Application In Wastewater Purification Research Articles

PTFE composite membrane with peroxymonosulfate activation self-cleaning for highly-efficient oil-water emulsion separation and dye degradation

Combining membrane separation with advanced oxidation technology can make the membrane self-cleaning, extending its service life. However, the preparation of composite membranes with excellent catalytic ability, self-cleaning performance, and stability remains a key research direction. In this study, a PTFE composite membrane with peroxymonosulfate activation self-cleaning ability was successfully prepared by in-situ growth of CoOOH and ZIF-67 on the surface of a l-DOPA/PEI modified PTFE membrane. The as-prepared membrane is superhydrophilic and has significant superoleophobic surfaces underwater, the separation efficiency of the as-prepared membrane for multiple oil-water emulsions exceeded 98.4 %. Meanwhile, the effective degradation of several organic dyes under visible light was simulated, with still high degradation efficiency (>99 %) after 10 cycles. Overall, this study puts forward a approach towards self-cleaning membranes based on PTFE material; the resulting composite membrane's high separation efficiency, stability under repeated use conditions as well as its self-cleaning ability position it as an attractive candidate for long-term wastewater purification applications.

Construction of black g-C3N4/loofah/chitosan hydrogel as an efficient solar evaporator for desalination coupled with antibiotic degradation

The utilization of solar evaporator for interfacial seawater evaporation and wastewater treatment presents a promising concept; however, inadequate evaporation and degradation rates and complicated preparation procedures significantly hinder its practical application. Herein, the black g-C3N4/loofah/chitosan (BCN/LF/CS) hydrogel as an efficient dual-function solar evaporator was constructed for desalination coupled with antibiotic degradation. The experimental results show that in 3.5 wt% NaCl solution, the effective evaporation rate of optimal BCN-1/LF/CS evaporator can reach 2.1 kg m−2 h−1, and maintaining 91.4 % degradation of tetracycline (TC) solution (50 mg/L) within 6 h irradiation. This work introduced here combines the advantages of photothermal evaporation and photocatalytic degradation to obtain fresh water from a complicated water environment, providing inspiration for future exploration of photocatalyst construction and extensive application in wastewater purification.

Biochar modified by ammonium pyrrolidine dithiocarbamate for high selective adsorption of copper in wastewater

Biochar application in wastewater purification is extremely appealing. Although heteropolysaccharides like Gum Seyal biochar (BC GS500) display great surface area and porosity, the adsorption capacity for Cu (II) was relatively low due to the week-binding surface functional groups. In this work, an innovative modification with the chelating agent ammonium pyrrolidine dithiocarbamate (APDC) capable of selectively and effectively adsorbing Cu (II) was conducted. Gum Seyal biochar was grafted with pyrrolidine dithiocarbamate (C5H8NS2–), amine (–NH2), and imine (–NH) groups using APDC based on the “hard and soft acids and bases theory” (HSAB). Batch studies, along with characterization (FITR, XPS, and SEM-EDS), molecular electrostatic potential (MEP) mapping, and density functional theory (DFT) calculations, were implemented to investigate the adsorption performance and mechanism responsible for selectively adsorptive Cu (II) removal. It was found that Cu (II) adsorption by modified biochar occurred endothermically and spontaneously. The adsorption data at pH 5 matched the pseudo-second-order kinetic model and the Langmuir isotherm (211.24 mg/g). DFT calculations show that modified biochar selectively binds Cu (II) superior to common ions such as Mg (II) and Ca (II) through a unique chelating mechanism. Their performance in real electroplating wastewater was investigated, and the production cost was estimated. It was concluded that the modified biochar (BC APDC) could have high applicable potential for Cu (II)-laden wastewater purification.

