Improved photocatalytic oxidation of micropollutant in wastewater by solar light: assisted palladium-doped graphitic carbon nitride.

The escalating global industrial expansion has led to the extensive release of organic compounds into water bodies, resulting in substantial pollution and posing severe threats to both human health and the ecosystem. Among common micropollutants, bisphenol A (MP-BA) has emerged as a significant endocrine-disrupting chemical with potential adverse effects on human health and the environment. This study aims to develop an efficient photocatalyst, specifically by incorporating palladium-doped graphitic carbon nitride (Pd@GCN), to eliminate MP-BA pollutants present in industrial wastewater. The examination of optical properties and photoluminescence indicates that incorporating Pd into GCN enhances the visible light absorption spectra, which extends beyond 570 nm, and accelerates the separation rate of electron-hole pairs. The photocatalytic degradation efficiency of MP-BA increases from 81.7 to 98.8% as the solution pH rises from 5.0 to 9.0. Moreover, Pd@GCN significantly improves the removal rate of MP-BA in wastewater samples, reaching an impressive 92.8% after 60 min of exposure to solar light. Furthermore, the Pd@GCN photocatalyst exhibits notable reusability over six cycles of MP-BA degradation, indicating its promising potential for the treatment of organic pollutants in wastewater under solar light conditions.

Removal of bisphenol a micropollutants released from plastic waste using Pt-ZnO photocatalyst.

Plastic pollution is becoming increasingly severe and is attracting global attention. One of its consequences is the recent discovery of micropollutant discharge into water, with Bisphenol A (BA-MP) being a typical example. This study utilizes an advanced oxidation process based on Pt-doped ZnO photocatalyst to remove BA-MP. Health concerns related to the release of BA-MP from plastic waste are discussed. Besides, the results of the photodegradation experiment show that the Pt-ZnO photocatalyst can remove 94.1% of BA-MP within 60 min when exposed to solar light. Moreover, after five reuse cycles, Pt-ZnO retains a high BA-MP removal efficiency of 71.2%, and its structure remains largely unchanged compared to the original material. The removal efficiency of BA-MP leaching from plastic waste was measured at 98.8%, confirming the suitability of Pt-ZnO for the treatment of micropollutants. Furthermore, this study also highlights the prospects and challenges of using Pt-ZnO for the treatment of micropollutants discharged from plastic waste.

Graphitic carbon nitride metal-free photocatalyst for the simultaneous removal of emerging pharmaceutical pollutants in wastewater.

The presence of pharmaceutical pollutants in water has emerged as a significant public health concern due to their potential adverse impacts, including the development of antibiotic resistance. Consequently, advanced oxidation processes based on photocatalysis have garnered considerable attention for treating pharmaceutical contaminants in wastewater. In this study, graphitic carbon nitride (g-CN), a metal-free photocatalyst, was synthesized by the polymerization of melamine and assessed as a potential candidate for the photodegradation of acetaminophen (AP) and carbamazepine (CZ) in wastewater. Under alkaline conditions, g-CN demonstrated high removal efficiencies of 98.6% and 89.5% for AP and CZ, respectively. The relationships between degradation efficiency and catalyst dosage, initial pharmaceutical concentration, and photodegradation kinetics were investigated. Increasing the catalyst dose facilitated the removal of antibiotic contaminants, with an optimum catalyst dose of 0.1 g, achieving a photodegradation efficiency of 90.2% and 82.7% for AP and CZ, respectively. The synthesized photocatalyst removed over 98% of AP (1 mg/L) within 120 min, with a rate constant of 0.0321 min-1, 2.14 times faster than that of CZ. Quenching experiments revealed that g-CN was active under solar light and generated highly reactive oxidants such as hydroxyl (•OH) and superoxide (•O2-). The reuse test confirmed the good stability of g-CN for treating pharmaceuticals during three repeated cycles. Finally, the photodegradation mechanism and environmental impacts were discussed. This study presents a promising approach for treating and mitigating pharmaceutical contaminants in wastewater.

