Statistical modeling optimization for antibiotics decomposition by ultrasound/electro-Fenton integrated process: Non-carcinogenic risk assessment of drinking water

The present work proposes an ultrasound (US) assisted electro-Fenton (EF) process for eliminating penicillin G (PNG) and ciprofloxacin (CIP) from aqueous solutions and the process was further optimized by response surface methodology (RSM)- Box-Behnken design (BBD). The impact of pH, hydrogen peroxide (H₂O₂) concentration, applied voltage, initial pollutant concentration, and operating time were studied. The capability application of the electro-Fenton (EF) and US processes was compared separately and in combination under the optimum conditions of pH of 4, a voltage of 15 V, the initial antibiotic concentration of 20.7 mg/L, H₂O₂ concentration of 0.8 mg/L, and the operating time of 75 min. The removal efficiency of PNG and CIP using the sono-electro-Fenton (SEF) process, as the results revealed, was approximately 96% and 98%, respectively. The experiments on two scavengers demonstrated that ^⦁OH contributes significantly to the CIP and PNG degradation by SEF, whereas ^⦁O^-₂ corresponds to only a negligible amount. The total organic carbon (TOC) and chemical oxygen demand (COD) analyses were used to assess the mineralization of CIP and PNG. The efficiency of COD and TOC removal was reached at 73.25% and 62.5% for CIP under optimized operating circumstances, and at 61.52% and 72% for PNG, respectively. These findings indicate that a sufficient rate of mineralization was obtained by SEF treatment for the mentioned pollutants. The reaction kinetics of CIP and PNG degradation by the SEF process were found to follow a pseudo-first-order kinetic model. In addition, the human health risk assessment of natural water containing CIP and PNG that was purified by US, EF, and SEF processes was done for the first time. According to the findings, the non-carcinogenic risk (HQ) caused by drinking purified water by all three systems was calculated in the acceptable range. Thus, SEF is a proper system to remove various antibiotics in potable water and reduces their human health risks.

Removal of ciprofloxacin antibiotic pollutants from wastewater using nano-composite adsorptive membranes

The emergence of antibiotics in water has been globally recognized as a critical pollution issue. Antibiotics (such as Ciprofloxacin (CPFX) pose a serious threat to humans and to the ecosystem due to its accumulation in water sources which can lead to chronic health problems and endanger aquatic life. It is therefore crucial to properly remove them from water. In this work, a nano-composite adsorptive membrane based on Zirconium Phosphate (ZrP) adsorbent supported on Polyethersulfone (PES) was synthesized and evaluated for the removal of CPFX from synthetic aqueous solutions. The membranes described here showed a very high antibiotic removal rate. The effect of various parameters such as the initial concentration of the antibiotic, the adsorbent dosage, contact time, pH, and temperature was studied. The equilibrium data were found to reasonably best fit with the Temkin isotherm model. The membranes showed a high ciprofloxacin removal (99.7%) as opposed to (68%) when PES membrane alone was used. Moreover, a significant improvement in the membrane's water flux (100.84 L/m².h) and permeability (97.62 L/m².hr.bar) were noticed as opposed to pure PES membrane's flux and permeability. The adsorptive membranes were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and Brunauer-Emmett-Teller (BET). The results confirmed the successful formation of ZrP nanoparticles adsorbent within the membrane matrix, and with enhanced hydrophilic properties. The membrane was successfully regenerated and reused up to 5 times. The results of this work showed the potential of such membranes for the removal of ciprofloxacin and at a high efficiency.

Adsorption behaviors of three antibiotics in single and co-existing aqueous solutions using mesoporous carbon

The residual antibiotics detected frequently in aquatic environment may pose a potential threat to human health and ecosystem. Exploring a possible way to remove them from antibiotic polluted-water is a key problem demanding prompt solution. To investigate their adsorption characteristics, three antibiotics including tetracycline (TC), ciprofloxacin (CIP), and sulfadiazine (SDZ) have been removed using sucrose-based mesoporous carbon (SMC) in single and co-existing systems. Characterization revealed that the SMC had a high Brunauer-Emmett-Teller (BET) surface area (1215.48 m²/g), large mesoporous pore size (6.36 nm), and abundant oxygen-containing functional groups, which might offer sufficient adsorption sites for antibiotics. The process of antibiotics adsorption was described well using pseudo-second-order model. The rate constant K₂ at various temperatures followed the order 308 K > 298 K > 288 K. This finding suggesting the increase in temperature could promote the removal of antibiotics. The maximum adsorption capacities for TC (232.10 mg/g), CIP (257.30 mg/g), and SDZ (204.28 mg/g) of SMC were obtained using Langmuir isotherm (pH = 4-6, T = 308K, SMC dosage = 10 mg, C₀ = 30-40 mg/L). These data implied SMC had the excellent adsorptive property and affinity to antibiotics. In binary systems, SMC offers efficient removal percentages (>90%) for each of the target antibiotic. While the removal efficiencies of TC, CIP, and SDZ by SMC in the ternary system were 90.40, 72.99, and 80.46%, respectively. These results suggested the competition on active sites of SMC happened among the three antibiotics. The affinities of SMC to three antibiotics followed the order TC > SDZ > CIP. The removal of antibiotics by SMC were mainly attributed to the mechanisms including electrostatic interactions, hydrophobic interactions, hydrogen bonding and so on. This study will provide a technical support for antibiotic wastewater treatment.