Scalable multifunctional MOFs-textiles via diazonium chemistry

Cellulose fiber-based textiles are ubiquitous in daily life for their processability, biodegradability, and outstanding flexibility. Integrating cellulose textiles with functional coating materials can unlock their potential functionalities to engage diverse applications. Metal-organic frameworks (MOFs) are ideal candidate materials for such integration, thanks to their unique merits, such as large specific surface area, tunable pore size, and species diversity. However, achieving scalable fabrication of MOFs-textiles with high mechanical durability remains challenging. Here, we report a facile and scalable strategy for direct MOF growth on cotton fibers grafted via the diazonium chemistry. The as-prepared ZIF-67-Cotton textile (ZIF-67-CT) exhibits excellent ultraviolet (UV) resistance and organic contamination degradation via the peroxymonosulfate activation. The ZIF-67-CT is also used to encapsulate essential oils such as carvacrol to enable antibacterial activity against E. coli and S. aureus. Additionally, by directly tethering a hydrophobic molecular layer onto the MOF-coated surface, superhydrophobic ZIF-67-CT is achieved with excellent self-cleaning, antifouling, and oil-water separation performances. More importantly, the reported strategy is generic and applicable to other MOFs and cellulose fiber-based materials, and various large-scale multi-functional MOFs-textiles can be successfully manufactured, resulting in vast applications in wastewater purification, fragrance industry, and outdoor gears.

Review on recent advancements of 2D MXene-based nanostructures on different possible approaches for wastewater treatment

In this review, a brief perspective of MXene (since 2011) with recent research for new and advanced applications for wastewater treatments through various approaches have been discussed. Current information’s about MXenes are summarized to fully understand their nature, promising properties and reduce the challenges that have opened the new era of their uses. Primarily, the existing modest problem is the availability of potable water to sustain healthy human-chain and entire ecosystem, as contaminated water has harsh consequences and poses serious threats to human-health worldwide. In the current stage, supply of potable water for society with cheap and low-cost technology has become the key requirement for the growing economy. Efficient techniques to remove several contaminants (including dyes, heavy metal ions, pharmaceutical or organic products) from wastewater have been transformed gradually to mitigate this scarcity. In this direction, MXene based nanostructures have become a promising material for the wastewater treatment. These structures have unique hydrophilicity, high surface area, a good photocatalytic activity, and wonderful adsorption capacity for contaminates. Numerous advanceshavebeen observed in the optimized rational designs of MXene-derived nanocomposites and their applications in wastewater purification. Hence, timely updates are necessary to emphasize on toxic removals and characterizations including merits and demerits of these MXene-based nanostructures. Thus, this study summarizes the guidelines for the synthesis and applications of MXene-based nanocomposites in wastewater purification, which may stimulate the scientific community to develop a variety of MXene-derived nanostructures with well-defined structures, constitution, and enhanced physicochemical properties for effectively removal of noxious pollutants from wastewater using cost-effective and feasible techniques.

3D printing of a photo-curable hydrogel to engineer mechanically robust porous structure for ion capture or sustained potassium ferrate(VI) release for water treatment

Contaminated water and scarcity of clean water are becoming progressively serious environmental concerns. Removal of hazardous pollutants from wastewater is vital and urgently needed attention for the protection of pure water resources. To tackle the aforementioned challenges, macroporous structures have great potential to be used in the treatment of heavy metal ions to improve the adsorption efficiency and sustainability of wastewater treatment methodologies. In this context, additive manufacturing technologies have gained considerable attention because of their ability to construct intricate macroporous shapes with multifunctionalities using diverse materials. Here, we used a photocrosslinking graft copolymerization of polyvinyl alcohol/acrylic acid-based ink using UV irradiation in the presence of Norrish type II photosensitizer through a hot-melt extrusion-type 3D printer to improve the printing quality of crosslinked ink. The photocured inks offered strong shear-thinning behavior that allowed layer-by-layer deposition to generate well-defined 3D structures, while having sufficiently high viscoelasticity to retain the shape after printing process. With an adequate viscosity at the higher extrusion shearing forces, the 3D printed structures could create multifaceted self-supporting scaffolds with an internal lattice structure that possesses high level of porosity. The hierarchically porous structure of 3D objects showed a recoverable structure yet robust matrix, offering more specific surface area, capable of effectively removing heavy metal ions from water with fast-responsiveness and a high capacity. The ferrate(VI)-contained 3D capsule-like object was also detected to be efficient regarding chemical oxygen demand reduction and decolorization of real wastewater. Such 3D-printed hierarchical macroporous objects can offer great prospects in the treatment of water and wastewater purification applications.

