Study of diclofenac removal by the application of combined zero-valent iron and calcium peroxide nanoparticles in groundwater

Diclofenac(DCF)is one of the most frequently detected pharmaceuticals in groundwater,posing a great threat to the environment and human health due to its toxicity.To mitigate the DCF contamination,experiments on DCF degradation by the combined process of zero-valent iron nanoparticles(nZVI)and nano calcium peroxide(nCaO_(2))were performed.A batch experiment was conducted to examine the influence of the adding dosages of both nZVI and nCaO_(2)nanoparticles and pH value on the DCF removal.In the meantime,the continuous-flow experiment was done to explore the sustainability of the DCF degradation by jointly adding nZVI/nCaO_(2)nanoparticles in the reaction system.The results show that the nZVI/nCaO_(2)can effectively remove the DCF in the batch test with only 0.05 g/L nZVI and 0.2 g/L nCaO_(2)added,resulting in a removal rate of greater than 90%in a 2-hour reaction with an initial pH of 5.The degradation rate of DCF was positively correlated with the dosage of nCaO_(2),and negatively correlated with both nZVI dosage and the initial pH value.The order of significance of the three factors is identified as pH value>nZVI dosage>nCaO_(2)dosage.In the continuous-flow reaction system,the DCF removal rates remained above 75%within 150 minutes at the pH of 5,with the applied dosages of 0.5 g/L for nZVI and 1.0 g/L for nCaO_(2).These results provide a theoretical basis for the nZVI/nCaO_(2)application to remove DCF in groundwater.

Stimulated Growth of Aerobic Microbes Using Calcium Peroxide

With continuous and slow oxygen-release characteristic, calcium peroxide （CaO2） has been a new source of supplying oxygen for aerobic microbes in bioremediation of contaminated groundwater. Batch experiments were conducted to evaluate the oxygen-release rate of CaO2reacting with water, the regulation of high pH, as well as the growth of mixed aerobic microbes in the medium containing CaO2, The results show that the oxygen-release process of CaO2 comprises three phases. In the first phase, dissolved oxygen levels of water increased sharply, and average oxygen-release rates increased as the adding weight of CaO2 increased, However, the rates almost kept invariable in the latter phases and were approximately 0.48; and 0. 084 mg O2·h^-1, respectively. As the necessary components of medium, potassium dihydrogen phosphate （KH2PO4 ） and amrnoniurn sulphate （（NH4）2SO4） at a certain ratio could regulate pH caused by CaO2 from 12, 1 to the range of 6.5 -8.5, which is helpful for microbial growth, In addition, diauxic growth curve observed in the medium containing CaO2 suggested that the growth of mixed aerobic microbes could be stimulated by the addition of CaO2.

Complexes of cupric ion and tartaric acid enhanced calcium peroxide Fenton-like reaction for metronidazole degradation

To surmount the obstacles of traditional Fenton method and synchronously utilize Cu^(2+)and polyphenol in water,an improved Fenton-like reaction applying calcium peroxide(CaO_(2))as H_(2)O_(2)source and regulating by the complex of Cu^(2+)-tartaric acid(TA,a representative of polyphenol)was constructed.A typical antibiotic,metronidazole(MTZ)could be effectively eliminated by the Cu^(2+)/TA/CaO_(2)system,and the optimized parameters were as follows:0.1 mmol/L Cu^(2+),2 mmol/L TA,2 mmol/L CaO_(2),and initial pH5.UV spectrum confirmed the formation of Cu^(2+)-TA complex,which promoted the Cu^(2+)/Cu+circulation through decreasing the Cu^(2+)/Cu^(+) couple redox potential,which further enhanced the H_(2)O_(2)decomposition and the formation of reactive species.Hydroxyl radical was dominant for MTZ degradation,followed by oxygen and superoxide radical.The degradation intermediates of MTZ were detected and their evolution way was speculated.Furthermore,the ternary process showed a wide p H tolerance(3–8)for removing MTZ and broad applicability for eliminating other dyes and antibiotics.This work provided a reference for Cu-based Fenton-like strategy for organic wastewater settlement.

Ferric ion-ascorbic acid complex catalyzed calcium peroxide for organic wastewater treatment:Optimized by response surface method

Hydrogen peroxide(H_(2)O_(2))disproportionation,iron precipitation,and narrow pH range are the drawbacks of traditional Fenton process.To surmount these barriers,we proposed a ferric ion(Fe^(3+))-ascorbic acid(AA)complex catalyzed calcium peroxide(CaO_(2))Fenton-like system to remove organic dyes in water.This collaborative Fe^(3+)/AA/CaO_(2)system presented an obvious improvement in the methyl orange(MO)decolorization,and also effectively eliminated other dyes.Response surface method was employed to optimize the running parameters for this coupling process.Under the optimized arguments(2.76 mmol/L Fe^(3+),0.68 mmol/L AA,and 4 mmol/L CaO_(2)),the MO removal achieved 98.90%after 15 min at pH 6.50,which was close to the computed outcome of 99.30%.Furthermore,this Fenton-like system could perform well in a wide range of pH(3-11),and enhance the H_(2)O_(2)decomposition and Fe ions recycle.The scavenger experiment result indicated that hydroxyl radical,superoxide anion free radical,and singlet oxygen were acted on the dye elimination.Moreover,electron spin resonance analysis corroborated that the existences of these active species in the Fe^(3+)/AA/CaO_(2)system.This study could advance the development of Fenton-like technique in organic effluent disposal.

