Innovative Adsorbents for Pollutant Removal: Exploring the Latest Research and Applications

Yan Z., Jiang S., Meng L., Lou Y., Xi J., Xiao H., Wu W.

The widespread use of synthetic dyes has serious implications for both the environment and human health. Therefore, there is an urgent need for the development of novel, high-efficiency adsorbents for these dyes. In this study, a Zirconium-based metal-organic framework (MOF) with controllable morphology was in-situ grown on bacterial nanocellulose (BC) via a solvothermal method. The resulting BC@MOF composite nanofibers have a high specific surface area of 651 m

Karimi M., Shirzad M.

Shah A., Akhtar S., Mahmood F., Urooj S., Siddique A.B., Irfan M.I., Naeem-ul-Hassan M., Sher M., Alhoshani A., Rauf A., Amin H.M., Abbas A.

In the current study, polar leaves extract of the plant Fagonia arabica (FALE) from the Zygophyllaceae family was used to synthesize sunlight-assisted gold nanoparticles (FALE@AuNPs) with defined size and shape and of excellent colloidal stability. The effect of different physiochemical parameters (FALE dosage, Au3+ ions concentration, sunlight exposure time) on the formation of AuNPs was also studied. The synthesized FALE@AuNPs were characterized using UV-visible spectrophotometry, scanning electron microscopy-energy dispersive X-rays (SEM-EDX), Fourier-transform infrared spectroscopy (FTIR), powder XRD, zeta potential (ZP) and dynamic light scattering (DLS). The successful synthesis of FALE@AuNPs in solution was confirmed by the appearance of a localized surface plasmon resonance (LSPR) characteristic peak at 535 nm in UV-Vis spectra. The size estimated by UV-Vis (∼59 nm) was found in good agreement with that determined by SEM (∼60 nm) and DLS (∼61 nm). A zeta potential value of -28±1.5 mV confirms the colloidal stability of FALE@AuNPs. The FALE@AuNPs were utilized as a colorimetric nano-sensor for Cd2+ ion 15 nM limit of detection (LOD) and linear range detection of 0-600 nM. When utilized to identify Cd2+ ion in actual water samples, the nano-probe demonstrated high recovery rates of over 98% and a low relative standard deviation (RSD) of about 4%, demonstrating its dependability and efficiency in doing so. FALE@AuNPs were found to be antibacterial against gram-positive as well as gram-negative bacteria. An exceptionally high photocatalytic activity was shown by FALE@AuNPs with 80% efficiency of degradation examined against methylene blue and methyl orange dye.

Ma L., Li D., Chen X., Xu H., Tian Y.

In this work, a sustainable 3D carbon aerogel (AO-WPC) is prepared from waste paper (WP), and used for efficient antibiotics removal from water. The AO-WPC aerogel shows good mechanical property and can recover after 100th of 30 % compression strain. The specific surface area of AO-WPC aerogel is up to 654.58 m

Khan F., Siddique A.B., Irfan M.I., Hassan M.N., Sher M., Alhazmi H.A., Qramish A.N., Amin H.M., Qadir R., Abbas A.

