Enzyme-linked carbon nanotubes as biocatalytic tools to degrade and mitigate environmental pollutants.

A wide array of organic compounds have been recognized as pollutants of high concern due to their controlled or uncontrolled presence in environmental matrices. The persistent prevalence of diverse organic pollutants, including pharmaceutical compounds, phenolic compounds, synthetic dyes, and other hazardous substances, necessitates robust measures for their practical and sustainable removal from water bodies. Several bioremediation and biodegradation methods have been invented and deployed, with a wide range of materials well-suited for diverse environments. Enzyme-linked carbon-based materials have been considered efficient biocatalytic platforms for the remediation of complex organic pollutants, mostly showing over 80% removal efficiency of micropollutants. The advantages of enzyme-linked carbon nanotubes (CNTs) in enzyme immobilization and improved catalytic potential may thus be advantageous for environmental research considering the current need for pollutant removal. This review outlines the perspective of current remediation approaches and highlights the advantageous features of enzyme-linked CNTs in the removal of pollutants, emphasizing their reusability and stability aspects. Furthermore, different applications of enzyme-linked CNTs in environmental research with concluding remarks and future outlooks have been highlighted. Enzyme-linked CNTs serve as a robust biocatalytic platform for the sustainability agenda with the aim of keeping the environment clean and safe from a variety of organic pollutants.

Stem Cells and Tissue Engineering-Based Therapeutic Interventions: Promising Strategies to Improve Peripheral Nerve Regeneration.

Unlike the central nervous system, the peripheral one has the ability to regenerate itself after injury; however, this natural regeneration process is not always successful. In fact, even with some treatments, the prognosis is poor, and patients consequently suffer with the functional loss caused by injured nerves, generating several impacts on their quality of life. In the present review we aimed to address two strategies that may considerably potentiate peripheral nerve regeneration: stem cells and tissue engineering. In vitro studies have shown that pluripotent cells associated with neural scaffolds elaborated by tissue engineering can increase functional recovery, revascularization, remyelination, neurotrophin expression and reduce muscle atrophy. Although these results are very promising, it is important to note that there are some barriers to be circumvented: the host's immune response, the oncogenic properties attributed to stem cells and the duration of the pro-regenerative effects. After all, more studies are still needed to overcome the limitations of these treatments; those that address techniques for manipulating the lesion microenvironment combining different therapies seem to be the most promising and proactive ones.

Insight of nanotechnological processing for nano-fortified functional foods and nutraceutical-opportunities, challenges, and future scope in food for better health.

In the twenty-first century food sector, nanotechnological processing is a new frontier that has vibrant impact on enhancing the food quality, nutritional value, food safety, and nano-fortified functional foods aspects. In addition, the added-value of various robust nano-scale materials facilitates the targeted delivery of nutraceutical ingredients and treatment of obesity and comorbidities. The recent advancement in nanomaterial-assisted palatability enhancement of healthy foods opened up a whole new area of research and development in food nanoscience. However, there is no comprehensive review available on promises of nanotechnology in the food industry in the existing literature. Thus, herein, an effort has been made to cover this leftover literature gap by spotlighting the new nanotechnological frontier and their future scope in food engineering for better health. Following a brief introduction, promises of nanotechnology have revolutionized the twenty-first century food sector of the modern world. Next, recent and relevant examples discuss the exploitation and deployment of nanomaterials in food to attain certain health benefits. A detailed insight is also given by discussing the role of nano-processing in nutraceutical delivery to treat obesity and comorbidities. The latter half of the work focuses on improving healthy foods' palatability and food safety aspects to meet the growing consumer demands. Furthermore, marketed products and public acceptance of nanotechnologically designed food items as well as future prospects are also covered herein.

Functionalized graphene oxide-zinc oxide hybrid material and its deployment for adsorptive removal of levofloxacin from aqueous media.

