Peroxide Dosage Research Articles

A non-fired ceramsite construction material with enhanced lightweight high strength properties

The combustion of low calorific value coal in circulating fluidized bed boilers produces a large amount of fly ash with low activity and utilization. In this paper, the lightweight high strength ceramsite was prepared by a non-fired method using low-activity circulating fluidized bed fly ash (CFBFA) as raw material. And the effects of reinforcing agent and foaming agent on the properties of ceramsite were studied. The dosages of cement, quicklime, desulfurization gypsum and hydrogen peroxide were 15.0 wt%, 6.0 wt%, 6.0 wt% and 2.0 wt%, respectively. The hydration reaction in the system can be maximized by steam curing at 70 ℃ for 12 h. The bulk density and cylinder compressive strength of the obtained ceramsite were 695.34 kg/m3 and 5.5 MPa, respectively, which belonged to 700 grade high strength fly ash ceramsite. The corresponding apparent density and apparent porosity of the products were 1091.88 kg/m3 and 51.86 %, respectively. The admixture of cement, quicklime and desulfurization gypsum can all promote the hydration reaction in the system to produce denser needle-like and flocculent CSH. In addition, the admixture of hydrogen peroxide only enhanced the porosity of ceramsite and had no effect on the phase. The experimental process was simple, green and energy saving. In particular, the total solid waste utilization was up to 79 %.

Role of Pel and Psl polysaccharides in the response of Pseudomonas aeruginosa to environmental challenges: oxidative stress agents (UVA, H2O2, sodium hypochlorite) and its competitor Staphylococcus aureus.

Pseudomonas aeruginosa is a versatile bacterium capable of adapting to a wide range of stress factors, including solar UVA radiation (400-315 nm). High UVA doses produce lethal effects due to the action of reactive oxygen species. Sublethal UVA doses also induces oxidative damage, but, in addition, it triggers a variety of adaptive responses, including the overexpression of pelA and pslA genes in P. aeruginosa. These genes encode the synthesis of Pel and Psl, which are essential polysaccharides in biofilm formation. The present study analysed the role of Pel and Psl in the adaptive responses generated by exposure to low UVA doses, and their importance in the response to lethal doses of UVA, hydrogen peroxide (H2O2), and sodium hypochlorite, in both planktonic cells and submerged and air-liquid interface (ALI) biofilms. It also studied the roles of Pel and Psl in P. aeruginosa-Staphylococcus aureus interaction. The results demonstrate that the capacity of sublethal UVA exposure to increase cell hydrophobicity and cell attachment and generate cross-protection phenomena in P. aeruginosa depends on the presence of Pel and Psl. The study also shows that Pel and Psl have a key role in the tolerance to lethal doses of UVA radiation, sodium hypochlorite and H2O2, in both biofilms and planktonic cells. Finally, co-culture assays showed total inhibition of S. aureus growth in presence of P. aeruginosa. This phenomenon depends, at least in part, on the simultaneous presence of Pel and Psl in planktonic cells and biofilms, suggesting a relevant role of these polysaccharides in the interaction between these species.

Recent advances in Fenton-like treatment of radioactive ion exchange resins

Ion exchange resins (IERs) are widely used to remove radioactive contaminants from various commercial nuclear power plant systems. After the completion of their useful life cycle, IERs are removed from the nuclear facility and are known as spent resins. In the past few decades, the development of Fenton/Fenton-like treatments for the management of spent resins has received considerable attention because of their potential to completely break down the IER structure into harmless compounds (e.g., carbon dioxide, water, and inorganic salts). In addition, after Fenton-like treatments, the resulting solutions containing radionuclides can be easily immobilized to stable waste. In this review, we critically discuss the key developments in Fenton/Fenton-like dissolution, degradation, and mineralization of spent resins. We describe the important reaction parameters (initial pH, resin dosage, catalyst type and dosage, hydrogen peroxide dosage, flow rates of the catalyst and oxidant, reaction temperature, treatment time, and other specific parameters) for various Fenton/Fenton-like treatments of spent resins. Moreover, this review focuses heavily on the major reaction intermediates generated in Fenton-like treatments. In the final section of this review (conclusions and perspectives), we discuss the major challenges and suggest future research directions need to be addressed to improve the efficiency of Fenton-like treatments of spent resins.

