Simultaneous Removal Research Articles

Simultaneous Removal of Strontium, Manganese, Lead and Arsenate from Wastewaters Using a Green and Low-Cost Adsorbent Derived from Nut Residues

The potential of a nut residue, activated only by physical means, to simultaneously adsorb Sr2+, Mn2+, Pb2+ and As5+ from contaminated waters was investigated. Mono-metal and multi-metal adsorption behavior and adsorption capacities by the solid material were compared for a range of initial metals concentrations, adsorbent dose, contact time and solution pH. The mechanisms of adsorption were examined by conducting structural, mineralogical and chemical analyses and applying two isotherm models to simulate experimental data. In the case of mono-metal adsorption, the maximum uptake of Sr2+ by the biochar was 12.3, of Mn2+ 23.8, of Pb2+ 24.7 and of As5+ 12.4 mg/g. In the case of multi-metal adsorption, the uptake of each metal was enhanced as the total ion flux density increased, revealing that there was no competition between these ions for biochar’s sorption sites. For an adsorbent dose of 2 g/L, the maximum adsorption capacity of biochar for Sr2+, Mn2+, Pb2+ and As5+ could be raised up to 47.6, 49.9, 25 and 48.7 mg/g, respectively. Potential adsorption mechanisms were chemical complexation or electron coordination between the metals and the biochar matrix, as well as mineral precipitation on the adsorbent surface.

A new carbon-negative hydrogen production cycle for better sustainability

Carbon dioxide removal is considered by many as an essential piece to achieve global net zero targets which was also mentioned by the third working group of Intergovernmental Panel on Climate Change. On top of this, green hydrogen is badly needed to achive carbon-free society long-term sustainability. This study proposes a new five-step sodium hydroxide thermochemical cycle for simultaneous hydrogen production and carbon dioxide removal, which is driven by the heat at least 400 °C. The proposed integrated cycle can be driven by clean energy sources that can be utilized to generate heat at required temperatures. The proposed system is designed and analyzed by using energy and exergy approaches of thermodynamics. A case study is also developed in order to understand the effects of changing parameters on system performance. A thermochemical hydrogen production cycle is designed with an unequilibrium reaction where the respective heat capacity calculation models are employed. According to the calculations, more than half of the energy content of process heat can be converted into hydrogen, where maximum energy and exergy efficiencies of the thermochemical cycle are found as 50.05% and 76.61% when the separation reaction is carried out at 400 °C. According to the case study results, a parabolic trough collector type concentrated solar energy system with 295 kW of heat sink capacity, can generate 5216.65 kg of hydrogen and capture 19,991.97 kg of carbon dioxide in a location where 1500.11 kWh of solar energy is reached per m2 of area in a typical year.

Simultaneous electrochemical removal of three microcystin congeners and sulfamethoxazole in natural water

Microcystins (MCs), frequently detected in freshwater ecosystems, have raised significant human health and ecological concerns. New approaches are being developed to control and remove MCs. In this study, we examined factors influencing the efficacy of electrochemical oxidation as a means of control. Anode material (Pt/Ti, Ta2O5-IrO2/Ti, SnO2-SbO2/Ti, boron-doped diamond (BDD)/Si), anode surface area ratios and solution volumes, initial pollutant concentrations, and the co-existing antibiotic sulfamethoxazole (SMX) were investigated. MCs and SMX were dissolved in filtered Taihu Lake water to simulate the natural aquatic environment. The results showed that non-active anodes, lower initial concentration of MC, larger surface area ratio of anode to cathode, and smaller ratio of reaction solution volume to anode surface area could promote the degradation target pollutants. Under optimal conditions in this study, the degradation rates of MC-LR, MC-YR, MC-RR, and SMX each reached more than 90% within 6 hours, and the removal efficiency of MC-YR was the highest among three congeners. The effect of SMX on the degradation of MC congeners depended mainly on their concentration differences, such that when the initial concentration of SMX was one to two orders of magnitude lower than microcystin, the presence of SMX would promote the degradation of MCs. In contrast, when the initial concentration of SMX was higher than that of microcystin by approximately an order of magnitude, sulfamethoxazole would inhibit the degradation of MCs by between 4.6% and 24.5%. Ultra-high-performance liquid chromatography tandem mass spectrometry analysis revealed that the three MC congeners were electrochemically degraded through aromatic ring oxidation, alkene oxidation, and bond cleavage on the ADDA (3-amino-9-methoxy-2,6,8-trimethyl-10-phenyldeca-4,6-dienoic acid) side chain. Notably, the removal of MCs was accompanied by a decline in the hardness of the reaction water. This study provided insights into electrochemical degradation of microcystins and antibiotics in natural water, offering suggestions for its practical application.