Enhanced degradation of trichloroethene by calcium peroxide activated with Fe（III） in the presence of citric acid

Trichloroethene （TCE） degradation by Fe（III）- activated calcium peroxide （CP） in the presence of citric acid （CA） in aqueous solution was investigated. The results demonstrated that the presence of CA enhanced TCE degradation significantly by increasing the concen- tration of soluble Fe（III） and promoting H202 generation. The generation of HO· and O2^-· in both the CP/Fe（III） and CP/Fe（III）/CA systems was confirmed with chemical probes. The results of radical scavenging tests showed that TCE degradation was due predominantly to direct oxidation by HO·, while O2^-· strengthened the generation of HO· by promoting Fe（III） transformation in the CP/Fe （III）/CA system. Acidic pH conditions were favorable for TCE degradation, and the TCE degradation rate decreased with increasing pH. The presence of Cl·-, HCO3·-, and humic acid （HA） inhibited TCE degradation to different extents for the CP/Fe（III）/CA system. Analysis of Cl·- production suggested that TCE degradation in the CP/Fe （III）/CA system occurred through a dechlorination process. In summary, this study provided detailed information for the application of CA-enhanced Fe（III）-activated calcium peroxide for treating TCE contaminated groundwater.

Enhanced nitrogen removal upon the addition of volatile fatty acids from activated sludge by combining calcium peroxide and low-thermal pretreatments

This study investigated a combined low-thermal and CaO_(2)pretreatment to enhance the volatile fatty acid(VFA)production from waste activated sludge(WAS).The fermentative product was added to a sequencing batch reactor(SBR)as an external carbon source to enhance nitrogen removal.The results showed that the combined pretreatment improved WAS solubilization,releasing more biodegradable substrates,such as proteins and polysaccharides,from TB-EPS to LB-EPS and S-EPS.The maximum VFA production of 3529±188 mg COD/L was obtained in the combined pretreatment(0.2 g CaO_(2)/g VS+70℃for 60 min),which was 2.1 and 1.4-fold of that obtained from the sole low-thermal pretreatment and the control test,respectively.Consequently,when the fermentative liquid was added as an external denitrification carbon source,the effluent total nitrogen decreased to Class A of the discharge standard for pollutants in rural wastewater treatment plants in most areas of China.

Sprayed PAA-CaO_(2)nanoparticles combined with calcium ions and reactive oxygen species for antibacterial and wound healing

The most common socioeconomic healthcare issues in clinical are burns,surgical incisions and other skin injuries.Skin lesion healing can be achieved with nanomedicines and other drug application techniques.This study developed a nano-spray based on cross-linked amorphous calcium peroxide(CaO_(2))nanoparticles of polyacrylic acid(PAA)for treating skin wounds(PAA-CaO_(2)nanoparticles).CaO_(2)serves as a‘drug’precursor,steadily and continuously releasing calcium ions(Ca^(2+))and hydrogen peroxide(H_(2)O_(2))under mildly acidic conditions,while PAA-CaO_(2)nanoparticles exhibited good spray behavior in aqueous form.Tests demonstrated that PAA-CaO_(2)nanoparticles exhibited low cytotoxicity and allowed L929 cells proliferation and migration in vitro.The effectiveness of PAA-CaO_(2)nanoparticles in promoting wound healing and inhibiting bacterial growth in vivo was assessed in SD rats using full-thickness skin defect and Staphylococcus aureus(S.aureus)-infected wound models based thereon.The results revealed that PAA-CaO_(2)nanoparticles demonstrated significant advantages in both aspects.Notably,the infected rats’skin defects healed in 12 days.The benefits are linked to the functional role of Ca^(2+)coalesces with H_(2)O_(2)as known antibacterial and healing-promoted agents.Therefore,we developed nanoscale PAA-CaO_(2)sprays to prevent bacterial development and heal skin lesions.

Delayed treatment of secondary degeneration following acute optic nerve transection using a combination of ion channel inhibitors

Studies have shown that a combined application of several ion channel inhibitors immediately after central nervous system injury can inhibit secondary degeneration. However, for clinical use, it is necessary to determine how long after injury the combined treatment of several ion channel inhibitors can be delayed and efficacy maintained. In this study, we delivered Ca^2＋ entry-inhibiting P2X7 receptor antagonist oxidized-ATP and AMPA receptor antagonist YM872 to the optic nerve injury site via an iPRECIO-@ pump immediately, 6 hours, 24 hours and 7 days after partial optic nerve transection surgery. In addition, all of the ion channel inhibitor treated rats were administered with calcium channel antagonist lomerizine hydrochloride. It is important to note that as a result of implantation of the particular pumps required for programmable delivery of therapeutics directly to the injury site, seromas occurred in a significant proportion of animals, indicating infection around the pumps in these animals. Improvements in visual function were observed only when treatment was delayed by 6 hours; phosphorylated Tau was reduced when treatment was delayed by 24 hours or 7 days. Improvements in structure of node/paranode of Ranvier and reductions in oxidative stress indicators were also only observed when treatment was delayed for 6 hours, 24 hours, or 7 days. Benefits of ion channel inhibitors were only observed with time-delayed treatment, suggesting that delayed therapy of Ca^2＋ ion channel inhibitors produces better neuroprotective effects on secondary degeneration, at least in the presence of seromas.