Influence of Foliar Application of Hydrogen Peroxide on Gas Exchange, Photochemical Efficiency, and Growth of Soursop under Salt Stress.

Hydrogen peroxide at low concentrations has been used as a salt stress attenuator because it induces a positive response in the antioxidant system of plants. This study aimed to assess the gas exchange, quantum yield, and development of soursop plants cv. Morada Nova grown with saline water irrigation and foliar hydrogen peroxide application. The experiment was carried out under greenhouse conditions using a randomized block design in a 4 × 4 factorial scheme corresponding to four levels of electrical conductivity of irrigation water, ECw (0.8, 1.6, 2.4, and 3.2 dS m-1), and four doses of hydrogen peroxide, H2O2 (0, 10, 20, and 30 μM), with three replicates. The use of irrigation water with electrical conductivity above 0.8 dS m-1 inhibited stomatal conductance, internal CO2 concentration, transpiration, maximum fluorescence, crown height, and vegetative vigor index of the Morada Nova cultivar of soursop. Compared to untreated plants, the hydrogen peroxide concentration of 30 μM resulted in greater stomatal conductance. Water salinity of 0.8 dS m-1 with hydrogen peroxide concentrations of 16 and 13 μM resulted in the highest variable fluorescence and quantum efficiency of photosystem II, respectively, of soursop plants cv. Morada Nova at 210 days after transplantation.

Efficacy and safety of carbamide peroxide tooth-whitening gels

Carbamide and hydrogen peroxide are the most frequently utilized compounds for various whitening techniques, that differ as per peroxide level, method of administration, and exposure period, when it comes to the active solutions accessible for important tooth whitening. The 10±1% carbamide peroxide dosage was the only level to date to acquire the American Dental Association's stamp of approval, ensuring its safety and effectiveness for at-home tooth whitening with customized trays. There has been a noticeable growth in the range of in-office tooth whitening compounds commercially available, which typically use elevated carbamide peroxide levels (30 to 37%) with or without an additional illumination. Even though tooth sensitivity appears to be the most frequent side effect of carbamide peroxide bleaching, discomfort goes away when the plan of care is finished. Sensitivity is typically linked to a background of sensitive teeth, greater administration rate, or use of greater carbamide peroxide levels. Additionally, studies have showed that using 10% carbamide peroxide at home to lighten teeth had comparable effectiveness to other methods (over the counter or in-office whitening). Patients generally prefer home vital bleaching with 10% carbamide peroxide to office procedures with 35% hydrogen peroxide. When comparing the safety utilizing 16% carbamide peroxide for nightguard vital bleaching to a placebo or 10% carbamide peroxide, patients receiving 16% reported higher gingival soreness than those administered a 10% carbamide peroxide or a placebo.

Household ovicidal alternative for complementary control of Aedes aegypti in the Gran San Miguel de Tucuman agglomerate, Tucumán, Argentina

Aedes aegypti is closely related to human behavior that allows its establishment through the accumulation of urban solid waste where it lays resistant eggs. Generally, adulticides and larvicides are applied in excess, without ovicidal alternatives, and some household products can help reduce the abundance of quiescent eggs in breeding sites by affecting the viability of eggs. A community involved in prevention and control is one of the most effective strategies for adequate vector management. In this investigation, new alternative strategies for the control of Ae. aegypti are assessed, valuing in laboratory the eggs’ response to diverse household products. Susceptibility to different doses of bleach, oil, salt, sodium bicarbonate, vinegar, coffee, garlic, peroxide, and alcohol was measured, as well as its duration over time. New home products were found as alternative ovicidal method. Bleach and sunflower oil had an ovicidal effect at their maximum doses and at almost all of the evaluation times. In contrast, vinegar and coffee had no ovicidal effect at any time, turning out to be stimulators of hatching in the laboratory. These alternative and complementary applications could optimize the surveillance and control of Ae. aegypti in the area, allowing new approaches to reduce populations by eliminating eggs on human microhabitats.