Performance of a pilot-scale microbial electrolysis cell coupled with biofilm-based reactor for household wastewater treatment: simultaneous pollutant removal and hydrogen production.

The septic tank is the most commonly used decentralized wastewater treatment systems for household wastewater treatment in on-site applications. The removal rate of various pollutants is lower in different septic tank configurations. The integration of a microbial electrolysis cells (MEC) into septic tank or biofilm-based reactors can be a green and sustainable technology for household wastewater treatment and energy production. In this study, a 50-L septic tank was converted into a 50-L MEC coupled with biofilm-based reactor for simultaneous household wastewater treatment and hydrogen production. The biofilm-based reactor was integrated by an anaerobic packed-bed biofilm reactor (APBBR) and an aerobic moving bed biofilm reactor (aeMBBR). The MEC/APBBR/aeMBBR was evaluated at different organic loading rates (OLRs) by applying voltage of 0.7 and 1.0V. Result showed that the increase of OLRs from 0.2 to 0.44kg COD/m3 d did not affect organic matter removals. Nutrient and solids removal decreased with increasing OLR up to 0.44kg COD/m3 d. Global removal of chemical oxygen demand (COD), biochemical oxygen demand (BOD), total nitrogen (TN), ammoniacal nitrogen (NH4+), total phosphorus (TP) and total suspended solids (TSS) removal ranged from 81 to 84%, 84 to 85%, 53 to 68%, 88 to 98%, 11 to 30% and 76 to 88% respectively, was obtained in this study. The current density generated in the MEC from 0 to 0.41 A/m2 contributed to an increase in hydrogen production and pollutants removal. The maximum volumetric hydrogen production rate obtained in the MEC was 0.007 L/L.d (0.072 L/d). The integration of the MEC into biofilm-based reactors applying a voltage of 1.0V generated different bioelectrochemical nitrogen and phosphorus transformations within the MEC, allowing a simultaneous denitrification-nitrification process with phosphorus removal.

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

Simultaneous removal of vanadium and nitrogen in two-stage vertical flow constructed wetlands: Performance and mechanisms.

Vanadium (V(V)) and nitrate, as co-concomitant pollutants in water bodies, pose potential threats to the eco-environment and human health. This study was to reveal the feasibility of simultaneous removal of V(V) and nitrate in the series-wound vertical flow constructed wetlands (CWs) with iron ore (B-CWs)/manganese ore (C-CWs)-wood substrates. The results showed that B-CWs could achieve efficient V(V) and NO3--N removal with the influent of 2 and 10 mg/L (V(V)/NO3--N=1:5), respectively. With the increase of V(V)/NO3--N ratio (V(V)/NO3--N=1:1), B/C-CWs exhibited better combined pollution removal. Even when nitrate was removed (V(V)/NO3--N=1:0), the systems could maintain a good capacity for V(V) removal. High V(V) (20 mg/L) significantly inhibited V(V) removal, with a slight recovery of the performance as the decrease of V(V) influent. High NO3--N concentration (10 mg/L) effectively enhanced V(V) removal and restored C-CWs to the better level. V(IV) precipitates/oxides were the main reducing end-products. High abundance of V(V)-reducing bacteria and iron/manganese cycling pumps ensured efficient V(V) removal.

Nano-Fe3O4/FeCO3 modified red soil-based biofilter for simultaneous removal of nitrate, phosphate and heavy metals: Optimization, microbial community and possible mechanism

Nano-Fe3O4/FeCO3 modified red soil-based biofilter for simultaneous removal of nitrate, phosphate and heavy metals: Optimization, microbial community and possible mechanism

Reaction site-isolation for simultaneous removal of NO and toluene: A reverse strategy to realize bifunctional catalysis

Reaction site-isolation for simultaneous removal of NO and toluene: A reverse strategy to realize bifunctional catalysis

Amino-enriched Zn-MOFs with self-reduction for energy-free simultaneous removal and electrochemical detection of heavy metal ions in the aquatic environment

Amino-enriched Zn-MOFs with self-reduction for energy-free simultaneous removal and electrochemical detection of heavy metal ions in the aquatic environment

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.

