Polythyleneimine-modified original positive charged nanofiltration membrane: Removal of heavy metal ions and dyes

Exploring biosynthesis strategies to boost the yield of exopolysaccharide-protein blend from Bacillus arachidis SY8(T), an isolated native strain, as a potent adsorbent for heavy metals removal

This investigation centers on the synthesis of a polysaccharide-protein blend produced by an isolated native strain (99.12 % phylogenetic affinity with Bacillus arachidis SY8(T)). The primary objective was to investigate the production of extracellular polymeric substances (EPS) under diverse stress conditions, encompassing exposure to heavy metal ions, salt, and toxic agents. Additionally, the impact of environmental parameters, namely pH, inoculation percentage, and time, on the production was investigated. Subsequently, the study examined the biosorption potential of the EPS produced for Pb(II), Cu(II), and Mn(II). The EPS obtained was thoroughly characterized via various tests. Rheological evaluations of an EPS solution (2 wt%) confirmed its pseudo-plastic and non-Newtonian fluid properties, while TGA analysis demonstrated its thermal stability up to 600 °C. Additional analyses, including GPC, FTIR, and H-NMR, provide further insights into the produced EPS. The best conditions for EPS production are determined: 5 % NaCl salt, serving as an effective stress inducer, and 37 °C, pH 6, with a 5 % inoculation, over 96 h. EPS demonstrates remarkable removal efficiencies of 99.9, 99.4 and 78.9 % for Pb(II), Cu(II), and Mn(II), respectively. These findings highlight the potential of EPS as an effective agent for removing heavy metal ions.

Microbial strategies for copper pollution remediation: Mechanistic insights and recent advances

Environmental contamination is aninsistent concern affecting human health and the ecosystem. Wastewater, containing heavy metals from industrial activities, significantly contributes to escalating water pollution. These metals can bioaccumulate in food chains, posing health risks even at low concentrations. Copper (Cu), an essential micronutrient, becomes toxic at high levels. Activities like mining and fungicide use have led to Copper contamination in soil, water, and sediment beyond safe levels. Copper widely used in industries, demands restraint of heavy metal ion release into wastewater for ecosystem ultrafiltration, membrane filtration, nanofiltration, and reverse osmosis, combat heavy metal pollution, with emphasis on copper.Physical and chemical approaches are efficient, large-scale feasibility may have drawbackssuch as they are costly, result in the production of sludge. In contrast, bioremediation, microbial intervention offers eco-friendly solutions for copper-contaminated soil. Bacteria and fungi facilitate these bioremediation avenues as cost-effective alternatives. This review article emphasizes on physical, chemical, and biological methods for removal of copper from the wastewater as well asdetailing microorganism's mechanisms to mobilize or immobilize copper in wastewater and soil.

Eco-friendly polycaprolactone-bound diatomite filter for the removal of metal ions and micro/nanoplastics from water

Over the last few decades, pollution levels in aquatic environments due to heavy metal ions and micro/nanoplastics have increased owing to industrial development, causing adverse effects on microorganisms. Adsorbent-based filtration is a well-developed technique for removing contaminants from aquatic environments. However, this technique should be improved from the perspectives of eco-friendliness and cost-effectiveness, as commercial adsorbents require energy-intensive synthesis and post-processing with chelating agents. In this study, an eco-friendly filtration system was developed. This system employs biodegradable, natural materials, such as diatomite to remove metal ions and micro/nanoplastics and polycaprolactone (PCL) to make the free-form shapes. The filter removes metal ions via adsorption and micro/nanoplastics via physical size filtration and adsorption. This PCL-bound diatomite filter was fabricated from a mixture of acetone, PCL, and diatomite, varying its size, thickness, shape, and stacking number for a particular objective and usage. The adsorption capacity, kinetics, and permeation flux of the membrane were measured, and the stacking number of the membranes were optimized to maximize the removal efficiency of the target contaminants. This filter is completely biodegradable, as indicated by the degradation of the PCL binder within 60 days in water, without any treatment. The degradable, eco-friendly PCL-bound diatomite filter is a low-cost and sustainable component that can be utilized in various applications, especially potable drinking water production from river in developing country and filtering the micro/nanoplastics from the commercially bottled drinking water in daily life.