A bioactive nanocomposite sponge for simultaneous hemostasis and antimicrobial therapy

Uncontrollable bleeding and bacterial infections are the major reasons for the high mortality of post-traumatic.In this study,a composite hemostatic chitosan sponge CaO_(2)@SiO_(2)/CS was prepared by combining a novel core-shell inorganic nano hemostatic CaO_(2)@SiO_(2)nanoparticles with carboxylated chitosan,which presents a multi-layered structure with a rough and hydrophilic surface for rapid absorption of blood.When the CaO_(2)@SiO_(2)nanoparticles in the CaO_(2)@SiO_(2)/CS come into contact with blood,the silanol group on its surface and the released H_(2)O_(2)and Ca2+can recruit and activate platelets,while generating fibrin clots and activating the endo-exogenous coagulation cascade reaction to achieve rapid clotting.The H_(2)O_(2)released from CaO_(2)@SiO_(2)shows the antimicrobial capacity and stimulates the production of tissue factors by endothelial cells.Meanwhile,the silica coating reduces the cytotoxicity of bare CaO_(2),thus reducing the risk of secondary bleeding at the site of vascular injury.CaO_(2)@SiO_(2)/CS(48 s)showed a 1.83-and 2.52-fold reduction in hemostasis time compared to commercial gelfoam and CS in a femoral artery hemorrhage model.This study illustrates the hemostatic mechanism of CaO_(2)@SiO_(2)and provides a reference for the development of clinical biomedical inorganic hemostatic materials.

Remediation of 2,4-dichlorophenol-contaminated groundwater using nano-sized CaO_(2)in a two-dimensional scale tank

This study evaluates the applicability of nano-sized calcium peroxide(CaO_(2))as a source of H_(2)O_(2)to remediate 2,4-dichlorophenol(2,4-DCP)contaminated groundwater via the advanced oxidation process(AOP).First,the effect and mechanism of 2,4-DCP degradation by CaO_(2)at different Fe concentrations were studied(Fenton reaction).We found that at high Fe concentrations,2,4-DCP almost completely degrades via primarily the oxidation of·OH within 5 h.At low Fe concentrations,the degradation rate of 2,4-DCP decreased rapidly.The main mechanism was the combined action of·OH and O_(2)^(·−).Without Fe,the 2,4-DCP degradation reached 13.6%in 213 h,primarily via the heterogeneous reaction on the surface of CaO_(2).Besides,2,4-DCP degradation was significantly affected by solution pH.When the solution pH was>10,the degradation was almost completely inhibited.Thus,we adopted a two-dimensional water tank experiment to study the remediation efficiency CaO_(2)on the water sample.We noticed that the degradation took place mainly in regions of pH<10(i.e.,CaO_(2)distribution area),both upstream and downstream of the tank.After 28 days of treatment,the average 2,4-DCP degradation level was≈36.5%.Given the inadequacy of the results,we recommend that groundwater remediation using nano CaO_(2):(1)a buffer solution should be added to retard the rapid increase in pH,and(2)the nano CaO_(2)should be injected copiously in batches to reduce CaO_(2)deposition.

Oxygen generating scaffolds regenerate critical size bone defects

Recent innovations in bone tissue engineering have introduced biomaterials that generate oxygen to substitute vasculature.This strategy provides the immediate oxygen required for tissue viability and graft maturation.Here we demonstrate a novel oxygen-generating tissue scaffold with predictable oxygen release kinetics and modular material properties.These hydrogel scaffolds were reinforced with microparticles comprised of emulsified calcium peroxide(CaO_(2))within polycaprolactone(PCL).The alterations of the assembled materials produced constructs within 5±0.81 kPa to 34±0.9 kPa in mechanical strength.The mass swelling ratios varied between 11%and 25%.Our in vitro and in vivo results revealed consistent tissue viability,metabolic activity,and osteogenic differentiation over two weeks.The optimized in vitro cell culture system remained stable at pH 8-9.The in vivo rodent models demonstrated that these scaffolds support a 70 mm^(3) bone volume that was comparable to the native bone and yielded over 90%regeneration in critical size cranial defects.Furthermore,the in vivo bone remodeling and vascularization results were validated by tartrate-resistant acid phosphatase(TRAP)and vascular endothelial growth factor(VEGF)staining.The promising results of this work are translatable to a repertoire of regenerative medicine applications including advancement and expansion of bone substitutes and disease models.