Contaminants In Wastewater Research Articles

Green synthesis of carbon nanotubes functionalized with iron nanoparticles and coffee husk biomass for efficient removal of losartan and diclofenac: Adsorption kinetics and ANN modeling studies

The presence of emerging contaminants in wastewater poses a global environmental challenge, requiring the development of innovative materials or methods for their treatment. This study focused on the production of green functionalized carbon nanotubes (CNTs) and using them in the adsorption of the pharmaceuticals Losartan (LOS) and Diclofenac (DIC). The efficiency of the methodology was verified by characterization techniques. Elemental composition analysis indicated a significant increase in the iron content after the green functionalization, proving the effectiveness of the method. Thermogravimetric analysis showed similar thermal degradation profiles for pristine CNTs and functionalized CNTs, indicating better post-functionalization thermal stability. BET analysis revealed mesoporous characteristics of CNTs, with increased surface area and pore volumes after functionalization. X-Ray diffraction confirmed the preservation of the lattice structure of the CNTs post-functionalization and post-adsorption, with changes in peak broadening suggesting surface modifications. LOS and DIC adsorption were evaluated via kinetic studies at four different concentrations (0.1–0.4 mmol/L) that were best represented by the pseudo-second order model, suggesting chemisorption mechanisms, with faster and higher uptakes for DIC (0.084–0.261 mmol/g; teq = 5 min) when compared to LOS (0.058–0.235 mmol/g; teq = 20 min). The curves were also studied via artificial neural networks (ANN) and revealed that the best ANN architecture for representing the experimental data is a network with [3 5 5 2] neurons trained using the Bayesian-Regularization algorithm and the Log-sigmoid (hidden layers) and Linear (output layer) transfer functions. The desorption study showed that CaCl2 had better performance in CNT regeneration, reaching its removal capacity above 50% up to 3 cycles, for both pharmaceuticals. These findings reveal the potential of the developed material as a promising adsorbent for targeted removal of pollutants, contributing to advances in the remediation of emerging contaminants and the application of artificial intelligence in adsorption research.

Cobalt single-atom catalyst tailored ceramic membrane for selective removal of emerging organic contaminants

Water reuse is an effective way to solve the issues of current wastewater increments and water resource scarcity. Ultrafiltration, a promising method for water reuse, has the characteristics of low energy consumption, easy operation, and high adaptability to coupling with other water treatment processes. However, emerging organic contaminants (EOCs) in municipal wastewater cannot be effectively intercepted by ultrafiltration, which poses significant challenges to the effluent quality and sustainability of ultrafiltration process. Here, we develop a cobalt single-atom catalyst-tailored ceramic membrane (Co1-NCNT-CM) in conjunction with an activated peroxymonosulfate (PMS) system, achieving excellent EOCs degradation and anti-fouling performance. An interfacial reaction mechanism effectively mitigates membrane fouling through a repulsive interaction with natural organic matter. The generation of singlet oxygen at the Co-N3-C active sites through a catalytic pathway (PMS→PMS∗→OH∗→O∗→OO∗→1O2) exhibits selective oxidation of phenols and sulfonamides, achieving >90% removal rates. Our findings elucidate a multi-layered functional architecture within the Co1-NCNT-CM/PMS system, responsible for its superior performance in organic decontamination and membrane maintenance during secondary effluent treatment. It highlights the power of integrating Co1-NCNT-CM/PMS systems in advanced wastewater treatment frameworks, specifically for targeted EOCs removal, heralding a new direction for sustainable water management.

Al/Ca-doped CuFe2O4 prepared from waste printed circuit boards as a magnetic peroxymonosulfate activator for the degradation of organic pollutants

