Removal Efficiency Research Articles

Polysaccharides and Composite Adsorbents in the Spotlight for Effective Agrochemical Residue Removal from Water

Agrochemical residues, including pesticides and herbicides, pose significant environmental and health risks when present in water sources. Conventional water treatment methods often fall short in effectively removing these persistent pollutants, necessitating innovative solutions. This review explores the use of polysaccharides and composite adsorbents as sustainable alternatives for agrochemical residue removal from water. Biopolymers such as chitosan, alginate, and cellulose are highlighted for their biodegradability, biocompatibility, and ability to be functionalized for enhanced adsorption performance. Recent advances in the development of composite materials incorporating nanomaterials, such as graphene, oxide, and metal oxides, have shown significant promise in enhancing the efficiency and selectivity of agrochemical adsorption. The review also addresses the fundamental mechanism of adsorption, such as electrostatic interactions, hydrogen bonding, and hydrophobic forces, that contribute to the effectiveness of these materials. Challenges associated with scalability, regeneration, and real-world applications are discussed, as well as future opportunities for integrating emerging technologies like 3D printing and machine learning into adsorbent design. Overall, polysaccharides and composites offer a promising pathway toward achieving efficient and sustainable agrochemical residue removal, with ongoing research needed to overcome current limitations and optimize their practical application in water treatment.

Selective and Efficient Phosphate Removal Using Ca–La Layered Double Hydroxide-Functionalized Sludge Biochar

Selective and Efficient Phosphate Removal Using Ca–La Layered Double Hydroxide-Functionalized Sludge Biochar

Synthesis and application of pH- and thermoresponsive PVCL-PVA hydrogel/MWCNTs nanocomposite for efficient removal of methylene blue from water solutions

Synthesis and application of pH- and thermoresponsive PVCL-PVA hydrogel/MWCNTs nanocomposite for efficient removal of methylene blue from water solutions

Resource Recovery from Abandoned Mine Drainage Galleries via Ion Exchange: A Case Study from Freiberg Mining Area, Germany

The discharge of metal-loaded mining-influenced waters can significantly pollute downstream water bodies for many kilometers. Addressing this issue at the earliest discharge point is crucial to prevent further contamination of the natural environment. Additionally, recovering metals from these discharges and other sources of contamination can reduce the environmental impacts of mining and support the circular economy by providing secondary raw materials. This study focused on optimizing zinc recovery from mining-influenced water in the Freiberg mining region in Germany, where significant loads of zinc are released into the Elbe River. By employing pretreatment techniques, conducting 100 mL scale ion-exchange column experiments, and refining the regeneration process, we aimed to identify optimal conditions for efficient zinc removal and recovery. Initial tests showed that aminophosphonic functionalized TP 260 resin had a high affinity for aluminum, occupying 93% of the resin’s capacity, while zinc capacity was limited to 0.2 eq/L. To improve zinc recovery, selective precipitation of aluminum at pH 6.0 was introduced as a pretreatment step. This significantly increased the zinc loading capacity of the resin to 1 eq/L. Under optimal conditions, a concentrated zinc solution of 18.5 g/L was obtained with 100% recovery. Sulfuric acid proved more effective than hydrochloric acid in eluting zinc from the resin. Further analysis using SEM-EDX revealed residual acid on the resin, indicating a need for additional study on long-term resin performance and capacity variation. The research also highlighted the environmental impact of the Freiberg mining area, where three drainage galleries currently contribute nearly 85 tons of zinc annually to the Elbe River. This study underscores the feasibility of efficient zinc recovery from these point sources of pollution using advanced ion-exchange processes, contributing to circular economy efforts and environmental conservation.