This work reports on the synthesis of aspartic acid-functionalized graphene oxide-zinc oxide, as a functional porous material, and its potential to mitigate levofloxacin (LFXN). The adsorbent was characterized by various techniques, including ultraviolet-visible (UV-Vis), Fourier transform infrared (FT-IR) spectroscopy, powder X-ray diffraction (PXRD), and scanning electron microscopy (SEM). The average crystallite size of the prepared composite was about 17.30 nm. Batch adsorption studies were carried out to elucidate the adsorption process for LFXN. Different parameters, including contact time, LFXN initial concentration, adsorbent concentration, pH, temperature, and ionic strength were studied. The mechanism and kinetics were studied by fitting the data to Freundlich and Langmuir isotherms, pseudo-first-order and pseudo-second-order kinetic models, respectively. The isotherm data was better fitted to Langmuir isotherm (R2 = 0.999) as compared to the Freundlich model. The maximum adsorption capacity obtained at equilibrium was 73.15 mg/g. For kinetic studies, Pseudo first order was better fitted with R2 = 0.87797, confirming the physisorption process. Thermodynamics parameters revealed that the process was exothermic and spontaneous at low temperatures. The adsorption mechanism was studied and the impregnation of LFXN in the adsorbent was confirmed by FTIR studies. This research proved that the designed GO/Asp-ZnO was a novel and promising adsorbent for the removal of LFXN with an efficiency of 95.12% at 30 mg/L LFXN by 0.6 g/L adsorbent in 24 h at pH = 7 and T = 25 °C.

Hydrothermally improved natural manganese-containing catalytic materials to degrade 4-chlorophenol.

Natural manganese-containing mineral (NMM) was used as a catalyst in heterogeneous catalytic ozonation for 4-chlorophenol (4-CP) degradation. The surface and structural properties of NMM were modified by the hydrothermal aging process and called H-NMM. The catalytic activity of NMM and H-NMM were evaluated for the catalytic ozonation process (COP). The synergistic effect of NMM and H-NMM in ozonation processes for 4-CP degradation under optimal conditions (pH of 7, 1 g/L of NMM and H-NMM, 0.85 mg/min of O3, and 15 min of reaction time) was measured by 3.04 and 4.34, respectively. During the hydrothermal process, Mn4+ and Fe2+ were converted to Mn2+ and Fe3+, which caused better performance of the H-NMM than the NMM. During the catalytic ozonation process, Mn2+ is completely oxidized, which increases the production of Hydroxyl radical (•OH). The reactive oxygen species (ROS) generated in the system were identified using radical scavenging experiments. •OH, superoxide radical (•O2-), and singlet oxygen (1O2) represented the dominant reactive species for 4-CP degradation. The O3/H-NMM process indicated a powerful ability in the mineralization of 4-CP (66.31% of TOC degradation). H-NMM exhibited excellent stability and reusability in consecutive catalytic cycles, and the NMM exhibited desirable performance. This study offers NMM and H-NMM as effective, stable, and competitive catalysts for hastening and enhancing the ozonation process to mitigate environmentally related pollutants of high concern.

Pharmaceutical pollution fingerprinting and waterbodies remediation using waste-derived carbon dots as sustainable advanced nanomaterials.

The conversion of biomass waste into high-value nanomaterials such as carbon dots might represent a great advancement towards a circular economy system. Biomass wastes are an excellent choice as carbon precursors because of their wide availability, abundance, chemical composition, and eco-friendly nature. Moreover, their use as a raw material might decrease the total cost of the synthesis processes and reduce the environmental impacts. In addition, the complex composition of biomass leads to carbon dots with abundant functional groups, which in turn enhances water dispersibility and photoluminescence properties. In this manner, the effective transformation of biomass wastes into carbon dots reduces environmental pollution through the inadequate management of waste while producing carbon dots with enhanced performances. Therefore, this review describes biomass wastes as potential candidates for the synthesis of carbon dots through different synthesis methods. In addition, we have analyzed the great potential of biomass-derived carbon dots (CDs) for the degradation and detection of emerging pharmaceutical pollutants by promoting a circular economy approach. Finally, we identified current challenges to propose possible research directions for the large-scale and sustainable synthesis of high-quality biomass-derived CDs.

Bio-mitigation of organic pollutants using horseradish peroxidase as a promising biocatalytic platform for environmental sustainability.

A wide array of environmental pollutants is often generated and released into the ecosystem from industrial and human activities. Antibiotics, phenolic compounds, hydroquinone, industrial dyes, and Endocrine-Disrupting Chemicals (EDCs) are prevalent pollutants in water matrices. To promote environmental sustainability and minimize the impact of these pollutants, it is essential to eliminate such contaminants. Although there are multiple methods for pollutants removal, many of them are inefficient and environmentally unfriendly. Horseradish peroxidase (HRP) has been widely explored for its ability to oxidize the aforementioned pollutants, both alone and in combination with other peroxidases, and in an immobilized way. Numerous positive attributes make HRP an excellent biocatalyst in the biodegradation of diverse environmentally hazardous pollutants. In the present review, we underlined the major advancements in the HRP for environmental research. Numerous immobilization and combinational studies have been reviewed and summarized to comprehend the degradability, fate, and biotransformation of pollutants. In addition, a possible deployment of emerging computational methodologies for improved catalysis has been highlighted, along with future outlook and concluding remarks.

