Synthetic Fe-rich nontronite as a novel activator of bisulfite for the efficient removal of tetracycline

Fe(III)/peroxymonosulfate oxidation system for the degradation of rhein, a toxic component abundance in rhubarb residue

Rhubarb is widely used in health care, but causing a great amount of rhein-containing herbal residue. Rhein with several toxicities might pollute environment, damage ecology and even hazard human health if left untreated. In this study, the degradation effects of bisulfite- (BS) and peroxymonosulfate- (PMS) based oxidation systems on rhein in rhubarb residue were compared and investigated. The effects of BS and PMS with two valence states of ferric ion (Fe) on the degradation of rhein in rhubarb residue were optimized for the selection of optimal oxidation system. The influences of reaction temperature, reaction time and initial pH on the removal of rhein under the optimal oxidation system were evaluated. The chemical profiles of rhubarb residue with and without oxidation process were compared by UPLC-QTOF-MS/MS, and the degradation effects were investigated by PLS-DA and S plot/OPLS-DA analysis. The results manifested that PMS showed relative higher efficiency than BS on the degradation of rhein. Moreover, Fe(III) promoted the degradation effect of PMS, demonstrated that Fe(III)/PMS is the optimal oxidation system to degrade rhein in rhubarb residue. Further studies indicated that the degradation of rhein by the Fe(III)/PMS oxidation system was accelerated with the prolong of reaction time and the elevation of reaction temperature, and also affected by the initial pH. More importantly, Fe(III)/PMS oxidation system could degrade rhein in rhubarb residue completely under the optimal conditions. In conclusion, Fe(III)/PMS oxidation system is a feasible method to treat rhein in rhubarb residue.

Degradation of organic pollutants through activating bisulfite with lanthanum ferrite-loaded biomass carbon

The removal of methylene blue (MB) in water is a challenging task due to its toxicity, carcinogenicity and resistance to biodegradation. Accordingly, a novel composite catalyst (BC@LF) was prepared by loading lanthanum ferrite (LaFeO3) on biomass carbon (BC) to activate bisulfite (BS) for methylene MB removal in this study. Characterization via scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) indicated that LaFeO3 was successfully loaded on BC. X-ray photoelectron spectroscopy (XPS) analysis suggested that [triple bond, length as m-dash]Fe(iii) was the main active site for BS activation. It was found that 99.4% MB was removed within 60 min in BC@LF/BS system. Sulfate radical (SO4˙-) and hydroxyl radicals (HO˙) were proved to be responsible for MB removal in the BC@LF/BS system and SO5˙- might also be involved in MB removal. The degradation efficiency of MB in the BC@LF/BS system decreased with increasing pH, while the adsorption efficiency of BC@LF for MB improved with increasing pH. Additionally, BC@LF exhibited good reusability for BS activation in successive uses. The BC@LF/BS system exhibited favorable removal effect for various organic compounds, indicating that it has good applicability in the treatment of organic wastewater.

Clays and the Origin of Life: The Experiments

There are three groups of scientists dominating the search for the origin of life: the organic chemists (the Soup), the molecular biologists (RNA world), and the inorganic chemists (metabolism and transient-state metal ions), all of which have experimental adjuncts. It is time for Clays and the Origin of Life to have its experimental adjunct. The clay data coming from Mars and carbonaceous chondrites have necessitated a review of the role that clays played in the origin of life on Earth. The data from Mars have suggested that Fe-clays such as nontronite, ferrous saponites, and several other clays were formed on early Mars when it had sufficient water. This raised the question of the possible role that these clays may have played in the origin of life on Mars. This has put clays front and center in the studies on the origin of life not only on Mars but also here on Earth. One of the major questions is: What was the catalytic role of Fe-clays in the origin and development of metabolism here on Earth? First, there is the recent finding of a chiral amino acid (isovaline) that formed on the surface of a clay mineral on several carbonaceous chondrites. This points to the formation of amino acids on the surface of clay minerals on carbonaceous chondrites from simpler molecules, e.g., CO₂, NH₃, and HCN. Additionally, there is the catalytic role of small organic molecules, such as dicarboxylic acids and amino acids found on carbonaceous chondrites, in the formation of Fe-clays themselves. Amino acids and nucleotides adsorb on clay surfaces on Earth and subsequently polymerize. All of these observations and more must be subjected to strict experimental analysis. This review provides an overview of what has happened and is now happening in the experimental clay world related to the origin of life. The emphasis is on smectite-group clay minerals, such as montmorillonite and nontronite.