Catalytic recovery of metals from end-of-life polycrystalline silicon photovoltaic cells: Experimental insights into silver recovery.

A steady increase in end-of-life (EoL) polycrystalline silicon photovoltaic (c-Si PV) panels is necessitating the development of recycling technologies to guarantee sustainable environmental management and a circular economy. Herein, we propose a comprehensive EoL c-Si PV recycling strategy with an emphasis on selective silver (Ag) recovery. Primarily, a combination of physical and thermal treatment led to the isolation of PV cell fraction from the EoL PV module. Thereafter, a less-toxic, sulphuric acid-hydrogen peroxide (1 M H2SO4- H2O2 1% (v/v %)) lixiviant was used for Ag leaching at 70 °C. A novel catalytic process using platinum-embedded activated carbon (Pt/AC) was used with only hydrogen gas and air to recover selectively and concentrate the Ag+ from the synthetic PV cells leachate. Finally, pure metallic silver (Ag > 99.0 %) was obtained by the conventional electrowinning process. This study also proposes an explicit recovery process for Al, Cu, and Si. In addition, the Pt/AC catalytic process could efficiently recover Cu from the PV cells, similar to Ag. Following the complete recovery of Ag and Cu through Pt/AC, there is sufficient scope to isolate other metals like Al and Pb leaving behind crude Si wafers. Hence, the as-proposed recycling and metal recovery process is a newer approach benefiting industrial implementation.

Effect of Injectable Platelet-Rich Fibrin with a Nano-Hydroxyapatite Bone Graft on the Treatment of a Grade II Furcation Defect.

Background: Periodontal diseases lead to bone loss, crestal defects and even loss of the tooth, which also further makes it difficult to replace the tooth. Autogenous bone grafts are considered the gold standard in bone regenerative procedures. This study aimed to compare and evaluate the bone regenerative effects of i-PRF (Injectable- Platelet-rich fibrin) with a bone graft and a bone graft alone in mandibular grade II furcation defects over a period of 9 months. Method: This was a comparative study of 12 participants, who were randomly selected and grouped into two groups: test and control. Following phase I therapy, both groups were subjected to open flap debridement. In the test group, after debridement, a nano-hydroxyapatite bone graft mixed with i-PRF was inserted, whereas in the control group only a nano-hydroxyapatite bone graft was inserted. The clinical parameters such as plaque index (PI), gingival index (GI), pocket probing depth (PPD), clinical attachment level (CAL), horizontal probing depth (HPD) and vertical probing depth (VPD) were recorded at baseline, 3 months, 6 months and 9 months following the surgery. The bone area fill (BAF) was assessed using intraoral periapical radiographs (IOPARs) taken at baseline and 9 months after surgery. Results: At the baseline, there was no statistically significant difference between the tested parameters. After 9 months all the clinical parameters, PI, GI, PPD, CAL, HPD and VPD as well as radiographic bone fill showed a significant increase in both the groups (p < 0.05) (PI-TGr; CGr−VPD­3.5 ± 0.54 to 0.66 ± 0.51; 3.3 ± 0.81 to 2 ± 0.63/BAF­2.9 ± 0.88 to 5.6 ± 1.10; 3.4 ± 1.39 to 3.9 ± 1.4). On comparison the test group showed better results for each clinical parameter. Conclusion: The results showed increased improvement in clinical conditions in both groups, although better results were seen in the group where i-PRF with a nano-HA bone graft was used in the furcation defect.

Photocatalytic degradation of lomefloxacin antibiotics using hydrothermally synthesized magnesium titanate under visible light-driven energy sources.

Antibiotics in water system pose a human health risk due to the rise of antibacterial activity in the environmental web. Advanced oxidation processes are the potential to become an effective treatment technology for targeting antibiotics. This study demonstrates the visible light photocatalysis of lomefloxacin using magnesium titanate (MgTiO3). The nanomaterial was subjected to computational analysis to study morphology, functional, and optical characteristics through FESEM, XRD, FTIR, BET, UV-Vis, etc. Importantly, MgTiO3 had band gap energy of 3.09 eV. The photocatalytic studies were performed to observe different parameters affecting lomefloxacin degradation such as initial concentration, catalyst dosage, and pH. The nanomaterial exhibited the maximum lomefloxacin degradation. The study revealed that 30 mg/L of catalyst was optimum to degrade 10 mg/L of lomefloxacin with 30-W LED irradiation up to 150 min. Reactive species, namely, electron, hole, hydroxyl, and superoxide radicals, comprised the primary photocatalytic mechanism for lomefloxacin degradation. Ultimately, the summative result from this study highlights the suitability of the photocatalytic system to treat persistent antibiotics in aqueous environment.

Degradation of doxycycline antibiotics using lanthanum copper oxide microspheres under simulated sunlight.