Environmental concerns and bioaccumulation of psychiatric drugs in water bodies - Conventional versus biocatalytic systems of mitigation.

The COVID-19 pandemic has brought increments in market sales and prescription of medicines commonly used to treat mental health disorders, such as depression, anxiety, stress, and related problems. The increasing use of these drugs, named psychiatric drugs, has led to their persistence in aquatic systems (bioaccumulation), since they are recalcitrant to conventional physical and chemical treatments typically used in wastewater treatment plants. An emerging environmental concern caused by the bioaccumulation of psychiatric drugs has been attributed to the potential ecological and toxicological risk that these medicines might have over human health, animals, and plants. Thus, by the application of biocatalysis-assisted techniques, it is possible to efficiently remove psychiatric drugs from water. Biocatalysis, is a widely employed and highly efficient process implemented in the biotransformation of a wide range of contaminants, since it has important differences in terms of catalytic behavior, compared to common treatment techniques, including photodegradation, Fenton, and thermal treatments, among others. Moreover, it is noticed the importance to monitor transformation products of degradation and biodegradation, since according to the applied removal technique, different toxic transformation products have been reported to appear after the application of physical and chemical procedures. In addition, this work deals with the discussion of differences existing between high- and low-income countries, according to their environmental regulations regarding waste management policies, especially waste of the drug industry.

Microalgae-Based Biotechnology as Alternative Biofertilizers for Soil Enhancement and Carbon Footprint Reduction: Advantages and Implications.

Due to the constant growth of the human population and anthropological activity, it has become necessary to use sustainable and affordable technologies that satisfy the current and future demand for agricultural products. Since the nutrients available to plants in the soil are limited and the need to increase the yields of the crops is desirable, the use of chemical (inorganic or NPK) fertilizers has been widespread over the last decades, causing a nutrient shortage due to their misuse and exploitation, and because of the uncontrolled use of these products, there has been a latent environmental and health problem globally. For this reason, green biotechnology based on the use of microalgae biomass is proposed as a sustainable alternative for development and use as soil improvers for crop cultivation and phytoremediation. This review explores the long-term risks of using chemical fertilizers for both human health (cancer and hypoxia) and the environment (eutrophication and erosion), as well as the potential of microalgae biomass to substitute current fertilizer using different treatments on the biomass and their application methods for the implementation on the soil; additionally, the biomass can be a source of carbon mitigation and wastewater treatment in agro-industrial processes.

Growth Behavior, Biomass Composition and Fatty Acid Methyl Esters (FAMEs) Production Potential of Chlamydomonas reinhardtii, and Chlorella vulgaris Cultures.

The production of biomolecules by microalgae has a wide range of applications in the development of various materials and products, such as biodiesel, food supplements, and cosmetics. Microalgae biomass can be produced using waste and in a smaller space than other types of crops (e.g., soja, corn), which shows microalgae's great potential as a source of biomass. Among the produced biomolecules of greatest interest are carbohydrates, proteins, lipids, and fatty acids. In this study, the production of these biomolecules was determined in two strains of microalgae (Chlamydomonas reinhardtii and Chlorella vulgaris) when exposed to different concentrations of nitrogen, phosphorus, and sulfur. Results show a significant microalgal growth (3.69 g L-1) and carbohydrates (163 mg g-1) increase in C. reinhardtii under low nitrogen concentration. Also, higher lipids content was produced under low sulfur concentration (246 mg g-1). It was observed that sulfur variation could affect in a negative way proteins production in C. reinhardtii culture. In the case of C. vulgaris, a higher biomass production was obtained in the standard culture medium (1.37 g L-1), and under a low-phosphorus condition, C. vulgaris produced a higher lipids concentration (248 mg g-1). It was observed that a low concentration of nitrogen had a better effect on the accumulation of fatty acid methyl esters (FAMEs) (C16-C18) in both microalgae. These results lead us to visualize the effects that the variation in macronutrients can have on the growth of microalgae and their possible utility for the production of microalgae-based subproducts.

Sustainable production of biofuels from the algae-derived biomass.