Enhanced photodegradation of tetracycline in wastewater and conversion of CO2 by solar light assisted ZnO/g-C3N4.

Synthesized graphitic carbon nitride-based (CN) heterojunction photocatalysts are considered as a promising material for photodegradation of organic compounds and CO2 conversion. In this work, ZnO-loaded g-C3N4 (ZnO/CN) heterojunction photocatalyst was investigated for the enhanced photooxidation of tetracycline (TC) and CO2 conversion . After modification, the photocatalysts showed an improvement in the light absorption range and the photogenerated separation rate of electron/hole due to the heterojunction structure of ZnO/CN. The degradation rate of TC was found to be 92.6% within 60 min, while CO production rate was 7.68 µmol/g/h. The rate constants of TC by using ZnO/CN were 0.0812, 0.0539, 0.0336, 0.0249, and 0.0185 min-1, corresponding to the TC level of 1, 10, 30, 50, and 100 mg/L, respectively. The photodegradation rate of TC by ZnO/CN was 5 times higher than that of CN, demonstrating the advantage of heterojunction photocatalyst. The modified ZnO/CN exhibited superior degradation performance of TC and higher CO2 conversion rate than those of unmodified CN. It also exhibited high stability with 82% removal efficiency of TC at the 6th run and the CO2 conversion rate of 71% after reused 5 times. The heterojunction ZnO/CN can be utilized as an efficient material for various photocatalytic applications.

Synthesis of solar-driven Cu-doped graphitic carbon nitride photocatalyst for enhanced removal of caffeine in wastewater.

Caffeine (CaF), a widely consumed compound, has been associated with various harmful effects on human health, including metabolic, cardiovascular disease, and reproductive disorders. Moreover, it poses a signifincant threat to organisms and aquatic ecosystems, leading to water pollution concerns. Therefore, the removal of CaF from wastewater is crucial for mitigating water pollution and minimizing its detrimental impacts on both humans and the environment. In this study, a solar-driven Cu-doped graphitic carbon nitride (Cu/CN) photocatalyst was synthesized and evaluated for its effectiveness in oxidizing CaF in wastewater. The Cu/CN photocatalyst, with a low band gap energy of 2.58eV, exhibited superior performance in degrading CaF compared to pure graphitic carbon nitride (CN). Under solar light irradiation, CuCN achieved a remarkable CaF degradation efficiency of 98.7% CaF, surpassing CN's efficiency of 74.5% by 24.2%. The synthesized Cu/CN photocatalyst demonstrated excellent removal capability, achieving a removal rate of over 88% for CaF in wastewater. Moreover, the reusability test showed that Cu/CN could be successfully reused up to five cycles maintaining a high removal efficiency of 74% for CaF in the fifth cycle. Additionally, the study elucidated the oxidation mechanism of CaF using solar-driven Cu/CN photocatalyst and highlighted the environmental implications of the process.

TiO2 nanoparticles derived from egg shell waste: Eco synthesis, characterization, biological and photocatalytic applications.

Biosynthesis of metal oxide nanoparticles has attracted much attention in recent years owing to the increasing impact for improving hygienic substances, cost effective approaches, environment friendly solvents and reusable resources. The present study has shown the eco synthesis of TiO2 nanoparticles using the aqueous extract of egg shell waste. UV, XRD, FT-IR, and FE-SEM with EDX methods were implied for TiO2 nanoparticles. The agar well approach was used to investigate the antimicrobial properties of biosynthesized nanoparticles against pathogenic organisms. The cytotoxicity analysis was investigated by MTT assay method and photocatalytic activity was studied using methylene blue, methyl orange and Congo red dye. X-ray diffraction studies showed that the presence of tetragonal structure. The crystallite size of synthesized TiO2 nanoparticles is 27.3 nm. FE-SEM analysis indicates that the average grain size of the prepared sample was found to be in the range of 30-40 nm. Eco synthesis of TiO2 nanoparticles displayed amazing antimicrobial efficacies against human pathogenic organisms and obtained excellent cytotoxicity investigation was performed against Osteosarcoma cell lines (MG-63). Further it was also found that the expression of impressive catalytic efficiency, 91.1 percent decreased in 60 min for methylene blue. From the results, we found that eco synthesized TiO2 nanoparticles has promising utility in multidisciplinary like antimicrobial, anticancer and photocatalytic applications.

