Fractionation of carbon and hydrogen isotopes of TSR-altered gas products under closed system pyrolysis.

Thermochemical sulfate reduction (TSR) is common in marine carbonate gas reservoirs, leading to complicated isotope characteristics of TSR-altered gas. This study aims to better understand how TSR affects the geochemical and isotopic compositions of alkanes in pyrolysis products. Pyrolysis of TSR were conducted with crude oil, nonane (C9) and methylnaphthalene (MN) in the presence of MgSO4 solution at temperatures of 350 °C, 360 °C, and 370 °C for different durations of 4-219 h in a closed system. Results show that carbon and hydrogen isotope compositions of alkane gas resulting from TSR (pyrolysis with crude oil and MgSO4) became heavier with increasing carbon number, i.e., δ13C1 < δ13C2 < δ13C3 and δ2H-C1 < δ2H-C2 < δ2H-C3. Compared with the δ13C1, δ13C2 and δ13C3 increased in a much wider range as heating continued. Carbon and hydrogen isotopes of alkane gas produced by TSR became heavier with increasing gas souring index. Values for δ13C1-δ13C2 and δ2H-C1- δ2H-C2 typically decreased as oil and C9 underwent thermal cracking. Comparative experiments using C9 in the presence of MgSO4 produced partially reversed carbon isotope series (δ13C1 > δ13C2), which, for the first time, confirmed the ability of TSR to cause isotopic reversal from pyrolysis. The residual heavy alkanes gradually became 13C-enriched during TSR, which increased δ13C2 values and changed the partially reversed isotope sequence to a positive sequence (δ13C1 < δ13C2). The discovery of a partial reversal of the carbon isotope series of alkane gases through pyrolysis will further deepen the understanding of TSR-altered natural gas.

Unique Layer-Doping-Induced Regulation of Charge Behavior in Metal-Free Carbon Nitride Photoanodes for Enhanced Performance.

Photoinduced charge carrier behavior is critical in determining photoelectrocatalytic activity. In this study, a unique layer-doped metal-free polymeric carbon nitride (C3 N4 ) photoanode is fabricated by using one-pot thermal vapor deposition. With this method, a photoanode consisting of a phosphorus-doped top layer, boron-doped middle layer, and pristine C3 N4 bottom layer, was formed as a result of the difference in thermal polymerization kinetics associated with the boron-containing H3 BO3 -melamine complex and the phosphorus-containing H3 PO4 -dicyandiamide complex. This layer-doping fabrication strategy effectively contributes to the formation of dual junctions that optimizing charge carrier behavior. The ternary-layer C3 N4 photoanode exhibits significantly enhanced photoelectrochemical water oxidation activity compared to pristine C3 N4 , with a record photocurrent density of 150±10 µA cm-2 at 1.23 V vs. RHE. This layer-doping strategy provides an effective means for design and fabrication of photoelectrodes for solar water oxidation.

Mimicking π Backdonation in Ce-MOFs for Solar-Driven Ammonia Synthesis.

π Backdonation is the core process to break through the kinetically complex and energetic hurdle for catalyzing effectively the NH3 synthesis but only occurs on certain transition metals with empty and filled d orbitals. Herein, mimicking π backdonation enables MOF-76(Ce) materials to convert N2/NH3 effectively. Note that, by virtue of the intrinsic mechanism of ligand-to-metal charge transfer, metal cerium species in MOF-76(Ce) serve as an electron sink for accumulating the photogenerated electrons. Taken together, experimental and theoretical analyses reveal that such metal cerium species with coordination unsaturated state (Ce-CUS) on a MOF-76(Ce) nanorod surface can also provide unoccupied and occupied 4f orbitals to accept from and then donate electrons back to nitrogen molecules. Remarkably, it shows outstanding photocatalytic nitrogen reduction performance with high average NH3 yield (34 µmol g-1 h-1) under ambient conditions. This work provides fresh insights into rational designing and engineering highly active catalysts with rare earth elements.