Process parameters study of sanitary landfill leachate treatment using photo-Fenton-like systems

In this study, the effects of the combination of classical Fenton (CFP) and modified Fenton (MFP) processes with UV light on the treatment of sanitary landfill leachate have been investigated. Iron (Fe2+ and Fe0) dosage, hydrogen peroxide dosage, reaction time, pH and different UV lamps have been optimized to achieve high COD removal. In addition, zeroth, first and second order kinetic models are applied for all processes under optimum conditions. For CFP and MFP; optimum pH 3, reaction time 30 min, 4 g/kg TS Fe2+ and Fe0 and 5 g/kg TS H2O2 have been determined. The COD removal efficiency is determined as 48.86% for CFP and 59.27% for MFP under optimum conditions. COD removal efficiencies increased in photo Fenton application under UV light. The efficiency is found to increase under UVA light source from 48.86% to 49.17% and from 59.27% to 70.72% in in CFP and MFP, respectively. In the kinetic study, the highest R2 values are obtained in the CFP/UV process, while CFP and MFP are found to fit the 0th order kinetic model. In this study, it has been concluded that Fenton and photo Fenton applications are effective in reducing the COD values of landfill leachate.

Therapeutic effect of induced pluripotent stem cell -derived extracellular vesicles in an in vitro and in vivo osteoarthritis model.

Osteoarthritis (OA) is a multifactorial joint disease associated with the deterioration of chondrocytes and inflammation. Treatment of OA is only aimed at reducing pain and improving joint function. Recently, extracellular vesicles (EVs) secreted from stem cells have emerged as a cell regenerative tool in several degenerative diseases, including OA. We hypothesised that induced pluripotent stem cell (iPSC)-derived EVs would be beneficial for regenerating chondrocytes and OA therapy. Therefore, we aimed to investigate iPSC-EVs' effects on chondrocyte behaviour in an interleukin 1 beta (IL-1β)-induced in vitro OA model and anterior cruciate ligament transection (ACLT)-induced in vivo OA model of rabbit articular cartilage. The iPSC-EVs were isolated by sequential ultracentrifugation from a 48-h-incubated conditional medium of iPSC. The isolated iPSC-EVs were characterised by transmission electron microscopy, western blot analyses, and dynamic light scatter. The effects of iPSC-EVs on the viability of human primary chondrocytes and cell senescence were analysed. Premature senescence of cells was induced by long-term incubation with low doses of hydrogen peroxide. To investigate the therapeutic effect of iPSC-EVs on OA chondrocytes in vitro, IL-1β was used to induce chondrocyte damage. Inflammatory macrophages were activated from THP-1 monocytes to observe the impact of iPSC-EV on macrophage polarisation. The phenotypes of the macrophages exposed to iPSC-EVs were evaluated by ELISA and western blot analyses. The primary chondrocytes were co-cultured with different phenotypes of macrophages to observe the expression of collagen II and catabolic enzymes in chondrocytes. iPSC-EVs were injected intraarticularly into the rabbit with an ACLT-induced OA model. The progression of lesions was assessed through macroscopic and histopathological studies. We showed that iPSC-EVs significantly stimulated the proliferation of primary human chondrocytes and suppressed cell senescence by regulating the expression of p21 and collagen II. iPSC-EVs reduced matrix degradation enzymes and IL-6 expression and attenuated IL-1β-mediated cell death of chondrocytes. Furthermore, iPSC-EVs modulated macrophage polarisation, resulting in the rescue of damaged chondrocytes in an inflammatory microenvironment. In the rabbit ACLT model, the OA-like lesions, including inflammation, subchondral bone protrusion, and articular cartilage destruction, were ameliorated by iPSC-EV. A histopathological study consistently revealed that iPSC-EVs attenuated ACLT-mediated alteration of MMP13 and ADAMTS5 and collagen II expression. iPSC-EVs protected chondrocytes by enhancing cell proliferation, suppressing premature senescence, and maintaining homeostasis of collagen II synthesis and matrix degradation enzymes such as matrix metalloproteinases (MMPs) and ADAMTS5. iPSC-EVs also reduced cell death in IL-1β-mediated chondrocyte cell damage. In the rabbit ACLT-induced OA model, iPSC-EV injection reduced cartilage destruction, as indicated by the upregulation of collagen II and down-regulation of MMP13 and ADAMTS5. Overall, our results suggest that iPSC-EVs possess therapeutic potential and may be used as an OA treatment option. This study highlights the potential of iPSC-EVs as a therapeutic option for chondrocyte regeneration and OA treatment.