In this study, lanthanum copper oxide was synthesized under hydrothermal techniques and characterized for doxycycline degradation. The catalyst exhibited enhanced photocatalytic doxycycline degradation under visible light owing to its compatible bandgap energy (1.7 eV). The XRD data revealed high crystallinity of the material with no noticeable impurities. Three-dimensional microspheres of varying sizes (average diameter of 2.52 µm) were observed from SEM. EDX confirms the successful synthesis of La2CuO4. The effect of DC concentration, catalyst dosage, and initial pH on the degradation rate of DC was studied methodically. Interestingly, about 85% of doxycycline (10 mg/L) was degraded within 120 min of light-emitting diode irradiation at pH 10. Oxygen vacancies and surface defects were determined through photoluminescence spectra. The recyclability experiments suggested that the catalyst is capable of degrading DC for three consecutive runs. Radical trapping trials suggested that holes (h+), superoxide radicals (●O2-), and hydroxyl radicals (●OH) are involved in the photodegradation of DC. Herein, the novel approach of La2CuO4 synthesis and the efficient visible-light harvesting capability of as-prepared catalyst reveal the potentiality for DC degradation thereby opening a new horizon of research employing La2CuO4 used for various environmental applications.

Recent advances in photocatalytic remediation of emerging organic pollutants using semiconducting metal oxides: an overview.

Many untreated and partly treated wastewater from the home and commercial resources is being discharged into the aquatic environment these days, which contains numerous unknown and complex natural and inorganic compounds. These compounds tend to persist, initiating severe environmental problems, which affect human health. Conventionally, physicochemical treatment methods were adopted to remove such complex organic chemicals, but they suffer from critical limitations. Over time, photocatalysis, an advanced oxidation process, has gained its position for its efficient and fair performance against emerging organic pollutant decontamination. Typically, photocatalysis is a green technology to decompose organics under UV/visible light at ambient conditions. Semiconducting nanometal oxides have emerged as pioneering photocatalysts because of large active surface sites, flexible oxidation states, various morphologies, and easy preparation. The current review presents an overview of emerging organic pollutants and their effects, advanced oxidation processes, photocatalytic mechanism, types of photocatalysts, photocatalyst support materials, and methods for improving photodegradation efficiency on the degradation of complex emerging organic pollutants. In addition, the recent reports of metal-oxide-driven photocatalytic remediation of emerging organic pollutants are presented in brief. This review is anticipated to reach a broader scientific community to understand the first principles of photocatalysis and review the recent advancements in this field.

Sonochemical synthesis of graphitic carbon nitride-manganese oxide interfaces for enhanced photocatalytic degradation of tetracycline hydrochloride.

The present study focuses on the sonochemical synthesis of graphitic carbon nitride-manganese oxide (GCN/MnO2) nanocomposite for photocatalytic degradation of an environmentally hazardous pharmaceutical compound, tetracycline hydrochloride (TcH). The sonochemical synthesis aided in tailoring the morphology of GCN/MnO2. The characterization results of SEM/FESEM, XRD, FTIR, UV-Vis spectra, EIS, CV, etc., revealed on the morphology, composition, crystallinity, and other photo-electro-intrinsic properties of the materials. The synergy of GCN and MnO2 results in rapid electron transfer, efficient visible-light absorption, and slower electron-hole pair recombination through its photo-responsive traits against TcH. It was noted that ~ 93% TcH (20 mg L-1) degradation was achieved for 30-mg catalyst dose under light-emitting diode (LED) irradiation (9 W, 220 V) in 135-min duration. The TcH mineralization results were well fit to pseudo-first-order kinetics with a rate constant of 0.02 min-1 (R2 = 0.994). In addition, the composite possessed fair reusability for consequent cycles. Hence, the as-synthesized composite applied for photocatalysis and photoelectrocatalysis fosters a fit-for-purpose and reliable system in the decontamination of TcH in environmental samples. Graphical Abstract.

Quantification, distribution, and effects of di (2-ethylhexyl) phthalate contamination: Risk analysis and mitigation strategies in urban environment.

Phthalate acid ester, di (2-ethylhexyl) phthalate (DEHP) is ubiquitously detected contaminant of emerging concerns (CECs) in all the environmental samples. The present study attempted to understand the fate and transport of DEHP in urban areas by evaluating the quantities, distribution, risk, and effects in the Mysuru city, India. The study is anticipated to serve as a vital document for local and national regulators to frame a robust DEHP management plan and mitigate the risks associated. Liquid-liquid microextraction followed by gas chromatographic analysis was adopted to determine the concentrations of DEHP. The risk quotient method was adopted to assess potential risk, and a conceptual planning model framework was designed to mitigate the DEHP contamination. The municipal wastewater contained 115 ± 9.2 µg/L, whereas treated municipal wastewater showed 95 ± 7.6 µg/L DEHP that was attributed to the inefficiency of the treatment plant. Further, sediments in surface water, as well as groundwater samples of the study area, showed 8 ± 0.64 to 12 ± 0.96 µg/L and 32 ± 2.56 to 40 ± 3.2 µg/kg of DEHP, respectively. The risk quotient of 19.17 for samples in around treatment indicated highest risk, whereas groundwater samples had a risk quotient of 1-2 indicating relative risk to aquatic organisms. In addition, the study highlighted the source, possible entry pathways, and management strategies including treatment aspects to draw an understanding of the distribution and potential ecological imbalances with contamination of DEHP in the urban sector. PRACTITIONER POINTS: Understand the fate and transportation of DEHP in urban wastewater. Primary investigation and assessment to possible health and environmental risks of DEHP contamination in urban wastewater. Revealed the associated health risks and proposed possible management strategies.