The massive environmental pollution caused by widespread industrialization jeopardizes human life and ecosystems. Among several pollutants, heavy metal ions in fresh water reservoirs pose a major threat that needs an immediate attention. One of the feasible, cheap and robust approaches to mitigate this pollution is the sorption on efficient and easily available materials. Hence, the contemporary study is designed to the synthesis, characterization, and application of the sodic form of hydroxyethyl cellulose maleate (HEC-MAL-Na) for the selective uptake of Cd(II) metal ions from the spiked aqueous solution. The esterification of hydroxyethyl cellulose (HEC) with maleic anhydride was initially carried out to synthesize HEC-MAL. HEC-MAL was subsequently neutralized by NaHCO3 to form HEC-MAL-Na. The sodic form of HEC-MAL was characterized by comparing the FT-IR spectra of HEC-MAL-Na, HEC-MAL and HEC. Zero-point charge pH of HEC-MAL-Na confirmed the neutralization of HEC-MAL by NaHCO3. HEC-MAL-Na was utilized as an adsorbent for the treatment of polluted water by removing Cd(II) ions via an ion-exchange mechanism. The optimum conditions for the effective removal of Cd(II) ions from the aqueous solution were determined by screening different parameters such as temperature, pH, contact time, sorbent dose and initial metal ion concentration. The experimental data supported the pseudo-second order kinetics and Langmuir isothermal model for removal of Cd(II) ions from aqueous solution with the maximum sorption capacity of 277.7 mg/g at pH 5.5, initial metal ion concentration (110 mg L−1), sorbent dosage (40 mg) and contact time (30 min) at 298 K. The thermodynamic parameters, such as ∆S°, ∆H° and ∆G° were also estimated, and their values indicated the exothermic, spontaneous and feasible nature of the sorption process. Regeneration studies  demonstrated the feasibility of the repeated use of activated adsorbent for removal of heavy metal ions.

Khan A.W., Lali N.S., Sabei F.Y., Irfan M.I., Naeem-ul-Hassan M., Sher M., Safhi A.Y., Alsalhi A., Albariqi A.H., Kamli F., Amin H.M., Abbas A.

This work aims to establish a novel approach for the selective synthesis of gold nanoparticles (Au NPs) with defined shape and size as well as excellent colloidal stability via a facile and environmentally friendly manner. The polar extract from the leaves of the plant E. diffusum (EDLE), also known as horsetail, was used to synthesize gold NPs (EDLE@Au NPs). Fourier-transform infrared (FTIR) and UV–visible spectroscopy, scanning electron microscopy-energy dispersive X-rays (SEM-EDX), PXRD, dynamic light scattering (DLS), and zeta potential (ZP) were used to characterize as-synthesized EDLE@Au NPs. The SEM imaging revealed the cubic shape of EDLE@Au NPs. Interestingly, EDLE@Au NPs interacted with different metal ions, and a shift in the LSPR band to a higher wavelength was observed only in the case of Pb2+ ions. This provided a basis for using the EDLE@Au NPs as a selective colorimetric sensor for Pb2+ ions. A linear range of 20–350 µM and a limit of detection of 4.4 µM for Pb2+ detection was achieved. To elucidate the sensing mechanism, DLS and zeta potential analyses were carried out after addition of Pb2+. A significant decrease in the zeta potential along with an increase in the particle size of the Au NPs was observed after the addition of Pb2+, suggesting the aggregation of the nanoparticles. Further, the results of the antimicrobial study showed that EDLE@Au NPs were active against both gram-positive and gram-negative bacteria. An exceptional photocatalytic activity with 96.5% degradation efficiency of EDLE@Au NPs was examined against methylene blue dye.

Walling B., Borah A., Hazarika S., Bharali P., Ramachandran D., Kanagasabai V., Dutta N., Maadurshni G.B., Manivannan J., Mudoi P., Kaman P.K., Sorhie V., Gogoi B., Alemtoshi, Acharjee S.A., et. al.

The possibility of using stillage of rice beer as a source of carbon for the manufacture of bacterial nanocellulose (BNC) was investigated in this work. 16.434 g L−1 of BNC was produced by Komagataeibacter saccharivorans NUWB1 using the rice beer stillage along with the other media components of Hestrin-Schramm (HS) medium. Findings showed that obtained BNC possessed dense nano-fibrous network with a signature of cellulose I type, crystallinity index of 86.23%, and higher thermostability up to 380 °C could withstand tensile loads of 68.044 MPa, and exhibited a water holding capacity of 97.53 g g−1. N2 adsorption-desorption isotherm of the BNC was found to be of type IV, suggesting mesoporous type structure with a total pore volume and surface area of 3.294e-03cc g−1 and 21.065 m2 g−1. The effectiveness of the BNC in adsorbing the cationic methylene blue dye was investigated. The BNC showed remarkable adsorption capacity against the dye, and resultant data from adsorption studies fit well for the Langmuir isotherm (R2=0.99) and pseudo-second-order model. According to thermodynamic studies, the adsorption was found to be spontaneous and endothermic. The efficiency of the BNC was also examined in a number of sorption-desorption cycles, which demonstrated its recyclable nature. The present investigation evidently suggests the possibility of valorizing waste distillery stillage into an efficient green sustainable adsorbent material that could find its wide-scale environmental applications.

