Enhanced removal of Pb(II) from acid mine drainage using green reduced graphene oxide/silver nanoparticles.

Mining activities can potentially release high levels of Pb(II) in acid mine drainage (AMD), which thereafter poses a significant threat to ecological security. In this study, green reduced graphene oxide/silver nanoparticles (rGO/Ag NPs) were successfully synthesized via a one-step approach using a green tea extract and subsequently used as a cost-effective absorbent to remove Pb(II) from AMD. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy indicated that organic functional groups in the green tea extracts, such as C=O-C, CO, and CC, acted both as reductants and stabilizers in the synthesis of rGO/Ag NPs. In addition, the removal efficiency of Pb(II) by rGO/Ag NPs (84.2 %) was much better than either rGO (75.4 %) or Ag NPs (12.3 %) alone. Also, in real AMD, the distribution coefficient (Kd) of Pb(II) (4528 mL/g), was much higher than other heavy metal indicating the adsorbent had a high selective affinity for Pb(II). Interestingly, after five cycles of use, the removal efficiency of Pb(II) by rGO/Ag NPs from AMD actually increased from 46.4 to 65.2 % due to iron oxides (i.e., Fe2O3 and Fe3O4) being generated when rGO/Ag NPs was exposed to AMD. The removal of Pb(II) via adsorption on the rGO/Ag NPs surface involved formation of hexagonal rod-like precipitates. This work demonstrated the potential of rGO/Ag NPs to be continuously used for the removal of Pb(II) from AMD.

Improved recovery selectivity of rare earth elements from mining wastewater utilizing phytosynthesized iron nanoparticles.

While rare earth elements (REEs) play key roles in many modern technologies, the selectivity of recovering of REEs from mining wastewater remains a critical problem. In this study, iron nanoparticles (FeNPs) synthesized from euphorbia cochinchinensis extracts were successfully used for selective recovery of REEs from real mining wastewater with removal efficiencies of 89.4% for Y(III), 79.8% for Ce(III) and only 6.15% for Zn(Ⅱ). FTIR and XPS analysis suggested that the high selective removal efficiency of Y(III) and Ce(III) relative to Zn(Ⅱ) on FeNPs was due to a combination of selective REEs adsorption via complexing with O or N, ion exchange with H+ present in functional groups contained within the capping layer and electrostatic interactions. Adsorptions of Y(III) and Ce(III) on FeNPs conformed to pseudo second-order kinetics and the Langmuir isotherm model with maximum adsorption capacities of 5.10 and 0.695 mg∙g-1, respectively. The desorption efficiencies of Y(III) and Ce(III) were, respectively, 95.0 and 97.9% in 0.05 M acetic acid, where desorption involved competitive ion exchange between Y(III), Ce(III) and Zn(Ⅱ) with H+ contained in acetic acid and intraparticle diffusion. After four consecutive adsorption-desorption cycles, adsorption efficiencies for Y(III) and Ce(III) remained relatively high at 52.7% and 50.1%, respectively, while desorption efficiencies of Y(III) and Ce(III) were > 80.0% and 95.0%, respectively. Overall, excellent reusability suggests that FeNPs can practically serve as a potential high-quality selectivity material for recovering REEs from mining wastewaters.

Recovery of rare earth elements from mine wastewater using biosynthesized reduced graphene oxide.

Recycling rare earth elements (REEs) from sources of secondary waste such as REEs mine wastewater has emerged as a sustainable approach with both waste reuse and wastewater processing. In this study, green reduced graphene oxide (G-rGO) was prepared utilizing green tea extract with the advantages of being environmentally friendly, sustainable, and low cost. To understand how G-rGO functions, it was compared to commercial reduced graphene oxide (rGO), and the efficiencies in adsorbing Y(III) were 91.6% and 11.9%, respectively. This indicated there is a synergistic adsorption between the capping layer of G-rGO and rGO alone. G-rGO and rGO were characterized before and after exposure to Y(III). This comparison indicated that Y(III) was adsorbed on the surface of G-rGO through complexation and electrostatic interaction. The adsorption kinetics best fit the pseudo-second-order model and the Langmuir model isotherm model, with adsorption capacities of 24.54 mg g-1. A probable adsorption mechanism of Y(III) by G-rGO was proposed, involving electronic complexation, electrostatic adsorption and ion exchange. Furthermore, the adsorption efficiencies of G-rGO for Y(III), Ce(III) and Zn(II) in mine wastewater were 22.1%, 89.1% and 14.6%, respectively. These results demonstrate that G-rGO has great potential in the recovery of REEs from mine wastewater.