Cu-containing heterogeneous catalysts are being increasingly used to activate peroxymonosulfate (PMS) and remove organic pollutants from wastewater. However, expensive raw materials and limited metal resources restrict the practical applications of these catalysts. In this study, waste printed circuit boards (PCBs), a typical Cu-rich electronic waste, were used to prepare Al/Ca-doped CuFe2O4 (PCBs-CuFe2O4) with the assistance of Fe3+. The obtained PCBs-CuFe2O4, doped with the catalytically inert metals Al and Ca, possessed abundant porous structures, high specific surface areas, rich surface oxygen vacancies, and excellent magnetic properties. Despite its relatively poor purity and crystallinity compared to those of CuFe2O4 prepared using commercial chemicals, PCBs-CuFe2O4 exhibited superior performance in reactive blue 19 (RB19) degradation by activating PMS. Additionally, the PCBs-CuFe2O4/PMS system exhibited strong resistance to pH and water matrices, confirming the practical application of PCBs-CuFe2O4 for the elimination of organic pollutants in wastewater. Furthermore, the results of electrochemical measurements, quenching experiments, and electron paramagnetic resonance analysis revealed that 1O2 plays an important role in the degradation of RB19. The Cu(I)/Cu(II), Fe(II)/Fe(III), and OV of PCBs-CuFe2O4 dominate the activation of PMS. Thus, this study presents a novel strategy for reutilizing waste PCBs and eliminating organic contaminants in wastewater.

Environmental health hazards of untreated livestock wastewater: potential risks and future perspectives.

Due to technological and economic limitations, waste products such as sewage and manure generated in livestock farming lack comprehensive scientific and centralized treatment. This leads to the exposure of various contaminants in livestock wastewater, posing potential risks to both the ecological environment and human health. This review evaluates the environmental and physical health risks posed by common pollutants in livestock wastewater and outlines future treatment methods to mitigate these risks. Residual wastes in livestock wastewater, including pathogenic bacteria and parasites surviving after epidemics or diseases on various farms, along with antibiotics, organic wastes, and heavy metals from farming activities, contribute to environmental damage and pose risks to human health. As the livestock industry's development increasingly impacts society's future negatively, addressing the issue of residual wastes in livestock wastewater discharge becomes imperative. Ongoing advancements in wastewater treatment systems are consistently updating and refining practices to effectively minimize waste exposure at the discharge source, mitigating risks to environmental ecology and human health. This review not only summarizes the "potential risks of livestock wastewater" but also explores "the prospects for the development of wastewater treatment technologies" based on current reports. It offers valuable insights to support the long-term and healthy development of the livestock industry and contribute to the sustainable development of the ecological environment.

Synthesis, Characterization, and Photocatalytic Performance of ZnFe2O4-g-C3N4 Composites for Tetracycline Removal from Contaminated Water

The presence of emerging contaminants in wastewater like tetracycline poses a significant challenge in water reuse worldwide. The implementation of a p-n heterojunction and dye-sensitized techniques in the enhancement of graphite carbon nitride provides a promising alternative for visible light-driven degradation of emerging contaminants present in wastewater. The present study investigated dye-sensitized and plain composites in degrading tetracycline using natural sunlight in a parabolic trough reactor. The study synthesized four composites of ZnFe2O4-g-C3N4 at 5, 15, and 25 wt% loading of the ferrite by direct annealing of melamine, followed by thermal and ultrasonic exfoliation of bulk graphite carbon nitride and in situ precipitation with zinc ferrites to yield a composite photocatalyst. The photocatalysts were characterized using X-ray diffraction (XRD) analyses which confirmed that all the spinel ferrite phases of ZnFe2O4 were well bonded with g-C3N4 nanosheets to form a composite. The crystallite sizes were calculated by the Debye–Scherrer equation indicating crystal sizes of between 4.63 and 8.61 nm confirming the nanostructures. The scanning electron microscope-energy dispersive spectroscopy (SEM-EDX) tests verified that the spherical globules of ZnFe2O4 were well attached to the mesoporous layers of g-C3N4 and absence of contaminant phases. The UV-Vis analysis for 25% ZF-GCN revealed a band gap reduction from 2.67 eV to 2.03 eV. The PL intensity for all the composites decreased at excitation of 266 nm and 550 nm which was evidence for suppressed charge recombination. A 25% ferrite loading resulted in the best photocatalytic performance with tetracycline degradation of 93.64% and total organic carbon (TOC) removal of 51.89%. The sensitization of the 25% ZF-GCN composite with Eosin Y further improved its performance for degradation of tetracycline to 94.62% and TOC removal to 68.29%. Therefore, dye sensitization is an efficient way of improving the photocatalytic activity of a multicomponent photocatalyst for the removal of emerging pollutants.