Noormohammadi M., Zabihi M., Faghihi M.

Design and synthesis of plate-shaped adsorbents supported on anodized aluminum as a substrate were successfully carried out for the adsorption of methyl orange (MO) and arsenic [As(V)] ions in aqueous solutions. Chitosan, clay, and iron was also used on the anodized aluminum as a substrate to make a nanocomposite adsorbent. The specific properties of the prepared samples were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and Brunauer–Emmett–Teller (BET) analysis to determine the textural structure of the nanocomposites. The FESEM results showed that the formation of pores over the anodic surface was strongly related to anodizing time. Aluminum oxide and iron (hematite) phases were detected by XRD, which showed that the composite adsorbents were well synthesized. Isotherm adsorption was conducted using two models, of which the Langmuir model was in good agreement with the experimental results. The calculated maximum adsorption capacities based on the Langmuir equation for the adsorption of MO and As(V) ions were 53.48 and 14.70 mg/g, respectively. Pseudo first- and second-order models were used to demonstrate the adsorption mechanism of the anionic pollutants over the supported nanocomposites. The kinetic results indicated that the linearized pseudo second-order equation conformed best with the experimental data. The adsorption capacity was measured in six consecutive cycles to demonstrate the performance of the anodic adsorbent for removal of contaminants. The results illustrated 10 % and 15 % reductions in adsorption capacity of the anodized nanocomposite following six repeated cycles for MO and As(V) adsorption, respectively.

Fabregat V., Pagán J.M.

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.

Eddahhaoui F.Z., Najem A., Elhawary M., Boudalia M., Campos O.S., Tabyaoui M., Garcia A.J., Bellaouchou A., Amin H.M.

The inhibition effect of a methanolic extract of Chamaerops humilis (CHFE) on the corrosion of low-carbon steel in 1 M HCl solution was evaluated by weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy. The extract was obtained from the fruit seeds by the Soxhlet extraction method. The CHFE demonstrated promising anticorrosive performance, and the inhibition efficiency increased with increasing the concentration of the extract, peaking at 93% at only 500 ppm. Importantly, the inhibitor exhibited a remarkable stability after 48 h of immersion, reaching an efficiency of 94%. The extract revealed a mixed-type inhibitive behavior. In addition, elevating the solution temperature showed a negative influence on the inhibition efficacy. Thermodynamic parameters suggested that the steel dissolution is an endothermic, spontaneous process. In addition, the experimental findings match well with the Langmuir adsorption isotherm and physisorption of the extract prevails. Furthermore, SEM/EDX and UV-Vis analyses demonstrated that the steel surface is protected by the extract molecules, confirming the electrochemical results. Density functional theory (DFT), Fukui function and molecular dynamics (MD) calculations unraveled the nature of inhibitor—metal surface interactions and provided insights into the most favorable electrophilic and nucleophilic active sites of oleic acid, a major constituent of the extract, helping to elucidate the mechanism of corrosion inhibition at the molecular level.

Samee G., Arsalani N., Same S., Navidi G., Esfangare H.K.