Cyclic-di-AMP synthesis by the diadenylate cyclase CdaA is modulated by the peptidoglycan biosynthesis enzyme GlmM in Lactococcus lactis.

The second messenger cyclic-di-adenosine monophosphate (c-di-AMP) plays important roles in growth, virulence, cell wall homeostasis, potassium transport and affects resistance to antibiotics, heat and osmotic stress. Most Firmicutes contain only one c-di-AMP synthesizing diadenylate cyclase (CdaA); however, little is known about signals and effectors controlling CdaA activity and c-di-AMP levels. In this study, a genetic screen was employed to identify components which affect the c-di-AMP level in Lactococcus. We characterized suppressor mutations that restored osmoresistance to spontaneous c-di-AMP phosphodiesterase gdpP mutants, which contain high c-di-AMP levels. Loss-of-function and gain-of-function mutations were identified in the cdaA and gdpP genes, respectively, which led to lower c-di-AMP levels. A mutation was also identified in the phosphoglucosamine mutase gene glmM, which is commonly located within the cdaA operon in bacteria. The glmM I154F mutation resulted in a lowering of the c-di-AMP level and a reduction in the key peptidoglycan precursor UDP-N-acetylglucosamine in L. lactis. C-di-AMP synthesis by CdaA was shown to be inhibited by GlmM(I154F) more than GlmM and GlmM(I154F) was found to bind more strongly to CdaA than GlmM. These findings identify GlmM as a c-di-AMP level modulating protein and provide a direct connection between c-di-AMP synthesis and peptidoglycan biosynthesis.

Replenishing the cyclic-di-AMP pool: regulation of diadenylate cyclase activity in bacteria.

Bacteria can sense environmental cues and alter their physiology accordingly through the use of signal transduction pathways involving second messenger nucleotides. One broadly conserved second messenger is cyclic-di-AMP (c-di-AMP) which regulates a range of processes including cell wall homeostasis, potassium uptake, DNA repair, fatty acid synthesis, biofilm formation and central metabolism in bacteria. The intracellular pool of c-di-AMP is maintained by the activities of diadenylate cyclase (DAC) and phosphodiesterase (PDE) enzymes, as well as possibly via c-di-AMP export. Whilst extracellular stimuli regulating c-di-AMP levels in bacteria are poorly understood, recent work has identified effector proteins which directly interact and alter the activity of DACs. These include the membrane bound CdaR and the phosphoglucosamine mutase GlmM which both bind directly to the membrane bound CdaA DAC and the recombination protein RadA which binds directly to the DNA binding DisA DAC. The genes encoding these multiprotein complexes are co-localised in many bacteria providing further support for their functional connection. The roles of GlmM in peptidoglycan synthesis and RadA in Holliday junction intermediate processing suggest that c-di-AMP synthesis by DACs will be responsive to these cellular activities. In addition to these modulatory interactions, permanent dysregulation of DAC activity due to suppressor mutations can occur during selection to overcome growth defects, rapid cell lysis and osmosensitivity. DACs have also been investigated as targets for the development of new antibiotics and several small compound inhibitors have recently been identified. This review aims to provide an overview of how c-di-AMP synthesis by DACs can be regulated.

Solution structure of the PAS domain of a thermophilic YybT protein homolog reveals a potential ligand-binding site.