Novel fluorescent carbon dots derived from shikimic acid for ultra-high sensitive detection and efficient removal of sulfasalazine

The extensive use of sulfasalazine (SSZ) poses potential threats to human health and ecosystems. Therefore, sensitive detection and simultaneous efficient removal of sulfasalazine is greatly desirable. Meanwhile, shikimic acid, a natural product obtained from Chinese star anise is a promising precursor for carbon dots construction due to its unique structure. Taking the above into account, in this work, novel fluorescent carbon dots (SA-CDs) for sensitive detection and highly efficient removal of sulfasalazine have been developed. SA-CDs were facilely obtained from shikimic acid by using one-pot hydrothermal synthesis. The structure and composition of SA-CDs were fully characterized with TEM, PXRD, FT-IR, DLS and XPS tests. Strong fluorescent emission centered at 428 nm was recorded for SA-CDs, enabling the detection of SSZ. Quantitatively speaking, SA-CDs can selectively detection SSZ amount 17 antibiotics with an experimental limit of detection (LOD) of 100 nM and a calculated LOD of 60 pM. Adsorption experiments suggested that chemical monolayer adsorption predominates in the adsorption process, with a maximum adsorption capacity of 22.67 mg/g. Aggregations formed during detection enable the simultaneous removal of SSZ upon centrifugation. Moreover, SA-CDs have been successfully applied to the detection of SSZ in real samples, including river water, soil, tea and eggs.

Pilot-scale bioremediation of rare earths wastewater by Chlamydomonas sp. YC

The extraction of rare earth elements (REEs) through in-situ leaching with ammonium sulphate [(NH4)2SO4] had resulted in the production of a large volume of ammonium-rich wastewater, causing severe environmental pollution. This study aimed to assess the ability of an indigenous microalga Chlamydomonas sp. YC, isolated from REEs wastewater, to directly treat real REEs wastewater under outdoor conditions in 50 L airlift photobioreactors (AL-PBRs) and 5.0 m3 open race-way photobioreactors (ORWPs). Additionally, the harvested Chlamydomonas sp. YC biomasses from these two pilot photobioreactors were comprehensively analyzed to evaluate the nutritional values. The results showed that Chlamydomonas sp. YC in AL-PBRs exhibited higher biomass production (1.1 g/L), greater removal efficiencies in NH4+-N (24.9%) and total nitrogen (20.4%), as well as higher CO2 fixation rate (125.0 mg/(L·d)), compared to those of ORWPs. Moreover, the Chlamydomonas sp. YC biomasses obtained from the two pilot photobioreactors contained 44.5% and 49.4% protein, 9.1% and 14.3% lipids. Moreover, Chlamydomonas sp. YC in the two pilot photobioreactors displayed essential amino acid indexes (EAAI) of 0.900, which was higher than that of soybean protein (0.657), indicating superior nutritional values. In conclusion, the implementation of the process involving Chlamydomonas sp. YC in AL-PBRs under outdoor conditions holds promise as a coupled microalgal biotechnology for the simultaneous removal of NH4+-N from REEs wastewater, and the capture of CO2 for the production of valuable biomass.

Simultaneous removal of Pb(II) and Cr(VI) from a steel company wastewater using various green adsorbents: Material characterization and numerical optimization

ABSTRACT This study focuses on the simultaneous uptake of Pb(II) and Cr(VI) from industrial wastewater by walnut shell (WS), almond shell (AS), peanut shell (PS), and coconut shell (CS) adsorbents. Among the used adsorbents, the CS adsorbent exhibited the greatest BET surface area of 18.97 m2/g and porosity of 63.17% and the WS adsorbent also had the highest pore volume of 0.3536 m3/g. Lead and chromium removal were optimized using response surface methodology via a central composite design (CCD) approach. The efficiency of lead and chromium uptake from the wastewater was enhanced by increasing the concentration of WS, AS, PS, and CS adsorbents (Cads.) and decreasing the flow rate (Q) of the wastewater. Under the optimal conditions (Cads. = 0.85 g/L and Q = 2.5 mL/min), the maximum lead and chromium uptake from steel company wastewater was achieved using CS (92%) and WS (97.2%) adsorbents, respectively. The actual lead and chromium removal values were well-fitted based on a high Rpred2, confirming the validity of the CCD model. The acceptable performance of these green adsorbents in the simultaneous removal of chromium and lead from the wastewater introduces the WS, AS, PS, and CS adsorbents as inexpensive and available candidates for industrial wastewater treatment containing heavy metals.