Efficient removal of perfluorooctanoic acid from aqueous matrices using cationic surfactant functionalized graphene oxide nanocomposite: RSM and ANN modeling, and adsorption behaviour

Perfluorooctanoic acid (PFOA), a persistent and recalcitrant emerging organic contaminant, has garnered worldwide attention due to its pervasiveness and strong bioaccumulation, emphasizing the urgent necessity for effective removal strategies. To address PFOA contamination in the global aquatic environment, this study prepared cetyltrimethylammonium bromide (CTAB)-functionalized graphene oxide (GO-C) nanocomposites. The functionality of GO-C is controlled by varying loading ratios of CTAB to achieve satisfactory performance. After preliminary experiments that confirmed the superior performance of GO-C0.5 in PFOA removal, the response surface methodology (RSM) revealed the effects of different process parameters, which followed the sequence: adsorbent dose > pH > time. The optimum PFOA removal of 98.5 % was achieved at adsorbent dose: 200 mg/L, pH: 3.5, and time: 50 min, at an experimental temperature of 298 K. Furthermore, a predictive model using an artificial neural network was developed for PFOA adsorption, which closely aligns with the experimental data (R2: 0.9999). The PFOA adsorption was most accurately represented by Freundlich isotherm (R2: 0.9747) and pseudo-second-order kinetics (R2: 0.9995), with a maximum experimental adsorption capacity of ~709.94 mg/g under RSM optimized conditions. The adsorption mechanism involves electrostatic and hydrophobic interactions and hydrogen bonding, as confirmed by the spectroscopic and zeta potential analyses. Lastly, the competitive adsorption and regeneration experiments underscore the potential of GO-C nanocomposite in removing PFOA. Overall, this study provides insights into the development and application of sustainable and promising adsorbent for the removal of PFOA in wastewater stream.

Efficient removal of nitrate and ammonium by strain Pseudomonas poae EH-E3 under acidic pH and low-temperature conditions

The combined effect of low temperature and an acidic environment may restrict the growth and metabolic activity of microorganisms involved in nitrogen removal. To overcome poor biological nitrogen removal efficiency during low-temperature treatment of acidic wastewater, a novel pure strain of Pseudomonas poae EH-E3 was successfully isolated and screened based on its strong heterotrophic nitrification and aerobic denitrification capacity. Strain EH-E3 could completely eliminate inorganic nitrogen sources of nitrate within 30h and ammonium within 20h at 15 °C and pH 5.0, with corresponding removal efficiencies for total nitrogen of 95.13% and 91.35%, respectively. Nitrogen balance testing indicated that strain EH-E3 removed 43.25% of ammonium, 45.72% of nitrate, and 51.20% of nitrite in the form of gaseous products. Enzyme activity assays revealed that the specific activities of ammonia monooxygenase, nitrate reductase, and nitrite reductase were 0.533, 0.956, and 0.011 U/mg proteins, respectively. These findings suggest that strain EH-E3 has strong potential for use in low-temperature treatment of acidic wastewater.

Spherical sponge-inspired design of chitosan/silver cluster-loaded cellulose nanofibrils/Cu-ZIF-8 gel beads for efficient removal of Cr(VI)

Traditional photocatalysts for Cr(VI) often suffer from low catalytic activity, difficult separation and recovery, and weak stability. To address these limitations, we proposed a spherical sponge-inspired design to construct chitosan/silver cluster-loaded cellulose nanofibrils/Cu-ZIF-8 gel beads (CSCZ). This design featured a chitosan-based gel bead (the shell of the spherical sponge), silver cluster-loaded cellulose nanofibrils (the flagella of the spherical sponge), and Cu-ZIF-8 (the collar cell of the spherical sponge), which collectively endowed the CSCZ with remarkable properties. These included a high adsorption capacity (171.2 mg/g), a notable rate constant (0.2812 min−1), and enhanced stability (retaining 84.9 % of its initial removal rate after 10 cycles). In addition to the structural design, the “adsorption–reduction” synergy significantly enhanced Cr(VI) removal efficiency, as confirmed by both experimental characterizations and theoretical calculations. Furthermore, the CSCZ was utilized to treat industrial wastewater, and a custom-built flow-through reactor packed with CSCZ demonstrated the efficiency and practicability of CSCZ. This study demonstrates CSCZ’s potential to efficiently remove Cr(VI) and advances the development of photocatalytic adsorbents inspired by spherical sponge concepts.

