mesh films, containing position- and density-defined pores that determine the position and density of the remaining structures after etching, are extremely important for achieving high quality Si nanowires. By adding a structural inversion process, a Au metal mesh with arrays of high density nanopores is devised as a catalyst for metal-assisted chemical etching of silicon. The density of Si nanowires can be increased to two times that of the single-layer PS microspheres and further to three times when a double layer of PS microspheres is introduced. The two-step template method for the preparation of high-density Si nanowires shows great potential in the fields of nanofabrication and nanoelectronics.

A new route to fabricate large-area, compact Ag metal mesh films with ordered pores.

Ordered Si nanowire (SiNW) arrays can be fabricated by metal-assisted chemical etching. The metal mesh films (MMFs) are extremely important for achieving a high quality of the SiNWs. We have developed a two-step chemical deposition method to obtain compact porous Ag MMFs. By the separation of the nucleation and growth stages of the metal in the two-step deposition processes, the overgrowth of the metals to form randomly aggregated irregular metal particles can be overcome. Hexagonally arranged polystyrene (PS) latex microspheres have been employed as a template for the deposition of porous Ag MMFs. The spacing of the pores in the Ag MMFs is determined by the diameter of PS microspheres, and the pore size can also be tuned by changing Ar plasma etching time. One of the main advantages of the two-step deposition method lies in that Ag MMFs can be produced with PS microspheres that are not limited to a single layer, which dramatically simplifies the tedious processes of producing a monolayered PS template. The two-step chemical deposition method shows great potential in metal-assisted chemical etching.

Solvents-dependent selective fabrication of face-centered cubic and hexagonal close-packed structured ruthenium nanoparticles during liquid-phase laser ablation.

Ruthenium nanoparticles (Ru NPs) with face-centered cubic (fcc) structure possess higher catalytic activity than that with hexagonal close-packed (hcp) structure. However, a high temperature above 1800 K is needed for the formation of the metastable fcc Ru phase. In this study, we present a tunable fabrication strategy of fcc and hcp Ru NPs by laser ablation of Ru target in solvents. In methanol, ethanol or acetone organic solvent, both fcc and hcp Ru NPs encapsulated in carbon layer could be obtained, while in deionized water only pure hcp Ru NPs formed. The extreme conditions, that is, the laser-target interaction induced high temperature and high-pressure plasma plume (4000-5000 K, 10-15 GPa) together with its subsequent quenching process, favored the formation of metastable fcc phase. Significantly, the graphite carbon layers sourced from the thermal decomposition of solvent molecules prevent the further evolution of metastable fcc phase into stable hcp phase. Clarification of the solvents and pulse energy effects promise the tunable fabrication of Ru NPs with desired crystallographic structure during laser ablation in liquids (LAL).

Microwave pyrolysis of oily sludge under different control modes.

The effects of temperature and power on product distribution and characteristics of oily sludge (OS) pyrolysis were investigated in a microwave reactor. The maximum oil yield was 72.55 wt% at 550 °C and 71.47 wt% at 800 W, respectively. X-ray photoelectron spectroscopy (XPS) indicated that C-C and C-O were the main forms of carbon in OS char (OC). The sulfur (S) content in OC increased as the temperature/power rose, implying that S might exist in the form of inorganics or OC had S retention ability. In temperature control mode, the changes of functional groups on OC surface were more sensitive. The maximum hydrocarbon content in oil was 14.56% at 350 °C and 13.40% at 900 W, respectively. The contents of oxygenated compounds and heterocycles in oil from temperature control mode were higher. The CO yield increased with increasing temperature/power, reaching the maximum of 9.60 wt% at 650 °C and 7.75 wt% at 900 W, respectively. Compared with power control mode, it seemed that more heavy metals (HMs) were retained in OC in temperature control mode. The Er of HMs were at the clean level and RI indicated the HMs in OC had a low environmental risk.

Microwave-assisted pyrolysis of oily sludge from offshore oilfield for recovery of high-quality products.