The Bacillus subtilis protein YybT (or GdpP) and its homologs were recently established as stress signaling proteins that exert their biological effect by degrading the bacterial messenger cyclic di-AMP. YybT homologs contain a small Per-ARNT-Sim (PAS) domain (~80 amino acids) that can bind b-type heme with 1:1 stoichiometry despite the small size of the domain and the lack of a conserved heme iron-coordinating residue. We determined the solution structure of the PAS domain of GtYybT from Geobacillus thermodenitrificans by NMR spectroscopy to further probe its function. The solution structure confirms that PASGtYybT adopts the characteristic PAS fold composed of a five-stranded antiparallel ß sheet and a few short α-helices. One α-helix and three central ß-strands of PASGtYybT are noticeably shorter than those of the typical PAS domains. Despite the small size of the protein domain, a hydrophobic pocket is formed by the side chains of nonpolar residues stemming from the ß-strands and α-helices. A set of residues in the vicinity of the pocket and in the C-terminal region at the dimeric interface exhibits perturbed NMR parameters in the presence of heme or zinc protoporphyrin. Together, the results unveil a compact PAS domain with a potential ligand-binding pocket and reinforce the view that the PASYybT domains function as regulatory domains in the modulation of cellular cyclic di-AMP concentration.

Effect of antibiotics and sanitizers on Salmonella biofilms associated with seafood contact surfaces.

This study investigates the effect of antibiotics and sanitizers on biofilm forming Salmonella isolated from different seafood contact surfaces. Four Salmonella were isolated from 384 swab samples collected from various contact surfaces of fishing boats, fish landing centres and seafood processing plants. One out of four isolates was from the fishing boat (FB I -1) other three isolates were from the seafood processing plant (FPPII -4, FPPII- 5, FPPI-3). The ability of Salmonella to form biofilms on different contact surfaces (HDPE, stainless steel, wood, glass, tiles) was tested with the microbial load on different incubation days, and a higher count was observed on day five. The effect of sanitizer viz., sodium hypochlorite (20, 50, 100, 200 mg/l) and iodophor (2, 5, 10 mg/l) on the biofilm formed on different seafood contact surfaces were investigated. A reduction of 2-3 log was observed on surfaces of HDPE and stainless steel when they were treated with a minimum of 5 mg/l of iodophor or 20 mg/l of sodium hypochlorite after a contact time of 5 min. Antibiotic resistance of biofilm forming Salmonella was tested for different classes of antibiotics (penicillin, ß-lactams, quinolones, macrolides, aminoglycosides, phenol drugs, sulfonamides, cephalosporin). All four isolates showed intermediate resistance to ciprofloxacin, a quinolone drug. Only one isolate FB I -1 (fishing boat deck) expressed resistance to more drugs, viz., ßlactams (AMC, AMP, penicillin G), macrolides (AZM) and nitrofurantoin (NIT). These findings shall help the seafood processors to mitigate the formation of Salmonella biofilms on various seafood contact surfaces with different sanitizers and the antibiotic resistance of biofilm forming Salmonella shall give knowledge on human clinical treatments. With this study, we shall recommend the regulatory authorities control the contamination level of fish handling areas.

Exploring attitudes to research involving human subjects among Vietnamese university students: establishing a prospective longitudinal mixed-methods student cohort at the University of Medicine and Pharmacy at Ho Chi Minh City.

Research capacity is increasing in low- and middle-income countries (LMICs), with progressive development in the range and complexity of studies being undertaken, often in collaboration with high-income country partners. Although senior local stakeholders are typically involved in ensuring that research is conducted according to accepted standards for ethical and scientific quality, to date there has been little exploration of the views of younger generations around the ethics of research involving human subjects. We present our protocol to establish a longitudinal mixed-methods student cohort at the University of Medicine and Pharmacy at Ho Chi Minh City, Vietnam, that is investigating students' views around the ethics of clinical and public-health oriented research. We use a synergistic approach involving initial deliberative engagement activities ( e.g. science cafes, debates) to inform participants about complex concepts, prior to formal quantitative and qualitative methods (surveys, focus group discussions and in-depth interviews) that are designed to explore the students' views in detail. We focus in particular on dengue research, i.e. research that addresses a locally relevant disease with which the students are likely familiar, and probe their thoughts on such themes as appropriate remuneration for research participants, involvement of vulnerable groups, use of human challenge trials in LMICs etc. A snapshot of the cohort and its activities after one year is also presented; among 429 active students, primarily from the Faculty of Medicine, the proportions of male and female students were similar, the majority were from southern or central Vietnam where dengue is endemic, and available data indicates the cohort to be representative of the expected spectrum of socioeconomic groups. The cohort provides a unique resource to investigate the views of young people on medical ethics, an important but hitherto underrepresented group in such discussions. Feedback indicates a clear interest in contributing thoughts and ideas to the development of clinical research in Vietnam.