Enhanced activity of Fe/Mn nanoparticles using a response surface methodology and mechanism for removing oxytetracycline and copper ion.

As feed additives, oxytetracycline (OTC) and copper ion (Cu(II)) are often detected in livestock and poultry farming wastewater. To address this issue, firstly, the synthesis conditions of Fe/Mn nanoparticles (Fe/Mn NPs) were initially optimized using a response surface methodology (RSM) to yield highly active Fe/Mn NPs, where the application of RSM significantly increased the Fe/Mn NPs' efficiency in removing co-contamination OTC and Cu(II),respectively, from 45.8 to 86.2% and 14.9-67.2%. Secondly, scanning electron microscope and Nitrogen adsorption-desorption isotherms results showed that Fe/Mn NPs were composed of elliptic particles between 20 and 40 nm, a specific surface area of 59.5 m2 g-1, and a mean pore diameter of 5.27 nm. Fourier infrared spectrometer and X-ray photoelectron spectroscopy analysis revealed that amino, carboxyl and hydroxyl functional groups existed on the surface. Zeta potential indicated that Fe/Mn NPs maintained a high negative charge density between pH 1 and 11. These surface properties possessed by the green synthesized Fe/Mn NPs resulted in high adsorption efficiency for co-contamination OTC and Cu(II). Based on this, a removal mechanism based on a combination of complex-bridging effect, pore-filling, hydrogen bonding, surface complexation, ion exchange and electrostatic attraction was proposed. Finally, the assessment of Fe/Mn NPs used in swine wastewater demonstrated that both 99.9% OTC and 55.6% Cu(II) were removed.

Performance of the Human Papillomavirus E6/E7 mRNA Assay in the Primary Screening of Cervical Cancer: Opportunistic Screening in Fujian, China.

Purpose: A high-risk human papillomavirus E6/E7 mRNA (HR-HPV mRNA) assay is widely used in cervical cancer screening in China. However, it is still unclear whether stand-alone HR-HPV mRNA testing is sufficient for primary screening. The purpose of this study was to investigate the feasibility of a stand-alone HR-HPV mRNA assay for primary screening of cervical cancer. Methods: Women aged 21 and older were recruited in Fujian Province, China, from January 2020 to January 2022. Cervical exfoliated cells were collected for cervical cytology and HR-HPV mRNA assays, and women with positive results on either assay were referred for colposcopy. The screening effectiveness of the assay was calculated based on the cervical histology. When comparing the efficacy of the different screening strategies, only women aged 25 and older were included. Results: A total of 9927 women were recruited. This study identified 217 cases of high-grade squamous intraepithelial disease or worse (HSIL+). The overall age-specific HR-HPV infection rate showed a U-shaped distribution. The sensitivity of the HR-HPV mRNA assay to identify CIN2+ and CIN3+ was 97.2% and 97.9%, respectively, which was significantly higher than that of cytology (82.9% and 88.6%, P<0.001 and 0.002). The sensitivity of the HR-HPV mRNA primary screening strategy to identify CIN2+ and CIN3+ was 92.2% and 94.3%, respectively, which was similar to the co-testing strategy (P=0.336 and 0.394) and higher than the cytology primary screening (P=0.002 and 0.048). In addition, the HR-HPV primary screening strategy had a lower referral rate for colposcopy than cytology primary screening (5.4% vs 6.6%, P<0.001), and the screening cost was lower than co-testing ($29,594.3 per 1000 screened women vs $55,140 per 1000 screened women, P<0.001). Conclusion: In conclusion, the detection of CIN2+/CIN3+ by HR-HPV mRNA is both specific and sensitive. It may be suitable for primary screening of cervical cancer in China.

Assessment of High-Risk Human Papillomavirus Infection Characteristics in Cervical Squamous Cell Carcinoma and Adenocarcinoma in China.