Microwave pyrolysis of oily sludge (OS) was investigated in this study. In this case, the highest oil yield (85.93 wt%) was achieved at 500 °C. The molar ratio of H/C was lower for OS char (OC) at higher pyrolysis temperatures, indicating good stability of OC owing to high degree of carbonization and aromaticity. Then, iodine adsorption value of OC reached maximum (531.2 mg/g) at 750 °C. While methylene blue (MB) uptake slightly increased with temperature and reached maximum (384.08 mg/g) at 850 °C. In order to improve the quality of pyrolysis products, different catalysts were employed in OS pyrolysis. The maximum content (64.31%) of aromatic hydrocarbon was found in PO500-10ß. In addition, ß-zeolite also reduced oxygenates content in oil, beneficial for stability of oil products. The gas products from catalytic pyrolysis were abundant in CO and CH4, and KOH achieved the highest CO (5.9 wt%), CH4 (16.9 wt%) and H2 (2.4 wt%) yields. Finally, a reaction mechanism pathway for OS pyrolysis was proposed to show the production routes of gas, liquid, and solid products.

Ultrafine copper nanoparticles anchored on reduced graphene oxide present excellent catalytic performance toward 4-nitrophenol reduction.

Downsizing copper nanoparticles (Cu NPs) can effectively improve their catalytic activity, but simultaneously ensuring the structural stability is always a challenge. In this study, by laser ablating a Cu target in graphene oxide (GO) solution along with a reduction treatment, pure Cu NPs (2.0 ± 0.4 nm) are evenly scattered on reduced graphene oxide (rGO). As-prepared Cu/rGO nanocomposites (NCs) are applied as catalysts for 4-nitrophenol (4-NP) reduction, which display high values of mass-normalized rate constant (k/m, 3.118 s-1 mgCu-1) and turnover frequency (TOF, 2.987 × 10-4 mmol mgCu-1 s-1), over those of most reported Cu catalysts. In addition, owing to the stable conjugation between ultrafine Cu NPs and rGO, the Cu/rGO catalysts reveal good catalytic stability that the conversion efficiency of 4-NP is still over 92.0% even after 10 successive cycles.

Amphiphilic random glycopolymer based on phenylboronic acid: synthesis, characterization, and potential as glucose-sensitive matrix.

This study is devoted to developing amphiphilic, random glycopolymers based on phenylboronic acid, which self-assemble to form nanoparticles (NPs), as a glucose-sensitive agent. Maleimide-glucosamine was copolymerized with 3-acryl aminophenylboronic acid in methanol at 70 degrees C. Using the nanoprecipitation method, NPs with a narrow size distribution were successfully generated. Transmission electron microscopic analysis showed that the NPs were well dispersed as individual, spherically shaped particles. The swelling behavior of the NPs and the in vitro release profiles of insulin at different glucose concentrations revealed definite glucose sensitivity of the glycopolymers. Further, circular dichroism spectroscopy demonstrated that the overall tertiary structure of the released insulin was not altered compared with standard insulin. The analysis of relative cell proliferation suggested that the glycopolymer NPs had good biocompatibility. The glycopolymers that responded to changes in the glucose concentration of the surrounding environment are being aimed for use in self-regulated insulin delivery.

Glucosamine-carrying temperature- and pH-sensitive microgels: preparation, characterization, and in vitro drug release studies.

Glucosamine-carrying temperature- and pH-sensitive microgels with an average diameter of about 100 nm were successfully prepared by free radical precipitation polymerization. The thermo- and pH-responsive properties of the microgels were designed by the incorporation of N-isopropylacrylamide (NIPAM) and acrylic acid (AAc) to copolymerize with acrylamido-2-deoxyglucose (AADG). The stimuli sensitivity of the microgels was studied by the measurement of their sizes and volume phase transition temperature (VPTT) under different surrounding conditions. The results showed that the microgels were responsive to temperature, pH, and ionic strength, and could have a desired VPTT by modifying AADG and AAc contents. The effect of temperature and pH on insulin release from the microgels was also investigated. The release of drug at the tumor-surrounding environment is faster than that under normal physiological conditions. A preliminary in vitro cell study showed that the glucosamine-carrying microgels are more biocompatible to mouse fibroblast cells, compared to the microgels without glucosamine. These glucosamine-carrying dual-sensitive microgels may be promising carriers for targeted drug delivery to tumors.