Empirical Modeling of Bromate Formation and Chemical Control Strategies at Multiple Water Reuse Facilities Using Ozone

ABSTRACT As an increasing number of potable water reuse projects consider feasibility of implementing ozonation for achieving disinfection goals and removal of trace organic compounds, bromate formation presents a practical barrier. In this study, data received from five potable water reuse facilities showed that ozone dissolution method such as fine bubble diffusion resulted in lower concentrations of bromate compared to side-stream addition. When using multipoint ozone dissolution some reduction in bromate formation was also observed. Data from these facilities displayed a positive correlation between ozone (as a function of O3:TOC ratio) and bromate formation (as molar ratio of bromide converted to bromate) with lower formation as monochloramine or hydrogen peroxide concentrations increase. This study provides an empirical model with four equations which can be used to estimate the bromate formation and the required monochloramine or hydrogen peroxide dose to achieve adequate bromate control, i.e. below MCL of 10 µg/L, if a desired O3:TOC ratio and initial bromide concentration are known. The empirical model estimates for monochloramine and hydrogen peroxide were found to be in good agreement with experimental data (R2 = 0.96 and R2 = 0.87, respectively) while within a set of boundary conditions expressed by range of concentrations of typical water quality parameters.

Extraction of iron from laterite soil and green synthesis of laterite nano iron catalyst (GLaNICs) for its application as Fenton's catalyst in the degradation of triclosan.

Laterite based nano iron particles were synthesized using natural laterite extract as a precursor and Psidium guajava plant extract for its application as Fenton's catalyst in the degradation of triclosan. Chemical digestion method was used for the extraction of iron from laterite soil. Synthesized nano iron catalyst was characterized using SEM-EDS, XRD and FTIR and evaluated for its catalytic application in the Fenton's oxidation of triclosan. Maximum triclosan degradation of 69.5% was observed with nano iron catalyst dosage of 0.1 g/L and hydrogen peroxide dosage of 200 mg/L at acidic pH of 3. Hydrogen peroxide influence on the process was observed with Fenton's oxidation. Role of iron in the process has been accessed by control experiment with no nano catalyst addition in which degradation is considerably low. Fenton's oxidation was compared with conventional Fenton's oxidation driven by a green nano iron catalyst. Study claims the usage of natural laterite iron as a replacement for commercial iron in Fenton's degradation of triclosan. Regeneration and reusability studies on catalyst were studied and synthesized catalyst was observed to be reusable in three consecutive cycles. Degradation of triclosan in Fenton's oxidation follows pseudo-second order reaction with linear fit.

Mo@ZIF-8 nanozyme preparation and its antibacterial property evaluation.

Types of nanozymes can produce free radicals and/or reactive oxygen species (ROS) to serve as broad spectrum antibacterial materials. Developing nanozyme-based antibacterial materials with good biocompatibility exhibits promising application prospects. In this study, we doped Mo to ZIF-8 (both components have good biocompatibility) to prepare a new nanozyme, Mo@ZIF-8, which can produce hydroxyl radicals (•OH) triggered by a low dosage of hydrogen peroxide (H2O2), exhibiting effective antibacterial capability against both Gram-negative bacteria (Escherichia coli) and Gram-positive bacteria (Staphylococcus aureus). This work provides a reference for the design of antibacterial nanozymes with good biocompatibility.