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.

Effects of activated carbon, biochar, and carbon nanotubes on the heterogeneous Fenton oxidation catalyzed by pyrite for ciprofloxacin degradation

Pyrite and engineering carbon materials have received increasing attention for their catalytic potential in Fenton reactions due to their extensive sources and low cost. However, effects of carbon materials on the degradation of pollutants by pyrite-catalyzed heterogeneous Fenton oxidation have not been fully understood. In this study, the performance of pyrite-catalyzed heterogeneous Fenton system on the degradation of ciprofloxacin (CIP) was investigated in the presence of activated carbon (AC), biochar (BC), and carbon nanotubes (CNTs). Synchronous and asynchronous experiments (adsorption and catalysis) were conducted to elucidate the roles of the carbon materials in pyrite-catalyzed Fenton reactions. The results demonstrated that all the three carbon materials accelerated the pyrite-catalyzed Fenton oxidation of CIP. Under the experimental conditions, the reaction rates, which were obtained by fitting the synchronous experimental results with the pseudo-first-order kinetic model, of pyrite/AC, pyrite/BC and pyrite/CNTs with H₂O₂ for the removal of CIP were 8.28, 3.40 and 3.37 times faster than that of pyrite alone. Adsorption experiments and characterization analysis showed that AC had a higher adsorption capacity than BC and CNTs for CIP, which enabled it to distinguish itself in assisting the pyrite-catalyzed Fenton oxidation. In the presence of the carbon materials, the adsorption effect should not be neglected when studying the catalytic performance of pyrite. Free radical quenching experiments and electron spin-resonance spectroscopy (ESR) were used to detect and identify free radical species in the reactions. The results showed that hydroxyl radicals (•OH) contributed significantly to the degradation of CIP. The addition of carbon materials promoted the production of •OH, which favored the degradation of CIP. The results of this study suggested that the synergistic effect of oxidation and adsorption promoted the removal of CIP in pyrite/carbon materials/H₂O₂ systems, and coupling pyrite and carbon materials shows great potential in treating antibiotic wastewater.

Mesoporous BiVO4/TiO2 heterojunction: enhanced photoabsorption and photocatalytic ability through promoted charge transfer

BiVO₄ has been constructed into heterojunctions with TiO₂ to boost the photocatalytic ability under visible illumination. Here, mesoporous BiVO₄/TiO₂ nanocomposites have been fabricated by a facile sol-gel approach utilizing nonionic surfactant and addressed for morphological, optical, structural, and degradation of ciprofloxacin (CIP) in water under visible illumination as an antibiotic pollutant model. The TEM images demonstrated that the TiO₂ NPs are homogenous in terms of shape and size (15 ± 5 nm). The introduction of BiVO₄ into mesoporous TiO₂ could effectively enhance the rapid separation efficiency of the photoinduced carriers and optical absorption. The 3%BiVO₄/TiO₂ photocatalyst possessed the best degradation efficiency (100%) within 60 min which was promoted 20-folds larger than TiO₂ NPs (5%). 3%BiVO₄/TiO₂ nanocomposite exhibited the fastest degradation rate (2.15 × 10^-2 min^-1), which was 40 times faster than bare TiO₂ photocatalyst (0.05 × 10^-2 min^-1). The enhanced photocatalytic ability originated from superior charge separation characteristics and high solar energy absorption in mesopore structures. The recombination rate and mobility of charge carriers were characterized utilizing photoluminescence (PL) and photoelectrochemical measurements. This work highlights the advantages of mesoporous heterojunction BiVO₄/TiO₂ nanocomposites for photocatalytic performances and provides a multilateral route to design an effective wide-spectrum response photocatalyst for the development of comparable materials. The photocatalytic mechanism for degradation CIP over BiVO₄/TiO₂ was discussed in detail..