Growth of CuS nanowire on copper mesh for efficient solar-driven water evaporation and wastewater purification

This study proposed a multifunctional material, CuS nanowire, grown on a copper mesh (CM), for application in wastewater purification. CuS/CM could rapidly evaporate and collect water under solar irradiation. CuS nanowires were successfully synthesized on CM through a liquid–solid reaction at room temperature, followed by sulfidation. Water evaporation experiments conducted using meshes suspended in water to determine the most efficient configuration revealed that CuS/CM was the most efficient material. Owing to the localized surface plasmon resonance induced by oxygen vacancies, CuS/CM exhibited a high water evaporation rate (4.0523 kg·m-2h−1 @ 3 sun) and energy conversion efficiency (96.1 %) in Structure A with a vertical length of 4 cm under 3 sun irradiation. To evaluate its effectiveness in wastewater treatment, CuS/CM was used to evaporate and collect methylene blue (MB)-contaminated water at rates of 1.5747 and 0.8624 kg·m-2h−1. Furthermore, CuS/CM demonstrated photocatalytic activity during MB degradation. Under xenon lamp illumination for 6 h, CuS/CM exhibited a 73 % degradation efficiency for MB, indicating its photocatalytic properties. CuS/CM effectively purify dyeing wastewater due to their fast water evaporation rate and the photocatalytic capability of CuS, making them promising for wastewater treatment and desalination applications.

PVDF-based nanofiber membrane decorated with Z-scheme TiO2/MIL-100(Fe) heterojunction for efficient oil/water emulsion separation and dye photocatalytic degradation

Membrane separation is one of the most widely used methods for water purification, but membrane fouling is a stumbling block that must be overcome for its further promotion and application. In this work, a self-cleaning PVDF-based hybrid nanofiber membrane with core-sheath structure were constructed via electrospinning and in-situ synthesis, using polyvinylidene fluoride/polyvinyl pyrrolidone (PVDF-PVP) electrospun nanofibers as skeleton cores and in-situ synthesis of Z-scheme TiO2/MIL-100(Fe) heterojunctions as photocatalytic sheaths. The hybrid membrane exhibited excellent superhydrophilicity (water contact angle of 0°) and underwater superoleophobicity (underwater oil contact angle of 161.4°) with high permeate fluxes and superior separation efficiencies (more than 99.5%) for various oil/water emulsions. Furthermore, the Z-scheme TiO2/MIL-100(Fe) heterojunctions anchored on the nanofibers possessed robust photocatalytic activity with the removal efficiency of dyes up to 99.9% under simulated sunlight. More importantly, the membrane has excellent recyclability due to its outstanding anti-fouling and self-cleaning properties. Therefore, the hybrid membrane has attractive potential application in wastewater purification.

Green synthesis of recyclable reduced graphene oxide-gold nanocatalyst using Alstonia scholaris: Applications in waste water purification and microbial field

The green synthetic approaches are the alternative methods for the preparation of various types of nanoparticles to keep sustainable evolution. A novel green synthesis of gold- reduced graphene oxide nanocomposites was conducted through simple heating method using Alstonia scholaris (A. scholaris) bark extract. There are several techniques that confirm the formation of the nanocomposites for synthesis of gold nanoparticles on reduced graphene oxide (RGO), such as X-ray diffraction (XRD), UV–visible spectroscopy (UV–vis) and Fourier transformed infrared spectroscopy (FT-IR). The size distributions of the gold nanoparticles (Au NPs) grown on RGO surface was measured using two different methods: particle distribution study and transmission electron microscopy (TEM) image. These two methods provided similar size distribution which is around 5–8 nm. Subsequently, the catalytic performance was evaluated by 4-nitro aniline (4-NA). The photocatalytic activities were investigated using different organic hazardous dyes, such as methylene blue (MB), methyl orange (MO) and the change of photocatalytic behaviour was shown by varying the catalyst amount and pH. The chemical oxygen demand (COD) analyses for complete removal of organic dye were carried out using the two nanocomposite samples. To perceive the effect on different bacterial strains, antibacterial and antiprotozoal studies have been carried out with this nanocomposite.