Heat resistance and salt hypersensitivity in Lactococcus lactis due to spontaneous mutation of llmg_1816 (gdpP) induced by high-temperature growth.

During construction of several gene deletion mutants in Lactococcus lactis MG1363 which involved a high-temperature (37.5°C) incubation step, additional spontaneous mutations were observed which resulted in stable heat resistance and in some cases salt-hypersensitive phenotypes. Whole-genome sequencing of one strain which was both heat resistant and salt hypersensitive, followed by PCR and sequencing of four other mutants which shared these phenotypes, revealed independent mutations in llmg_1816 in all cases. This gene encodes a membrane-bound stress signaling protein of the GdpP family, members of which exhibit cyclic dimeric AMP (c-di-AMP)-specific phosphodiesterase activity. Mutations were predicted to lead to single amino acid substitutions or protein truncations. An independent llmg_1816 mutant (Δ1816), created using a suicide vector, also displayed heat resistance and salt hypersensitivity phenotypes which could be restored to wild-type levels following plasmid excision. L. lactis Δ1816 also displayed improved growth in response to sublethal concentrations of penicillin G. High-temperature incubation of a wild-type industrial L. lactis strain also resulted in spontaneous mutation of llmg_1816 and heat-resistant and salt-hypersensitive phenotypes, suggesting that this is not a strain-specific phenomenon and that it is independent of a plasmid integration event. Acidification of milk by the llmg_1816-altered strain was inhibited by lower salt concentrations than the parent strain. This study demonstrates that spontaneous mutations can occur during high-temperature growth of L. lactis and that inactivation of llmg_1816 leads to temperature resistance and salt hypersensitivity.

Visible-light photocatalysis of Ag-doped graphitic carbon nitride for photodegradation of micropollutants in wastewater.

This work reports on graphitic carbon nitride (C3N4) modified with silver to investigate its visible-light-driven photocatalysis for decomposition of micropollutants in wastewater. Various characterization methods were conducted to examine the physico-chemical properties of Ag-doped C3N4 (Ag-C3N4) photocatalyst. The results from structural, morphological, and surface chemical analysis indicated that C3N4 was successfully doped with Ag. Photoluminescence and transient photocurrent density studies revealed that the recombination rate of electron-hole pairs was reduced, leading to the enhancement of photocatalytic activities of the photocatalyst. Ag-C3N4 showed high photocatalytic performance for photodegradation of our target micropollutant, bisphenol A (BA). It could completely remove BA in 1 h with kinetic constant 6.2 times higher than that of the undoped C3N4 photocatalyst. Recycling test and the assessment of the photocatalyst in wastewater further confirmed the excellent stability and applicability of the Ag-C3N4 photocatalyst. This work could provide a new solution to the practical application of photocatalyts for the degradation of micropollutants in wastewater.

Enhanced Room-Temperature Ethanol Detection by Quasi 2D Nanosheets of an Exfoliated Polymeric Graphitized Carbon Nitride Composite-Based Patterned Sensor.