Automatic release of silicon nanowire arrays with a high integrity for flexible electronic devices.

Automatic release and vertical transferring of silicon/silicon oxide nanowire arrays with a high integrity are demonstrated by an Ag-assisted ammonia etching method. By adding a water steaming step between Ag-assisted HF/H2O2 and ammonia etching to form a SiOx protective layer sheathing Si nanowires, we can tune the composition of the nanowires from SiOx (0 ≤ x ≤ 2) to Si nanowires. Ag plays a key role to the neat and uniform release of Si/SiOx nanowire arrays from Si wafer in the ammonia etching process. The vertical Si nanowire array device, with both sides having high-quality Ohmic contact, can be transferred to arbitrary substrates, especially on a flexible substrate. The method developed here offers a facile method to realize flexible Si nanowire array functional devices.

Polyelectrolyte nanoparticles based on water-soluble chitosan-poly(L-aspartic acid)-polyethylene glycol for controlled protein release.

Water-soluble chitosan (WSC)-poly(L-aspartic acid) (PASP)-polyethylene glycol (PEG) nanoparticles (CPP nanoparticles) were prepared spontaneously under quite mild conditions by polyelectrolyte complexation. These nanoparticles were well dispersed and stable in aqueous solution, and their physicochemical properties were characterized by turbidity, FTIR spectroscopy, dynamic light scattering (DLS), transmission electron microscope (TEM), and zeta potential. PEG was chosen to modify WSC-PASP nanoparticles to make a protein-protective agent. Investigation on the encapsulation efficiency and loading capacity of the bovine serum albumin (BSA)-loaded CPP nanoparticles was also conducted. Encapsulation efficiency was obviously decreased with the increase of initial BSA concentration. Furthermore, its in vitro release characteristics were evaluated at pH 1.2, 2.5, and 7.4. In vitro release showed that these nanoparticles provided an initial burst release, followed by a slowly sustained release for more than 24 h. The BSA released from CPP nanoparticles showed no significant conformational change compared with native BSA, which is superior to the BSA released from nanoparticles without PEG. A cell viability study suggested that the nanoparticles had good biocompatibility. This nanoparticle system was considered promising as an advanced drug delivery system for the peptide and protein drug delivery.

Chitosan-NAC nanoparticles as a vehicle for nasal absorption enhancement of insulin.

The purpose of this work was to investigate chitosan-N-acetyl-L-cysteine (chitosan-NAC) nanoparticles as a potential carrier system for the nasal delivery of insulin. For the study, we used insulin-loaded chitosan-NAC nanoparticles (140-210 nm in diameter) prepared by in situ gelation with tripolyphosphate (TPP), with positive zeta potential values of +19.5-31.7 mV and insulin loading capacities of 13-42%. The physicochemical properties of the nanoparticles were affected by the number of thiol groups present. Mucoadhesive properties, which were evaluated by measuring the in vitro absorbed mass of mucin, of chitosan-NAC nanoparticles were >1.8-fold that of unmodified chitosan nanoparticles. In aqueous solution, chitosan-NAC nanoparticles exhibited fast swelling behavior. Insulin was released from chitosan-NAC nanoparticles in vitro in an initial burst followed by slow release. Intranasal administration of chitosan-NAC nanoparticles in rats enhanced the absorption of insulin by the nasal mucosa compared with unmodified chitosan nanoparticles and control insulin solution. In light of these observations, the novel thiolated chitosan nanoparticles represent a promising vehicle for nasal insulin administration.