Evaluation of ozone as an adjunct to scaling and root planing in the treatment of chronic periodontitis: A randomized clinico-microbial study.

BACKGROUND AND OBJECTIVES: Mechanical plaque control is an essential part of periodontal therapy. In the present study, the efficacy of ozone water irrigation as an adjunct to scaling and root planing was evaluated in the treatment of generalized chronic periodontitis. MATERIALS AND METHODS: Twenty-four patients with chronic periodontitis selected for the study were randomly divided into Group A and Group B, receiving ozone water irrigation and distilled water irrigation, respectively, after scaling and root planing. Subgingival plaque was collected from the selected investigational teeth and was analyzed using BANA-Zyme™ Processor to evaluate the "red complex" periodontal pathogens. The clinical and microbiological parameters were recorded at baseline, 14 days, 21 days, and 2 months. RESULTS: The mean probing pocket depth scores for Group A and Group B at the baseline were 6.833 ± 1.193 and 7.833 ± 1.276; on day 14th, they were 6.616 ± 1.403 and 7.083 ± 1.378; on day 21st, they were 5.166 ± 0.937 and 6.083 ± 1.443;and on the 2nd month, they were 4.500 ± 0.797 and 5.166 ± 1.029, respectively. At the 2nd month, in Group A, 9 samples showed BANA negative and 3 samples showed BANA positive, and in Group B, 12 samples showed BANA negative and 0 sample showed BANA positive. The microbiological analysis showed a reduction in periodontal pathogens in both the groups. CONCLUSION: Significant improvement in both clinical and microbiological parameters suggests that subgingival ozonated water irrigation could be an efficient adjunct to scaling and root planing in the treatment of chronic periodontitis.

Potentiometric polyphenol oxidase biosensor for sensitive determination of phenolic micropollutant in environmental samples.

The present study demonstrates the development of polyphenol oxidase (PPO) biosensor for the detection of catechol using strontium copper oxide (SrCuO2) and polypyrrole nanotubes (PPyNT) matrix. The SrCuO2 micro-seeds, a perovskite compound, are synthesized by co-precipitation under pH 8.0. The as-synthesized micro-seeds are characterized by scanning electron microscopy (SEM), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction spectroscopy (XRD). The proposed sensor is fabricated on pencil graphite (P-Gr) by successive deposition of PPyNT, SrCuO2, and PPO enzyme. The developed PPO/SrCuO2/PPyNT/P-Gr sensor is characterized by cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS) techniques. The PPO/SrCuO2/PPyNT/P-Gr displayed excellent electrocatalytic activity towards the oxidation and detection of catechol. The as-developed sensor showed sensitive response ascribing to limit of detection (LOD) of 0.15 µM and sensitivity of 15.60 µA µM-1 cm-2. The fabricated sensor exhibited excellent repeatability and longer shelf life. The proposed biosensor finds its application within the broad linear range of 1-50 µM. Real sample analysis of mineral water, tap water, and domestic wastewater using developed sensor showed acceptable recovery. Hence, the biosensor endeavors its application in environmental monitoring and protection.

Evaluation of anorganic bovine-derived hydroxyapatite matrix/cell binding peptide as a bone graft material in the treatment of human periodontal infrabony defects: A clinico-radiographic study.

BACKGROUND: Various bone graft materials have been used in the treatment of periodontal defects. A synthetic bone substitute material composed of P-15 with anorganic bone mineral has been scantly studied. Hence, the present study was aimed to evaluate and compare the efficacy of anorganic bovine-derived hydroxyapatite matrix (ABM)/cell binding peptide (P-15) in human periodontal infrabony defects with that of open flap debridement (OFD) alone. MATERIALS AND METHODS: A split-mouth, randomized controlled clinical study was designed to investigate the efficacy of ABM/P-15. In this clinical trial, 10 patients having bilateral periodontal infrabony defects were treated either with ABM/P-15 or OFD and followed for a period of 9 months. At baseline and at 9 months probing pocket depth (PPD), relative attachment level (RAL), depth of a defect, and radiographic bone level were measured; and compared between test and control sites. RESULTS: A statistically significant reduction (P < 0.001) in PPD was observed in test sites compared to control sites. Both sites showed a gain in RAL without any significant difference. Similarly, the radiographic evaluation revealed significantly higher radiographic defect fill in test sites as compared to control sites (P < 0.001). CONCLUSION: ABM/P-15 bone graft material appears to be useful and beneficial in the treatment of human periodontal infrabony defects.