Doping effect of non-metal group in porous ultrathin g-C3N4 nanosheets towards synergistically improved photocatalytic hydrogen evolution.

Searching for effective approaches of accelerating charge separation and broadening optical absorption is critical for designing a high-performance photocatalytic system. Herein, a photocatalyst based on the non-metal group doped porous ultrathin g-C3N4 nanosheets (CNB NS) was prepared through a combined methodology of precursor reforming and thermal condensation. The synergistic effect of non-metal group doping and porous ultrathin nanosheet-architecture not only endow the material with improved light harvesting and regulated band structure, but also facilitate the electron-hole pair separation, supplying numerous active reactive sites and electron diffusion channels. As a result, the CNB NS photocatalyst exhibits a highly efficient photocatalytic H2 performance (the apparent quantum efficiency is 7.45% at 420 nm) and stability in water under the visible light, which is approximately 13 times higher than that of pure g-C3N4. This study may open a new perspective for designing the non-metal group doped g-C3N4 photocatalyst and further fabricate other advanced photocatalytic materials.

Recovery of high purity sulfuric acid from the waste acid in toluene nitration process by rectification.

Waste sulfuric acid is a byproduct generated from numerous industrial chemical processes. It is essential to remove the impurities and recover the sulfuric acid from the waste acid. In this study the rectification method was introduced to recover high purity sulfuric acid from the waste acid generated in toluene nitration process by using rectification column. The waste acid quality before and after rectification were evaluated using UV-Vis spectroscopy, GC/MS, HPLC and other physical and chemical analysis. It was shown that five nitro aromatic compounds in the waste acid were substantially removed and high purity sulfuric acid was also recovered in the rectification process at the same time. The COD was removed by 94% and the chrominance was reduced from 1000° to 1°. The recovered sulfuric acid with the concentration reaching 98.2 wt% had a comparable quality with commercial sulfuric acid and could be recycled back into the toluene nitration process, which could avoid waste of resources and reduce the environmental impact and pollution.

Isotherm type shift of hydrophobic interaction adsorption and its effect on chromatographic behavior.

Adsorption isotherm type is a key factor in simulating chromatographic profiles. In this study, the adsorption isotherm type of pure bovine serum albumin (BSA) and immunoglobulin G (IgG) on hydrophobic interaction chromatography (HIC) media was found to shift from Freundlich to Langmuir with the increase of salt concentration. For BSA on butyl-, phenyl- and octyl-sepharose, the isotherm type shift occurred when the salt concentrations were higher than 1.8, 1.5 and 1.4 mol/L, respectively. For IgG, the turning points were 1.0 mol/L on phenyl-sepharose and 0.9 mol/L on octyl-sepharose. Circular dichroism spectra and high-performance size-exclusion chromatography found no obvious conformational change or oligomer formation for the proteins in the solutions with different salt concentrations. HIC profiles of BSA and IgG revealed that the isotherm type shift greatly affected the chromatographic behavior, because the original single peak was coincidentally split into two peaks at the salt concentrations over which the isotherm type shift occurred. Combining both the isotherm type shift and peak-splitting phenomena, it was possible that the change of protein-protein repulsion among adsorbed protein molecules under different salt concentrations caused the abnormal behavior of adsorption isotherm and chromatographic profiles.

A simple and rapid procedure for purification of haptoglobin from human plasma fraction IV.

Human plasma fraction IV is an intermediate precipitate during the production of human serum albumin using cold ethanol method. Haptoglobin locates in this fraction can be purified for various applications. A new process integration of polyethylene glycol (PEG) precipitation and ion-exchange chromatography (IEC) was developed for purification of haptoglobin, which could effectively purify the haptoglobin from 16.6% to 95%. The recovery of the new process was 58.2% in comparison to 30.3% of the conventional affinity chromatography. Furthermore, 175 mg haptoglobin production in a scaled-up process showed the method to be simple, fast, and low-cost.