A novel room-temperature gas sensor composed of polymeric graphitic carbon nitride composite was fabricated and used for the detection of ethanol vapor under ambient conditions. Polymeric carbon nitride (PCN) microstructures composed of fluffy nanosheets were synthesized via a thermal polycondensation mechanism using melamine as the precursor, followed by vigorous chemical exfoliation. These sheet-like microstructures were employed as active materials in the form of composites, along with carbon paste consisting of graphite nanoplatelets and carbon black. The active sensing layer was fabricated on a PET sheet and assembled on an interdigitated gold electrode. The as-fabricated sensor exhibited excellent sensing efficiency (>100% response at 10 ppm) along with high selectivity and stability. In particular, for ultralow concentrations such as 1 ppm (>10% response), this resistive-based sensor exhibited a swift response time provided under ambient conditions. The exfoliated PCN composite sensor was found to be working with appreciable efficiency at moderate relative humidity (%) with the least fluctuation in response signals also demonstrating long-term stability for 30 days with consistent response signals.

Synthesis and Corrosion Inhibition Potential of Cerium/Tetraethylenepentamine Dithiocarbamate Complex on AA2024-T3 in 3.5% NaCl.

In this work, a cerium/tetraethylenepentamine dithiocarbamate complex was synthesized and evaluated for the corrosion inhibition capability on an AA2024-T3 Al alloy in a 3.5% NaCl medium. The synthesized compounds were characterized via spectroscopic techniques. The corrosion inhibition behaviour of the complex was elucidated by electrochemical measurements and surface analysis techniques. Based on electrochemical test results, the corrosion inhibition efficiency of the complex increases with the immersion time of aluminium alloy in the test solution. The corrosion inhibition reaches 96.80% when the aluminium is immersed in a 3.5% NaCl solution containing a corrosion inhibitor for 120 h. The potentiodynamic polarization test results show that the complex acts as a mixed-type corrosion inhibitor and the passive range is widened. The surface analysis methods reveal that the corrosion inhibition ability of the complex originated from the formation of a protective layer on the Al surface. This film is created from the physisorption and chemisorption of cerium ions and organic parts simultaneously released from the complex molecules.

Improved photodegradation of antibiotics pollutants in wastewaters by advanced oxidation process based on Ni-doped TiO2.

The number of antibiotic compounds in wastewaters has been growing globally due to the covid-19 problem. Using antibiotics to treat the patients would produce larger amounts of these compounds into the environment with negative impacts. Hence, finding out the method for the elimination of toxic organic pollutants as well as antibiotics in water is urgent (In this study, the treatment of antibiotic pollutants including cefalexin (CF) and tetracycline (TC) was investigated by applying the advanced oxidation process based on Ni-doped TiO2 (Ni-TiO2). The characterizations technologies such as XRD, XPS, UV-vis, PL, and PC indicated that Ni doping would improve the photocatalytic performance of TiO2. In the photodegradation experiments, the Ni-TiO2 possessed high photocatalytic degradation efficiencies with 93.6% for CF and 82.5% for TC. Besides, the removal rates of antibiotics after five cycles are higher than 75%, implying excellent stability of Ni-TiO2 photocatalyst. The result from the treatment of wastewater samples revealed that the Ni-TiO2 photocatalytic had good performance for removal of CF and TC at a high level of 88.6 and 80.2%, respectively.

Study of synergistic effect of cobalt and carbon codoped with TiO2 photocatalyst for visible light induced degradation of phenol.

In this work, we reported synthesis of cobalt and carbon codoped TiO2 (Co-C-TiO2) nanoparticles were prepared using co-precipitation technique. The synthesized catalysts are analyzed by various methods. The powder XRD pattern confirmed that all the samples were polycrystalline of anatase phase and particle size of resultant nanoparticle was reduced correlated with bare TiO2 sample. FTIR measurements exhibit the identification of functional groups present at the surface of TiO2. FESEM micrograph showed that the shape of codoped TiO2 nanoparticles are approximately sphere. The attained energy gap of Co doped and C codoping of TiO2 modifies to a level below the energy gap of TiO2 anatase specifying a high capability to absorb visible light. The recombination rate of photo-induced electrons and holes for Co-C codoped TiO2 nanoparticles is significantly reduced. The synthesized samples are assessed in degradation of phenol by the illumination of visible light. The results confirmed that photocatalytic activity enhanced due to doping and codoping of Co and C. As a result, Co-C codoped TiO2 nanoparticles exhibited a higher visible-light photocatalytic activity in compared with Co-TiO2 and bare TiO2 with the maximum degradation efficiency of 98, 75 and 15%, respectively. And also, the reusability of the catalyst was proved when 95% degradation could be achieved after consecutive batches. It is predictable that this work will provide new insights to increase the visible light active photocatalysts for environmental problems.