Effects of ZIF-L Morphology on PI@PDA@PEI/ZIF-L Composite Membrane's Adsorption and Separation Properties for Heavy Metal Ions

Composite polymolecular separation membranes were prepared by combining multi-branched ZIF-L with high-porosity electrospinning nanofibers PI. Meanwhile, PDA and PEI were introduced into the membrane in order to improve its adhesion. The new membrane is called the "PI@PDA@PEI/ZIF-L-4" composite membrane. Compared with the PI@PDA@PEI/ZIF-8 composite membrane, the new membrane's filtration rates for heavy metal ions such as Cd2+, Cr3+, and Pb2+ were increased by 7.0%, 6.6%, and 9.3%, respectively. Furthermore, the new membrane has a permeability of up to 1140.0 L·m-2·h-1·bar-1, and displayed a very stable performance after four repeated uses. The separation mechanism of the PI@PDA@PEI/ZIF-L composite membrane was analyzed further in order to provide a basis to support the production of separation membranes with a high barrier rate and high flux.

Combining phthalimide innate of a positive-charge nanofiltration membrane for high selectivity and rejection for bivalent cations

A positively charged nanofiltration (NF) membrane is known to have exceptional separation performance for bivalent cations in aqueous solutions. In this study, a new NF activity layer was created using interfacial polymerization (IP) on a polysulfone (PSF) ultrafiltration substrate membrane. The aqueous phase combines the two monomers of polyethyleneimine (PEI) and phthalimide, while successfully producing a highly efficient and accurate NF membrane. The conditions of the NF membrane were studied and further optimized. The aqueous phase crosslinking process enhances the polymer interaction, resulting in an excellent pure water flux of 7.09 L·m^-2·h^-1·bar^-1 under a pressure of 0.4 MPa. Additionally, the NF membrane shows excellent selectivity toward inorganic salts, with a rejection order of MgCl₂ > CaCl₂ > MgSO₄ > Na₂SO₄ > NaCl. Under optimal conditions, the membrane was able to reject up to 94.33% of 1,000 mg/L of MgCl₂ solution at an ambient temperature. Further to assess the antifouling properties of the membrane with bovine serum albumin (BSA), the flux recovery ratio (FRR) was calculated to be 81.64% after 6 h of filtration. This paper presents an efficient and straightforward approach to customize a positively charged NF membrane. We achieve this by introducing phthalimide, which enhances the membrane's stability and rejection performance.

Removal of Copper Ions from Wastewater: A Review

Copper pollution of the world's water resources is becoming increasingly serious and poses a serious threat to human health and aquatic ecosystems. With reported copper concentrations in wastewater ranging from approximately 2.5 mg/L to 10,000 mg/L, a summary of remediation techniques for different contamination scenarios is essential. Therefore, it is important to develop low-cost, feasible, and sustainable wastewater removal technologies. Various methods for the removal of heavy metals from wastewater have been extensively studied in recent years. This paper reviews the current methods used to treat Cu(II)-containing wastewater and evaluates these technologies and their health effects. These technologies include membrane separation, ion exchange, chemical precipitation, electrochemistry, adsorption, and biotechnology. Thus, in this paper, we review the efforts and technological advances made so far in the pursuit of more efficient removal and recovery of Cu(II) from industrial wastewater and compare the advantages and disadvantages of each technology in terms of research prospects, technical bottlenecks, and application scenarios. Meanwhile, this study points out that achieving low health risk effluent through technology coupling is the focus of future research.

