Potassium Permanganate Pre-oxidation Research Articles

Adsorption–desorption behavior of malachite green by potassium permanganate pre-oxidation polyvinyl chloride microplastics

Microplastics (MPs) and the typical hydrophilic organic pollutant Malachite green (MG) are frequently detected in sewage treatment plants. Potassium permanganate (KMnO4) pre-oxidation is an economical and effective technology in wastewater treatment. It is important to study the surface physicochemical characteristics of MPs and understand their fate in wastewater treatment plants after pre-oxidation. In this study, Polyvinyl chloride (PVC) MPs were treated by single and composite KMnO4 pre-oxidation with different pH values. After the pre-oxidation treatment, the appearance of OMn spectra and surface nanoparticles indicated the oxides (MnO2) were produced on the MPs surface. Moreover, the adhesion of MnO2 is helpful to improve the hydrophilicity and adsorption capacity of MG. The adsorption capacity of pristine PVC for MG was 2.6 mg/g. But the adsorption capacity increased to 7.0 mg/g for single oxidation and 140.7 mg/g for composite oxidation, respectively. The desorption experiment results indicate the pre-oxidation process could reduce the release efficiency of MG from the PVC MPs due to the better binding of surface MnO2 nanoparticles to MG. However, the total desorption capacity is still high. which illustrates that there is a high potential risk of MG which can transfer from the surface of the PVC MPs to the gastrointestinal fluids.

Enhanced coagulation of covalent composite coagulant with potassium permanganate oxidation for algae laden water treatment: Algae and extracellular organic matter removal

The enhanced coagulation performance for algae and extracellular organic matter (EOM) removal by using novel Al/Fe-based covalently bonded composite coagulants (CAFM) coupled with potassium permanganate oxidation was evaluated in the current study. For the CAFM coagulation and potassium permanganate oxidation combination process, two dosage sequences of oxidant and coagulant, the potassium permanganate pre-oxidation method, and the simultaneous oxidation method, was compared for algae and EOM removal. Polyaluminum chloride (PAC) and polyacrylamide (PAM) were selected as common used coagulants to compare with CAFM. The results show that 21.1% UV254, 99.6% OD686, and 98.2% turbidity were removed from EOM algae laden water at CAFM dosage of 5.4 mg/L and KMnO4 dosage of 1 mg/L. UV254 removal rate was increased by 10% in potassium permanganate oxidation treatment compared with CAFM coagulation. In addition, pre-oxidation method exhibited better extracellular organic matter removal efficiency compared with simultaneous oxidation method. Furthermore, SEM, FTIR, XRD and XPS were employed to study the physical and chemical structure of flocs, whereas ICP-MS, EEM, GCMS– and GPC were used to analyze water quality before and after treatment for coagulation and oxidation in mechanism exploration. This study proposes a new process for algal bloom control, organic pollution reduction and ensure water quality of water plant effluent to provide research basis.

Surface characteristic and sinking behavior modifications of microplastics during potassium permanganate pre-oxidation

Microplastics (MPs) occur in the source water of worldwide drinking water treatment plants (DWTPs). Pre-oxidation treatments become the initial stage for MPs treatment in DWTPs. Investigating the modifications of MPs after pre-oxidations is important to understand their fate in DWTPs. In this study, potassium permanganate oxidation (PPO) was applied to treat four high abundant MPs in DWTPs, including polyethylene (PE), polyethylene terephthalate (PET), polyvinylchloride (PVC) and polystyrene (PS). Influences of polymer types, sizes and pH were considered. After 10 mg L−1 PPO, only slight corrosions were observed on all MPs. Whereas, the appearances of O-Mn spectrum and the observation of nano-scale particles indicated the generation of nascent state Mn-oxides (MnO2) on MPs surface. This adhesion of MnO2 contributed to increasing density and hydrophilicity. As a result, the sinking performance of MPs was enhanced, e.g. the sinking ratio of 6.5 µm MPs increased 30% (PET), 20% (PVC) and 30% (PS) compared with pristine ones upon pH 7 PPO. These results implied that the practical PPO can enhance the sinking behavior of MPs. Of note, PE seems to be persistent and requires special concern.