Interface engineering of 1D/2D FeVO4/MoS2 hetero-structured nanocomposite with effective interfacial charge transfer: Facile synthesis and antibiotic drug degradation

The rapid accumulation of organic contaminants in wastewater is a considerable environmental concern. We are investigating nanoscale FeVO4 and MoS2 structures for enhanced removal of organic pollutants to overcome this challenge. The FeVO4/MoS2 nanocomposite was synthesized via a hydrothermal technique. This study looks at how the FeVO4/MoS2 nanocomposite could be explored as a good catalyst for the degradation of ciprofloxacin drug through Photo-Fenton process. The synergy between FeVO4 and MoS2 and hydroxyl radicals leads to accelerated degradation. Our findings imply that FeVO4/MoS2 nanocomposites could remove pharmaceutical pollutants from wastewater sources, contributing to water treatment technology.

Advancement in Sustainable Wastewater Treatment: A Multifaceted Approach to Textile Dye Removal through Physical, Biological and Chemical Techniques

AbstractThe global manufacturing sector heavily relies on the textile industry, yet the widespread utilization of synthetic dyes within this sector has raised serious environmental apprehensions, notably regarding wastewater contamination. The release of untreated wastewater containing residual dyes poses a significant risk to both aquatic ecosystems and human well‐being. In reaction to this issue, considerable efforts have been made to develop efficient and sustainable methods for the removal of textile dyes from wastewater. This comprehensive review paper furnishes in‐depth literature information covering various aspects of dyes, including their classification, toxicity effects, and evaluation of recent advancements in dye removal technology, emphasizing their advantages, limitations, and future potential. Various strategies are covered, including physical, chemical, and biological methods. Physical techniques like adsorption, filtration, and membrane technologies are contrasted with chemical approaches such as coagulation, precipitation, and advanced oxidation processes. Biological methods include the utilization of micro‐organisms, fungi, and enzymes to break down or metabolize dye compounds. Key considerations in the critical analysis include the efficiency, cost‐effectiveness, and scalability of each method. This review focuses on enzyme breakdown (biological) and adsorption (physical) color removal procedures, which are currently considered the most effective. It also proposes the utilization of a composite adsorbent, anticipating enhanced efficiency and faster removal of dyes through this technique.

Adsorption Capacity of Carbon-Silica Composites Towards Diclofenac in Poly(acrylic acid) Containing Systems: A Crucial Study on Common Wastewater Contaminants.

Diclofenac is one of the most popular over-the-counter non-steroidal anti-inflammatory drug and poly(acrylic acid) is a frequently used as thickener, filler or stabilizer. For these reasons, they are common organic contaminants in raw wastewater. The purpose of the presented studies was to compare the adsorption capacity of three carbon-silica composites - metal-free C/SiO2, iron-enriched C/Fe/SiO2 and manganese-enriched C/Mn/SiO2 towards diclofenac. The studies were carried out in single, and mixed systems in the presence of poly(acrylic acid) polymer. Adsorption, desorption and kinetics of the adsorption process were investigated. The concentration of diclofenac in the supernatants was determined using high-performance liquid chromatography. The solids were also characterized with an ASAP apparatus using low-temperature nitrogen desorption adsorption isotherms at liquid nitrogen temperature. In addition, potentiometric titrations and electrophoretic mobility measurements, as well as stability tests of the studied suspensions were carried out. The most efficient composite among investigated ones proved to be C/Fe/SiO2 removing diclofenac at the level of 46.68 mg/g for its initial concentration of 90 ppm. The results obtained clearly demonstrated that the carbon-silica composites are effective in separation of drugs from aqueous solutions and can be successfully used in the future for the removal of organic pollutants from water environment.

Selective Reduction of Aqueous Nitrate to Ammonium with an Electropolymerized Chromium Molecular Catalyst.