Biochar as an Enzyme Immobilization Support and Its Application for Dye Degradation

Wastewaters generated by the textile industry often contain significant amounts of harmful (carcinogenic and mutagenic) cationic dyes, whose efficient removal is of crucial importance. This study investigates the laccase immobilization on biochar obtained from sour cherry stones (SCS-B), as a cost effective adsorbent, and evaluates its application for brilliant green (BG) degradation. The successful immobilization of laccase on biochar was achieved via adsorption and confirmed using scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and Fourier transform infrared spectroscopy (FTIR). An immobilization efficiency of 66% was achieved using 0.274 U/mL of laccase at pH 5 and a temperature of 40 °C. The adsorption kinetics of laccase followed a pseudo-second-order model, indicating that chemical adsorption plays a significant role in the immobilization process. The BG degradation by immobilized system was further optimized by evaluating effects of pH, temperature, dye concentration, and contact time. More than 92% of BG (50 mg/L) was removed within 4 h at pH 5 and temperature of 30 °C. These findings suggest that SCS-B can effectively be used as an enzyme carrier and be further utilized for the removal of emerging pollutants, positioning it as a sustainable solution for wastewater treatment.

FeOx-carbon composite-based catalytic degradation of bisphenol-A in heterogeneous Fenton system: Structure regulation mechanism of different Fe precursors and natural organic acids

Bisphenol A (BPA) is ubiquitous in the environment and can cause human health risks; therefore, its efficient removal from the environment is an essential issue. Catalytic degradation of BPA in heterogeneous Fenton oxidation system (HFO) is of great concern; however, trials for improving the reactivity of HFO are needed. The impacts of Fe precursors and crystalline structure of Fe oxides on the reactivity of FeOx-based carbon composites (FeCC) and their efficient catalytic degradation of BPA have not yet been explored. Also, the promoting effect of different natural organic acids (NOAs) on the degradation mechanisms of BPA using FeCC in HFO has not yet been verified. Therefore, five FeOx-carbon (biochar; BC) composites i.e. FeCl3@BC, FeCl2@BC, FeNO3@BC, Fe2(SO4)3@BC, and FeSO4@BC derived from different Fe salt (e.g. FeCl3, FeCl2, FeNO3, Fe2(SO4)3, and FeSO4, respectively) were prepared, characterized using advanced techniques, and used as catalysts for BPA degradation in HFO, as affected by NOAs addition. FeCl3@BC showed the highest BPA degradation efficiency (˃ 99.9 %), within 1 min; while it was <20 %, within 10 min, for all FeCC, particularly FeSO4@BC (<10 %). BPA degradation using FeCl3@BC was ˃ 99.9 % at pH = 3, 38.5 % at pH = 5, and <1.0 % at pH = 7–9. Addition of NOAs significantly improved the efficiency of FeSO4@BC for BPA degradation under a wide range of pH (3–9). The complexation and reduction capacities of NOAs significantly promoted the Fe3+/Fe2+ cycle, improving the degradation efficiency of BPA. Four types of reaction intermediates (C15H16O3, C15H16O4, C9H12O3, C9H10O4) were generated during degradation. This work sheds lights on development of FeCC for BPA catalytic degradation.

Synthesis of palygorskite based microspheres for efficient and recyclable simultaneous removal of radioactive iodine and iodide

Synthesis of palygorskite based microspheres for efficient and recyclable simultaneous removal of radioactive iodine and iodide

Fe (II)/Fe (III) regulated adaptive biofilm responses and microbial metabolic mechanisms for enhanced cycloalkane biodegradation

