[Adsorption Performance and Mechanism of Oxytetracycline in Water by KOH Modified Biochar Derived from Corn Straw].

The pollution control of tetracycline antibiotics in the environment has become a hot topic, and biochar adsorption has become an important technology to remove organic pollutants. Pyrolytic biochars (BC400, BC500, and BC600) were prepared from corn straw and then were modified by KOH to obtain KBC400, KBC500, and KBC600. Among them, KBC400 was selected for secondary pyrolysis activation at 400-600℃ to obtain AKBC400, AKBC500, and AKBC600. The structure characteristics and surface properties of AKBC were also characterized. The adsorption kinetics and thermodynamic characteristics of oxytetracycline hydrochloride (OTC) in the solution by AKBC were investigated using batch experiments. Compared to that of BC400, the specific surface area and pore structure of AKBC were significantly improved, and the aromaticity was also enhanced, resulting in the notable enhancement of the adsorption capacities for OTC. The pseudo-second-order kinetics model could better fit the adsorption process, and AKBC500 had the largest adsorption rate constant and capacity. Both the intraparticle diffusion and film diffusion were the rate-limiting steps. The Langmuir, Freundlich, and Temkin models could fit the adsorption isotherms perfectly. The adsorption of OTC on AKBC was a spontaneous, endothermic, and entropy-increasing process by both physisorption and chemisorption. The pH values in the range of 3.0-7.0 were favorable for the adsorption of OTC by AKBC. The adsorption capacity decreased with the humic acid concentration over 10 mg·L-1. The adsorption mechanism of OTC by AKBC involved pore filling, hydrogen bonding, π-π conjugation, cation-π bond, and strong electrostatic effect. AKBC still had good reusability for OTC removal after five times of regeneration. The obtained AKBC is a potential adsorbent for OTC removal from water due to the good pore structure, high adsorption capacity, and stable adsorption effect.

Efficient photocatalytic H2 evolution and Cr(VI) reduction under visible light using a novel Z-scheme SnIn4S8/CeO2 heterojunction photocatalysts.

Semiconductor photocatalysis technology is a promising method for hydrogen production and water pollution treatment. Here, the SnIn4S8/CeO2 (SISC) composites were fabricated by a stirring and calcination method, and the mass ratio of SnIn4S8 to CeO2 was optimized. The 50 wt% SISC heterojunction photocatalyst has the highest visible light catalytic activity. The degradation rate of hexavalent chromium (Cr (VI)) is 98.8% in 75 min of light irradiation, which is 2.48 times that of pure CeO2. Besides, the 50 wt% SISC composite photocatalyst also has the highest photocatalytic hydrogen production efficiency (0.6193 mmol g-1 h-1), which exhibits a higher photocatalytic activity than pure CeO2 and SnIn4S8. The enhanced photocatalytic performance can be attributed to the Z-scheme heterojunction structure between CeO2 and SnIn4S8, which can effectively separate and transfer photo-generated charges, thereby reducing the recombination of photo-generated carriers. We hope this work can provide ideas for constructing Z-scheme heterojunction structures and improving photocatalytic activity under visible light.

Highly efficient activation of peroxymonosulfate by Co3O4/Bi2WO6 p-n heterojunction composites for the degradation of ciprofloxacin under visible light irradiation.

Photocatalytic technology assisted via peroxymonosulfate (PMS) has good potential in water treatment. In this study, the Co3O4/Bi2WO6 composite was constructed via an in-situ calcination process and used to activate PMS for the degradation of ciprofloxacin (CIP) under visible light irradiation. The obtained 5 wt% Co3O4/Bi2WO6(CBWO-2) can highly effectively remove 86.2% CIP within 5 min visible light irradiation in presence of PMS. The excellent degradation performance of Co3O4/Bi2WO6/PMS system can be attributed to the synergistic effect between p-n heterojunction and PMS activation. The conduction band and valence band deviation between Co3O4 and Bi2WO6 were calculated by XPS techniques. Besides, DFT calculations were performed to further confirm the internal structure between Co3O4 and Bi2WO6. This work not only provides an approach to fabricate heterostructures but also indicated that Co3O4/Bi2WO6/PMS/Vis system is a potential environment remediation alternative for the efficient removal of recalcitrant organic compounds from wastewaters.

