Cost-effective Sorbent Research Articles

Adsorptive removal of 2,4-dichlorophenol from aqueous solution using micronized oil shale

This study investigated the utilization of a unique oil shale as a sorbent for the removal of 2,4-dichlorophenol (2,4-DCP) from aqueous solutions. The influence of various process parameters, including the contact time, sorbent/liquid ratio, pH, and temperature, on the sorption process was evaluated. The results indicated the near-complete sorption of 2,4-DCP within 24 h. Favorable sorption was observed either at a sorbent/liquid ratio of 1:10, at elevated temperatures (40 °C), or at lower pH values (pH = 5) within the examined range. The maximum adsorption capacity at 40 °C has the potential to reach up to 20.0 µmol/g. Langmuir, Freundlich, and Sips isotherms were applied to the experimental data, but the Sips isotherm provided a superior fit, suggesting a heterogeneous sorption. Kinetic studies revealed a two-stage process: intraparticle diffusion dominated the initial stage, whereas other rate-limiting mechanisms may have contributed to the second stage. The first- and second-order kinetic models suggested a combined mechanism. According to the thermodynaic study, the adsorption process was spontaneous and exothermic, as indicated by the negative Gibbs free energy change and enthalpy change, which suggest that physisorption predominated. These findings demonstrate the potential of the investigated oil shale as an unconventional and cost-effective sorbent, potentially serving as a substitute for activated carbon in 2,4-DCP removal.Graphical abstract

Salts-activated synthesis of Cu/Co co-doped biochar for efficient removal of elemental mercury from coal combustion flue gas

Mercury immobilization from coal combustion flue gas remains challenging due to the shortage of cost-effective sorbents. In this study, Cu/Co co-doped biochar (CuxCoyBCT) was synthesized through one-step pyrolysis of wood loaded with Cu and Co salts, which was applied to remove elemental mercury (Hg0) from the simulated flue gas. The BET surface area and pore volume of CuxCoyBC650 were vastly higher compared with CuBC650 because of the catalytic effect of cobalt. The synergistic effects between Cu and Co facilitated the transformation of Cu2O into CuO during pyrolysis. The doping of Co resulted in a more uniform dispersion of CuOx and highly dispersed CoOx was also observed in CuxCoyBCT. For this reason, the Hg0 removal performance of CuxCoyBCT was obviously improved after Co doping. The optimal Cu/Co molar ratio and pyrolysis temperature were 1:1 and 650 °C, respectively. The sample of Cu1Co1BC650 showed satisfactory Hg0 removal efficiency (>88 %) over a broad temperature range (100 °C–180 °C). It was remarkable that SO2 facilitated Hg0 removal and H2O had negligible effect on Hg0 removal over CuxCoyBCT. The presence of O2 and NO was conductive to Hg0 removal. The mechanism of Hg0 removal over CuxCoyBCT was further revealed. The results indicated that the heterogeneous adsorption and catalytic oxidation of Hg0 occurred simultaneously, where chemisorbed oxygen, CuO, and Co3O4 served as active components.

Removal of per- and polyfluoroalkyl substances (PFAS) from water using magnetic cetyltrimethylammonium bromide (CTAB)-modified pine bark

Per- and polyfluoroalkyl substances (PFAS) have gained global attention in recent years due to their adverse effect on environment and human health. In this study, a novel and cost-effective sorbent was developed utilizing forestry by-product pine bark and tested for the removal of PFAS compounds from both synthetic solutions and contaminated groundwater. The synthesis of the adsorbent included two steps: 1) loading of cetyltrimethylammonium bromide (CTAB) onto the pine bark and followed by 2) a simple coating of magnetite nanoparticles. The developed sorbent (MC-PB) exhibited 100 % perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) removal from synthetic solution (10 µg/L PFOA and PFOS) and enabled quick magnetic separation. A rapid removal of PFOA (> 80 %) by MC-PB was observed within 10 min from synthetic PFOA solution and the adsorption equilibrium was reached within 4 h, achieving > 90 % removal of PFOA (dosage 2 g/L, PFOA 10 mg/L, initial pH 4.2). The PFOA adsorption kinetics fitted well to an optimized pseudo-order model (R2=0.929). Intra-particle diffusion and Boyd models suggested that the adsorption process was not governed by pore diffusion. The maximum PFOA adsorption capacity was found to be 69 mg/g and the adsorption isotherm was best described by the Dual Mode Model (R2=0.950). The MC-PB demonstrated > 90 % PFOA and PFOS removal from contaminated groundwater. Furthermore, both short- and long-chain perfluorosulfonic acids and 6:2 fluorotelomer sulfonate were efficiently removed resulting in 83.9 % removal towards total PFAS (2 g/L dosage).

