Triple-layer membranes were prepared using a combination of poly(piperazine-amide), poly(vinyl alcohol), and polysulfone membranes. The poly(piperazine-amide) and poly(vinyl alcohol) layers are coated alternately and vice-versa on polysulfone membranes. The effects of changing the sequence of the PVA-MA layer in the three-layer system of poly(piperazine-amide) composite membranes on physical parameters (viz. surface roughness, water contact angle, and zeta potential) of the skin layer were studied. The separation performances of triple-layer membranes were evaluated through pure water flux and defluoridation. Scanning electron microscopy (SEM), and atomic force microscopy (AFM) measurements were utilized for visual characterization of modified membranes. The defluoridation performances of Memb-I, (R% 91, PVA-MA serves as the inter-layer) were always better compared to Memb-II R% 77.4, in which PVA-MA served as the surface layer. The defluoridation performances of membranes of both types decreased as the total dissolved solutes (TDS) increased of water matrices (water matrix-I > water matrix-II > water matrix- III). The time-dependence defluoridation performance suggested that there was little deterioration in separation and more downtrend followed as the TDS of water matrices increased.

Metalloid arsenic in its inorganic form features the most toxicity in its mobile form, water. Arsenic in water is a concern and a threat to humanity. The water containing arsenic is aptly termed as ‘devil’s water’. Significant developments have occurred in the past few decades regarding water purification. Researchers have developed various materials to remove arsenic from water. Remediation of arsenic through different technologies (viz. adsorption, precipitation and membrane) has been met. The materials used in these technologies for conducting remediation tasks are identified. The present study covers from activated carbon to polymeric membranes. Hybrid technologies are relevant in this direction. A few field deployments are also covered.

Water pollution due to fluoride (F−) is a significant threat worldwide. Fluoride contamination affects many life forms (both plants and humans) when they enter the food chain. Poly(piperazine-amide) membranes have a promising role in nanofiltration activities. However, piperazine, as a cyclic secondary aliphatic amine, reacts with 1,3,5-trimesoyl chloride (TMC) in the interfacial polymerization. The physical characterization of the membranes was performed through different analytical tools like Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), and contact angle analyzer. The selectivity in separating bivalent and monovalent salts is well observed in this composite membrane. The composite membranes show their potentiality in defluoridation. The rejection profile is 84

Globally, nutrient pollution is a serious and challenging concern. Wastewater treatment plants (WWTPs) are designed to prevent the discharge of contaminants resulting from anthropogenic sources to the receiving water bodies. In this study, seasonal nutrient pollution load, and biological nutrient removal efficiency of an anoxic aerobic unit based WWTP were investigated. Seasonal assessment revealed that the average total nitrogen removal efficiency and total phosphorus removal efficiency of the WWTP do not meet the discharge standard of 10 mg/L and 1 mg/L, respectively. Furthermore, the WWTP does not utilize the energy contained in the wastewater. In this regard, dual chamber MFC (D-MFC) has emerged as a promising solution that can not only treat wastewater but can also convert chemical energy present in the wastewater into electrical energy. However, higher N O (3) (57 +/- 4 mg/L) and P-P O-4(3-) (6 +/- 0.52 mg/L) concentration in cathodic effluent is a major drawback in D-MFC. Therefore, to solve this issue, D-MFC was transformed into a microbial nutrient recovery cell (MNRC) which demonstrated a final N H-4(+) -N and P-P O-4(3-) concentration of nearly 1 mg/L with N H-4(+) -N and P-P O-4(3-) recovery up to 74 % and 69 %, respectively in the recovery chamber. Besides, MNRC attained a maximum power density of 307 mW/m(3) and a current density of 1614 mA/m(3), thus indicating MNRC is an eco-friendly, energy-neutral, and promising technology for electricity generation and recovering nutrients.

Excessive nitrate (NO3--N) release contributes to eutrophication, prompting the exploration of integrating heterotrophic denitrification with electricity generation in microbial fuel cells (MFCs) for wastewater treatment and bioelectricity production. The C/N ratio in MFC drives the proliferation of denitrifying and electrochemically active bacterial population which in turn influences the denitrification and electricity generation potential. Lack of consensus among researchers on this ratio motivated this study to examine the impact of varying C/N ratios (10, 8, 6, 4) on MFC performance, revealing that NO3--N addition enhances power density up to a C/N ratio of 6. Power overshoot occurs at low C/N ratios due to competition between denitrifying and electroactive bacteria, while maintaining a C/N ratio of 8 and increasing NO3--N concentration up to 600 mg/L sustains stable performance. Additionally, optimal NO3--N and COD removal rates are achieved at a C/N ratio of 8. Overall, this study investigates the effect of electron utilization bifurcation due to a shift in metabolism from anode respiration to denitrification on bioanode performance at different C/N ratio. Furthermore, the study proposes and validates optimum C/N ratio to enhance MFC performance for treatment of NO3--N enriched wastewater to preserve the aquatic ecosystem.