The worldwide fossil fuel reserves are rapidly and continually being depleted as a result of the rapid increase in global population and rising energy sector needs. Fossil fuels should not be used carelessly since they produce greenhouse gases, air pollution, and global warming, which leads to ecological imbalance and health risks. The study aims to discuss the alternative renewable energy source that is necessary to meet the needs of the global energy industry in the future. Both microalgae and macroalgae have great potential for several industrial applications. Algae-based biofuels can surmount the inadequacies presented by conventional fuels, thereby reducing the 'food versus fuel' debate. Cultivation of algae can be performed in all three systems; closed, open, and hybrid frameworks from which algal biomass is harvested, treated and converted into the desired biofuels. Among these, closed photobioreactors are considered the most efficient system for the cultivation of algae. Different types of closed systems can be employed for the cultivation of algae such as stirred tank photobioreactor, flat panel photobioreactor, vertical column photobioreactor, bubble column photobioreactor, and horizontal tubular photobioreactor. The type of cultivation system along with various factors, such as light, temperature, nutrients, carbon dioxide, and pH affect the yield of algal biomass and hence the biofuel production. Algae-based biofuels present numerous benefits in terms of economic growth. Developing a biofuel industry based on algal cultivation can provide us with a lot of socio-economic advantages contributing to a publicly maintainable result. This article outlines the third-generation biofuels, how they are cultivated in different systems, different influencing factors, and the technologies for the conversion of biomass. The benefits provided by these new generation biofuels are also discussed. The development of algae-based biofuel would not only change environmental pollution control but also benefit producers' economic and social advancement.

Different stages of microbial community during the anaerobic digestion of food waste.

Large-scale food waste (FW) disposal has resulted in severe environmental degradation and financial losses around the world. Although FW has a high biomass energy contents and a growing large number of national projects to recover energy from FW by anaerobic digestion (AD) are being developed. AD is a promising solution for FW management and energy generation when compared to typical disposal options including landfill disposal, incineration, and composting. AD of FW can be combined with an existing AD operation or linked to the manufacture of value-added products to reduce costs and increase income. AD is a metabolic process that requires four different types of microbes: hydrolyzers, acidogens, acetogens, and methanogens. Microbes use a variety of strategies to avoid difficult situations in the AD, such as competition for the same substrate between sulfate-reducing bacteria and methane-forming bacteria. An improved comprehension of the microbiology involved in the anaerobic digestion of FW will provide new insight into the circumstances needed to maximize this procedure, including its possibilities for use in co-digestion mechanisms. This paper reviewed the present scientific knowledge of microbial community during the AD and the connection between microbial diversity during the AD of FW.

Biosensors for the detection of disease outbreaks through wastewater-based epidemiology.

Wastewater-Based Epidemiology (WBE) is a novel community-wide monitoring tool that provides comprehensive real-time data of the public and environmental health status and can contribute to public health interventions, including those related to infectious disease outbreaks (e.g., the ongoing COVID-19 pandemic). Nonetheless, municipalities without centralized laboratories are likely still not able to process WBE samples. Biosensors are a potentially cost-effective solution to monitor the development of diseases through WBE to prevent local outbreaks. This review discusses the economic and technical feasibility of eighteen recently developed biosensors for the detection and monitoring of infectious disease agents in wastewater, prospecting the prevention of future pandemics.

Novel strategies and advancement in reducing heavy metals from the contaminated environment.

The most contemporary ecological issues are the dumping of unprocessed factories' effluent. As a result, there is an increasing demand for creative, practical, environmentally acceptable, and inexpensive methodologies to remediate inorganic metals (Hg, Cr, Pb, and Cd) liquidated into the atmosphere, protecting ecosystems. Latest innovations in biological metals have driven natural treatment as a viable substitute for traditional approaches in this area. To eliminate pesticide remains from soil/water sites, technologies such as oxidation, burning, adsorption, and microbial degradation have been established. Bioremediation is a more cost-effective and ecologically responsible means of removing heavy metals than conventional alternatives. As a result, microorganisms have emerged as a necessary component of methyl breakdown and detoxification via metabolic reactions and hereditary characteristics. The utmost operative variant for confiscating substantial metals commencing contaminated soil was A. niger, which had a maximum bioaccumulation efficiency of 98% (Cd) and 43% (Cr). Biosensor bacteria are both environmentally sustainable and cost-effective. As a result, microbes have a range of metal absorption processes that allow them to have higher metal biosorption capabilities. Additionally, the biosorption potential of bacterium, fungus, biofilm, and algae, inherently handled microorganisms that immobilized microbial cells for the elimination of heavy metals, was reviewed in this study. Furthermore, we discuss some of the challenges and opportunities associated with producing effective heavy metal removal techniques, such as those that employ different types of nanoparticles.