Nitrate (NO3-) is a common nitrogen-containing contaminant in agricultural, industrial, and low-level nuclear wastewater that causes significant environmental damage. In this work, we report a bioinspired Cr-based molecular catalyst incorporated into a redox polymer that selectively and efficiently reduces aqueous NO3- to ammonium (NH4+), a desirable value-added fertilizer component and industrial precursor, at rates of ∼0.36 mmol NH4+ mgcat-1 h-1 with >90% Faradaic efficiency for NH4+. The NO3- reduction reaction occurs through a cascade catalysis mechanism involving the stepwise reduction of NO3- to NH4+ via observed NO2- and NH2OH intermediates. To our knowledge, this is one of the first examples of a molecular catalyst, homogeneous or heterogenized, that is reported to reduce aqueous NO3- to NH4+ with rates and Faradaic efficiencies comparable to those of state-of-the-art solid-state electrocatalysts. This work highlights a promising and previously unexplored area of electrocatalyst research using polymer-catalyst composites containing complexes with oxophilic transition metal active sites for electrochemical nitrate remediation with nutrient recovery.

Technical–Economic Feasibility of a New Method of Adsorbent Materials and Advanced Oxidation Techniques to Remove Emerging Pollutants in Treated Wastewater

The focus on emerging contaminants (ECs) in wastewater has intensified due to the considerable risks they present to human health and wildlife. This paper presents the results of the technical–economic assessment of the Clean Up solution, carried out in the framework of the project entitled “Validation of Adsorbent Materials and Advanced Oxidation Techniques to Remove Emerging Pollutants in Treated Wastewater”. The viability of the Clean Up system is evaluated by being applied as an advanced treatment system for treated urban wastewater, that is, for the elimination of pathogens and emerging pollutants (EPs), while considering the established quality criteria by current regulations. In this sense, it is a technology that has been successfully validated at an experimental level, and that offers similar removal performance compared to that of the most efficient alternatives available on the market. The technical–economic assessment has been conducted through a systematic process. Initially, the estimation involved the calculation of treatment costs for the Clean Up system when applied at an industrial scale. Subsequently, the treatment costs were estimated for the most favorable technological alternative to the Clean Up system from a technical–economic standpoint, also applied at an industrial scale, within identical scenarios and conditions as those assumed for the Clean Up system. The final step involved a comprehensive comparison of treatment costs between both alternatives, implemented uniformly under analogous conditions and assumed similar performance across all cases.

Tunning MIL-101(Cr) MOF polymorphism towards efficient adsorption and localized Fenton-like degradation of para-nitroaniline by Fe incorporation

The employment of metal–organic frameworks (MOFs) in the context of eliminating organic contaminants from water has garnered significant interest in contemporary research. This study investigated the impact of varying quantities of iron on the MIL-101(Cr) adsorbent. For the first time, a polymorphic Cr/Fe-MOF was utilized for the adsorption and localized Fenton-like degradation of p-nitroaniline (PNA). Importantly, the Fe centers exhibited a ternary role of (i) transforming MIL-101 into MIL-53lt morphology, (ii) boosting PNA adsorption on the MIL(Cr) material, and (iii) enabling the Fenton-like decomposition of the adsorbed PNA in reduced solution volume. Cr:Fe(50:50) exhibited the highest adsorption capacity of 378.9 mg/g, notwithstanding its smaller surface area (SBET = 8.9 m2/g). Overall, adsorption kinetics and isotherms correlated better with pseudo-second-order and Langmuir models, respectively. The adsorption mechanism was attributed to breathing effect, H-bonding and π-π interaction. Besides, PNA degradation kinetics stood at 0.21 min−1, and the reactive oxygen species were identified as •OH, •O2– and 1O2. During continuous removal of PNA, the Cr:Fe(50:50) MOF immobilized onto cotton met the environmental discharge standard (1 mg/L) up to 52 bed volumes (initial P = 10.0 mg/L at 1 mL/min). This study not only presents a superior polymorphic MOF adsorbent but also promotes the fabrication of localized Fenton-like catalysts for the removal of organic contaminants in wastewater.