Oxidation of organic contaminants by iron-cycling microorganisms is an effective remediation strategy for contaminated environments. However, studies on the removal of cycloalkane using this method have been limited, and little is known about how microbes adapt to iron concentrations and how the latter stimulates contaminant degradation. Here, we investigated the biodegradation of cyclohexane (CyH) in three sequencing batch bioreactors (SBRs) with different iron concentrations (SBRs are named: Low 2.5 μM, Suit 7.5 μM, High 75 μM). The Suit reactor showed a more efficient CyH removal performance (average 98.61 ± 0.62 %) than the Low reactor (average 55.75 ± 3.38 %), which was associated with more extracellular polymeric substances (EPS) release and improved biofilm structure. The High reactor exhibited a gradual adaptation process due to the apparent accumulation of reactive oxygen species (ROS) under iron stress, with an average removal efficiency of (86.83 ± 18.81 %). However, the High reactor had a higher microbial activity (1.08-fold increase in ATPase activity) and electron transport system activity (1.18-fold increase) to facilitate direct electron transfer in the presence of insoluble iron compared to the Suit one, largely due to the dominant genus Novosphingobium. Metagenomics and metatranscriptomics analyses revealed lactone (a key intermediate) formation as a potential degradation pathway across three SBRs in our study under iron regulation. Notably, there were differences in the key functional genes expressed under different iron concentrations: genes related to anti-oxidative stress and iron-driven pathways, biofilm regulation-related pathways, and encoding protein complexes III and IV were found in the High, Suit, and Low reactors, respectively. This study enhances understanding of microbiota adaptation mechanisms to iron-disturbed conditions and provides a new insight into iron-cycling mediated biofilm formation and inhibition.

Acetic acid-modified nitrogen-doped biochar loaded Fe-Co bimetal promotes persulfate activation for efficient quinoline removal and its 1O2 and O2•- pathways

Acetic acid-modified nitrogen-doped biochar loaded Fe-Co bimetal promotes persulfate activation for efficient quinoline removal and its 1O2 and O2•- pathways

Melamine-Derived Mesoporous Carbon for Efficient and Selective Removal of Trace Hg(II) from Honeysuckle Decoction

Melamine-Derived Mesoporous Carbon for Efficient and Selective Removal of Trace Hg(II) from Honeysuckle Decoction

Efficient nitrogen removal and stable operation of a dynamic membrane bioreactor (DMBR) for landfill leachate treatment

Efficient nitrogen removal and stable operation of a dynamic membrane bioreactor (DMBR) for landfill leachate treatment

Evaluation of large-scale poultry manure-derived biochar for efficient cadmium removal in zinc smelter wastewater

Cadmium (Cd), a carcinogen, is released from industrial activities like metal refineries and battery runoff, with significant contamination reported near zinc smelters in Korea. This study addresses the issue using an efficient, economical adsorption process with waste-derived biochar-based adsorbents known for high Cd removal. Poultry manure (PM), typically used as fertilizer, can lead to environmental pollution if mismanaged; therefore, it was pyrolyzed to produce biochar. The resulting poultry manure biochar (PMBC) was produced on a large scale (15 ton/day), demonstrating feasibility for large-scale implementation. The effectiveness of PMBC as an adsorbent for Cd was evaluated using wastewater discharged from a zinc smelter. The Cd adsorption capacity of PMBC (60.39 mg/g) was lower than that (302.0 mg/g) of hen manure biochar produced at a laboratory scale in our previous study but was comparable to other biochars reported in the literature. Response surface methodology analysis indicated that reaction time, dose, and agitation significantly influenced Cd removal by PMBC, whereas pH had a negligible impact. Notable contributions to Cd adsorption include the release of K+ from PMBC and the presence of O-containing functional groups. Under continuous flow conditions with real wastewater, Cd was not detected in the effluent for the initial 8 h, and PMBC sustained a removal efficiency of 40.77% until saturation was reached. The results from wastewater treatment and large-scale biochar production offer valuable insights into the potential of biochar as a medium for addressing environmental issues in real-world applications.