Background: The characteristics of high-risk human papillomavirus (HR-HPV) infection in different pathological types of cervical cancer in China are unclear. The aim of this study was to evaluate HR-HPV genotypes and age stratification with cervical squamous cell carcinoma (SCC) and adenocarcinoma (ADC) in China. Materials and Methods: Patients diagnosed with cervical cancer by histopathology in Fujian Maternity and Child Health Hospital from January 1, 2014, to December 31, 2017, were included in this study. The HR-HPV genotype was analyzed in cervical specimens. Logistic regression was used to calculate odds ratios (ORs). All tests of statistical significance were two-sided, and the P value<0.05. Results: A total of 1,590,476 women were screened for cervical cancer, and 688 cervical cancers were detected, including 554 SCC and 93 ADC. The overall HR-HPV infection rate in SCC was higher than that in ADC (91.2% vs 81.7%, P=0.005). HPV-16 was the most prevalent genotype in SCC (70.0%) but was only 31.2% in ADC (P<0.001). However, the prevalence of HPV-18 in ADC was significantly higher than that in SCC (45.2% vs 7.0%; P<0.001). In SCC, the prevalence of HPV-16 was consistently much higher than that of HPV-18 regardless of age group. Among ADC, the prevalence of HPV-18 was higher than that of HPV-16 in women aged ≥45 years. Interestingly, in those aged <35 years, the highest prevalence was observed for HPV-16. HPV-18 infection has the highest risk of ADC (OR= 12.109; P< 0.001), and HPV-45 and HPV-51 were also found to be associated with the occurrence of ADC. However, HPV-16 infection greatly increased the risk of having histological SCC. Conclusion: HPV-16 and HPV-18 infections are key risk factors for SCC and ADC. The use of HR-HPV genotyping tests in cervical cancer screening and vaccination against major HPV genotypes could reduce the incidence of cervical cancer.

Postoperative reproductive results of infertile patients with intrauterine adhesions: A retrospective analysis.

OBJECTIVE: To explore the reproductive outcomes after hysteroscopic separation of intrauterine adhesions (IUA) in infertile patients due to IUA. METHODS: This retrospective study enrolled patients with fertility requirements and infertility due to IUA. Data were collected from the hospital medical records and by follow-up by telephone. The impact on pregnancy and pregnancy outcome of preoperative adhesion, menstrual conditions before and after surgery and postoperative re-adhesion was analysed. RESULTS: A total of 106 patients (median age, 28 years) were enrolled in the study. There was a significant correlation between preoperative menstrual patterns and pregnancy rate. There were 56 pregnancies (pregnancy rate 52.83%) after the operation. Patients with improved menstruation after the operation had a significantly higher pregnancy rate (pregnancy rate 56.25%; 45 of 80 patients) compared with the patients that did not experience any improvement in their postoperative menstrual status (pregnancy rate 21.43%; three of 14 patients). Of the 56 pregnancies, 40 (71.43%) resulted in live births and six (10.71%) patients had miscarriages. A total of 54 of 56 patients (96.43%) became pregnant within 2 years. CONCLUSION: Pregnancy after intrauterine adhesion separation has a high rate of miscarriage and obstetric complications, so close monitoring of the patient is required.

Synthesis of ferroferric oxide@silicon dioxide/cobalt-based zeolitic imidazole frameworks for the removal of doxorubicin hydrochloride from wastewater.

Due to its low-cost, eco-friendliness and easy mode of separation biosynthesized magnetic ferroferric oxide (Fe3O4) can be successfully used for the removal of organic contaminants from wastewater. However, there are some challenges that to date have limited this compound's practical removal efficiency. Thus, in this study, a cobalt-based zeolitic imidazole frameworks (ZIF-67) coated biosynthesized ferroferric oxide@silicon dioxide (Fe3O4@SiO2) magnetic composite (Fe3O4@SiO2/ZIF-67) was prepared to address these issues and subsequently used to remove doxorubicin hydrochloride (DOX). Characterization results showed that the fabricated composite exhibited significant magnetic properties (16.1 emu·g-1) with a size ranging between 50 and 250 nm. The amount of DOX adsorbed by the composite (90.7 mg·g-1) was much higher than either of the component parts, which were only 35.7 and 82.5 mg·g-1 for Fe3O4@SiO2 and ZIF-67 respectively. This indicated enhanced DOX adsorption by Fe3O4@SiO2/ZIF-67. The DOX adsorption best fit a pseudo-second order kinetic and Langmuir adsorption model. These studies suggested that the DOX adsorption mechanism involved a combination of electrostatic interactions, π-π stacking, hydrogen bonding and pore filling. Regeneration and application studies, exposing Fe3O4@SiO2/ZIF-67 to real water samples, practically demonstrated that Fe3O4@SiO2/ZIF-67 with propensity for magnetic separation and recycle is a promising nanomaterial for DOX removal.