Remediation of pharmaceutical pollutants using graphene-based materials - A review on operating conditions, mechanism and toxicology

Graphene is a high surface area special carbon compound with exceptional biological, electronic and mechanical properties. Graphene-based materials are potential components used in water treatment on different modes and processes. Ibuprofen and ciprofloxacin are two commonly found pharmaceutical contaminants discharged into water bodies from industrial, domestic and hospital sources. Their concentration levels in water bodies are reported in the range of 1 μg/L to 6.5 mg/L and 0.050-100 μg/L respectively. Their toxic effects pose very high risk to the inhabiting organisms. Their ability to resist biodegradation and capacity to bioaccumulate makes the conventional methods less effective in removal. In the present article, treatment of these compounds via three methods, adsorption, photocatalytic degradation and electro-fenton reactions using graphene-based materials along with the methods adopted for synthesis and treatment are reviewed. The uptakes obtained by graphene-derived adsorbents are presented along with the optimal operating conditions. Studies reported complete removal of ibuprofen from wastewater was achieved at 7 pH for 60 min using graphene membrane as adsorbent and uptake of 99% of ciprofloxacin was exhibited for graphene nanoplates/boron nitrate aerogel at a pH of 7 and 60 min. The reduced graphene oxide surface exhibits higher affinity to light adsorption which leads to the formation of photo generated electrons. The future perspectives for improved applications of graphene-based materials and the research gap currently existing are highlighted.

Synthesis of biochar from iron-free and iron-containing microalgal biomass for the removal of pharmaceuticals from water

The contamination of natural water bodies with pharmaceutical compounds has raised significant concerns about ecological and public health safety. In this study, biochars were synthesized from iron-free microalgal biomass (harvested by centrifugation) and iron-containing microalgal biomass (harvested by coagulation) and tested for the adsorption of ciprofloxacin (CIP) and diclofenac (DIC) from water in batch and fixed-bed column continuous studies. The physicochemical properties of synthesized biochars were analyzed using Brunauer, Emmett and Teller (BET) surface area analyzer, elemental analyzer, Fourier Transformed Infrared spectroscopy (FTIR), X-ray Diffractometer (XRD), and Scanning electron microscope with energy dispersive spectroscopy (SEM-EDS). The maximum monolayer adsorption capacities of iron-containing biochar (FBC750W) and iron-free biochar (MBC750W) based on the Langmuir model were obtained as 75.97 mg/g and 39.08 mg/g for CIP, and 40.99 mg/g and 6.77 mg/g for DIC, respectively. Comparatively, maximum monolayer adsorption capacities of commercial activated carbon (C-AC) were found to be 50.97 mg/g and 46.39 mg/g for CIP and DIC, respectively. In fixed-bed column continuous adsorption studies, the effects of flow rate (1 and 2 mL/min) and the adsorbent amount (50 and 100 mg) on adsorption performance were evaluated. Column kinetic models, such as Bohart-Adams model and Fractal-like Bohart-Adams model were examined. The adsorption mechanisms were proposed as pore filling, π-π interaction, and electrostatic interaction. Overall, the results of this study revealed that microalgal biomass, harvested with FeCl₃, can be used for the direct synthesis of iron-containing biochar for the removal of pharmaceuticals from water.

Antibiotic degradation and mineralization: efficiency increase on combining different chemical treatment processes

The goal of this study was to assess the efficiency of antibiotic degradation applying different chemical treatment methods and their combinations. Thus, improvement in the efficiency of these methods when combined was quantified. The methods tested to degrade/mineralize the antibiotics amoxicillin (AMX) and ciprofloxacin (CIP) under different pH conditions (4, 7 and 10) were ultra-violet irradiation (UV_254 nm), ultrasound (US), hydrogen peroxide (H₂O₂) and ozone (O₃) alone and in combination. The results showed that individual methods were only partially efficient in the degradation/mineralization of antibiotics, except for ozonation at alkaline pH. In the combined methods, the best performance was obtained with US/UV/H₂O₂/O₃ (pH 10, 20-min treatment), where the degradation rates for the antibiotics were 99.8% for CIP and 99.9% for AMX. For the mineralization efficiency the values obtained were 71.3% for CIP and 79.2% for AMX. The results of this study could contribute to the development and improvement of wastewater treatment aimed at avoiding the presence of residual antibiotics in the environment.