Fenton-like degradation of direct blue dye using green synthesised Fe/Cu bimetallic nanoparticles

This study relates to synthesis of bentonite-supported iron/copper nanoparticles through the biosynthesis method using eucalyptus plant leaf extract, which were then named E-Fe/Cu@B-NPs. The synthesised E-Fe/Cu@B-NPs were examined by a set of experiments involving a heterogeneous Fenton-like process that removed direct blue 15 (DB15) dye from wastewater. The resultant E-Fe/Cu@B-NPs were characterised by scanning electron microscopy, Brunauer–Emmet–Teller analysis, zeta potential analysis, Fourier transform infrared spectroscopy and atomic force microscopy. The operating parameters in batch experiments were optimised using Box–Behnken design. These parameters were pH, hydrogen peroxide (H2O2) dosage, E-Fe/Cu@B-NP dosage, initial DB15 concentration and temperature. The results showed that 94.32% of 57.5 mg/l DB15 was degraded within 60 min with an optimum hydrogen peroxide dosage of 7.5 mmol/l, an E-Fe/Cu@B-NP dosage of 0.55 g/l, a pH of 3.5 and a temperature of 50°C. The kinetic study indicated that the DB15 degradation kinetics fit the second-order kinetic model, and the thermodynamic factors proved that the process is non-spontaneous, endothermic and endergonic with an activation energy E a of 62.961 kJ/mol.

Insulating foamed lightweight cementitious composite with co-addition of micro-sized aerogel and hydrogen peroxide

Noise pollution and thermal discomfort are major concerns in urban areas these days. The building sector consumes a large amount of total energy to fulfill the thermal comfort demands, which are rapidly increasing with modern advancements. The overwhelming energy demand and noise pollution prevalent in the building sector can be controlled using insulating cementitious composites. Therefore, this research investigates the properties of foamed lightweight cementitious composite (FLCC) which incorporates the co-addition of micro-sized aerogel and hydrogen peroxide. Different contents of aerogel (0.5%, 1%, and 1.5% by weight of cement) were used as additives along with various dosages of hydrogen peroxide (1%, 2%, and 3% by weight of cement) to produce the FLCC. The optimum content of the FLCC comprising 1% aerogel and 3% hydrogen peroxide, has a low oven-dry density of 380 kg/m3 with an adequate compressive strength (about 3 MPa) for application as an insulating cementitious composite. The high porosity characteristic (up to 76%) of the FLCC improved sound absorption and thermal conductivity (reduction by 88%). Overall, the results highlighted the promising role of aerogel and hydrogen peroxide incorporated FLCC as a useful insulating construction material.

Non-antibiotic antimicrobial polydopamine surface coating to prevent stable biofilm formation on satellite telemetry tags used in cetacean conservation applications

Satellite telemetry tags, used to monitor the migratory behavior of cetaceans, have the potential to be a vehicle for infection due to their invasive nature. Antibiotic coatings have been previously employed to reduce the chances of infection via the formation of a stable biofilm on the surface of the tags. However, increased use of antibiotics has the potential to lead to the development of antibiotic-resistant pathogens. To prevent the formation of antibiotic-resistant pathogens, a polydopamine surface coating that, when exposed to oxygen, releases low doses (~40-100µM) of hydrogen peroxide over a prolonged period (>24 hours) can be used to replace current antibiotic coatings used in the field. These pDA coatings can reduce bacterial adhesion from model bacteria from the two most common genotypes found on the skin of cetaceans (Psychrobacter and Tenacibaculum). The adhesion of Psychrobacter bacteria was reduced by 80% (p<0.01) while Tenacibaculum was reduced by 70% (p<0.001). When the bacteria were dosed with a non-lethal quantity of hydrogen peroxide (200µM) prior to being exposed to pDA surface coatings, there was no decrease in the efficacy of the coatings. This indicates a resistance to hydrogen peroxide will not be formed quickly. Overall, the polydopamine surface coatings were able to reduce the adhesion of model bacteria strains on the surface of medical grade stainless steel, which could increase the functional tag service life while reducing the chances of infection.