Highly Selective Methodology for Entrapment and Subsequent Removal of Cobalt (II) Ions under Optimized Conditions by Micellar-Enhanced Ultrafiltration

Micellar-enhanced ultrafiltration (MEUF), being a separation technique, was used to remove cobalt metal ion (Co²⁺) from their aqueous solutions in an application to reduce the toxicity level from industrial effluents using a micellar solution of anionic and cationic surfactants. The metal ions were first adsorbed by using anionic surfactants, i.e., sodium dodecyl sulfate (SDS) and sodium oleate (SO). The calculations for partition (K_x) and binding constants (K_b) and their respective free energy of partition and binding (ΔG_p and ΔG_b kJmol^-1) helped significantly to find out the extent of binding or interaction of Co²⁺ with the surfactant and ΔG_p and ΔG_b were found to be -29.50 and -19.38 kJmol^-1 for SDS and -23.95 and -12.67 kJmol^-1 in the case of SO. MEUF work was also performed to find out the optimal conditions to remove metal pollutants from the aqueous system. For the said purpose, various factors and concentrations effect were studied, such as the concentration of the surfactant, concentration of the electrolyte (NaCl), transmembrane pressure, RPM, and pH. The efficiency of this process was checked by calculating various parameters, such as rejection percentage (R%) and permeate flux (J). A maximum rejection of 99.95% with SDS and 99.99% with SO was attained.

Polymer Membranes as Innovative Means of Quality Restoring for Wastewater Bearing Heavy Metals

The problem that has aroused the interest of this review refers to the harmful effect of heavy metals on water sources due to industrial development. In this respect, the review is aimed at achieving a literature survey on the outstanding results and advancements in membranes and membrane technologies for the advanced treatment of heavy metal-loaded wastewaters. Particular attention is given to synthetic polymer membranes, for which the proper choice of precursor material can provide cost benefits while ensuring good decontamination activity. Furthermore, it was also found that better removal efficiencies of heavy metals are achieved by combining the membrane properties with the adsorption properties of inorganic powders. The membrane processes of interest from the perspective of industrial applications are also discussed. A noteworthy conclusion is the fact that the main differences between membranes, which refer mainly to the definition and density of the pore structure, are the prime factors that affect the separation process of heavy metals. Literature studies reveal that applying UF/MF approaches prior to RO leads to a better purification performance.

Ultrasonically synthesized MOFs for modification of polymeric membranes: A critical review

Metal-organic framework (MOF) membranes hold the promise for energy-efficient separation processes. These nanocrystalline compounds can effectively separate materials with different sizes and shapes at a molecular level. Furthermore, MOFs are excellent candidates for improving membrane permeability and/or selectivity due to their unique properties, such as high specific area and special wettability. Generally, MOFs can be used as fillers in mixed matrix membranes (MMMs) or incorporated onto the membrane surface to modify the top layer. Characteristics of the MOFs, and correspondingly, the properties of the MOF-based membranes, are majorly affected by their production technique. This critical review discusses the sonication technique for MOF production and the opportunities and challenges of using MOF for making membranes. Effective parameters on the characteristics of the synthesized MOFs, such as sonication time and power, were discussed in detail. Although the ultrasonically synthesized MOFs have shown great potential in the fabrication/modification of membranes for gas and liquid separation/purification, so far, no comprehensive and critical review has been published to clarify such accomplishments and technological gaps for the future research direction. This paper aims to review the most recent research conducted on ultrasonically synthesized MOF for the modification of polymeric membranes. Recommendations are provided with the intent of identifying the potential future works to explore the influential sonication parameters.

Recent trends and challenges with the synthesis of membranes: Industrial opportunities towards environmental remediation

The industrial and agricultural revolution has posed a serious and potential threat to environment. The industrial and agricultural pollutants are directly released into the environment. This issue has clinched the scientists to work on different materials in order to decontaminate the environment. Among all other techniques, the membrane filtration technology has fascinated researchers to overcome the pollution by its promising features. This review elaborated various membrane synthesis approaches along with their mechanism of filtration, their applications towards environmental remediation such as removal of heavy metals, degradation of dyes, pharma waste, organic pollutants, as well as gas sensing applications. The membrane synthesis using different sort of materials in which inorganic, carbon materials, polymers and metal organic framework (MOFs) are highlighted. These materials have been involved in synthesis of membrane to make it more cost effective and productive to remove such hazardous materials from wastewater. Based on the reported literature, it has been found that inorganic and polymer membranes are facing issues of brittleness and swelling prior to the industrial scale applications related to the high temperature and pressure which needs to be addressed to enhance the permeation performance.