Biosynthesis of silver nanoparticles using three different fruit extracts: Characterization, formation mechanism and estrogen removal.

Plant-mediated synthesis of silver nanoparticles (Ag NPs) is a green and economically viable method, which can offer numerous benefits over traditional chemical and physical methods. In this paper, three fruit extracts (tomato, orange, and grapefruit) served simultaneously as stabilizing and reducing agents during the biosynthesis of Ag NPs. The formation of Ag NPs, were monitored using the UV-visible absorption spectra of Ag NPs which exhibited three distinct bands centered at 439, 413, and 410 nm. SEM and TEM analysis indicated that these bands corresponded to three distinct spherical-shaped Ag NPs having average particle sizes of 73, 24, and 31 nm, respectively. XRD and EDS spectral analyses were used to verify the degree of crystallinity, nanostructure, and presence of Ag NPs. Advanced analysis using XPS, FTIR, and GC-MS indicated that the Ag NPs were coated with a variety of organic compounds including acids, aldehydes, esters, and ketones, indicating that fruit derived phytochemicals had a significant role in synthesis, and subsequently a mechanism of Ag NPs formation was proposed. The fabricated nanoparticles were also successfully used in Fenton-like oxidation for the environmental remediation of estrone and estriol, with removal efficiencies of 52.1 and 35.9%, respectively.

Simultaneous removal of Sb(III) and Sb(V) from mining wastewater by reduced graphene oxide/bimetallic nanoparticles.

Antimony (Sb) contamination is a significant environmental issue in mining impacted areas, where the use of nanomaterials to remove such metalloid species has attracted much research attention. In this study, the simultaneous removal of Sb(III) and Sb(V) was investigated using a reduced graphene oxide/Fe/Ni (rGO-Fe/Ni NPs) composite. Compared to rGO alone the composite exhibited enhanced removal efficiency. For rGO-Fe/Ni NPs the maximum Sb(III) and Sb(V) adsorption capacities were 2.00 and 1.41 mg·g-1, respectively, compared to 1.70 and 1.02 mg·g-1 for Sb(III) and Sb(V), respectively, when using rGO only. This indicated that Fe/Ni enhanced the simultaneous removal of Sb(III) and Sb(V). Advanced characterization via SEM and XPS before and after exposure to Sb indicated that both Sb(III) and Sb(V) were adsorbed on to the surface of rGO-Fe/Ni NPs, followed by oxidation of Sb(III) to Sb(V). Adsorption and oxidation kinetics both conformed to pseudo-second order models, where the mechanism for the simultaneous removal of Sb(III) and Sb(V) by rGO-Fe/Ni NPs involved a combination of both adsorption and oxidation. Moreover, the practical adsorption capacity of rGO-Fe/Ni was not limited to Sb, since in a real mining wastewater; containing a mixture of metal(loid)s, while rGO-Fe/Ni exhibited a Sb adsorption capacity of 1.59 mg·g-1, it also exhibited similar adsorption capacities for As (2.61 mg·g-1), Pb (2.41 mg·g-1), and Cd (1.25 mg·g-1). The composite was also highly reusable with a removal efficiency for Sb(III) as high as 72.7% after 4 cycles of use. Thus, rGO-Fe/Ni NPs has significant potential for the practical removal of Sb species and other heavy metal(loid)s in mining impacted wastewaters.

A one step synthesis of hybrid Fe/Ni-rGO using green tea extract for the removal of mixed contaminants.