Nutrient-rich waste streams from domestic and industrial sources and the increasing application of synthetic fertilizers have resulted in a huge-scale influx of reactive nitrogen and phosphorus in the environment. The higher concentrations of these pollutants induce eutrophication and foster degradation of aquatic biodiversity. Besides, phosphorus being non-renewable resource is under the risk of rapid depletion. Hence, recovery and reuse of the phosphorus and nitrogen are necessary. Over the years, nutrient recovery, low-carbon energy, and sustainable bioremediation of wastewater have received significant interest. The conventional wastewater treatment technologies have higher energy demand and nutrient removal entails a major cost in the treatment process. For these issues, bio-electrochemical system (BES) has been considered as sustainable and environment friendly wastewater treatment technologies that utilize the energy contained in the wastewater so as to recovery nutrients and purify wastewater. Therefore, this article comprehensively focuses and critically analyzes the potential sources of nutrients, working mechanism of BES, and different nutrient recovery strategies to unlock the upscaling opportunities. Also, economic analysis was done to understand the technical feasibility and potential market value of recovered nutrients. Hence, this review article will be useful in establishing waste management policies and framework along with development of advanced configurations with major emphasis on nutrient recovery rather than removal from the waste stream.

While many composite membranes have been explored using phase inversion and coatings, few are there apart from the polyamide. In this present study, asymmetric polysulfone (PS) membranes were prepared by a wet phase inversion process and crosslinking mechanistic pathways to provide facile formation of coating materials suitable for filtration. Poly(vinyl alcohol) (PVA)-coated on polysulfone membranes were crosslinked using Butene dioic acid(cis/trans) (viz. maleic(MA) and fumaric(FA)acid). The membrane properties (viz. hydrophilicity, roughness, zeta potential) differed due to conformational differences between the two crosslinkers. PS-PVA(MA) membranes showed better salt separation abilities compared to PS-PVA(FA) membranes. The selective bivalent (SO42-) salt separation abilities were observed compared to monovalent (Cl-) ones. PS-PVA(FA) membranes showed a better separation ratio(2.77) of bivalent and monovalent ions (RSO42-/ RCl-) compared to PS-PVA(MA) membranes(2.7) for water matrix-1(TDS 5.4). The defluoridation capabilities were also experimented. PS-PVA(MA) membranes showed a 3% better rejection ability compared to PS-PVA(FA) membranes. PS- PVA(MA) membranes developed a low bacterial settlement tendency compared to PS- PVA(FA) membranes.

Poly(vinyl alcohol) (PVA)-coated membranes on polysulfone (Ps) (Memb-Pv) were cross-linked using the dibasic maleic acid. The tailoring of membrane properties (viz. hydrophilicity, permeability) develops through the ester linkage due to cross-linking of PVA and maleic acid (MA). Series of Ps asymmetric membranes were prepared using the successive stages of phase inversion of Ps materials. The recyclability approaches of polysulfone (Ps) pertained. The characteristics and transport properties of all the membranes are evaluated. FTIR-ATR, scanning electron (SEM), and atomic force microscopy (AFM) are used for the structural characterization of the membranes. The salient features of Memb-Pv composite membranes support promising results in desalination. The work aimed to highlight the trade-off between the flux and selectivity of composite membranes’ salts (bi-/monovalent) through the recycled Ps matrix. The number of recycling stages influences the salt separation performance. The sulfate rejection differs from Memb-IPv (93.26

In the present scenario discharge of heavy-metal ions into water bodies is a global threat that is causing serious health hazards even in low concentrations. Thus, in order to remediate the heavy-metal [Hg(II) and Pb(II)] toxicity, an organic-inorganic hybrid functional porous metallo-polymeric network i. e, poly(Zirconyl methacrylate-co-1-vinyl imidazole) (pZrVIm) was fabricated via one-pot facile synthesis approach. The pZrVIm architecture has shown high removal efficiency for Hg(II) and Pb(II) aqueous medium even in extremely low quantities. Advanced instrumental techniques were used to characterize the structural and morphological characteristics of pZrVIm. Different experimental variables i.e., reaction time, pH, initial feed concentration, co-ion effects etc. were explored to examine adsorption behaviour. The maximum adsorption capacities (qmax) of pZrVIm5 were calculated as 168.06 and 162.34 mg g-1 for Hg(II) and Pb(II) respectively by the Langmuir isotherm model. Data from isotherms showed that monolayer adsorption on a homogeneous surface is the rate-limiting stage and followed pseudo-second-order kinetic process. The Artificial Neural Network (ANN) modelling was used to validate kinetics and isotherm data which revealed high accuracy of the model with correlation coefficient values (R = 0.99). Various types of isotherm models such as Langmuir, Freundlich, Dubinin-Radushkevich, Temkin, Redlich-Peterson, Toth and Koble-Corigen have been studied to determine the adsorption phenomena. The pore diffusion model revealed breakthrough time of 91 h and 84 h, Hg(II) and Pb(II) with the feed concentration of 15 mg L-1 respectively. The study revealed that pZrVIm5 has great potential for heavy metal ions remediation for water treatment.