Removal of hazardous ions from aqueous solutions: Current methods, with a focus on green ion flotation

Hazardous ions, like those of heavy metals, cause significant health and environmental problems when they are discharged into water resources naturally or through various industrial processes. Removing these ions from water is of significant importance in the provision of high-quality water for drinking and agricultural usage. This work discusses current techniques that are frequently used for the removal of heavy-metal ions from aqueous solutions by absorption, particularly the use of biodegradable surfactants in ion flotation. Certain new surfactants promise high efficiency in their use in the ion-flotation process and in their application in industrial-water treatment to remove heavy metals. As an example, this work demonstrates the high efficiency of surfactants based on an amino-acid (L-cysteine) in removing a range of heavy-metal ions in a simple, single-stage ion-flotation process. High foaming ability, the ability to operate in various temperatures and pHs, decomposing into natural products and high binding affinity for heavy-metal ions make the cysteine-based surfactants a highly suitable compound to replace current commercial surfactants in ion- and froth-flotation processes. Removal of particular ions can also be achieved in ion flotation; a suitable choice of parameters, such as pH and surfactant concentration, favours the surfactant binding to those ions. Further intensive work is required to develop an optimal process to recover valuable elements from waste solutions.

Synthesis of highly porous three-dimensional PVA/GO/ZIF-67 cryogel for the simultaneous treatment of waters contaminated with cadmium (II) and lead (II) heavy metal ions

In this research, PVA/GO/ZIF-67 cryogel as a highly porous three-dimensional polymeric adsorbent was synthesized by freeze-drying method and applied for the simultaneous removal of Cd2+ and Pb2+ ions from contaminated...

Synchronous degradation of phenol and aniline by Rhodococcus sp.strain PB-1entrapped in sodium alginate-bamboo charcoal-chitosan beads

The biodegradation of benzene series compounds is a difficult problem in environment pollution control, which is attributed to the deficiency of high efficiency bacteria and suitable embedding materials. In this study, the immobilized cells Rhodococcussp. strain PB-1 was used to synchronously biodegrade phenol and aniline by entrapped in sodium alginate (SA)-bamboo charcoal (BC)-chitosan acetate (CA) beads. The free cells of the strain PB-1 could completely degrade 1500 mg/L phenol or 800 mg/L aniline within 48 h, while the degradation rate of 2000 mg/L phenol and 1500 mg/L aniline was 35.76% and 68.06% at 72 h, respectively. The ortho-cleavage pathway was used to degrade phenol and aniline by strain PB-1. However, after entrapped with SA-BC-CA beads,the removal rate of 2000 mg/L phenol was 100% at 108 h, 1500 mg/L aniline was 100% at 62 h and 2000-3000 mg/L total toxic compounds was over 95% at 120 h. These beads could be used four times and were more effective than SA or SA-BC beads. The SA-BC-CA beads could remarkably improve the stability and degradation efficiency of strain PB-1, and thus provide a potential application in the removal of phenol and aniline in wastewater.