The synergistic effect of oxygen vacancies and acidic properties of SO42−/CexZr1−xO2 on enhancing the Electro-Fenton performance in antibiotics wastewater treatment

Recently, bi-functional catalysts have emerged as an effective approach for enhancing the performance of electro-Fenton in degrading antibiotics by simultaneously improving H2O2 generation and Fe circulation. Herein, we prepared a SO42- modified CexZr1-xO2 bi-functional catalyst to construct an efficient e-Fenton system for degrading norfloxacin. Results display that the fabricated catalyst exhibited superior performance in degrading norfloxacin owing to durative generated ⋅OH, which was proved to be the dominant active species. The H2O2 generation capacity of that catalyst was twice higher than the pure e-Fenton and its faradaic efficiency even came up to 75%. The amount of soluble total Fe and Fe2+ ions of that catalyst were both increased twofold compared to the blank system, declaring the acceleration of Fe recycling process. Characterizations and density function theory calculations proposed a synergistic mechanism that attributed the simultaneously improvement in H2O2 generation and Fe2+ circulation to the multiple regulated interface properties, the promoted 2e- ORR activity caused by enriched oxygen vacancies at Ce sites, and the accelerated electrons transfer owing to the strengthened acidic sites for the coordination between Zr sites and S species. Furthermore, that catalyst is also proved to be feasible, well-recycled and practical for application in wastewater purification.

Facile Fabrication of PANI/Fe2.85Ni0.15O4 Nanocomposites and Their Application for the Effective Degradation of Rhodamine B Dye

Nanocomposites of polyaniline (PANI)/Fe2.85Ni0.15O4 (PFN) were successfully prepared using the co-precipitation method combined with an in-situ polymerization process. The FN and PFN nanocatalysts were characterized using various methods for the photocatalytic degradation of Rhodamine B (RhB). The XRD, Raman, TEM, and DTA-DTG analyses suggest that the FN nanoparticles (NPs) were effectively coated by PANI and that there were interactions between FN and PANI. Magnetic measurements indicated that PFN nanocomposites exhibited good superparamagnetic behavior and high saturation magnetization (39.5–57.6 emu/g), which are suitable for separating photocatalysts from solution for reuse. Adsorption-desorption analysis showed that the specific surface area of PFN was higher than that of FN. The UV-vis absorption spectra of FN and PFN nanocomposites exhibited strong absorption of visible light, attributed to the doping of Ni, which resulted in the reduction of the band-gap energy (Eg) of Fe3O4 to 2.4 eV. PFN nanocomposites with different mass ratios of PANI demonstrated superior photocatalytic activity compared to FN NPs. Furthermore, it was observed that PFN with a 10% mass ratio of PANI exhibited the highest RhB degradation efficiency, achieving a rate of approximately 98% after 300 min of irradiation. Finally, the possible photocatalytic degradation mechanisms of the PFN nanocomposites on RhB were discussed. PFN photocatalysts with good photocatalytic activity, inexpensive materials, and easy preparation could be potential candidates for wastewater purification applications.