Composite of methyl polysiloxane and avocado biochar as adsorbent for removal of ciprofloxacin from waters

Two carbon composite materials were prepared by mixing avocado biochar and methyl polysiloxane (MK). Firstly, MK was dissolved in ethanol, and then the biochar was added at different times. In sample 1 (R1), the time of adding biochar was immediately after dissolving MK in ethanol, and in sample 2 (R₂), after 48 h of MK dissolved in ethanol. The samples were characterized by nitrogen adsorption/desorption measurements obtaining specific surface areas (S_BET) of 115 m2 g^-1 (R₁) and 580 m2 g^-1 (R₂). The adsorbents were further characterized using scanning electron microscopy, FTIR and Raman spectroscopy, adsorption of vapors of n-heptane and water, thermal analysis, Bohem titration, pHpzc, and C H N elemental analysis. R₁ and R₂ adsorbents were employed as adsorbents to remove the antibiotic ciprofloxacin from the waters. The t_1/2 and t_0.95 based on the interpolation of Avrami fractional-order were 20.52 and 246.4 min (R₁) and 14.00 and 157.6 min (R₂), respectively. Maximum adsorption capacities (Q_max) based on the Liu isotherm were 10.77 (R₁) and 63.80 mg g^-1 (R₂) for ciprofloxacin. The thermodynamic studies showed a spontaneous and exothermic process for both samples, and the value of ΔH° is compatible with physical adsorption.

Quantitative assessment of interactions of hydrophilic organic contaminants with microplastics in natural water environment

The interaction between microplastics (MPs) and hydrophilic organic contaminants (HOCs) in natural water environment has recently raised great public attentions due to the potential toxicity to humans. However, the quantitative assessment is less studied. In this study, the interaction between ciprofloxacin (CIP) and ofloxacin (OFL) (two important HOCs) and virgin and aged polystyrene (PS) was investigated. The aged PS showed higher adsorption rate and capacity than the virgin PS, due to its larger surface area and more O-containing groups. The pH-dependent adsorption of CIP was higher than OFL on both virgin and aged PS; the maximum adsorption for both HOCs occurred at pH 5. The sequential orders of functional groups for the adsorption were discovered according to the study by the 2D correlation Fourier transform infrared spectroscopy. Several mechanisms existed for the interaction: (1) at 3.0 < pH < 5.0, the electrostatic attraction (EA) was inhibited while H-bond (HB) was dominant, accounting for > 60% of the total uptake; (2) at 5.0 < pH < 8.0, the contribution of EA increased to around 50-60% while HB decreased to 30-40%; (3) at 8.0 < pH < 10.0, EA, HB and π-π conjugation caused 30-40%, 25-40% and 20-45% of the total uptake, respectively; (4) at 10.0 < pH < 12.0, π-π conjugation accounted for 90-100%. Notably, higher adsorption of CIP was mainly attributed to the presence of secondary amino groups and its higher pK_a value, correspondingly leading to the additional ordinary HB and negative charge-assisted HB, and EA interactions with PS. This study further provides clear evidences on the risk of MPs and HOCs on humans and aqueous living organisms.

Peroxydisulfate activation by nano zero-valent iron graphitized carbon materials for ciprofloxacin removal: Effects and mechanism

Since the discovery of the potential hazards of ciprofloxacin (CIP) to the ecosystem and human health, there has been an urgent need to develop effective technologies to solve the severe issue. In this work, the nanozero-valent iron graphitized carbon matrix (xFe@CS-T_m) were prepared via a hydrothermal method to activate peroxydisulfate (PDS) for degradation of CIP. Specifically, 0.5Fe@CS-T₇ exhibited the excellent catalytic performance for PDS activation to degrade CIP. Moreover, the catalyst exhibited vigorous interference resistance at various pH values, in the presence of various inorganic anions and under humic acid conditions. The characterization results demonstrated that Fe was successfully embedded on the carbon matrix and became the active sites to promote ROS production. It is demonstrated that O₂^•- was the main active species rather than •OH and SO₄^•-, based on quench trapping, EPR experiments and steady state concentrations calculations. The possible pathways of CIP degradation were proposed using LC-MS results and density functional theory. The outcomes of the toxicity estimation software tool found that the toxicity of CIP was reduced. This study not only investigated a novel methodology for the degradation of antibiotic wastewater but also provides a feasible pathway for carbon-neutral wastewater treatment.