Polarized electric field-mediated graphitic carbon nitride-based S-scheme heterostructure for efficient photocatalytic removal of bisphenol A

Polarized electric field-mediated graphitic carbon nitride-based S-scheme heterostructure for efficient photocatalytic removal of bisphenol A

Capacitive deionization exploiting La-based LDH composite electrode toward energy efficient and selective removal of phosphate

Capacitive deionization (CDI) is a promising technology for removing phosphate from wastewater. Its practical implementation is however hindered by the constraints on the electrode materials. To boost the adsorption capacity, phosphate selectivity, and cost-effectiveness of the electrode, this study proposed a composite electrode blending Lanthanum-based layered double hydroxide (CaLa LDH) and activated carbon (AC). It capitalizes on the synergistic effects of electric double layer capacitance (EDLC) of AC and the diffusion-controlled charge storage (pseudocapacitive behavior) of CaLa LDH. By optimizing the mass ratios of the constituents and the electrode material loading capacities, the composite electrode AC/Ca-La LDH-5020 was developed, which contains 20 mg of 50 wt% CaLa LDH. This composition achieved a remarkable phosphate adsorption capacity of 34.8 mg P /g and a low energy consumption of 0.0051 kWh/g P in constant voltage (CV) mode. It represented a 241 % increase in adsorption capacity (mg P/g) and 71 % decrease in specific energy consumption (kWh/g P) compared to the electrode made solely of AC. Particularly the moderate inclusion of Lanthanum contributes to its cost-effectiveness. Moreover, further studies extensively examined the impacts of electrical driving force, including applied voltage in constant current (CC) mode and applied current in constant voltage (CV) mode, on the phosphate removal efficiency. The composite electrode remained stable performance with the presence of the high content of coexisting anions (e.g.，Cl−，SO42−, HCO3−, NO3−), obtaining high selectivity coefficient of phosphate over other anions. This study highlighted the practical potential of AC/Ca-La LDH composite electrode for advancing CDI technology for phosphate removal in an efficient, energy-saving and cost-effective manner.

In situ construction of Flowerlike bismuth oxide (BiO2-x)/N-rich carbon nitride (C3N5) S-scheme heterojunctions with enhanced structural defects for the efficient photocatalytic removal of tetracycline antibiotic and RhB

Efficient photocatalysts for the simultaneous removal of organic dyes and antibiotics are crucial for sustainable environmental management. In this study, we designed and synthesized a C3N5/BiO2-x S-type heterojunction photocatalyst with structural defects using a hydrothermal method, aimed at degrading both Rhodamine B (RhB) and tetracycline (TC). The degradation kinetic constants for RhB and TC were 0.0809 min−1 and 0.0535 min−1, respectively, showing improvements of 9.52 and 25.48 times over pure C3N5, and 2.90 and 1.49 times over BiO2-x. This enhanced performance is attributed to the unique electron transfer mechanism of the S-scheme heterojunction and the structural defects that facilitate efficient separation of electron-hole (e−-h+) pairs. Free radical trapping experiments indicated that the main reactive oxygen species (ROS) involved are ·O2− and h+. Additionally, electrochemical impedance spectroscopy (EIS) and transient photocurrent response (TPR) measurements confirmed improved separation and transfer of photogenerated e−-h+ pairs in the C3N5/BiO2-x heterojunction. The higher density of structural defects in C3N5/BiO2-x compared to individual BiO2-x counterparts enhances its ability to activate and photo-oxidize TC and degrade RhB. Consequently, C3N5/BiO2-x demonstrates significant potential as a photocatalyst for improving water quality.

Amino acid functionalized carboxymethyl cellulose-based crosslinked aerogels for efficient removal of dye and metal ion from aqueous solution

Amino acid functionalized carboxymethyl cellulose-based crosslinked aerogels for efficient removal of dye and metal ion from aqueous solution

Synthesis of cubic mesoporous silica SBA16 functionalized with carboxylic acid in a one-pot process for efficient removal of wastewater containing Cu2+: Adsorption Isotherms, Kinetics, and Thermodynamics

Synthesis of cubic mesoporous silica SBA16 functionalized with carboxylic acid in a one-pot process for efficient removal of wastewater containing Cu2+: Adsorption Isotherms, Kinetics, and Thermodynamics