Multifunctional fully biobased aerogels for water remediation: Applications for dye and heavy metal adsorption and oil/water separation

Water ecosystem contamination from industrial pollutants is an emerging threat to both humans and native species, making it a point of global concern. In this work, fully biobased aerogels (FBAs) were developed by using low-cost cellulose filament (CF), chitosan (CS), citric acid (CA), and a simple and scalable approach, for water remediation applications. The FBAs displayed superior mechanical properties (up to ∼65 kPa m3 kg−1 specific Young’s modulus and ∼111 kJ/m3 energy absorption) due to CA acting as a covalent crosslinker in addition to the natural hydrogen bonding and electrostatic interactions between CF and CS. The addition of CS and CA increased the variety of functional groups (carboxylic acid, hydroxyl and amines) on the materials’ surface, resulting in super-high dye and heavy metal adsorption capacities (619 mg/g and 206 mg/g for methylene blue and copper, respectively). Further modification of FBAs with a simple approach using methyltrimethoxysilane endowed aerogel oleophilic and hydrophobic properties. The developed FBAs showed a fast performance in water and oil/organic solvents separation with more than 96% efficiency. Besides, the FBA sorbents could be regenerated and reused for multiple cycles without any significant impact on their performance. Moreover, thanks to the presence of amine groups by addition of CS, FBAs also displayed antibacterial properties by preventing the growth of Escherichia coli on their surface. This work demonstrates the preparation of FBAs from abundant, sustainable, and inexpensive natural resources for applications in wastewater purification.

Elimination of chloramphenicol through electro-fenton-like reaction: Reaction mechanism and electron transfer pathway

An electro-Fenton-like reaction process relying on peroxymonosulfate activation can stably degrade chloramphenicol (CAP) within 16 min, where the kinetic rate constant can be as high as 0.089 min−1 and the energy consumption value can be as low as 25.1 kWh•m^−3. Evidence indicated that the use of a Na2SO4 solution as the electrolyte can enhance CAP degradation due to rapid electron transfer properties. The generated electrons and active free radicals are responsible for CAP degradation, and the electrons can be transferred from the highest occupied molecular orbital of CAP to the lowest unoccupied molecular orbital of peroxymonosulfate via the PbO2 electrode. Density functional theory calculations based on Fukui index analysis elucidated the key attack sites in CAP; moreover, reaction-free energy calculations shed light on potential CAP degradation pathways. Not only does this study afford an insight into the activation of peroxymonosulfate for organic pollutant degradation but also provides an innovative technology with potential applications in wastewater purification.

Adsorption mechanism and removal efficiency of magnetic graphene oxide-chitosan hybrid on aqueous Zn(II)

Magnetic architecture incorporating graphene-chitosan has demonstrated encouraging application in wastewater purification. Herein, a ternary hybrid based on Fe3O4-graphene oxide-chitosan (MGOCS) was fabricated and employed as adsorbent to remove aqueous Zn(II). The adsorption mechanism was intensively inspected based on the hard and soft acid base (HSAB) theory. Results present, MGOCS removes 96.73 % of Zn(II) in 38 min, with adsorption quantity 386.92 mg·g−1. Electron transfer and energy lowering determined by the HSAB theory illuminate the plausible adsorption sites in each component of MGOCS: O2− in Fe3O4, -C(=O)NH-, -NH2 in chitosan and -OH in graphene oxide. The exploration was upheld by spectroscopic analyses. Thereby, following adsorption mechanism was proposed. (1) ZnO bond was formed featured by electron donation. (2) The -C(=O)NH- group formed via amidation between graphene oxide and chitosan contributes to Zn(Π) uptake. This work may inspire the development of efficient adsorbent based on magnetic graphene-chitosan for wastewater remediation.