Removal of Organic Matter from Water by Chemical Preoxidation Coupled with Biogenic Manganese Oxidation

In the process of drinking water treatment, potassium permanganate and iron-manganese oxides are typical pre-oxidation methods that can not only effectively remove organic matters in drinking water, but also reduce the production of disinfection by-products (DBPs). However these two pre-oxidation methods will produce Mn2+ that is genotoxic. In order to solve this problem, a concept was proposed to connect biogenic-manganese oxidation technology after chemical oxidation. The manganese-oxidizing microbe may convert Mn2+ into the bio-manganese oxide, which can further remove the pollutants by its strong oxidative and adsorption capacity to improve water purification. In the simulated contaminated water composed of natural organic tyrosine (Tyr) and synthetic organic 2-Hydroxy-4-Methoxybenzophenone-5-Sulfonic Acid (BP-4), we verified the proposed the concept. Pre-oxidation by potassium permanganate or iron-manganese oxides efficiently removed Tyr, but had negligible effect on BP-4. During this, Mn2+ was generated. In the subsequent biological system, the manganese-oxidizing bacteria Pseudomonas sp. QJX-1 could utilize the Tyr for growth and oxidize Mn2+ to Mn4+ oxide. The generated manganese oxides could then effectively remove BP-4. In comparison, the moderate potassium permanganate preoxidation coupled with bio-manganese oxidation had a desirable treatment effect, with 100%, 50%, and 98.9% removals for Tyr, BP-4, and Mn2+, respectively. Importantly, the study provides a new method for drinking water treatment.

Removal of Anabaena spiroides by potassium permanganate pre-oxidation: effect on photosynthetic capacity and molecular weight distribution.

Bench scale tests were conducted to investigate the effect of potassium permanganate pre-oxidation on the photosynthetic activity and molecular weight distribution of Anabaena spiroides. Different concentrations of potassium permanganate were added into the suspension of Anabaena spiroides, one of the dominant algae in water bloom, and after pre-oxidation of permanganate for 1h, the results show that the removal rate significantly increases by 33.99~36.35% compared to direct coagulation. Then, the algal characteristics, including photosynthetic ability, the changes in extracellular organic matter three-dimensional fluorescence, and the distribution of molecular weight were conducted and the results show that along with increasing concentration of potassium permanganate, the photosynthetic ability of algae decreases, more extracellular organic matter is secreted, and large molecular weight matter (humic-like and fulvic-like substances) are generated. Therefore, this study demonstrates that potassium permanganate could be used in addressing the algae-rich water.

Influence of potassium permanganate pre-oxidation on the interaction of humic acid with cadmium/arsenic

Permanganate pre-oxidation could enhance coagulation in water treatment of surface water in the presence of humic acid (HA).

Effect on membrane fouling and intrinsic characteristics of UF subjected to potassium permanganate pre-oxidation

The Extended Derjaguin–Landau–Verwey–Overbeek approach was used to investigate the mechanism of membrane fouling control with potassium permanganate (KMnO4) pre-oxidation in an ultrafiltration (UF) system. The polymeric membrane, made of polyvinylidene fluoride (PVDF), was selected as membrane material in the investigation. Results demonstrated that KMnO4 pre-oxidation increased the hydrophilicities of both membrane material and organic colloid and that the absolute value of calculated total interaction energy decreased by 33.5 and 33.6%, respectively, indicating the amelioration of membrane fouling. The results of transmembrane pressure and membrane resistance confirmed the mitigation of membrane fouling. It was found that the average pore size of the membrane material was decreased when UF system was subjected to KMnO4. The characteristics of influent organic colloids were changed due to KMnO4 pre-oxidation.

Application Research of Microfiltration Membrane Pilot Test in Water Treatment

Lake water is used as the raw water. The water carries the following characteristics: high organic content in individual sessions, high-algae and odor in summer. At present, the conventional treatment process is unable to cope with. The application of microfiltration system in the pilot test is studied. Filter effluent and air flotation effluent are used as the microfiltration influent. Membrane flux are 80L/m2/h, 90L/m2/h, 100L/m2/h.Water quality is stable. The average turbidity is 0.1NTU. Total coliform and total bacteria in effluent are not detected. The recovery of water is greater than 96.1%.Potassium permanganate preoxidation + powder carbon dosing + conventional treatment + microfiltration membrane system can effectively solve organics, high algae and odor problems. It also can improve the coping capacity to respond mutation of the water quality.