Efficient and synergistic degradation of fluoroquinolones by bacteria and microalgae: Design of environmentally friendly substitutes, risk regulation and mechanism analysis

Fluoroquinolones (FQs) are widely used as antimicrobial agents, and their nonbiodegradable in sewage has become an increasingly concerning. High-biochemical substitutes of FQs were designed with bacteria and microalgae as driving forces of biodegradation, and this is the first study on efficient synergistic degradation of FQs by multiple microorganisms. Among 143 designed FQ substitutes, only one was screened with high biodegradability (increased by 120.51 %), improved functional properties (genotoxicity: 13.66 %), less environmental impacts (bio-accumulation: -44.81 %), less human health and ecological risk (hepatotoxicity: -106.21 %). The complex functional protein with the synergistic degradation effect of bacteria and microalgae was constructed, which proved their synergistic degradation and realized the effect of "1 + 1 > 2″. The best risk regulation scheme determined using molecular dynamics simulation proved the degradation ability of complex functional protein and found the CIP-129 was easy to be degraded in real environment compared with CIP, and the degradation rate increased by 70.42 %. The synthesis path of CIP-129 and CIP were inferred and calculated, and the results showed the Gibbs free energies of three CIP-129 synthetic paths (40.64 a.u.; 40.61 a.u.; 40.65 a.u.) were close to the energy required for the CIP (39.43 a.u.), indicating there was no significant difference in the energy consumption of CIP-129 in laboratory synthesis.

Insights into highly effective catalytic persulfate activation on oxygen-functionalized mesoporous carbon for ciprofloxacin degradation

Nanocarbons have been demonstrated as promising carbon catalysts for substituting metal-based catalysts for the green treatment of wastewater. In this study, oxygen-functionalized mesoporous carbon (OCMK-3) was prepared by wet oxidation and exhibited high catalytic performance against ciprofloxacin (CIP) by activation of persulfate. The effects of environmental parameters (pH, temperature, coexisting ions) and process parameters (temperature, sodium persulfate concentration, catalyst agent dosage, initial concentration) on the removal of CIP were investigated. Compared with the pristine ordered mesoporous carbon (CMK-3), the removal efficiency of CIP by OCMK-3 was increased by 32% under optimal conditions. This rise in activity was attributed to the increase in oxygen-containing functional groups, porosity, and specific surface area of OCMK-3 with improved structural defects and electron transfer efficiency. Furthermore, based on active species scavenging experiments, a dual-pathway mechanism of the radical and nonradical pathways was discovered. The rational degradation pathway of CIP was investigated based on liquid chromatography-mass spectrometry (LC-MS). In addition, the OCMK-3/PS system exhibited high decomposition efficiency in pharmaceutical wastewater treatment. This study provides an in-depth mechanism for the degradation of organic pollutants by carbon-based PS-AOPs and provides theoretical support for further studies.

Unraveling the Origin of Enhanced Activity of the Nb2O5/H2O2 System in the Elimination of Ciprofloxacin: Insights into the Role of Reactive Oxygen Species in Interface Processes

The overlooked role of reactive oxygen species (ROS), formed and stabilized on the surface of Nb₂O₅ after H₂O₂ treatment, was investigated in the adsorption and degradation of ciprofloxacin (CIP), a model antibiotic. The contribution of ROS to the elimination of CIP was assessed by using different niobia-based materials in which ROS were formed in situ or ex situ. The formation of ROS was confirmed by electron paramagnetic resonance (EPR) and Raman spectroscopy. The modification of the niobia surface charge by ROS was monitored with zeta potential measurements. The kinetics of CIP removal was followed by UV-vis spectroscopy, while identification of CIP degradation products and evaluation of their cytotoxicity were obtained with liquid chromatography-mass spectrometry (LC-MS) and microbiological studies, respectively. Superoxo and peroxo species were found to significantly improve the efficiency of CIP adsorption on Nb₂O₅ by modifying its surface charge. At the same time, it was found that improved removal of CIP in the dark and in the presence of H₂O₂ was mainly determined by the adsorption process. The enhanced adsorption was confirmed by infrared spectroscopy (IR), total organic carbon measurements (TOC), and elemental analysis. Efficient chemical degradation of adsorbed CIP was observed upon exposure of the Nb₂O₅/H₂O₂ system to UV light. Therefore, niobia is a promising inorganic adsorbent that exhibits enhanced sorption capacity toward CIP in the presence of H₂O₂ under dark conditions and can be easily regenerated in an environmentally benign way by irradiation with UV light.