Constructing Fe(III)-bearing hydroxyapatite for Cr(VI) removal

Great importance has been attached to the utilization of low-cost, accessible, and high-pollution waste materials, particularly industrial solid wastes (i.e., steel slag) and hazardous solid wastes (i.e., spent adsorbents/catalysts). Herein, the transformation of Ca-containing whewellite precipitation originated from steel slag leaching solution into hydroxyapatite (Hap) nanorods is realized. Fe(III)-bearing Hap (xFe-Hap, x represents initial concentration of Fe3+ ions, mg/L) is then prepared via cation exchange between Fe3+ in solution and Ca2+ in Hap. The preferred 60Fe-Hap shows large specific surface area of 132.59 m2/g and 100% Cr(VI) photoreduction (60 mL, 40 mg/L Cr(VI)) with the assistance of oxalic acid (0.5 g/L) based on intramolecular charge transfer from oxalic acid to Fe(III) in [FeIII(C2O4)n]3-2n complex under visible light irradiation. This work thus offers a novel strategy for a high-efficient utilization of waste materials which may shift the waste materials into things of value in wastewater purification applications.

Cellulose based polyurethane with amino acid functionality: Design, synthesis, computational study and application in wastewater purification

Contamination in water is due to various environmental pollutants from natural and anthropogen activities. To remove toxic metals from contaminated water, we developed a novel adsorbent in foam form based on an olive industry waste material. The foam synthesis involved oxidation of cellulose extracted from the waste to dialdehyde, functionalization of the cellulose dialdehyde with an amino acid group, reacting the functionalized cellulose with hexamethylene diisocyanate and p-phenylene diisocyanate to produce the target polyurethanes Cell-F-HMDIC and Cell-F-PDIC, respectively. The optimum condition for lead(II) adsorption by Cell-F-HMDIC and Cell-F-PDIC were determined. The foams show the ability to quantitatively remove most of metal ions present in a real sample of sewage. The kinetic and thermodynamic studies confirmed a spontaneous metal ion binding to the foams with a second pseudo-order adsorption rate. The adsorption study revealed it obeys the Langmuir isotherm model. The experimental Qe values of both foams Cell-F-PDIC and Cell-F-HMDIC were 2.1929 and 2.0345 mg/g, respectively. Monte Carlo (MC) and Dynamic (MD) and simulations showed excellent affinity of both foams for lead ions with high adsorption negative energy value indicating vigorous interactions of Pb(II) with the adsorbent surface. The results indicate the usefulness of the developed foam in commercial applications. Environmental implicationElimination of metal ions from contaminated environments is important for a number of reasons. They are toxic to humans via interaction with biomolecules, resulting in disruption of the metabolism and biological activities of many proteins. They are toxic to plants. Industrial effluents and/or wastewater discharged from production processes, contain a considerable amount of metal ions.In this work, the use of naturally produced materials, such as olive waste biomass, as adsorbents for environmental remediation has received great attention. This biomass represents unused resources and presents serious disposal problems. We demonstrated that such materials are capable of selectively adsorbing metal ions.

Synergized selenium-vacancy heterogeneous interface and carbon nanotubes for insight into efficient oxidation of pollutants via photocatalytic peroxymonosulfate activation

Advanced strategies for enhancing catalytic performance of catalysts include multi-metal active site exposure, vacancy growth and electronic structure optimization. Here, carbon nanotube-loaded CoSe2/FeSe2 catalysts (Co/Fe-CNT) with multiphase boundaries and embedded selenium vacancies (VSe) were prepared using a one-step hydrothermal method. The catalysts feature unique electronic structures and abundant active sites, and were found to exhibit unexpectedly high activity and stability in photocatalytic mediated sulphate radical (SR-photo) system, with impressive oxidation capacity for complex matrix polluted water. The spontaneously formed internal electric field strongly promoted charge transport and significantly enhanced the photocatalytic property. The VSe formed at the heterogeneous interface could modulate the surface electronic structure and accelerate the redox cycling of transition metals, thereby accelerating the production of reactive oxygen species and boosting the efficiency of contaminant degradation. This work provides guidance for the design of high-performance catalysts for VSe engineering and expands their potential for application in wastewater purification.