Gums-based engineered bio-nanostructures for greening the 21st-century biotechnological settings.

Naturally occurring plant-based gums and their engineered bio-nanostructures have gained an immense essence of excellence in several industrial, biotechnological, and biomedical sectors of the modern world. Gums derived from bio-renewable resources that follow green chemistry principles are considered green macromolecules with unique structural and functional attributes. For instance, gum mostly obtained as exudates are bio-renewable, bio-degradable, bio-compatible, sustainable, overall cost-effective, and nontoxic. Gum exudates also offer tunable attributes that play a crucial role in engineering bio-nanostructures of interest for several bio- and non-bio applications, e.g., food-related items, therapeutic molecules, sustained and controlled delivery cues, bio-sensing constructs, and so on. With particular reference to plant gum exudates, this review focuses on applied perspectives of various gums, i.e., gum Arabic, gum albizzia, gum karaya, gum tragacanth, and gum kondagogu. After a brief introduction with problem statement and opportunities, structural and physicochemical attributes of plant-based natural gums are presented. Following that, considerable stress is given to green synthesis and stabilization of gum-based bio-nanostructures. The final part of the review focuses on the bio- and non-bio related applications of various types of gums polysaccharides-oriented bio-nanostructures.

Ultrasonication expedited As(III) adsorption onto chitosan impregnated Ni-Fe layered double hydroxide biosorbent: Optimization studies and artificial intelligence modelling.

Chitosan intercalated Ni-Fe layered double hydroxide (Ni-Fe LDH/Ch), prepared by co-precipitation was examined for adsorptive elimination of arsenic (III). Energy Dispersive X-ray analysis, X-ray diffraction, Fourier Transform Infrared spectroscopy, Scanning Electron Microscopy, and Dynamic Light Scattering validated the successful synthesis of the composite with enhanced adsorption sites. Maximal As(III) removal was obtained at adsorbent dose 1 gL-1, pH 7, ultrasonication time 30 min, temperature 298 K, and initial arsenic concentration 50 mgL-1. The experimentally obtained values fit the Langmuir isotherm and pseudo-second-order dynamics well (R2 > 0.98), while thermodynamic evaluation confirmed exothermic and spontaneous reaction (ΔG = -8.13 kJ mol-1). Further, adaptive neuro-fuzzy inference system and artificial neural network successfully predicted As(III) removal percentage with a high correlation coefficient (R2 > 0.94) and low statistical errors (MSE< 0.002, AARE< 0.063). The prepared material successfully brought down arsenic level by 62% in a natural water sample and showed good reusability up to 5 consecutive treatment cycles. The results recommended that Ni-Fe LDH/Ch has ample potential for arsenic remediation, and further investigations can be carried out for large-scale applications.

Omics approaches in bioremediation of environmental contaminants: An integrated approach for environmental safety and sustainability.

Non-degradable pollutants have emerged as a result of industrialization, population growth, and lifestyle changes, endangering human health and the environment. Bioremediation is the process of clearing hazardous contaminants with the help of microorganisms, and cost-effective approach. The low-cost and environmentally acceptable approach to removing environmental pollutants from ecosystems is microbial bioremediation. However, to execute these different bioremediation approaches successfully, this is imperative to have a complete understanding of the variables impacting the development, metabolism, dynamics, and native microbial communities' activity in polluted areas. The emergence of new technologies like next-generation sequencing, protein and metabolic profiling, and advanced bioinformatic tools have provided critical insights into microbial communities and underlying mechanisms in environmental contaminant bioremediation. These omics approaches are meta-genomics, meta-transcriptomics, meta-proteomics, and metabolomics. Moreover, the advancements in these technologies have greatly aided in determining the effectiveness and implementing microbiological bioremediation approaches. At Environmental Protection Agency (EPA)-The government placed special emphasis on exploring how molecular and "omic" technologies may be used to determine the nature, behavior, and functions of the intrinsic microbial communities present at pollution containment systems. Several omics techniques are unquestionably more informative and valuable in elucidating the mechanism of the process and identifying the essential player's involved enzymes and their regulatory elements. This review provides an overview and description of the omics platforms that have been described in recent reports on omics approaches in bioremediation and that demonstrate the effectiveness of integrated omics approaches and their novel future use.