Abstract Toxic pharmaceutical pollutants, such as nicotine, represent a significant threat to natural water sources due to their continuous discharge. To address this issue, clay minerals and their composites have demonstrated exceptional adsorptive and remedial capabilities for wastewater purification. This research focused on developing green clay-polymeric adsorbents for the efficient removal of pharmaceutical pollutants from industrial wastewater. The synthesis involves creating halloysite nanotube–polythiophene nanocomposites through a green and cost-effective method using vapour polymerization and a solvent-free, ball-milled technique for the adsorptive removal of nicotine from wastewater. The investigation evaluates the impacts of preparation, modification and environmental conditions on the adsorptive performance of these clay-based nanocomposites compared to pure polythiophene. The polymerization process was evaluated by varying the vapour polymerization holding time for a fixed amount of oxidant (FeCl3) and halloysite nanotube (HNT) to investigate the impacts of monomer vapour exposure time on the polymerization of nanocomposites. Following the characterization of the synthesized adsorbents using various methods, the study investigated the impacts of various parameters (e.g. adsorbent dosage, pH and contact time) on the adsorption capabilities of the materials on a laboratory scale. The results revealed that the incorporation of HNT improved the adsorbing performance of nanocomposites. The pH, absorbent concentration and contact time directly affect nicotine adsorption. Significantly, halloysite–polythiophene 3 with a 2 h polymerization duration demonstrated the maximum adsorption efficacy of 78.94% at pH 10 after a 24 h contact time. The environmentally friendly halloysite-based nanocomposite shows promising potential as an effective adsorbent for pharmaceutical pollutant (nicotine) removal from aquatic environments.

Chinglenthoiba C., Mahadevan G., Zuo J., Prathyumnan T., Valiyaveettil S.

Micro- and nanoparticles of plastic waste are considered emerging pollutants with significant environmental and health impacts at high concentrations or prolonged exposure time. Here we report the synthesis and characterization of a known metal-organic framework (MOF) using terephthalic acid (TPA) recovered from the hydrolysis of polyethylene terephthalate (PET) bottle waste. This approach adds value to the existing large amounts of bottle waste in the environment. Fully characterized zinc-TPA MOF (MOF-5) was used for the extraction and removal of engineered polyvinyl chloride (PVC) and polymethylmethacrylate (PMMA) nanoparticles from water with a high efficiency of 97% and 95%, respectively. Kinetic and isotherm models for the adsorption of polymer nanoparticles (PNPs) on the MOF surface were investigated to understand the mechanism. The Qmax for PVC and PMMA NPs were recorded as 56.65 mg/g and 33.32 mg/g, respectively. MOF-5 was characterized before and after adsorption of PNPs on the surface of MOF-5 using a range of techniques. After adsorption, the MOF-5 was successfully regenerated and reused for the adsorption and removal of PNPs, showing consistent results for five adsorption cycles with a removal rate of 83–85%. MOF-5 was characterized before and after adsorption of PNPs on the surface using a range of techniques. The MOF-5 with PNPs on the surface was successfully regenerated and reused for the adsorption and removal of polymer nanoparticles, showing consistent results for five extraction cycles. As a proof of concept, MOF-5 was also used to remove plastic particles from commercially available body scrub gel solutions. Such methods and materials are needed to mitigate the health hazards caused by emerging micro- and nanoplastic pollutants in the environment.

Radwan E.K., Hemdan B.A., El-Wakeel S.T., Omar R.A., Rashdan H.R., El-Naggar M.E.