There are unequivocal shreds of evidence that polymers touched every sphere of life.They are very versatile and used in many applications depending on the specific intrinsic properties of the materials.Over the last few decades, there has been growing evidence that applying polymer materials in water-purifying has been adopted worldwide.Water fluorine toxicity is challenging us to develop water-purifying polymeric materials.We are presenting the polymeric adsorbent and membrane materials advancement in terms of defluoridation of water.

ABSTRACT The development of thin-film polyamide composite membranes is a revolutionary aspect of the history of membrane science. ‘Wet phase inversion’ and ‘interfacial polymerization’ are two important steps in preparing thin-film polyamide composite (TFC) membranes. Poly (piperazinamide) TFC membranes make a strong pitch for greater regulation of selective passage of mono- and bi-valent salts. The result is a resounding success for the salt separation. In this work, an attempt has been made to study the consequence of salt in gelation bath and interfacial polymerization regarding the behavior of TFC membranes to separate salts from water. The water flux through the polysulfone (Ps) membrane decreases (776.15 LMH to 179.56 LMH) with TDS (salt up to 20000 mg/L. The increase in salt concentration in the aqueous phase (5 to 500 mg/L) of the interfacial reaction influences the salt separation abilities of the TFC membranes. It increases salt separation (Na2SO4 8–9% NaCl 4–6%) by adding 500 mg/L NaCl in piperazine-aqueous solution in different base membranes (Ps-I to Ps-VII). The defluoridation performances of the membranes in accordance with the similar trend as SO4 =. The separation follows the sequence: SO4 = > F− > Cl−. The rejection difference (between Pip-IC and Pip-VIIC) is highest as TDS increases, i.e., TDS: 500 mg/L. The flux reduction is similar (i.e., 30%) as in the case of SO4 = and Cl−.

Poly(vinyl alcohol) (PVA)-coated membranes on polysulfone (PS) were cross-linked using maleic acid. The membrane properties (viz. hydrophilicity) were tailored for the ester linkage due to PVA and maleic acid cross-linking. The separation of tea polyphenol by PS-PVA composite membrane was investigated in this study. Cross-linked PVA coated on two different molecular weight cut-off (MWCO) PS membrane systems was prepared for this purpose. The permeation flux and separation for tea polyphenol are the criteria for evaluation. The separation of tea-polyphenol follows the trend PS-PVA-IV > PS-PVA-III > PS-PVA-II > PS-PVA-I. Higher dilution deteriorated the tea-polyphenol separation performance of the membranes. The membranes showed their best performance at pH 6.5. The time dependence separation performance study revealed the order PS-PVA-IV > PS-PVA-III > PS-PVA-II > PS-PVA-I membranes.

Water is termed a 'prime natural resource' and 'basic human need'. It is worthwhile to ensure access to a good quality of life or enhance life expectancy. Water is considered the ingredient essential to human advancement. The biggest challenge encountered in dealing with water contaminants around the magnitude of the health hazard. Fluoride is a common ion that creates health problems for humans depending on their ingested qualities. The fluoride contamination in water, excess fluoride-related diseases, and the features of different defluoridation techniques are covered. The membrane is the key to tackling water contamination and the world's challenges today. In membrane separation, various influencing factors (viz. nature of membranes, the effect of ions, pH, feed concentration, applied pressure) are reviewed. The hybrid processes related to the membranes and membrane-linked other approaches are also emphasized. The strategic approaches to tackling the rejected water are also narrated.

Membrane research is the foundation of modern advancements in techniques in water purification. They are versatile and can be used in various applications depending on the membrane's specific intrinsic properties. This particular study focused our attention on poly (piperazine-amide) membranes because of their feature in the selectivity separation of bivalent and monovalent anion-based salts. Membrane development is a dynamic process that moves forward slowly, and recommendations are made based on the best science available. The addition of chemicals during the base membrane formation and interfacial polymerization during poly (piperazine-amide) formation improves the membranes' properties. We have categorized the trend of adding different chemicals (viz., organics, inorganics, polymers) and features to enhance properties.