Investigation of Glyphosate Removal from Aqueous Solutions Using Fenton-like System Based on Calcium Peroxide

Glyphosate [N-(phosphonomethyl)-glycine], an organophosphate broad-spectrum herbicide, is a serious environmental contaminant that poses a significant threat to humans. It can be detected as a contaminant in water; thus, effective procedures for its removal are urgently required. The present study investigated the performance of glyphosate removal from aqueous solutions using a Fenton-like system. Calcium peroxide (CaO2) was used as a source of hydroxyl free radicals with Fe2+ as a catalyst to trigger the Fenton reaction. Fourier transform infrared spectroscopy (FTIR), x-ray diffraction (XRD), and potassium permanganate titration were carried out for characterization of calcium peroxide. The effect of operating parameters such as pH, the molar ratio of Ca2+:Fe2+, the initial dosage of calcium peroxide, and the initial glyphosate concentration on the removal efficiency was studied, respectively. The maximum total phosphorus (TP) and chemical oxygen demand (COD) removal were 94.50% and 68.60%, respectively, within 120 min under optimal conditions (pH = 3.0, initial glyphosate concentration = 50 ppm, initial CaO2 dosage = 0.5 g, molar ratio of Ca2+:Fe2+ = 6, room temperature). Experimental data were analyzed using zero-order, first-order, second-order, and Behnajady, Modirshahla, and Ghanbary (BMG) kinetics models. The degradation kinetics of glyphosate could be mostly fitted with the BMG kinetics model. This study demonstrated that calcium peroxide could be considered an effective oxidant for glyphosate wastewater treatment.

Investigation of glyphosate removal from aqueous solution using calcium peroxide

Glyphosate, an organophosphate herbicide containing carboxyl group, is widely used in agriculture. It can be found as a contaminant in water, and procedures are required for its removal. The present study investigated the efficiency of glyphosate removal from aqueous solutions using a Fenton-like system. Calcium peroxide (CaO2) was used as a source of hydroxyl free radicals with Fe2+ as the catalyst to trigger Fenton reaction. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and potassium permanganate titration were carried out for characterization of calcium peroxide. The effect of operating parameters such as pH, molar ratio of Ca2+: Fe2+, and initial dosage of calcium peroxide on the total phosphorus (TP) removal efficiency was studied. The maximum TP removal was 94.50% under optimal conditions (pH = 3.0, initial glyphosate concentration = 50 ppm, initial CaO2 dosage = 0.5 g, molar ratio of Ca2+: Fe2+= 6). This study demonstrated that calcium peroxide could be considered as an effective oxidant for glyphosate wastewater treatment.

Sono-photocatalytic activity of sea sediment@400/ZnO catalyst to remove cationic dyes from wastewater

A photocatalyst was generated from sea sediments and ZnO and tested in the sono-photocatalytic removal of methylene blue (MB) and crystal violet (CV).. The results of FTIR, XPS, and XRD analyzes showed that there are different functional groups in the photocatalyst and also the photocatalyst has a crystalline structure. The BET surface area for sea sediment, sea sediment @400 °C, ZnO, and sea sediment @400 °C/ZnO was determined to be 1.787, 4.326, 24.057, and 9.212 m2.g−1, respectively. The maximum removal efficiency of MB (97.85%) and CV (99.14%) has happened at pH 8, contact time of 40 min, hydrogen peroxide dose of 50 µL/100 mL, catalyst dose of 1 g.L−1, and dye content of 10 mg.L−1 under ultrasonic process (180 W, 24 kHz). The effect of scavengers was investigated to determine the type of radicals effective in the removal process. The results showed that the •OH, •O2–, and electron radicals had an effective role in the dye removal process. The pseudo-first-order kinetic model had a good ability to describe data and the reaction rate constant for removing CV and MB dyes was determined to be 0.0671 and 0.052 min−1, respectively. The treatment of industrial wastewater was successfully done by the prepared photocatalyst. The treated aqueous solution had no toxicity for microorganisms, germination, and plant growth. Thus, the resulting water from the process can be used successfully for agricultural purposes.