Herein, we exploited xanthan gum (XG) and cationic dextran (CD) in designing a novel porous aerogel (XCD) loaded with different concentrations of a new bistriazole derivative (CPSC). The CPSC was deposited into and onto the pores of aerogels. The neat aerogel removed both AB40 dye and Cu2+ efficiently. Adding 0.5 g of CPSC to the neat aerogel (XCD-0.50 sample) improved slightly the adsorption of Cu2+ and has no effect on the adsorption of AB40 dye. XCD-0.50 removed almost completely 10 mg/L of AB40 dye in 10 min using 0.5 g/L at pHi 6 while for Cu2+ longer contact time (90 min) and higher dosage (2.0 g/L) were required to remove 10 mg/L solution at pHi 5. Relative to literature, the Langmuir adsorption capacity of XCD-0.5 toward AB40 dye (436 mg/g) was the highest and toward Cu2+ (60 mg/g) was comparable to others. The aerogel XCD-0.50 was regenerable and reusable for three cycles with reasonable efficiency. By submerging a bacterial solution (106 CFU/mL) in the XCD-0.75 aerogel for 90 min, an impressive 6-log decrease in the number of bacteria was obtained under ideal circumstances. Crucially, toxicity test clearly confirmed that the prepared aerogels had non-toxic impact. Across all investigated bacterial species, XCD-0.75 continuously achieved a 6-log CFU decrease after 180 min, demonstrating its efficacy in the context of disinfection experiment. The results of the study highlight the extraordinary potential of the biopolymer aerogel loaded with CPSC as a potent adsorbent and disinfectant. They show significant removal of toxic trace elements and dyes, along with microbial reduction in industrial wastewater, underscoring the aerogel's potential use in water treatment.

Doyo A.N., Kumar R., Barakat M.A.

Biopolymer-based materials are getting more attention for sustainable development in various applications, such as energy and environmental remediation. Chitosan, cellulose, and alginate are among the most widely studied biopolymers for water treatment. This review presented the applications of modified biopolymers for decontaminating heavy metals in wastewater. This review highlighted biopolymers' origin, preparation, alteration, and applications for heavy metal removal in the past decade. The chemically modified or synthesized composites based on chitosan, cellulose, and alginate biopolymers have been discussed in detail. The adsorption behavior of the heavy metals onto modified biopolymeric adsorbents concerning kinetics, isotherms, and regeneration has been presented. The review highlighted potential future research directions that could lead to developing biopolymeric composites more effective for pollutant removal from wastewater. Utilizing biopolymers and their composites as a potential alternative adsorbent to remove pollutants from the industrial effluent minimizes commercial adsorbents' cost and assures environmental sustainability. Many studies report potential applications of biopolymers and their composites to remove heavy metals from wastewater in a single pollutant system. Considering this, more research is necessary to examine the possible applications of biopolymeric composites on binary or multi-pollutant processes.

Waliullah R.M., Islam Rehan A., Eti Awual M., Islam Rasee A., Chanmiya Sheikh M., Shad Salman M., Sohrab Hossain M., Munjur Hasan M., Tul Kubra K., Nazmul Hasan M., Marwani H.M., Islam A., Rahman M.M., Abdul Khaleque M., Rabiul Awual M.

The prevalence of dyes in aquatic environments raises severe concerns on a global scale. Methyl orange (MO) is a typical anionic organic dye, which is widely used in industrial wastewater such as textile and paper making. Then the treatment of water contaminated with dyes is an important aspect. The recent decade has witnessed adsorption technology emerging as an advanced dye wastewater treatment with great potential and a grand blueprint, in which the specific surface area and active sites of the adsorbent are considered to be the two most important characteristics largely impacting the adsorption performance. In this study, chitosan-treated nanocomposite was prepared as an effective adsorbent for the removal of MO from contaminated water. The dye removal parameter was performed according to the solution acidity, reaction time, initial concentration, competing for ion affinity, maximum adsorption capacity, and reuse with potential use. The solution pH played a key role in MO dye removal and a suitable pH of 7.0 was selected according to high adsorption ability. The adsorption results were highly fitted with the Langmuir adsorption isotherm model and the maximum adsorption was 172.17 mg/g. The results revealed that introducing chitosan could improve the adsorption capacity and rate effectively even though sacrificing part of specific surface areas of the cotton, indicating that active sites might play a dominant role during the MO adsorption. In addition, the fabricated nanocomposite adsorbent was recycled rapidly by the eluent and regenerated simultaneously, which exhibited the advantages of easy operation as a potentially cost-effective material. The chitosan-based nanocomposite displayed high reusability based on the elution and simultaneous regeneration ability. Therefore, as a cheap green nanocomposite adsorbent with high adsorption performance for MO, chitosan-based fibrous nanocomposite adsorbent is expected to become one of the best candidate materials for future industrial wastewater treatment.