Optimization, Nature, and Mechanism Investigations for the Adsorption of Ciprofloxacin and Malachite Green onto Carbon Nanoparticles Derived from Low-Cost Precursor via a Green Route

The spread of organic pollutants in water spoils the environment, and among the best-known sorbents for removing organic compounds are carbonaceous materials. Sunflower seed waste (SFSW) was employed as a green and low-cost precursor to prepare carbon nanoparticles (CNPs) via pyrolysis, followed by a ball-milling process. The CNPs were treated with a nitric–sulfuric acid mixture (1:1) at 100 °C. The scanning electron microscopy (SEM) showed a particle size range of 38 to 45 nm, and the Brunauer–Emmett–Teller (BET) surface area was 162.9 m2 g−1. The elemental analysis was performed using energy-dispersive X-ray spectroscopy, and the functional groups on the CNPs were examined with Fourier transform infrared spectroscopy. Additionally, an X-ray diffractometer was employed to test the phase crystallinity of the prepared CNPs. The fabricated CNPs were used to adsorb ciprofloxacin (CFXN) and malachite green (MLG) from water. The experimentally obtained adsorption capacities for CFXN and MLG were 103.6 and 182.4 mg g−1, respectively. The kinetic investigation implied that the adsorption of both pollutants fitted the pseudo-first-order model, and the intraparticle diffusion step controlled the process. The equilibrium findings for CFXN and MLG sorption on the CNPs followed the Langmuir and the Fredulich isotherm models, respectively. It was concluded that both pollutants spontaneously adsorbed on the CNPs, with physisorption being the likely mechanism. Additionally, the FTIR analysis of the adsorbed CFXN showed the disappearance of some functional groups, suggesting a chemisorption contribution. The CNPs showed an excellent performance in removing CFXN and MLG from groundwater and seawater samples and possessed consistent efficiency during the recycle–reuse study. The application of CNPs to treat synthetically contaminated natural water samples indicated the complete remediation of polluted water using the ball-mill-fabricated CNPs.

Highly efficient photocatalytic oxidation of antibiotic ciprofloxacin using TiO2@g-C3N4@biochar composite

In this present study, a novel indirect Z-scheme TiO₂@g-C₃N₄@biochar (TiO₂@g-C₃N₄@BC) composite photocatalyst was successfully fabricated and characterized with SEM, TEM, EDS, XRD, FTIR, PL, XPS, and UV-vis DRS. The photocatalytic degradation behavior of ciprofloxacin (CIP) on the TiO₂@g-C₃N₄@BC was evaluated under UV-vis and visible light irradiation, and the possible reaction mechanism of photocatalytic oxidation of CIP on the TiO₂@g-C₃N₄@BC was explained. The TiO₂@g-C₃N₄@BC composite photocatalyst exhibited stronger photocatalytic oxidation activity for CIP in comparison with TiO₂, g-C₃N₄, TiO₂@BC, and TiO₂@g-C₃N₄. After 60 min of UV-vis and visible light irradiation, the photocatalytic removal efficiency of CIP by TiO₂@g-C₃N₄@BC was 99.3 and 89.2%, respectively. The photocatalytic removal performance of CIP was affected by the initial concentration of CIP, catalyst dosage, and pH value. The composite photocatalyst presented excellent stability and reusability after five cycles. An indirect Z-scheme principle of the CIP photocatalytic oxidation reaction on TiO₂@g-C₃N₄@BC was clearly proposed, and the whole process of photocatalytic degradation was the results of the interaction between CIP and reactive active species (·O₂^-, h⁺, and ·OH), of which ·O₂^- is the main active substance. Four CIP degradation pathways were proposed. This work may provide an effective strategy to remove antibiotics in wastewater.

New nanostructured activated biochar for effective removal of antibiotic ciprofloxacin from wastewater: Adsorption dynamics and mechanisms

Developing green inexpensive and effective adsorbents is critically needed for elimination of antibiotics from contaminated water. The current study assessed the nanostructured activated biochar (nPPAB) derived from pomegranate peels (PP) as a promising sorbent for efficient removal of the antibiotic ciprofloxacin (CIP). The results affirm that the second order and Langmuir models fit well to adsorption kinetics and equilibrium data respectively. The nPPAB adsorption capacity of Langmuir (q_max) for CIP was 142.86 mg g^-1 which is 26.85 times greater than that of bulk PP. Hydrogen bonding, π-π interaction, hydrophobic and electrostatic interactions are the dominant mechanisms of CIP adsorption by nPPAB. The efficiency of nPPAB for CIP removal from real wastewater using batch and packed-bed reactor were 89.94 and 84.74% respectively. This study clearly demonstrated the substantial capacity of nPPAB as an ecofriendly, feasible, and in-expensive adsorbent for successful elimination of CIP from wastewater.