Investigation of operation parameters on the removal efficiency of methyl orange pollutant by cellulose/zinc oxide hybrid aerogel

In this study, Cellulose/Zinc Oxide-x (CA/ZnO-x) hybrid aerogel with various concentrations of Zn²⁺ ion is synthesized through the hydrothermal method and used for organic pollutant removal. The CA/ZnO-x hybrid aerogel was characterized by XRD, UV-Visible, DRS, FTIR, FESEM, EDS, BET, LC-MS-MS analyses. In the present study, CA/ZnO-x hybrid aerogel as photocatalyst was used to investigate the influence of the photocatalytic degradation of methyl orange (MO) from an aqueous solution under UV irradiation. The morphology of CA/ZnO-x hybrid aerogels exhibited that the ZnO rice grain-like shape were successfully synthesized on the cellulose aerogel matrix. Also, the influence of various factors such as photocatalyst dosage, pH, initial concentration of MO, and irradiation intensity was investigated on the photocatalytic degradation rate of MO. The results revealed that the highest degradation efficiency and mineralization rate of MO were about 99.02% and 51.68%, respectively, after 90 min under UV irradiation using CA/ZnO-0.4 photocatalyst when pH = 3, C₀ = 10 ppm, photocatalyst dose = 9 g L^-1 under the 300 W UV light irradiation. Furthermore, the synthesized photocatalyst exhibited a considerable firmness and easily separated from an aqueous solution for reuse.

Polypropylene Glycol Modified Chitosan Composite as a Novel Adsorbent to Remove Cu(II) From Wastewater

Pollution by heavy metals has become a problem that needs to be solved urgently. Therefore, the development of new efficient adsorbents to treat this pollution is of great importance. Due to their excellent adsorption properties and good biodegradability, natural polymeric materials are potential problem solvers. This study reports on the production and application of polypropylene glycol modified chitosan composites (PMC). The PMC composite material has many functional groups (–OH and –NH2). Its maximum adsorption capacity for Cu(II) is 661.8 mg g–1. The corresponding adsorption studies, including the effects of pH, contact time and amount of adsorbent, showed that the PMC composite has potential application value.

A Review on Promising Membrane Technology Approaches for Heavy Metal Removal from Water and Wastewater to Solve Water Crisis

Due to the impacts of water scarcity, the world is looking at all possible solutions for decreasing the over-exploitation of finite freshwater resources. Wastewater is one of the most reliable and accessible water supplies. As the population expands, so do industrial, agricultural, and household operations in order to meet man’s enormous demands. These operations generate huge amounts of wastewater, which may be recovered and used for a variety of reasons. Conventional wastewater treatment techniques have had some success in treating effluents for discharge throughout the years. However, advances in wastewater treatment techniques are required to make treated wastewater suitable for industrial, agricultural, and household use. Diverse techniques for removing heavy metal ions from various water and wastewater sources have been described. These treatments can be categorized as adsorption, membrane, chemical, or electric. Membrane technology has been developed as a popular alternative for recovering and reusing water from various water and wastewater sources. This study integrates useful membrane technology techniques for water and wastewater treatment containing heavy metals, with the objective of establishing a low-cost, high-efficiency method as well as ideal production conditions: low-cost, high-efficiency selective membranes, and maximum flexibility and selectivity. Future studies should concentrate on eco-friendly, cost-effective, and long-term materials and procedures.

A Way to Membrane-Based Environmental Remediation for Heavy Metal Removal

During the last century, industrialization has grown very fast and as a result heavy metals have contaminated many water sources. Due to their high toxicity, these pollutants are hazardous for humans, fish, and aquatic flora. Traditional techniques for their removal are adsorption, electro-dialysis, precipitation, and ion exchange, but they all present various drawbacks. Membrane technology represents an exciting alternative to the traditional ones characterized by high efficiency, low energy consumption and waste production, mild operating conditions, and easy scale-up. In this review, the attention has been focused on applying driven-pressure membrane processes for heavy metal removal, highlighting each of the positive and negative aspects. Advantages and disadvantages, and recent progress on the production of nanocomposite membranes and electrospun nanofiber membranes for the adsorption of heavy metal ions have also been reported and critically discussed. Finally, future prospective research activities and the key steps required to make their use effective on an industrial scale have been presented

Adsorption of Reactive Red 195 from aqueous medium using Lotus (Nelumbo nucifera) leaf powder chemically modified with dimethylamine: characterization, isotherms, kinetics, thermodynamics, and mechanism assessment