Fite M.C., Karse S.D., Gode L.M.

Kumari S., Siingh S., Priyadarshanee M., Das S.

Neisan R.S., Cata Saady N.M., Bazan C., Zendehboudi S.

Abdelaziz M.M., Abdelaziz M.A., Omer N., Jame R., Alamri E.S., Mohamed E.I., Eledum H., Alhuwaiti A.M., Al-Balawi R.S., Al-Qarni G.

Elwakeel K.Z., Muhammad R.M., Alghamdi H.M., Elgarahy A.M.

Mirizadeh S., Casazza A.A., Converti A.

Gabr S.S., Fayad E., Binjawhar D.N., Keshawy M., El Sayed I.E., Moghny T.A., Mubarak M.F.

Huang J., Shen X., Lin J., Zhou J., Li Y.

Mahgoub S.M., Alawam A.S., Rudayni H.A., Allam A.A., Radalla A.M., Tawab D.A., Mahmoud R.

Rizvi H.I., Mushtaq A., Iqbal T., Afsheen S., Ashfaq Z., Al-Zaqri N., Warad I.

Sari N.K., Nugraha R.E., Ernawati D., Sari K.N., Lestari W.D., Tauviqirrahman M., Ammarullah M.I.

Tsauria Q.D., Gareso P.L., Tahir D.

Abstract Water contamination from heavy metals and synthetic dyes presents a persistent environmental challenge, necessitating the development of efficient and sustainable remediation strategies. This review critically evaluates chitosan-based adsorbents, focusing on chitosan-activated carbon composites, and explores recent breakthroughs in structural and functional modifications that enhance their adsorption capacity. Innovations such as nanoparticle integration, Metal-Organic Frameworks (MOFs), bio-based reinforcements, and surface functionalization have significantly improved selectivity, adsorption kinetics, and regeneration potential, enabling greater adaptability for wastewater treatment. Additionally, this review highlights the emergence of hybrid water treatment technologies, including adsorption-assisted photocatalysis, electrochemical regeneration, and nanostructured filtration systems, which offer promising solutions for overcoming challenges related to adsorbent stability, scalability, and process efficiency in complex wastewater matrices. The study comprehensively evaluates these advancements, offering insights into material innovations, process optimization strategies, and their alignment with circular economy principles for sustainable water treatment applications. Future research should prioritize enhancing long-term adsorbent stability, improving regeneration efficiency, and integrating predictive modeling techniques to bridge the gap between laboratory advancements and large-scale implementation.

Singh J., Bhattu M., Brar S.K., Jadeja R.

Pinto Leal R.V., Lima Sobrinho R.A., Souza M.T.

Di Vincenzo A., Madonia E., Librici C., Bambina P., Chillura Martino D., Guernelli S., Lo Meo P., Conte P.

This study investigates the functionalization of a poplar biochar (PB), obtained by high-temperature pyrolysis, under oxidative conditions typically used in organic synthesis. In particular, concentrated nitric acid, a sulfonitric mixture and a piranha mixture were applied as oxidants at different temperatures and reaction times. In order to assess the outcome of the reaction conditions on the characteristics of the resultant products, these were characterized by a combination of imaging (SEM), spectroscopic (ATR-FTIR, RAMAN) and FFC-NMR relaxometric techniques. The latter techniques, rationalized in terms of the Kohlrausch-type stretched exponential kinetic model, were analyzed using a recently developed heuristic Monte Carlo method, providing insights into the water dynamics within material pore networks. Additionally, the water-holding capacity of the modified biochars and their abilities to adsorb some model dyes were evaluated. The results clarify the relationship between oxidative treatment conditions and biochar properties, highlighting their impact on both structural modifications and water dynamics within the porous network, and enabling us to identify the best reaction conditions for optimizing the features of the oxidized product.