The use of biomass for the synthesis of value-added products, such as functional nanomaterial for the removal of contaminants, is a challenge. In this study, hybrid bimetallic Fe/Ni nanoparticles and reduced graphene supported bimetallic Fe/Ni nanoparticles (Fe/Ni-rGO) were prepared via a one-step green synthesis using green tea extract, and thereafter evaluated for the simultaneous removal of rifampicin (RIF) and Pb(II) from aqueous solution. The efficiencies of Pb(II) and RIF removal by Fe/Ni-rGO were 87.5 and 96.8%, respectively. The removal performance of the hybrid Fe/Ni-rGO was better than either nFe/Ni, rGO, or Fe-rGO. Detailed characterization and analyses of Fe/Ni-rGO indicated that both Fe and Ni nanoparticles were evenly distributed over the surface of rGO and that aggregation of Fe, Ni nanoparticles, and stacking of rGO in the hybrid were decreased. Furthermore, while LC-TOF-MS analysis showed that RIF was degraded into small-molecule fragments, XPS showed that Pb(II) was not reduced to Pb0. The major conditions impacting removal efficiency, adsorption kinetics, and fit to adsorption isotherm models were examined to better understand the removal mechanism. While the adsorption of both contaminants fit well a pseudo-second-order kinetic model, the adsorption of RIF fit the Freundlich isotherm model best, while the adsorption of Pb(II) fit the Langmuir isotherm model best. Thus, the removal mechanism of both contaminants firstly being chemical adsorbed onto the surface, while nFe/Ni continues to participate in the catalytic reduction of RIF. Moreover, Fe/Ni-rGO could be reused and performed well for wastewater treatment, thus suitable as a practical resource recycling technology.

Removal mechanism of Sb(III) by a hybrid rGO-Fe/Ni composite prepared by green synthesis via a one-step method.

The annual influx of antimony (Sb) into the environment due to the widespread use of Sb compounds in industry and agriculture has become of global concern. Herein, a functional nanomaterial composite based on loading bimetallic iron/nickel nanoparticles on reduced graphene oxide (rGO-Fe/Ni) was initially prepared in a one-step phytogenic synthesis using a green tea extract. Subsequently, when applied for Sb(III) removal, the removal efficiency of rGO-Fe/Ni reached 69.7% within 3 h at an initial Sb concentration of 1.0 mg·L-1. Advanced materials characterization via scanning electron microscopy-energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy revealed that Sb(III) was initially adsorbed onto the surface of rGO and then oxidized to Sb(V). This result was also supported by adsorption isotherm, kinetics, and thermodynamic analysis. These studies revealed that the adsorption was spontaneous and endothermic, following a Langmuir adsorption model with pseudo-second-order kinetics and allowed a Sb(III) removal mechanism based on adsorption and catalytic oxidation to be proposed. Furthermore, when rGO-Fe/Ni was practically used to remove Sb(III) in groundwater a 95.7% removal efficiency was obtained at 1 mg·L-1 Sb(III), thus successfully demonstrating that rGO-Fe/Ni has significant potential for the practical remediation of Sb contaminated groundwater.

Green magnetic nanomaterial as antibiotic release vehicle: The release of pefloxacin and ofloxacin.

The increased efflux of fluoroquinolone antibiotics to the environment has become of worldwide concern due to their potential to disturb aquatic ecosystems. How to improve the antibiotic release is a challenge. In this work, magnetic Fe3O4 nanoparticles as a drug release vehicle were prepared using the green synthesis method. It is a simple and environmental friendly technique that employs the plant extract as a reducing and coating agent during the preparation process. Antibiotics ofloxacin and pefloxacin served as the drug model and the drug release behavior was tested at various pH levels. The release efficiency of ofloxacin from Fe3O4 reached 99.6% and for pefloxacin it was 57.0% at 310 K after 120 h (pH 10.5). The scanning electron microscope images show that Fe3O4 particles ranged in size from 10 to 40 nm and magnetism testing indicated that saturation magnetization was 58.7 emu/g. Furthermore, zeta potential, FTIR, UV-VIS, XRD and XPS were used to provide the evidence to support the release mechanism, where was based on the pH control. Our work clearly demonstrated that Fe3O4 nanoparticles were a potential as a targeted drug delivery system.

Ovarian preservation and prognosis in adnexal torsion surgery - a retrospective analysis.

OBJECTIVES: This study aims to analyze the conditions of ovarian preservation during adnexal torsion surgery, and safety of ovarian preservation. MATERIAL AND METHODS: A retrospective analysis of 130 patients, who underwent surgery for ovarian benign tumor pedicle torsion in Fujian Provincial Maternal and Child Health Hospital from June 2013 to June 2018, was conducted. This study analyses the possible risk factors affecting the operation method using multiple logistic regression and analyses the complications and the recovery of ovarian function after the treatment of the ovarian preservation. RESULTS: Among these patients, 58 received ovarian cystectomy, while 72 received ovariectomy. There was no significant difference in terms of age, preoperative blood, operation time and surgical bleeding volume between the two groups (p > 0.05). However, there was a significant difference in preoperative adnexal blood flow, abdominal pain to the surgical interval, and a collection of torsion cycles (p < 0.05). There was an increased risk of ovarian resection in patients whose blood flow of the annex disappeared, whose time of abdominal pain was long, and whose number of twists were significant. For the preservation group, there were no increases in postoperative complications. CONCLUSIONS: According to clinical indicators, such as preoperative adnexal blood flow, abdominal pain to the interval of surgery and the number of torsion cycles, it was determined whether it was feasible to keep the ovary. Retaining the ovary is safe, effective and feasible in adnexal torsion.