NOVELTY STATEMENT

In the modern era, dyes are inevitable and their surging usage leads to colossal contamination of aqueous streams, thereby threatening both the land and aquatic species. One among such dye is anionic Reactive Red 195 (RR 195), and traceable even at minute concentrations of aqueous streams, posing a severe threat to living species. Moreover, RR 195 is highly recalcitrant offering resistance to biodegradation due to the presence of an azo (-N=N-) group within its structure. Thus, there is a definite need to address the issue of eliminating RR 195 from industrial wastewater effluents. In lieu of this, the primitive objective of this study is to test the effectiveness of the natural adsorbent lotus leaf (Nelumbo nucifera) for the selective sorption of RR 195 from the aqueous stream. Although ample literature is available on the direct utilization of lotus leaf as adsorbent, yet no study was performed on the chemical modification (dimethylamine) of the aforementioned adsorbent. Hence, an attempt has been made in this direction to add a new sorbent into the adsorbents database.

Pressure-Driven Membrane Process: A Review of Advanced Technique for Heavy Metals Remediation

Pressure-driven processes have come a long way since they were introduced. These processes, namely Ultra-Filtration (UF), Nano-Filtration (NF), and Reverse-Osmosis (RO), aim to enhance the efficiency of wastewater treatment, thereby aiming at a cleaner production. Membranes may be polymeric, ceramic, metallic, or organo-mineral, and the filtration techniques differ in pore size from dense to porous membrane. The applied pressure varies according to the method used. These are being utilized in many exciting applications in, for example, the food industry, the pharmaceutical industry, and wastewater treatment. This paper attempts to comprehensively review the principle behind the different pressure-driven membrane technologies and their use in the removal of heavy metals from wastewater. The transport mechanism has been elaborated, which helps in the predictive modeling of the membrane system. Fouling of the membrane is perhaps the only barrier to the emergence of membrane technology and its full acceptance. However, with the use of innovative techniques of fabrication, this can be overcome. This review is concluded with perspective recommendations that can be incorporated by researchers worldwide as a new problem statement for their work.

Boosting adsorption of heavy metal ions in wastewater through solar-driven interfacial evaporation of chemically-treated carbonized wood

Once the adsorbent is selected, almost introducing larger specific surface area and more surface functional groups becomes the only way to improve its adsorption performance. However, this approach is generally limited in practical application for intricate and costly engineering steps. Herein, we provided a novel avenue for boosting adsorption activities towards specific metal ions in wastewater. Solar-driven interfacial water evaporation produces the localized temperature field and concentration gradient of metal ions inside small pores, endowing with a new sorption mechanism. By using chemically-treated carbonized wood as all-in-one solar absorption and metal ion adsorption system, we achieved higher water evaporation rate and heavy metal ion removal efficiency than carbonization-only wood reported previously. In particular, this system exhibited a strong dependence of specific metal ion adsorption capacity on solar intensity. Pb²⁺ adsorption capacity was enhanced by over 225% with the solar intensity increased to 3.0 kW·m^-2. This could originate from the formed temperature field localized specially on the surface of adsorbents that not only induces Pb²⁺ concentration gradient near to solid-liquid interface but also activate inactive adsorption sites. Besides, the chemical-treated & carbonized wood showed excellent cyclic stability and can be directly utilized for wastewater treatment, recovery and reuse.

Data on the fabrication of hybrid calix [4]arene-modified natural bentonite clay for efficient selective removal of toxic metals from wastewater at room temperature