Effect of potassium permanganate pre-oxidation on fouling and pore size of ultrafiltration membrane for drinking water treatment

Membrane fouling is one of the most significant issues limiting the utilization of ultrafiltration (UF) technology in drinking water treatment. In this paper, UF system was used as an advanced treatment following the conventional sand filter process. The performance of membrane fouling control was investigated by using potassium permanganate (KMnO4) to oxidize UF influent, i.e. sand filter effluent. The optimal dosage of KMnO4 was 0.3 mg/L in terms of both permeate flux and product water quality in KMnO4/UF system. Membrane fouling was remarkably alleviated by KMnO4 pre-oxidation to transform characteristics of some organic pollutants. Scanning electron microscopy showed that loose fragments were formed on the filtration cake, which was easy to be removed by hydraulic washing, during the KMnO4/UF process. The increasing rate of transmembrane pressure was slower in KMnO4/UF system than that without being subjected to KMnO4 pre-oxidation. The pore sizes of the used membrane were found to be narrower than the virgin one due to the oxidation of KMnO4.

Effects of Potassium Permanganate Preoxidation Followed with Coagulation on the Fluorescence Spectrum of Algae

This study was performed to illustrate the effects of preoxidation by potassium permanganate on the fluorescence spectrum of Microcysis aeruginosa, a kind of blue-green algae. The results showed there were four dominate excitation/emission (Ex/Em) wavelength pairs, 230/334, 280/312, 280/334 and 620/642 nm/nm in the fluorescence spectra of algae and their derived organic matters (AOM). Coagulation resulted in desorption of the organic matter adsorbed in algae cells and produced two new fluorophores centered at 275/460 and 400/460 nm/nm. Potassium permanganate preoxidation could reduce the fluorescence intensity of algae and dissolved algal organic matters effectively and the descent rate increased with increasing potassium permanganate dosage.

Atomic force microscopy study on the microtopography of natural organic matter and newly formed hydrous MnO2

To understand the water purification mechanism of potassium permanganate as a coagulation-aid during the preoxidation process, the microtopography of its reductive products, the newly formed hydrous manganese dioxide and the aged hydrous manganese dioxide, was investigated. The morphology of natural organic matter (NOM) adsorbed by the newly formed hydrous manganese dioxide was also compared with that of NOM alone. By using the tapping mode atomic force microscopy (AFM), the observation results show that the newly formed hydrous manganese dioxide possess a perforated sheet (with a thickness of 0–1.75 nm) as well as some spherical particle structures compared with the hydrous manganese dioxide with 2 h aging time, which demonstrated that the newly formed hydrous manganese dioxide had a large surface area and adsorption capacity. When 1 mmol/L newly formed hydrous manganese dioxide was added, the microtopography of NOM molecules shifted from a loosely dispersed pancake shape (with adsorption height of 5–8.5 nm) to a densely dispersed and uniform spherical structure. These results provide a valid proof that it is the perfect adsorption capability of the newly formed hydrous manganese dioxide that might result in the coagulation aid effect of potassium permanganate preoxidation.

Quantitative Determination of Murine Dermal Elastic Fibers by Color Image Analysis: Comparison of Three Staining Methods

We compared three different staining methods to determine if the dermal elastic fiber content of the HRS/Skh-1 hairless mouse could be accurately measured by color image analysis. Comparisons were made among Kligman's modification of Luna's mast cell stain for elastin, Unna's orcein stain with or without potassium permanganate preoxidation, and Gomori's aldehyde fuchsin stain with potassium permanganate preoxidation. The color image analysis system could be used to identify and quantify murine dermal elastin fibers in sections stained by all three methods. Gomori's aldehyde fuchsin stain with preoxidation demonstrated twice the content of dermal elastic fibers demonstrated by either Kligman's modification of Luna's mast cell stain or Unna's orcein stain with or without preoxidation. Gomori's aldehyde fuchsin method with preoxidation should be considered the stain of choice for evaluating murine dermal elastic fiber content.

The Impact of Incorporated Organic Matter on the Dewatering Characteristics of Aluminum Hydroxide Sludges

The effects of coagulation of organic matter by alum (as influenced by coagulation pH, dosage, and potassium permanganate preoxidation) on the thickening and dewatering characteristics of aluminum hydroxide sludges were examined. Sludge dewatering characteristics worsened as the specific amount of organic matter incorporated into the sludge floc matrix increased. The observed changes in sludge characteristics were correlated to a decrease in sludge floc size and density that occurred when greater amounts of organic matter were incorporated into the floc structure. Addition of potassium permanganate improved sludge dewatering rates; the dosage required for improvement was a direct function of the amount of organic matter present in the sludge.