From ever-evolving techniques for desalination to wastewater treatment, membranes have been established themselves as front runners. Recent advances in the development of thin-film composite (TFC), membranes have enabled efficient contaminant separation in terms of ions as well as organics to improvise water treatment. In this study, poly(piperazine-amide) based three-layer membrane was developed through interfacial polymerization of piperazine (aq.) and 1,3,5-trimesoyl chloride (hexane) on a base polysulfone layer supported on non-woven polyester fabric. Membrane efficiency, in terms of permeate flux and salt rejection, was evaluated experimentally by separating NaCl/Na2SO4 from solutions having different salt concentrations (500-20,000 mg/L). The experimental results have been further modeled and simulated using artificial neural network (ANN) trained using efficient algorithms: Levenberg-Marquardt backpropagation (LM-BP), scaled conjugate gradient backpropagation (SCG-BP), and particle swarm optimization (PSO). Modeling performance has been compared using regression coefficient and mean square error. Optimal search of acceleration factors (c1 = 1.75/1.5, c2 = 1.75/2.5), weight of inertia (ω = 0.4), swarm size (10), and nodes (10) exhibited superior performance for PSO-ANN model than LM-BP-ANN and SCG-BP-ANN models to enable efficient modeling of output–input correlations. This combined experimental and computational study paves the way for study and development of next-generation TFC membrane materials for desalination and inherent process optimization.

Chitosan is in prominence as membrane materials. The present study based on chitosan–tannic acid crosslinked moiety on polyacrylonitrile support membranes. FTIR-ATR, zeta potential, XRD, SEM, AFM, TGA, DSC and contact angle are used to understand the characters of the membranes. The separation performances of salts (NaCl, Na2SO4) proved that membranes are associated with charged nanofiltration separation behaviour. Memb-III has reached a maximum difference in salt separation performance (Na2SO4 90.88% and NaCl 35.76%) at ~ 134.4 Lm−2 h−1 compared to Memb-I and II. The membrane performances are marked with organic molecule markers (e.g. glucose and sucrose). The separation of molecular markers shows its direct relationship with its molecular size. The pH-dependent studies show that separation of riboflavin increases at pH 9 compared to separation at pH 7, whereas the reverse happens for flux. Memb-III shows a maximum 84.1% riboflavin separation having flux 55.82 Lm−2 h−1 at pH 9. The study with bacteria (viz. E. coli, Bacillus subtilis) also proves that the surface is antibacterial.

The preparative membrane process is a dynamic one and intertwined with the separation arena. As for the progression of technology in membranes, our direction is to prepare polypyrrole interlayer-based thin-film composite (TFC) membrane. Polypyrrole shows its attachment ability with polysulfone membranes. The coverings of pores with the polypyrrole entity result in better flux in terms of TFC membranes compared to TFC membranes on polysulfone (Memb-I). The membranes are characterized by FTIR-ATR, contact angle, zeta potential, SEM, AFM. Polypyrrole interlayer-based membrane (Memb-II) show better flux though it sacrifices salt separation ability compared to Memb-I. Memb-II shows a better separation of pesticides (diuron and isoproturon) compared to Memb-I. Memb-II provides isoproturon's separation ability (89.52% rejection, 54.9 LMH), whereas, for diuron, it is 78.82%, 53.46 LMH. The antimicrobial property is seen for interlayer polypyrrole-based TFC membranes.

The reusability provisions for finding out the feasibility of a polysulfone (PS) membrane structure are considering the type of stimulating system. On the successive non-solvent phase inversion of PS, the Newtonian flow of PS solutions at different stages is well observed from the rheological study. The viscosities of PS solutions decrease with stages. The membranes (Memb.-I-Ps to Memb.-VIII-Ps) are prepared from PS, recycled from successive phase inversion stages. It develops better porosities and higher Molecular weight Cut-off (MWCO) (PEO 200,400KDa)). Poly(piperazine-amide) coating on different recycled stages of PS membranes (Memb.-I-Pip to Memb.-VIII-Pip) shows an MWCO (PEG 400 Da, 1000 Da) property. The wettability property, zeta potential, morphological features of the membranes vary with the number of recycled stages. The salt rejection profiles (NaCl and Na2SO4) increase with the successive stages of recycled PS, and the selectivity (Na2SO4/NaCl) decreases a little. The Marangoni effect can explain the rise in salt separation with the subsequent recycled stages. The study extends to the defluoridation of water and quite promising. The similar to 15% increase in separation for 10 mg/L fluoride from Memb.-I-Pip to Memb.-VIII-Pip. The maximum separation of fluoride is 84.9% for Memb.VIII-Pip. The decrease in separation results when the fluoride concentration increases from 10 to 100 mg/L.