Fresh water resources on the earth are less than 0.2%; meanwhile, around 80% of the freshwater is consumed daily in agriculture, industries, and household activities [1], [2]. There is an essential need to develop efficient adsorbents for wastewater treatment [1], [2], [3], [4], [5], [6], in this regards, hereafter we present the rationale synthesis and characterization of hybrid natural bentonite clay modified with Calix [4] arene (denoted as B-S-Calix) as efficient adsorbents for toxic metals from wastewater. This is driven by the facile photo-radical thiol-yne addition among the thiolated clay and an alkynylated calix[4]arene. The morphology, surface modifications, and Thermal degradation of B, B-S, and B-S-Calix were investigated using TEM, FTIR, and TGA techniques. The adsorption performance of B, BS and B-S-Calix towards toxic metals including cadmium (II) ion [Cd (II)], zinc (II) ion [Zn(II)], lead(II) ion [Pb(II)], strontium(II) ion [Sr (II)], cobalt(II) ion [Co (II)], copper(II) ion [Cu(II)], and mercury (II) ion [Hg(II)] from wastewater were benchmarked 25 °C. These data are related to the article entitled “hybrid Clay/Calix[4]arene Calix[4]arene-clicked clay through thiol-yne addition for the molecular recognition and removal of Cd(II) from wastewater’’ [7].

Nanolasers Incorporating CoxGa0.6-xZnSe0.4 Nanoparticle Arrays with Wavelength Tunability at Room Temperature

Semiconductor nanolaser has important research value and wide applications in many fields. However, it is still a challenge to obtain a nanolaser with tunability and high intensity at the nanoscale. Here, we report on lasers with two modes of emission wavelengths operating in near-infrared of nanohole filled with Co_xGa_0.6-xZnSe_0.4 nanoparticle arrays at room temperature. The nanohole arrays are drawn on the photoresist by using the method of three-beam laser interferometric etching. Graphene with graphite which is coated on nanohole arrays is conducted by pulsed laser deposition (PLD) to construct the cavity. The Co_xGa_0.6-xZnSe_0.4 nanoparticles are filled into the nanohole acting laser gain medium via the magnetic traction nanofilling technology. The results show that the laser at 868 and 903 nm is radiated, which can be tuned by changing the concentration and position of the filled nanoparticles in terms of wavelength and intensity. The nanolasers based on this approach represent an advantageous alternative to other design and fabrication methods. This nanoparticle nanolasers can be used in a micronano light source of an intelligent photonic chip.

Removal of pharmaceuticals and personal care products (PPCPs) and environmental estrogens (EEs) from water using positively charged hollow fiber nanofiltration membrane

Nanofiltration (NF) membranes show great potential for advanced water treatment, especially for trace organic pollutant removal. The removal efficiency of pharmaceuticals and personal care products (PPCPs) and environmental estrogenic hormones (EEHs) by positively charged hollow fiber NF membranes (PEI-NF) were evaluated. The separation properties were evaluated by changing the operating pressure, temperature, ionic strength, and cation species. A relationship between the physicochemical characteristics of the pharmaceuticals and the NF membrane retention behavior was established. The results showed that the rejection rates of the PEI-NF membrane for the selected PPCPs and EEHs ranged from 81 to ~ 91.26%. For positively (negatively) charged pharmaceutical molecules, the electrostatic repulsion (attraction) effect and steric hindrance were the dominant rejection mechanisms of the PEI-NF membrane. For neutral pharmaceutical molecules, in addition to the size sieving effect, the hydration-induced size increase of hydrophilic substances improved the rejection rates. Both the molecular structure and diffusion coefficient of pharmaceutical molecules influenced their rejection by the PEI-NF membrane to a certain extent. Moreover, the PEI-NF membrane showed a high removal effect for PPCPs and EEHs in water samples from actual tap water plants.

Removal of anionic (Acid Yellow 17 and Amaranth) dyes using aminated avocado (Persea americana) seed powder: adsorption/desorption, kinetics, isotherms, thermodynamics, and recycling studies