Modified green synthesis of Fe3O4@SiO2 nanoparticles for pH responsive drug release.

A magnetic field activated drug delivery and pH-sensitive controlled drug release system based on carboxyl-modified green synthesized Fe3O4@SiO2 (Fe3O4@SiO2-Glu) nanoparticles was established. Doxorubicin hydrochloride (DOX), as a drug model, was adsorbed onto the Fe3O4@SiO2-Glu nanoparticles' surface, where the observed drug loading capacity of 34.6 mg/g was attributed to electrostatic interaction between -COO- on the surface of Fe3O4@SiO2-Glu and -NH3+ of DOX. The structure, morphology and physiochemical properties of Fe3O4@SiO2-Glu were characterized via TEM, FTIR, XRD, N2 adsorption/desorption isotherms, and Zeta potential measurements. The green synthesized Fe3O4@SiO2-Glu nanoparticles exhibited multilayer architecture with a BET surface area of 79.9 m2/g and a magnetization saturation of 25.9 emu/g. Drug release experiments indicated that DOX was pH trigger released with 60.8% released within 72 h at pH 3.5. This system has important potential implications for the design of more effective and stable magnetic Fe3O4@SiO2-Glu materials as drug carriers for targeted and controlled drug release.

Mechanism and impact of synthesis conditions on the one-step green synthesis of hybrid RGO@Fe/Pd nanoparticles.

While a one-step green synthesis of a hybrid material composed of reduced graphene oxide and bimetallic Fe/Pd nanoparticles (RGO@Fe/Pd NPs) was previously successfully reported and evaluated for the removal of organic contaminants, the relationship between the formation of RGO@Fe/Pd and the resulting reactivity was unclear. In this paper the impact of the specific synthetic conditions on the reactivity of RGO@Fe/Pd was investigated in order to enhance the removal efficiency of antibiotics such as rifampicin. The hybrid material (RGO@Fe/Pd) successfully removed 96.1% of rifampicin compared to only 63.5 and 81.0% for Fe nanoparticles and RGO, respectively. The best synthetic conditions for the formation of RGO@Fe/Pd included GO/Fe = 1:1 and Fe/Pd = 100: 5. In addition, GC-MS and FTIR were used to identify the main reducing biomolecules in the green tea extract responsible for the one-step synthesis of RGO@Fe/Pd as Catechol, Caffeine, 1,3,5-Benzenetriol. The morphology, size and surface composition of RGO@Fe/Pd was characterized by Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), X-Ray powder diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). These advanced characterization techniques suggested that during synthesis GO was initially converted to RGO, and thereafter Fe/Pd NPs (10-50 nm) were dispersed on RGO. Finally, a plausible formation mechanism for the one-step synthesis of the hybrid material was proposed.

Removal mechanism of mitoxantrone by a green synthesized hybrid reduced graphene oxide @ iron nanoparticles.

Anti-tumor drugs, due to their non-specific toxicity will cause long-term delayed toxicity to organisms and humans when discharged into the environment. In this study, reduced graphene oxide @ iron nanoparticles (rGO@Fe NPs) were successfully prepared using green tea extract as reductant and subsequently used for mitoxantrone (MTX) removal. SEM and Raman spectroscopy showed that 30-60 nm sized Fe NPs were loaded on rGO and green tea extract successfully reduced GO to rGO. The removal efficiency of MTX by the hybrid material was higher (98.5%) than either rGO (77.5%) or Fe NPs (53.1%) alone. In addition, the removal efficiency of MTX by the hybrid material was as high as 95% within 5 min, MTX adsorption followed both a pseudo-second-order kinetic model and the Langmuir isotherm, and it is a spontaneous adsorption. Recycling experiments showed that the removal efficiency of MTX decreased from 99.9 to 76.8% after six cycles, and could be as high as 99% in both municipal and medical wastewater. Scanning electron microscopy (SEM), Fourier transform infrared Spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and High performance liquid chromatography (HPLC) were all used to characterize and analyze the hybrid material, and possible adsorption mechanisms which revealed that MTX adsorption probably involved a combination of π-π stacking interaction, hydrogen bonding, electrostatic interaction and pore-filling.