Novel Z-scheme W18O49/CeO2 heterojunction for improved photocatalytic hydrogen evolution.

The novel Z-scheme heterojunction photocatalyst W18O49/CeO2 was prepared by hydrothermal synthesis. The photocatalytic properties of W18O49/CeO2 were evaluated by photocatalytic hydrogen evolution under visible light. The result shows that the 15 wt% W18O49/CeO2 composite has the best hydrogen production efficiency of about 0.2061 mmol g-1h-1, which was 1.93 times higher than that the obtained pure CeO2. The characterization results demonstrated that the existence of Z-scheme heterojunction structure at the contact interface of W18O49 and CeO2 was the origin of the enhanced photocatalytic performance for hydrogen evolution, which could greatly increase the accumulation of photo-generated electrons and the separation efficiency of charge carrier. In accordance with density functional theory (DFT) calculation, we further confirmed the formation of Z-scheme heterojunction structures. This work is anticipated to expand the ideas for modifying CeO2 semiconductor materials to improve the rate of photocatalytic hydrogen production.

[Aging Law of PAHs in Contaminated Soil and Their Enrichment in Earthworms Characterized by Chemical Extraction Techniques].

To evaluate the effect of aging on the availability of PAHs, chemical extraction by exhaustive ( ASE extraction) and nonexhaustive techniques (Tenax-TA extraction, hydroxypropyl-p-cyclodextrin ( HPCD ) extraction, n-butyl alcohol ( BuOH) extraction) as well as PAHs accumulation in earthworms (Eisenia fetida) were conducted in yellow soil from Baguazhou, Nanjing, China, and red soil from Hainan, China, spiked with phenanthrene, pryene and benzo(a) pyrene and aged 0, 7, 15, 30 and 60 days. The results showed that the concentration of PAHs extracted by ASE and three nonexhaustive techniques and accumulated by earthworms significantly decreased with aging time, except the ASE extracted concentration between 30-and 60-day aging time. Furthermore, the relationships were studied in this experiment between chemical extracted PAHs concentration and accumulated concentration in earthworms. PAHs accumulated concentration in earthworms was not significantly correlated with the exhaustive extracted concentration of PAHs in soil (R² 0.44-0.56), which indicated that ASE extraction techniques could not predict PAHs bioavailability to earthworms because it overestimated the risk of PAHs. However, the PAHs accumulated concentration in earthworms was significantly correlated with the three nonexhaustive extracted concentrations of PAHs in soil, which indicated that all the three nonexhaustive techniques could predict PAHs bioavailability to earthworm to some extent, among which, HPCD extraction (R² 0.94-0.99) was better than Tenax-TA extraction (R² 0.62-0.87) and BuOH extraction (R² 0.69-0.94). So HPCD extraction was a more appropriate and reliable technique to predict bioavailability of PAHs in soil.

Characterization of Th1- and Th2-associated chemokine receptor expression in spleens of patients with immune thrombocytopenia.