Design and Synthesis of Menthol and Thymol Derived Ciprofloxacin: Influence of Structural Modifications on the Antibacterial Activity and Anticancer Properties

Sixteen new Ciprofloxacin derivatives were designed and successfully synthesized. In an in silico experiment, lipophilicity was established for obtained compounds. All compounds were screened for antimicrobial activity using standard and clinical strains. As for Gram-positive hospital microorganisms, all tested derivatives were active. Measured MICs were in the range 1–16 µg/mL, confirming high antimicrobial potency. Derivative 12 demonstrated activity against all standard Gram-positive Staphylococci, within the range of 0.8–1.6 µg/mL and was confirmed as the leading structure with MICs 1 µg/mL for S. pasteuri KR 4358 and S. aureus T 5591 (clinical strains). All compounds were screened for their in vitro cytotoxic properties via the MTT method. Three of the examined compounds (3, 11 and 16) showed good activity against cancer cells, and in parallel were found not to be cytotoxic toward normal cells. Doxorubicin SI ranged 0.14–1.11 while the mentioned three ranged 1.9–3.4. Selected Ciprofloxacin derivatives were docked into the crystal structure of topoisomerase II (DNA gyrase) in complex with DNA (PDB ID: 5BTC). In summary, leading structures were established (3, 11, 12 and 16). We have observed poor results in preformed studies for disubstituted derivatives, suggesting that 3-oxo-4-carboxylic acid core is the active DNA-gyrase binding site, and when structural changes were made in this fragment, there was an observed decrease in antibacterial potency.

The Effect of Conjugation of Ciprofloxacin and Moxifloxacin with Fatty Acids on Their Antibacterial and Anticancer Activity

Novel conjugates (CP) of moxifloxacin (MXF) with fatty acids (1m–16m) were synthesized with good yields utilizing amides chemistry. They exhibit a more pronounced cytotoxic potential than the parent drug. They were the most effective for prostate cancer cells with an IC₅₀ below 5 µM for respective conjugates with sorbic (2m), oleic (4m), 6-heptenoic (10m), linoleic (11m), caprylic (15m), and stearic (16m) acids. All derivatives were evaluated against a panel of standard and clinical bacterial strains, as well as towards mycobacteria. The highest activity towards standard isolates was observed for the acetic acid derivative 14m, followed by conjugates of unsaturated crotonic (1m) and sorbic (2m) acids. The activity of conjugates tested against an expanded panel of clinical coagulase-negative staphylococci showed that the compound (14m) was recognized as a leading structure with an MIC of 0.5 μg/mL denoted for all quinolone-susceptible isolates. In the group of CP derivatives, sorbic (2) and geranic (3) acid amides exhibited the highest bactericidal potential against clinical strains. The M. tuberculosis Spec. 210 strain was the most sensitive to sorbic (2m) conjugate and to conjugates with medium- and long-chain polyunsaturated acids. To establish the mechanism of antibacterial action, selected CP and MXF conjugates were examined in both topoisomerase IV decatenation assay and the DNA gyrase supercoiling assay, followed by suitable molecular docking studies.

Characterization of Edible Fungus Substrate Modified Biochar and Its Adsorption Capacity for Ciprofloxacin Hydrochloride

In this study, silver-ytterbium-modified biochar (MBC) was prepared to adsorb ciprofloxacin hydrochloride. It was compared with biochar (BC) and alkali-modified biochar (NBC). The results show that the MBC had more functional groups and a larger specific surface area than the BC and NBC. The saturated adsorption capacity of the MBC (312.500 mg g^-1) was 3 and 19 times higher than that of the NBC and BC, respectively. The adsorption data were consistent with the pseudo-second-order kinetics model and the Langmuir isotherm model. In addition, the mechanism of CIP adsorption onto NBC and MBC may be dominated by π-π electron donor-accepter interactions. C-O, C=O and -NH₂ play important roles in adsorption, and Ag-O and Yb-O groups participate in the adsorption of CIP onto MBC.