Mechanistic insights into Pb(II) removal from aqueous solution by green reduced graphene oxide.

As one of the important contaminants in wastewater, Pb(II) becomes a severe public health problem because of its non-biodegradable and persistent nature. In this study, reduced graphene oxide (RGO) prepared using green tea extract was successfully used to remove Pb(II) from aqueous solutions. A 96.6% of Pb(II) was removed at 10 mg/L Pb(II) and 0.4 g/L RGO with pH 4.5 at 30 °C, and the adsorption of Pb(II) by RGO followed pseudo-second-order kinetics. To confirm the removal mechanism, various methods (Transmission Electron Microscopy, Raman spectroscopy and X-ray diffraction) were used to characterize RGO before and after Pb(II) adsorption. The results showed that the surface of RGO after Pb(II) adsorption became rougher, and the interlayer spacing increased from 0.36 nm to 0.40 nm, indicating that Pb(II) was adsorbed on the surface and between the layers of RGO. Finally, the adsorption mechanism of Pb(II) by RGO was proposed, Pb(II) was adsorbed on the surface of RGO via the electrons on the π-bond on RGO and the interaction of Pb(II) with oxygen-containing functional groups, which were supported by the Fourier Transform Infrared and X-ray photoelectron spectroscopy results.

Adsorption of doxorubicin hydrochloride on glutaric anhydride functionalized Fe3O4@SiO2 magnetic nanoparticles.

Since Fe3O4 nanoparticles synthesized by plant extracts possess good bio-compatibility and superparamagnetic properties, the possibility of these could be used as a carrier in drug delivery. In this work, doxorubicin hydrochloride (DOX), an anti-cancer drug, loaded on glutaric anhydride-functionalized magnetic nanoparticles (Fe3O4@SiO2-Glu) was investigated at varying pH values for effective drug delivery. Various factors affecting the adsorption of DOX onto the Fe3O4@SiO2-Glu were examined, where the adsorption efficiency of DOX reached 92% at a concentration of 20 mg/L employing 10 mg of Fe3O4@SiO2-Glu at 303 K in pH 7.4. However, the adsorption efficiency of DOX was decreased to 18% at acidic pH value down to 3.0, implicating that the drug releasing process was controlled by pH. Adsorption kinetics was fitting to pseudo-second-order and the isothermal adsorption conformed to Freundlich isotherm. The morphology and surface composition of the synthesized Fe3O4@SiO2-Glu were characterized by SEM, TEM, and N2 adsorption/desorption isotherms, revealing that the specific surface area being 62.6 m2/g and the size ranging from ~30 to 50 nm. The zeta potential results indicated that Fe3O4@SiO2-Glu were negatively charged in various pH from 3 to 8.5. Characterizations by FTIR and UV-Vis techniques suggested that the DOX was absorbed and it can be delivered by Fe3O4@SiO2-Glu.

Highly efficient removal of antibiotic rifampicin from aqueous solution using green synthesis of recyclable nano-Fe3O4.

Antibiotics in water and soil are persistent, bioaccumulative and toxic to aquatic organisms and human health. To address it, as one of the new technologies, green synthesized magnetic Fe3O4 nanoparticles by Excoecaria cochinchinensis extract used to remove rifampicin (RIF) was investigated in this study. Results showed the adsorption efficiency of RIF reached 98.4% and the maximum adsorption capacity is 84.8 mg/g when 20 mL of RIF at a concentration of 20 M was adsorbed by 10 mg Fe3O4 at a temperature of 303 K. The morphology of the green Fe3O4 characterized by SEM demonstrated the dimensions ranging from 20 to 30 nm. The N2 adsorption/desorption isotherms revealed that the surface area of Fe3O4 was 111.8 m2/g. In addition, adsorption studies indicated that the kinetics fitted the pseudo second-order and isothermal adsorption conformed to the Langmuir isotherm. Furthermore, due to their magnetic properties, the Fe3O4 nanoparticles were easily separated and reused and the mechanism for removing RIF occurred through adsorption rather than chemical redox reaction. Finally, the reusability of Fe3O4 for adsorption of RIF showed that the removal efficiency decreased to 61.5% after five cycles.