Pharmaceutical Contaminants in Wastewater and Receiving Water Bodies of South Africa: A Review of Sources, Pathways, Occurrence, Effects, and Geographical Distribution

The focus of this review article was to outline the sources, pathways, effects, occurrence, and spatial distribution of the most prescribed pharmaceuticals in wastewater and receiving waters of South Africa. Google Scholar, Web of Science, and Scopus were used to gather data from different regions. A zone-wise classification method was used to determine the spatial distribution and data deficiencies in different regions of South Africa. This review revealed that over 100 pharmaceutical compounds have been reported in South Africa’s various water sources and wastewater, with most studies and highest concentrations being documented in Gauteng and Kwa-Zulu Natal. The pharmaceutical concentration in water samples ranged from ng/L to µg/L. Aspirin, ketoprofen, diclofenac, ibuprofen, naproxen, erythromycin, tetracycline, sulfamethoxazole, acetaminophen, streptomycin, ciprofloxacin, ampicillin, carbamazepine, atenolol, pindolol, efavirenz, and zidovudine residues were among the frequently detected pharmaceutical residues in water bodies and wastewaters of South Africa. Based on the spatial distribution data, Gauteng has the highest number of pharmaceuticals (108) detected in waste and surface water, with the Northern Cape having no monitoring evidence. Therefore, to precisely ascertain the geographical distribution of pharmaceutical contaminants in South Africa, this review recommends that further research be carried out to track their occurrence in aquatic environments and WWTP, especially in isolated regions like Limpopo.

Electro-activation of peroxymonosulfate using a carbon fiber membrane anode for high-efficient degradation of antibiotic wastewater: The dominant role of singlet oxygen

A flow-through peroxymonosulfate (PMS) electro-activation system with a polyacrylonitrile-based carbon fiber (PCF) membrane anode (denoted as E-PCF-PMS system) was developed. The introduction of the PCF membrane anode enabled the flow-through electrocatalytical system to achieve a remarkable tetracycline (TC) removal of 96.0 ± 0.2 % within 15 min, with a degradation rate of 0.273 min−1. Scavenging investigations revealed that singlet oxygen (1O2) was the dominant reactive oxygen species for TC degradation in the E-PCF-PMS system, and this finding was confirmed by electron paramagnetic resonance tests. Potential degradation pathways of TC were identified according to the detected intermediates and calculations of density functional theory, and a decreasing trend in the toxicity of TC intermediates was discovered. Thanks to the 1O2-dominated pathway, the constructed E-PCF-PMS system could achieve efficient TC degradation under different concentrations of several common anions (Cl−, NO3−, HPO42−, and HCO3−) and humic acid (HA). General applicability and reusability tests demonstrated the excellent practicability of the proposed system. The PMS electro-activation system offers a potential technique for high-efficient degradation of contaminants in water and wastewater.

Progress in the Elimination of Organic Contaminants in Wastewater by Activation Persulfate over Iron-Based Metal-Organic Frameworks.

The release of organic contaminants has grown to be a major environmental concern and a threat to the ecology of water bodies. Persulfate-based Advanced Oxidation Technology (PAOT) is effective at eliminating hazardous pollutants and has an extensive spectrum of applications. Iron-based metal-organic frameworks (Fe-MOFs) and their derivatives have exhibited great advantages in activating persulfate for wastewater treatment. In this article, we provide a comprehensive review of recent research progress on the significant potential of Fe-MOFs for removing antibiotics, organic dyes, phenols, and other contaminants from aqueous environments. Firstly, multiple approaches for preparing Fe-MOFs, including the MIL and ZIF series were introduced. Subsequently, removal performance of pollutants such as antibiotics of sulfonamides and tetracyclines (TC), organic dyes of rhodamine B (RhB) and acid orange 7 (AO7), phenols of phenol and bisphenol A (BPA) by various Fe-MOFs was compared. Finally, different degradation mechanisms, encompassing free radical degradation pathways and non-free radical degradation pathways were elucidated. This review explores the synthesis methods of Fe-MOFs and their application in removing organic pollutants from water bodies, providing insights for further refining the preparation of Fe-MOFs.