Removal performance and adsorption behaviour on Mg-based adsorbents in As(III) and F simultaneous removal as in comparison with As(V)

In this study, simultaneous removal tests, with fixed initial arsenic (As) concentration of 1 mg l −1 , for arsenite [As(III)] and fluoride (F) were performed using three types of Mg-based adsorbents. Their As(III) removal performance was of the order of MgCO 3 << Mg(OH) 2 < MgO. MgO met the environmental standards for As (0.01 mg l −1 ) at initial F concentrations ( C F0 ) of 15 and 30 mg l −1 . MgO and Mg(OH) 2 met the As effluent standard (0.1 mg l −1 ) even at C F0 = 60 mg l −1 . In contrast, MgCO 3 did not meet the effluent standards under the test conditions. The F removal performance of the Mg-based adsorbents followed the order of MgCO 3 < Mg(OH) 2 < MgO. MgO and Mg(OH) 2 met the environmental standard of F (0.8 mg l −1 ), whereas MgCO 3 met the effluent standards for F in non-marine areas (8 mg l −1 ) at C F0 = 15 and 30 mg l −1 , and in marine areas (15 mg l −1 ) even at C F0 = 60 mg l −1 . The As(III) adsorption data fit the Langmuir model for MgO and the Freundlich model for MgO and Mg(OH) 2 , but not MgCO 3 for either model. Notably, the As(III) adsorption behaviour of MgO was strongly influenced by C F0 . Meanwhile, the F adsorption data fit both the Langmuir and Freundlich models for all Mg-based adsorbents.

Uncovering pathway and mechanism of simultaneous thiocyanate detoxicity and nitrate removal through anammox and denitrification

Thiocyanate (SCN−) exists in various industries and is detrimental to the ecosystem, necessitating cost-effective and environmentally benign treatment. In response to alleviate the bacterial toxicity of SCN−, this study developed a two-stage coupled system by tandem of anammox in reactor 1 (R1) and SCN−-driven autotrophic denitrification in reactor 2 (R2), achieving simultaneous removal of SCN− and nitrogen. The total nitrogen removal efficiency of the coupled system was 92.42 ± 1.98%, with nearly 100% of SCN− elimination. Thiobacillus was responsible for SCN− degradation. The deduced degradation pathway of SCN− was via the cyanate pathway before coupling, followed by the co-action of cyanate pathway and carbonyl sulfide pathway after coupling. Although scaling-up study is needed to validate its applicability in real-world applications, this study contributes to the advancement of sustainable and cost-effective wastewater treatment technologies, being an attractive path for low-carbon nitrogen removal and greenhouse gas emission-free technology.

Biobased amphoteric aerogel with core-shell structure for the hierarchically efficient adsorption of anionic and cationic dyes

Efficient and simultaneous removal of anionic and cationic dyes from wastewater using low-cost and environmentally-friendly adsorbent is highly required. Herein, the carboxylated cellulose (carboxyl content: 2.97 mmol/g) derived from pomelo peel was extracted by a one-step H2O2/H2SO4-mediated oxidation method. Subsequently, a novel pomelo-peel cellulose/chitosan/sodium alginate (PCS) amphoteric aerogel with a specific core-shell structure was synthesized by multiple physical cross-linking strategies. The shell layer and core layer of the optimized P3CS0.75 aerogel can selectively adsorb cationic dyes and anionic dyes, in which, the theoretical maximum adsorption capacities were 888.27 mg/g and 1816.87 mg/g towards methylene blue (MB) and Congo red (CR), respectively. Especially, the aerogel’s core/shell layer exhibited hierarchical adsorption behavior without overlapping sites even in the binary dye systems. The adsorption performance of obtained amphoteric aerogel remained effective in a wide pH range and under different practical water systems. Moreover, the removal efficiencies for MB and CR were slightly reduced from 90.76 % and 99.66 % to 88.08 % and 91.39 %, respectively, after 5 adsorption-desorption cycles, and the aerogel’s structural integrity was also maintained due to its good compressive strength (487.16 KPa). In addition, the adsorption mechanism of PCS aerogel was investigated using adsorption kinetics, isotherm, thermodynamics, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. It was proved that the adsorption process was endothermic spontaneous-monolayer adsorption driven by electrostatic attraction and hydrogen bonding. Therefore, the prepared biobased aerogel was expected to be a prospective material for removing mixed dyes from wastewater.

Multifunctional lignin-reinforced cellulose foam for the simultaneous removal of oils, dyes, and metal ions from water

Pollutants emitted by industry pose an emerging threat to ecosystems, human health and native species, which has attracted global attention. At present, most of the biomass-based water remediation materials suffer from the poor mechanical properties, complexity of the modification process, single function and low adsorption capacity. Therefore, a high-strength lignin/cellulose foam absorbent (LCMA) with super-hydrophilic surface was developed for wastewater treatment by using lignin as the skeleton to crosslink cellulose through sol-gel method. Combined with an abundance of reactive functional groups and a highly porous structure, LCMA demonstrated a superior absorption and removal performance for cationic dyes and heavy metal ions, with separation efficiencies exceeding 99.76 % for cationic dyes and 99.85 % for heavy metal ions. Further modification of LCMA by a facile method using polydopamine (PDA) and polyethyleneimine (PEI) imparted superhydrophilicity to the foams. The developed LCMA@PDA@PEI exhibited an impressive immiscible oil-water separation performance and emulsion separation performance (Separation efficiency >99.95 % for immiscible oil-water mixtures and >99.05 % for oil-in-water emulsions). With the capabilities of simultaneous removal for dyes, heavy metal ions and oil pollutants from water, LCMA holds a broad application prospect in the water remediation, especially in the treatment of polluted water with complex components.