Aminated avocado seed powder (AASP)-an eco-friendly novel adsorbent has been used for the removal of Acid Yellow 17 (AY 17) and Amaranth (AMR) from an aqueous phase. The AASP (before and after adsorption) was systematically characterized by different analytical techniques such as FT-IR, FESEM, EDX, and N₂ adsorption-desorption analysis. Non-linear form of various kinetic (PFO and PSO) and isotherm (Langmuir and Freundlich) models were used to examine the adsorption behavior of AY 17 and AMR onto AASP. The adsorption of AY 17 and AMR onto AASP was well illustrated by the PSO kinetic model and Langmuir isotherm models. At 303 K, the maximum adsorption capacities (obtained from the Langmuir) of the AASP for AY 17 and AMR was 42.7 and 89.2 mg/g, respectively. The AY 17 and AMR adsorption was strongly pH-dependent with an optimum pH value of 2.0. Activation energy was calculated as 12.3 and 16.3 kJ/mol for AY 17 and AMR respectively, suggesting physical adsorption. The positive values of ΔG^o and ΔH^o indicated that the adsorption process of AY 17 and AMR onto AASP was non-spontaneous and endothermic. The negligible loss of adsorption capacity and excellent regeneration of AASP were observed for the five cycles. Statement of novelty: The present research majorly focused on the synthesis of adsorbent from Avocado seed for the removal of Acid Yellow 17 and Amaranth anionic dyes from aqueous solution. Although the literature is available on direct seed powder as adsorbent, to the best of our knowledge, no chemical modified adsorbent synthesis was not available. Hence, to fill the gap in the literature, we chose the following study that significantly enhanced the adsorption efficiency of the selected anionic dyes.

PMO synthesized and functionalized by p-phenylenediamine as new nanofiller in PES-nanofiltration membrane matrix for efficient treatment of organic dye, heavy metal, and salts from wastewater

Highly ordered periodic mesoporous organosilica (PMO) with large-pores (9.3 nm) synthesized using novel and cost-effective route. The synthesized PMO was then functionalized by p-phenylenediamine (PPD) and incorporated in polyethersulfone (PES) nanofiltration membrane‌ with various dosage using phase inversion method. The prepared membranes were characterized with FT-IR/ATR, FE-SEM and EDX techniques. The overall porosity, the mean of pore radius, water contact angle, fouling, permeation, and rejection were computed. As a result, the hydrophilicity and the pure water flux of membranes were significantly enhanced after modification with PMO-PPD due to its high hydrophilic nature as nanofiller. Ultimately, the modified membrane with 0.25 wt% of PPD was found the ideal membrane with water contact angle of 54.2%, pure water flux of 33.7 L/m² h, porosity of 74.1%, and mean pore radius of 4.96 nm. This membrane showed the maximum increase in water flux and superlative anti-fouling growth when compared to the other studied membranes. Moreover, among modified membranes with various quantity of PPD, the performance of the PES-PMO-PPD 0.25 wt% was the best for rejection of MO dye (96.7%), Pb(II) (93.1%), Na₂SO₄ (73.0%), MgSO₄ (41.6%), and NaCl (33.7%).

Biochar as an Eco-Friendly and Economical Adsorbent for the Removal of Colorants (Dyes) from Aqueous Environment: A Review

Dyes (colorants) are used in many industrial applications, and effluents of several industries contain toxic dyes. Dyes exhibit toxicity to humans, aquatic organisms, and the environment. Therefore, dyes containing wastewater must be properly treated before discharging to the surrounding water bodies. Among several water treatment technologies, adsorption is the most preferred technique to sequester dyes from water bodies. Many studies have reported the removal of dyes from wastewater using biochar produced from different biomass, e.g., algae and plant biomass, forest, and domestic residues, animal waste, sewage sludge, etc. The aim of this review is to provide an overview of the application of biochar as an eco-friendly and economical adsorbent to remove toxic colorants (dyes) from the aqueous environment. This review highlights the routes of biochar production, such as hydrothermal carbonization, pyrolysis, and hydrothermal liquefaction. Biochar as an adsorbent possesses numerous advantages, such as being eco-friendly, low-cost, and easy to use; various precursors are available in abundance to be converted into biochar, it also has recyclability potential and higher adsorption capacity than other conventional adsorbents. From the literature review, it is clear that biochar is a vital candidate for removal of dyes from wastewater with adsorption capacity of above 80%.