Bio-carbon coil aerogels from tea waste: A sustainable solution for efficient oil-water separation

Discharging wastewater containing oils, fats, and organic solvents into water bodies poses a significant threat to the already limited freshwater resources. In recent years, three-dimensional (3D) porous adsorbent materials, such as aerogel materials, have gained attention for their high separation effectiveness in adsorption technology. However, the poor mechanical strength of existing aerogel materials limits their application in oil–water separation. To address this challenge, this study proposes to use carbon coils obtained from tea waste as a template for producing low-cost, ultra-light, elastic, and highly recyclable bio-carbon coil aerogels (BCCA). The BCCA, featuring high porosity and a hierarchical porous structure, demonstrated exceptional performance in oil–water separation applications. Specifically, it exhibited a high adsorption capacity for organic solutions (39 ∼ 117 g/g) and oils (32 ∼ 41 g/g), respectively, along with excellent selectivity, rapid adsorption time of approximately 30s, and good reuse capability, maintaining an adsorption efficiency of 85 %. These remarkable properties can be attributed to the exceptional hydrophobicity of the BCCA, with a contact angle of 134°, and the rapid capillary action facilitated by the helical network structure. The use of tea waste-derived carbon coils as a precursor for producing efficient and sustainable carbon coil aerogels presents a promising solution for environmental remediation, particularly in oil–water separation applications. This research addresses the issue of wastewater contamination and contributes to the utilization of tea waste, a readily available and abundant biomass resource, in the development of value-added materials for environmental sustainability.

Prediction of zinc extraction from aqueous solution using iron oxide nanoparticles embedded formulation for tuning emulsion liquid membrane stability

The contamination of industrial wastewater with heavy metals poses a threat to both aquatic and human life. In this study, emulsion liquid membrane (ELM) as a great potential process was applied to remove and recover zinc (Zn) from industrial wastewater. However, the instability of ELM continues to hinder their commercialization. Consequently, this research focuses on studying the stability of water-in-oil-in-water (W/O/W) emulsion in ELM with the aid of nanoparticles in the formulation. The emulsion stability measurement based on volume and pH were applied. Additionally, a digital microscope with a camera is utilized to assess emulsion stability in terms of globule size. ELM formulation with incorporation of iron (III) oxide (Fe2O3) nanoparticles, and blended surfactant (Span 80 and Tween 80) were employed. The research investigates the optimal process parameters for W/O/W emulsion stability. This includes varying parameters such as nanoparticle concentration (0–0.08 % w/v), treat ratio (1:3 – 1:7), agitation speed (200–600 rpm), and time (1 – 5 min). The W/O/W emulsion with the highest stability was achieved at Fe2O3 concentration of 0.04 % (w/v), a treat ratio of 1:3, agitation speed, and time of 300 rpm and 3 min, respectively. Under these stable conditions, Zn extraction was predicted by simulation using a mathematical boundary breakage model of the process. The effects of the treat ratio, concentrations of synergist carrier (D2EHPA and Cyanex 302), stripping agent (acidic thiourea), and external feed phase were examined. The result showed that almost 100 % of Zn was extracted within 3 min at a 1:3 treat ratio, 0.03 M synergist carrier, and 1.37 M acidic thiourea for 50 ppm Zn concentration in the feed phase. This research highlights the tremendous potential of nanoparticle presence in enhancing emulsion stability and improving Zn extraction.

The Potential Role of Chromophiles (Absorbtion) Fungi from Polluted Landfill by Tannery Effluent Challawa Industrial Estates Kano State of Nigeria

The release of unprecedented tannery effluents into the environment as industrial wastes is one of the major causes of environmental pollution. Tannery waste containing heavy metals are usually disposed in landfills and streams in Challawa industrial estate Kano. In the present study tannery effluent discharge soil (polluted landfill), undischarged soil (control) were collected from the surrounding areas of tannery industry. The soil and physicochemical properties were examined in-situ. A total of eleven fungi species were found in the soil. The most common fungal strains viz., Aspergillus niger, Aspergillus sp, Rhizopus nigricans and Penicillium sp were tested for tolerance against chromium sulphate. The degree of tolerance was measured by their mycelia growth length of each respective culture colony and it was compared with control containing no chromium sulphate. Among the isolated fungal strains of all locations, Aspergillus niger was the most tolerant against chromium sulphate. It exhibit strong radial mycelia growth length from 0-4.0% followed by Rhizopus nigricans and the least was obtain by Penicillium sp. Effect of pH and temperature on tolerance of fungal isolates at 1% chromium concentration using different substrates tested were so effective at pH 4-5 and 32oC respectively. These fungi have shown a high level of tolerance to chromium sulphate tested which makes them so attracted and potentially candidate for further investigations regarding their ability to remove metals from contaminated waste waters.