Efficient Electrosynthesis of Valuable para-Benzoquinone from Aqueous Phenol on NiRu Hybrid Catalysts.

Electrocatalytic oxidation of aqueous phenol to para-benzoquinone (p-BQ) offers a sustainable approach for both pollutant abatement and value-added chemicals production. However, achieving high phenol conversion and p-BQ yield under neutral conditions remains challenging. Herein, we report a Ni(OH)2-supported Ru nanoparticles (NiRu) hybrid electrocatalyst, which exhibits a superior phenol conversion of 96.5% and an excellent p-BQ yield of 83.4% at pH 7.0, significantly outperforming previously reported electrocatalysts. This exceptional performance benefits from the triple synergistic modulation of the NiRu catalyst, including enhanced phenol adsorption, increased p-BQ desorption, and suppressed oxygen evolution. By coupling a flow electrolyzer with an extraction-distillation separation unit, the simultaneous phenol removal and p-BQ recovery are realized. Additionally, the developed electrocatalytic system with the NiRu/C anode displays good stability, favorable energy consumption, and reduced greenhouse gas emissions for phenol-containing wastewater treatment, demonstrating its potential for practical applications. This work offers a promising strategy for achieving low-carbon emissions in phenol wastewater treatment.

Efficient Electrosynthesis of Valuable para‐Benzoquinone from Aqueous Phenol on NiRu Hybrid Catalysts

Electrocatalytic oxidation of aqueous phenol to para‐benzoquinone (p‐BQ) offers a sustainable approach for both pollutant abatement and value‐added chemicals production. However, achieving high phenol conversion and p‐BQ yield under neutral conditions remains challenging. Herein, we report a Ni(OH)2‐supported Ru nanoparticles (NiRu) hybrid electrocatalyst, which exhibits a superior phenol conversion of 96.5% and an excellent p‐BQ yield of 83.4% at pH 7.0, significantly outperforming previously reported electrocatalysts. This exceptional performance benefits from the triple synergistic modulation of the NiRu catalyst, including enhanced phenol adsorption, increased p‐BQ desorption, and suppressed oxygen evolution. By coupling a flow electrolyzer with an extraction‐distillation separation unit, the simultaneous phenol removal and p‐BQ recovery are realized. Additionally, the developed electrocatalytic system with the NiRu/C anode displays good stability, favorable energy consumption, and reduced greenhouse gas emissions for phenol‐containing wastewater treatment, demonstrating its potential for practical applications. This work offers a promising strategy for achieving low‐carbon emissions in phenol wastewater treatment.

Different fates of the coexisting Sb(V) and nitrate in sulfur autotrophic bioreactor mediated by internal circulation: Performance and mechanism

The sulfur autotrophic bioreactor with internal circulation was established for the simultaneous and effective removal of antimonate (Sb(V)) and nitrate (NO3−) in water for the first time. At the hydraulic retention time (HRT) of 8 h and the recycle ratio (R) of 5, the removal efficiency of Sb(V) and TSb reached up to 98.14 % and 96.89 % with a concentration of 10 mg/L Sb(V) in the influent. Although the shortening of HRT and the increase of R inhibited the removal of Sb(V) and TSb, there was little effect on the NO3− removal (> 97.08 % with the influent of 20 mg-N/L). Meanwhile, the measured concentration of sulfate (SO42−) and alkalinity consumption in effluent were both greater than theoretical value, indicating the occurrence of S0 disproportionation in bioreactor. The shortened HRT and declined R reduced alkalinity consumption, which hindered S0 disproportionation. The precipitates were collected at end of bioreactor operation period, which was confirmed to be Sb2S3 by SEM-EDS, Raman, XRD and XPS analysis. High-throughput sequencing results indicated that Proteobacteria and Bacteroidetes were the dominant bacteria at phylum level for denitrification. Besides, Sulfuriferula, Thiovirga and Sulfuricurvum (at genus level) might be accountable for bio-reduction of NO3− and Sb(V), as well as S0 disproportionation.