Comparative photo-degradative treatment of dyeing industry wastewater containing diazo dye by UV/Peroxydate and UV/Persulfate − oxidation processes

Abstract Generation of anion sulfate radicals (SO4•−) and hydroxyl radicals (HO•) by UV/Persulfate and the UV/Peroxydate processes have been successfully studied to degrade Ponceau S dye. Under [PS] = 0.06 mM; [H2O2] = 2 mM; [S2O82-] = 2 mM, the UV/Persulfate process was effective (kapp = 0.163 min−1) than the UV/Peroxydate process (kapp = 0.054 min−1). The lack of dissolved oxygen, the excess of hydrogen peroxide (H2O2) dosage at 2 mM, and the alkaline pH of 10.01 significantly reduced the UV/Peroxydate efficiency. The scavenging effect of the hydrogenocarbonates and nitrates on the PS dye degradation by the UV/Persulfate process was significant, whereas chlorides had a slight influence. The composition of seawater in chlorides, sulfates, carbonates, and bromides decreased the photoactivity of the studied processes. The presence of phenol showed that the reactive affinity of the (HO•) is more superior to the SO4•−. The UV/Persulfate process achieved 82.35% of chemical oxygen demand removal against 59.56% for the UV/Peroxydate in about 100 min. This study demonstrated that the UV/Persulfate process is a viable option for PS dye degradation. To the best of our knowledge, this is the first report for studying the PS dye degradation under varying some new operational factors. However, the identification of by-products, their nature, and their concentration requires special attention.

Printing ink wastewater treatment using combined hydrodynamic cavitation and pH fixation.

Printing ink wastewater (PIW) carries a heavy load of pollutants, the composition of which makes treatment difficult, especially when trying to minimize the pollution load. According to the latter, the present study aims to investigate PIW treatment with different various methods and to determine the maximum color, COD (chemical oxygen demand) and TSS (total suspended solids) removal. First, hydrodynamic cavitation (HC) was tested and the effect of hydrogen peroxide dosage (0-10gL-1), and pH (3, 5, 8, 10) was examined concerning the removal of PIW initial COD concentrations 4000 and 8000mgL-1. Removal was high (more than 81%) only at pH 5 in HC reactor. The second method involved treatment with separate pH fixation of the undiluted PIW (COD 17000mgL-1, actual pH 8±0.2). This treatment, maximized removals, reaching reduction of the initial values more than 91%, at pH 5. Finally, PIW was treated with a combination of the above methods, leading to 93-97% removals for 8000mgL-1 PIW treatment and 97-99% for 17000mgL-1 PIW respectively. Process cost calculations showed that the latter method is an effective and affordable treatment method for PIW streams, while toxicity tests of the treated PIW showed substantial toxicity reduction.

Evaluation of iron-loaded granular activated carbon used as heterogeneous fenton catalyst for degradation of tetracycline

To optimize the efficiency of general adsorption-Fenton oxidation treatment, iron-loaded granular activated carbon (Fe-GAC) was prepared, characterized, and used as a catalyst in the heterogeneous Fenton oxidation of tetracycline (TC). Characterization revealed that the Fe(II) was successfully introduced onto the original granular activated carbon (GAC) and diversified the materials’ surface morphology and elemental compounds. Under an initial pH of 3.0, the Fe-GAC/Fenton system obtained a maximum removal rate of 92.6%, with hydrogen peroxide (H2O2) dosages of 9 mmol g−1. And the GAC/Fenton without iron supplementation was 89.5%, with H2O2 dosages of 8 mmol g−1. Additionally, the Fe-GAC/Fenton system consumed a lower Fe(II) dosage than GAC/Fenton, with Fe(II)/H2O2 molar ratios of 0.007:1 and 0.04:1, respectively. Analysis of total organic carbon demonstrated higher mineralization efficiency in the Fe-GAC/Fenton system (67.2%), which was approximately 1.3 times of GAC/Fenton. Desorption experiments showed that the adsorption and degradation accounted for 19.22% and 80.78% of the total TC removal by GAC/Fenton, and 10.58% and 89.42% in the Fe-GAC/Fenton system, respectively. Electron paramagnetic resonance (EPR) technique and quenching experiments demonstrated that the dominant reactive oxygen species (ROS) in synergistic treatments were hydroxyl (•OH) and hydroxy peroxyl (HO2•) radicals. In addition, three potential degradation pathways for TC were proposed according to the detected fourteen intermediates. Catalyst regeneration treatments were evaluated over six cycles, and the regeneration was 6.5% higher with the iron-supplemented carbon granules. Overall, the Fe-GAC can be used as an efficient catalyst in practical water treatment, and this study demonstrated a promising method to develop adsorption-Fenton technology.