Alginate-modified biochar derived from rice husk waste for improvement uptake performance of lead in wastewater.

In this work, alginate-modified biochar derived from rice husk waste was synthesized using a simple process. The modified biochar (MBC) and rice husk biochar (RhBC) were investigated for removing Pb (II) ions in wastewater. The BET result displayed significantly improved specific surface area of MBC up to 120 m2/g along with a total pore volume of 0.653 cm3/g. FTIR spectrums presented the higher oxygen-contained functional groups of MBC as compared to RhBC, resulting in increasing adsorption capacity of Pb (II). MBC had higher adsorption capacity (112.3 mg/g) and faster removal rate (0.0081 g mg-1 min-1) than those of RhBC (41.2 mg/g and 0.00025 g mg-1 min-1). Modified RhBC can remove more than 99% of Pb (II) from wastewater and it could be utilized for three cycles with a removal performance of over 90%. In addition, the Pb adsorption mechanism by using MBC was proposed and the practical application of MBC for the treatment of wastewater in Vietnam was discussed.

Photodegradation of ciprofloxacin antibiotic in water by using ZnO-doped g-C3N4 photocatalyst.

Ciprofloxacin antibiotic (CIP) is one of the antibiotics with the highest rate of antibiotic resistance, if used and managed improperly, can have a negative impact on the ecosystem. In this research, ZnO modified g-C3N4 photocatalyst was prepared and applied for the decomposition of CIP antibiotic compounds in water. The removal performance of CIP by using ZnO/g-C3N4 reached 93.8% under pH 8.0 and an increasing amount of catalyst could improve the degradation performance of the pollutant. The modified ZnO/g-C3N4 completely oxidized CIP at a low concentration of 1 mg L-1 and the CIP removal efficiency slightly decreases (around 13%) at a high level of pollutant (20 mg L-1). The degradation rate of CIP by doped sample ZnO/g-C3N4 was 4.9 times faster than that of undoped g-C3N4. The doped catalyst ZnO/g-C3N4 also displayed high reusability for decomposition of CIP with 89.8% efficiency remaining after 3 cycles. The radical species including ·OH, ·O2- and h+ are important in the CIP degradation process. In addition, the proposed mechanism for CIP degradation by visible light-assisted ZnO/g-C3N4 was claimed.

Adsorptive removal and recovery of organic pollutants from wastewater using waste paper-derived carbon-based aerogel.

In this study, carbon-based aerogels derived from waste paper (CWP) were explored as an efficent adsorbent to remove organic pollutants including phenol (Ph) and 2-chlorophenol (2CP) from wastewater. CWP exhibited a highly porous structure and large specific surface area of 892 m2 g-1, which facilitated the adsorption of Ph and 2CP in wastewater. The adsorption behavior of Ph and 2CP on CWP could be well described by the pseudo-second-order kinetics and Langmuir isotherm models. Based on the Langmuir isotherm, the maximum adsorption capacities of CWP for Ph and 2CP were 238 and 278 mg g-1, respectively, and these values were much higher than those of other adsorbents. The removal of the organic pollutants mainly occurred through electrostatic attraction, pore-filling, hydrogen bonding, and π-π interactions. The CWP can be directly applied for the removal of Ph and 2CP at low concentration (<200 mg L-1) in the wastewater, while they can be used with additional pre-treatment for wastewater containing high concentration of organic pollutants. The adsorptive recovery of organic compounds and potential reuse of treated wastewater were also discussed. This work provides an efficient approach to produce effective adsorbent for the removal and recovery of chemicals from wastewater.