Bioremediation and decontamination potentials of metallic nanoparticles loaded nanohybrid matrices - A review.

The current nanotechnological advancements provide an astonishing insight to fabricate nanomaterials for nano-bioremediation purposes. Exciting characteristics possessed by hybrid matrices at the nanoscale knock endless opportunities to nano-remediate environmentally-related pollunanomaterials tants of emerging concern. Nanometals are considered among the oldest generation of the world has ever noticed. These tiny nanometals and nanometal oxides showed enormous potential in almost every extent of industrial and biotechnological domains, including their potential multipurpose approach to deal with water impurities. In this manuscript, we discussed their role in the diversity of water treatment technologies used to remove bacteria, viruses, heavy metals, pesticides, and organic impurities, providing an ample perspective on their recent advances in terms of their characteristics, attachment strategies, performance, and their scale-up challenges. Finally, we tried to explore their futuristic contribution to nano-remediate environmentally-related pollutants of emerging concern aiming to collect treated yet safe water that can be reused for multipurpose.

Biodegradation of environmental pollutants using catalase-based biocatalytic systems.

The synergistic combination of biocatalysts and nanomaterials provides a new interface of a robust biocatalytic system that can effectively remediate environmental pollutants. Enzymes, such as catalase-based constructs, impart the desired candidature for catalytic transformation processes and are potential alternatives to replace conventional remediation strategies that have become laborious and somewhat inefficient. Furthermore, the controlled or uncontrolled discharge of various emerging pollutants (EPs) into water bodies is equally proportional to the fast-growing population and extensive urbanization. EPs affect the entire living being and continuously deteriorate the environmental system, directly or indirectly. The occurrence of EPs (even released after partial treatments, but still in bioactive forms) disturbs ecological integrity. Due to the ineffectiveness of in-practice traditional remediation processes, new and robust treatment measures as effective and sustainable remediation have become a meaningful goal. In this context, special attention has been shifted to engineering an enzyme (catalase)-based biodegradation system with immense prospects in environmental cleanup. The unique synergistic combination of nanomaterials (having multifunctional attributes) with enzymes of interest makes them a state-of-the-art interface that can further ameliorate bio-catalysis and biodegradation performance. This review covers current research and scientific advancement in developing and deploying catalase-based biocatalytic systems to mitigate several EPs from the environment matrices. The biocatalytic features of catalase, along with the mechanistic insight into H2O2 neutralization, several nano-based materials loaded with catalase, including nanoparticles (NPs), carbon nanotubes (CNTs), metal-organic frameworks (MOFs), polymeric-based composites, oxime-functionalized cryo-gel disks, electro-spun nanofibrous membranes, and other hybrid materials have also been discussed with suitable examples.

Degradation of 4-chlorophenol using MnOOH and γ-MnOOH nanomaterials as porous catalyst: Performance, synergistic mechanism, and effect of co-existing anions.

Transition metal catalysts have been proven to be a highly-potent catalyst for peroxymonosulfate (PMS) activation. The present work aimed to synthesizes the γ-MnOOH and MnOOH based on the one-pot hydrothermal method as PMS activators for efficient degradation of 4-chlorophenol (4-CP). The effect of operational parameters including solution pH, γ-MnOOH and MnOOH dose, PMS dose, 4-CP concentration, and also mixture media composition was elaborated. The results showed that the combination of MnOOH and γ-MnOOH with PMS noticeably creates a synergistic effect (SF) in 4-CP degradation by both PMS/MnOOH and PMS/γ-MnOOH process, with a SF value of 48.14 and 97.42, respectively. In both systems, the removal of 4-CP decreased in severely alkaline and acidic conditions, while no significant changes were observed in pH 5 to 9. Also, coexisting PO43- significantly reduced the removal efficiency of both systems. In addition, the effect of humic acid (HA) as a classical scavenger was investigated and showed that presence of 4 mg/L HA reduced the removal efficiency of 4-CP in the PMS/MnOOH process from 97.44% to 79.3%. The three consecutive use of both catalysts turned out that MnOOH has better stability than γ-MnOOH with lower Mn ions leaching. More importantly, quenching experiment showed that both non-radical (1O2 and O2-) and radical (SO4- and OH) pathways are involved in 4-CP degradation and non-radical pathway was the dominant one in both systems.