Model Unraveling the Ultra-Efficient Multi-Stage Flow-Through Anodes for Water Purification Application: Development of Design and Evaluation

Improving energy utilization efficiency is crucial to broadening the prospects in the field of electrochemical wastewater treatment. The electrochemical flow-through (FT) mode shows the potential prospect of high oxidation efficiency and low energy cost. In this study, based on the SnO2-Sb2O3 macroporous anode, we designed a multi-stage flow-through (MSFT) anode that significantly enhanced the organic removal performance than that of a conventional FT system. Accordingly, we first proposed the current reaction kinetics model that could appropriately describe the removal performance in the MSFT electrochemical oxidation process. The mass transfer impact of MSFT was also suitably evaluated by our model, which indicated that the MSFT could rapidly achieve the same diffusion flux for electrochemical oxidation limitations. The energy consumption per order of magnitude removal (EE/O) was below 0.12 kWh m–3 for low-concentration organics, which sharply decreased with an increase in the flow. For the simulation of low conductivity of water quality (∼439 μS cm–1), we found that the MSFT could obtain the voltage reduction of approximately 25% for saving energy without the extra electrolyte. Finally, we summarized the nominalized electron utilization performance of organic destruction on various electrochemical advanced oxidation anodes. The normalized removal rate of contaminants per current was greatly improved by the MSFT mode and our highly efficient anode. Notably, the MS design can prolong the anode usage lifetime. We anticipate that our work will provide design development for other anodic interfaces in the field of electrochemical wastewater purification applications.

Olive Industry Solid Waste-Based Biosorbent: Synthesis and Application in Wastewater Purification.

In this work, we present a process for converting olive industry solid waste (OISW) into a value-added material with ionic receptors for use in the removal of toxic metal ions from wastewater. This 3D polymer is a promising adsorbent for large-scale application, since it is a low-cost material made from agricultural waste and showed exceptional performance. The synthesis of the network polymer involved the carboxymethylation of OISW and curing of the carboxymethylated OISW at an elevated temperature to promote the formation of ester linkages between OISW's components. FT-IR, atomic force microscopy, and thermal analysis were performed on the crosslinked product. The adsorption efficiency of the crosslinked carboxymethylated OISW toward Pb(II), Cu(II), and other toxic metal ions present in sewage was evaluated as a function of adsorbent dose, temperature, pH, time, and initial metal ion. The percentage removal of about 20 metal ions present in a sewage sample collected from a sewer plant located in the Palestinian Territories was determined. The adsorption efficiency did not drop even after six cycles of use. The kinetic study showed that the adsorption process follows the Langmuir isotherm model and the second-order adsorption rate. The experimental Qe values of 13.91 and 13.71 mg/g were obtained for Pb(II) and Cu(II) removal, respectively. The thermodynamic results confirm the spontaneous metal bonding to the receptor sites of the crosslinked carboxymethylated OISW.

Ternary Mg-B-S co-modified Ficus virens biochar for ultra-high adsorption of rhodamine B in lab-scale and field-scale application: Adsorption behavior and mechanisms

To boost the adsorption activity of Ficus virens biochar for dye removal, S-doped biochar was co-modified by MgO and B2O3 (Mg-B/S-BC) via one-pot sulfurization. Mg-B/S-BC exhibits the higher adsorption capacity than S-doped biochar, MgO/biochar and B2O3/biochar for rhodamine B (RhB). The adsorption capacity of optimal Mg-B/S-BC is 1195.25 mg g−1, and declines to 1142.97 mg g−1 after nine cycles. The adsorption isotherms and kinetics of S-biochar based composites are well matched with Langmuir and second-order models, respectively. The mechanism of RhB adsorption on 4d-Mg-B/S-BC composites is through electrostatic attraction, H-bonding and ion exchange interactions, and it is a spontaneous process of physical adsorption and heat absorption. The field-scale results suggest that the adsorption capacity of optimal Mg-B/S-BC is 487.01 mg g−1, while reduces to 429.63 mg g−1 for RhB after nine cycles. The optimal Mg-B/S-BC exhibits the excellent adsorption activity for field-scale removal of tetracycline hydrochloride, ciprofloxacin, and methyl orange. Hence, Mg-B/S-BC composite is a promising material for industrial application in wastewater purification.