PURPOSE: In view of the numerous clinical observations and laboratory studies that suggest a critical role for the spleen in immune thrombocytopenia (ITP) pathophysiology, we aimed to characterize Th1-associated chemokine receptors CXCR3 and CCR5 and Th2-associated chemokine receptor CCR3 in spleens of ITP patients and assess the significance of their differential expression in the clinical setting. METHODS: The histopathology of spleens was observed using hematoxylin-eosin staining (HE), and the positive rate of CXCR3, CCR5 and CCR3 expression in spleens of 24 ITP patients and 12 patients with traumatic splenic rupture as normal controls was detected by immunohistochemistry using the SP method. CXCR3, CCR5 and CCR3 protein expression was analyzed by Western blot and mRNA levels were investigated by real-time polymerase chain reaction (RT-PCR). RESULTS: Reactive hyperplasia could be seen in follicles of the white pulp, the germinal central zone was enlarged and the marginal zone was thickened, the central arteries were thickened and fibrotic, and the density of the capillary vessel was increased in ITP patients. ITP group displayed a higher rate of expression of Th1-associated chemokine receptors CXCR3 and CCR5 (83.3% vs. 75%, 100% vs. 83.3%) but lower rate of expression of Th2-associated chemokine receptor CCR3 (50% vs. 66.7%) compared with the controls (P < 0.05, respectively). Western blot analysis revealed that CXCR3 and CCR5 protein expression was significantly increased in ITP patients while CCR3 was significantly reduced (P < 0.05, respectively). Meanwhile, ITP patients displayed increased mRNA levels of CXCR3 and CCR5 but decreased gene expression of CCR3 (P < 0.05, respectively). CONCLUSION: The data suggested that the abnormal expression of Th1/Th2 chemokine receptors may participate in splenic immune disorder in patients with ITP. Using corresponding inhibitors may inhibit Th1-dominant expression and mitigate the progress of the disease.

[Expression of CXCR3 and CCR5 chemokine receptor in spleens of patients with primary immune thrombocytopenia].

OBJECTIVE: To study CXCR3 and CCR5 chemokine receptor expression in spleens of patients with primary immune thrombocytopenia (ITP) and its clinical significance. METHODS: The splenectomy specimens from 10 ITP patients (ITP group) and 8 patients with traumatic splenic rupture (normal control group) were studied. Immunohistochemistry (IHC) was used to study the positive rate of CXCR3 and CCR5. Western blot was performed to detect CXCR3 and CCR5 protein expression, while real-time polymerase chain reaction (RT-PCR) was conducted to analyze their mRNA expression. RESULTS: The positive rate of CXCR3 and CCR5 were both higher in ITP group (90% and 100%, respectively) than those in control group (75% and 87.5%, respectively)(P < 0.05). The differences were statistically significant (P < 0.05). Protein and mRNA level of CXCR3 in ITP group were 3.0 and 3.5 times as high as those in control group, respectively. Those of CCR5 in ITP group were 1.2 and 1.7 times as high as those in control group, respectively. CONCLUSION: High expression of CXCR3 and CCR5 may play a part in the splenic immune disorders in patients with ITP.

Studies of the interaction between paraquat and bovine hemoglobin.

The interaction between paraquat (PQ) and bovine hemoglobin (BHb) was investigated using fluorescence and UV/vis absorption spectroscopy. The reactivity of the heme centers with superoxide anions formed by PQ was judged on the basis of the decrease of the Soret band. The experimental results showed that the fluorescence quenching of BHb by PQ was a result of the formation of PQ-BHb complex; static quenching was confirmed to result in the fluorescence quenching. The binding site number n, apparent binding constant K(A) and corresponding thermodynamic parameters were measured at different temperatures. The process of binding PQ molecule on BHb was a spontaneous molecular interaction procedure in which entropy increased and Gibbs free energy decreased. Hydrophobic and electrostatic interactions played a major role in stabilizing the complex. The effect of PQ on the conformation of BHb was analyzed using synchronous fluorescence spectroscopy.

Spectroscopic studies on the interaction between silicotungstic acid and bovine serum albumin.

The interaction between silicotungstic acid and bovine serum albumin (BSA) was investigated using fluorescence and UV/vis. The experimental results showed that the fluorescence quenching of BSA by silicotungstic acid is a result of the formation of SiW-BSA complex; static quenching and non-radiative energy transferring were confirmed to result in the fluorescence quenching. The binding site number n, apparent binding constant K(A) and corresponding thermodynamic parameters were measured at different temperatures. The process of binding SiW molecule on BSA was a spontaneous molecular interaction procedure in which entropy increased and Gibbs free energy decreased. Hydrophobic interaction force plays a major role in stabilizing the complex. The effect of silicotungstic acid on the conformation of BSA was analyzed using synchronous fluorescence spectroscopy.