The Optimization of Hydrodynamic Cavitation as an Advanced Oxidation Option for the Removal of Persistent Contaminants in Wastewater

Wastewater is increasingly becoming the primary source of potable water in many cities, thanks to the development of recycling facilities. Persistent contaminants such as dyes and perfluorinated compounds from textile industries as well as other contaminants necessitate the design of removal technologies to treat wastewater to reduce these chemicals before discharge or being used as feed to a potable water plant. Several chemical treatment techniques have been reported but the most utilized advanced chemical treatments lead to high costs and further environmental concerns. This study investigated an alternative approach to wastewater treatment using a hydrodynamic cavitation pilot plant combined with a venturi as a way to remove recalcitrant compounds. The optimization of the removal process was explored by testing the effect of orifices with size 2, 3, 4, 5, or 6 mm on the decoloration of orange II dye. The impact of the catalyst: iron(II); oxidizing agent: hydrogen peroxide; and contact time was evaluated to find the ideal conditions under which the removal of perfluorooctanoic acid (PFOA) could be achieved. The decoloration of 20 ppm of orange II dye in simulated industrial textile wastewater was achieved at 90% efficiency when the pressure at the inlet was maintained at 300 kPa, the temperature at 34 °C, the pH at 2, and the orifice size at 2 mm of diameter. The kinetic study proved the decoloration reaction was pseudo first order and the rate of decolourisation of orange II was 0.23/min.Ten parts per million of PFOA could not be degraded by free radical attack using advanced oxidation processes when the inlet pressure was maintained at 300 kPa, the temperature at 34 °C, the pH of 2, and the orifice diameter of 2 mm. This resistance to removal is due to the structure of PFOA which is made up of a fluorine ion which stabilizes the compounds by inductive effects while dye is made up of nitrogen ion and is compatible with the above removal methods. The study demonstrated that the combination of venturi and orifice requires the throat size of the venturi to be similar or equal to that of the orifice for better efficiency.

Alkali induced changes in spatial distribution of functional groups in carboxymethylated cellulose

The aim of the work was to investigate treatment parameters that exert most influence on performance of cellulose fibers carboxymethylated from aqueous solutions. Viscose fibers were carboxymethylated in alkaline solutions of sodium monochloroacetate at two temperatures (30 °C, 50 °C) and with different levels of alkali (0.5 mol/L and 4 mol/L NaOH). The degree of carboxymethylation was assessed with both back titration and conductometric titration methods, and the performance of carboxymethylated fibers was assessed from their propensity for sorption of the cationic dye methylene blue, a putative wastewater contaminant. Higher degrees of carboxymethylation were generally observed for fibers carboxymethylated in 4 mol/L NaOH, but in dye sorption propensities, the fibers carboxymethylated in 0.5 mol/L NaOH performed better. A combination of observations from dye sorption, color measurement and conductometric titration suggested that dye permeation was greater through fibers carboxymethylated in 0.5 mol/L NaOH as compared to 4 mol/L NaOH. As permeability differences were evinced in cases also where the degrees of carboxymethylation were very similar, it appears that the reaction conditions (i.e., alkali content during carboxymethylation), in addition to degree of carboxymethylation, affected fiber performance. The effect of alkali may stem from their influence on the topographical distribution of the substituted carboxymethyl functional groups.

Metal-Organic Frameworks Based Sensor Platforms for Rapid Detection of Contaminants in Wastewater.

Metal-organic frameworks (MOFs) are a type of multifunctional material with organic-inorganic doped metal complexes that have a lot of unsaturated metal sites and a consistent network structure. MOFs work has great performance for enhancing the mass transfer, signal, and sensitivity as well as analyte enrichment. This study highlights the recent advancements of MOFs-based sensors for pollutant detection in a water environment and summarizes the effect of various synthetic materials on the performance of MOFs-based sensors. The related challenges and optimization techniques have been discussed. Then the research results of various MOFs sensors in the detection of wastewater pollutants are analyzed. Finally, the challenges facing MOFs-based water sensor development and the outlook for future research are discussed.