Electrochemical-assisted ultraviolet light coupled peroxodisulfate system to degrade ciprofloxacin in water: Kinetics, mechanism and pathways

The persulfate advanced oxidation is an emerging and efficient pollutant treatment method, but usually requires the help of other materials or energy to catalyze and produce highly oxidizing active substances. In this paper, electrochemical-assisted ultraviolet light coupled peroxodisulfate system (E-UV-PDS) was used to degrade ciprofloxacin (CIP), and it was determined that electrolysis and ultraviolet photolysis were synergistic by calculation. The effects of initial pH, voltage, peroxodisulfate dosage, CIP concentration and coexisting anions on the degradation process were explored. The quenching experiments showed that ¹O₂, ⋅OH and SO₄^-⋅ were the main active oxygen species. Under the following conditions, ultraviolet light = 6 W, voltage = 4 V, [peroxodisulfate] = 20 mM, [pH]₀ = 7 and [CIP] = 100 mgL^-1, the degradation rate of CIP reached about 100% after 120 min, and the influence of inorganic anions was also discussed. Several intermediate products were identified by LC-MS, and three degradation pathways were speculated for CIP degradation. Finally, economic evaluation of the E-UV-PDS system was made, and it was useful to construct environmentally friendly and low-cost catalytic processes for the efficient degradation of organic pollutants.

Pyrolysis of marine algae for biochar production for adsorption of Ciprofloxacin from aqueous solutions

Biochars derived from three species of algae was synthesized by impregnating the green algae Ulva Ohnoi, red algae Agardhiella subulata, and brown algae Sargassum hemiphyllum with ZnCl₂ chemical activator and employed as a long-term adsorbent for ciprofloxacin (CIP) removal from water. The results revealed that combination of brown algae and ZnCl₂ chemical activator (ZBAB) successfully produced mesoporous biochar with excellent physicochemical characteristics and gave the best CIP adsorption capacity. The ZBAB yielded a high CIP adsorption capacity (190-300 mg g^-1) under various parameter effects (initial pH, temperature and major ions). Throughought the surface characterization techniques, the proposed adsorption mechanisms were electrostatic interaction, π-π EDA interaction, pore filling and hydrogen bonding. Moreover, not only algal biochars exhibited innovative and potential adsorbent for rapid and effective remediate pollution from water, but combination of algal biomass and ZnCl₂ activator also created renewable source of energy from biomass pyrolysis.

A biocompatible bismuth based metal-organic framework as efficient light-sensitive drug carrier

The low toxicity and good photo active property endow bismuth based metal-organic frameworks (MOFs) potential candidates for efficient light-sensitive drug carrier. In this work, SU-101, composed of Bi and ellagic acid (EA), is found to display high ciprofloxacin (CIP) loading ratio (85.8%) and controlled CIP release under light illumination (the maximum CIP release ratio is 95.56%). Further investigations suggest that hydrogen bond between the CO group in EA and the -OH group in CIP is responsible for above behavior. Light irradiation decreases the electron density around the CO group in EA, which consequently leads to the broken of the hydrogen bond and therefore the release of CIP. Further investigations suggest that SU-101 is universal for other drugs, such as norfloxacin (NOR), amoxicillin (AMO), tetracycline (TET) and doxorubicinhydrochloride (DOX), since all of them can form hydrogen bond with SU-101. This work suggests that SU-101 holds great potential as efficient light-sensitive drug carrier, and the investigation of other Bi based MOFs as drug carrier is under investigation.

Zn-doped Bi2MoO6 supported on reduced graphene oxide with increased surface active sites for degradation of ciprofloxacin

The reduced graphene oxide supported Zn-doped Bi₂MoO₆ nanocomposites (Zn_xBi_2-xMoO₆/RGO) are synthesized by an easy one-step solvothermal method for the rapid degradation of ciprofloxacin (CIP). Characterization analyses show that Bi₂MoO₆ nanosheets are uniformly supported on RGO, for which the agglomeration of Bi₂MoO₆ is effectively inhibited, leading to more exposure of surface active sites. The degradation rate of Zn_0.1Bi_1.9MoO₆/RGO₅ on CIP reached 90% after 120 min of visible light irradiation, which was 10.4 times the rate of unsupported Bi₂MoO₆. Zn doping and RGO loading synergistically reduce the recombination rate of photogenerated electron-hole pairs and result in the enhanced photocatalytic performance. Compared with previously reported catalysts, Zn_0.1Bi_1.9MoO₆/RGO₅ can get higher degradation efficiency with shorter time and less dosage. In addition, after five cycles, the degradation efficiency is maintained at about 85%, showing perfect cycling stability of Zn_0.1Bi_1.9MoO₆/RGO₅. Photocatalytic mechanism suggests that the photogenerated •O₂^- and h⁺ are main species for degrading CIP based on Zn_xBi_2-xMoO₆/RGO complex.