Removal of antibiotics from aqueous solutions: insights of competitive adsorption onto Ni-impregnated biochar of spent coffee grounds

Antibiotics are among the most widely used pharmaceutically active compounds. Possessing the capability to adversely impact the ecological system, existence of antibiotics in the environment is an escalating concern. With the purpose of removing two widely used antibiotics efficiently from aqueous solutions, the competency of two biochar (BC)-based sorbents derived from spent coffee (SC) grounds was investigated. Both pristine (SCBC) and nickel (II) oxide-impregnated (Ni-SCBC) biochars were utilized as sustainable and cost-effective sorbents to remove daunorubicin (DAYN) and tigecycline (TIGY) from single synthetic aqueous solutions and binary combinations. Batch adsorption experiments were controlled implementing Box–Behnken design. The removal efficiency of Ni-SCBC was superior compared to SCBC (TIGY: 67.06%, DAYN: 94.30%). Results of characterizations showed that impregnation with NiO changed the degree of crystallization with a remarkable increase in the surface area from 49.23 m2/g in SCBC to 86.06 m2/g in Ni-SCBC. Adsorption of DAYN and TIGY (single solutions) conformed well to Freundlich, and Langmuir isotherms, respectively. A maximum adsorption capacity (qmax) of 136.62 mg/g (DAYN) and 73.15 mg/g (TIGY) was reported in single solutions, compared to 23.50 mg/g (DAYN) and 58.42 mg/g (TIGY) in binary mixture. Adsorption kinetics onto Ni-SCBC fitted well with the pseudo-second-order (PSO) and Elovich models. Acquired results demonstrated that SCBC and Ni-SCBC are promising adsorbents for remedying antibiotics.

Peanut shell biochar for Rhodamine B removal: Efficiency, desorption, and reusability

A high-performance and affordable peanut shell-derived biochar was employed for the efficient removal of Rhodamine B (RhB) from aqueous solutions. The properties of peanut shell biochar (PSB) were investigated through Fourier transform infrared (FTIR) spectroscopy and Brunauer–Emmett–Teller surface area measurements. The FTIR analysis revealed numerous active sites and functional groups for the binding of dye molecules, while the BET surface area was determined to be 351.11 m2g-1. Four different isotherms and kinetic models were applied to determine the equilibrium adsorption of RhB, and the results indicated that the Freundlich isotherm was the most appropriate model. A maximum dye removal rate of 94.0% occurred at a pH of 3 with an adsorbent dose of 0.325 g L−1. The prepared adsorbent showed excellent sorbent behaviour and can be reused multiple times after regeneration, with the surface area decreasing from 351.11 m2g-1 to 140.13 m2g-1 after the third cycle. The negative Gibbs free energy ΔGo at all applied temperatures suggested that spontaneous adsorption occurred and RhB adsorption on the PSB was found exothermic, as evidenced by the negative value of ΔHo. The regenerated PSB can be utilized as an efficient, environmentally friendly, and cost-effective sorbent for the removal of dyes at temperatures lower than ambient temperature, providing both technical and financial advantages for sustainable environmental management.

All-solid-waste-derived CaO-based sorbents for simultaneously enhanced calcium looping CO2 capture and thermochemical energy storage

Calcium looping (CaL) process relying on CaO as high-temperature CO2 sorbents is a prospective alternative technology for simultaneously cyclic CO2 capture and thermochemical energy storage. However, the cyclic stability and the energy storage density of the CaO-based sorbents decay drastically over repeated carbonation-calcination cycles. Herein, we yielded CaO-based sorbents derived from all industrial solid wastes with carbide slag (CS) as precursor and coal fly ash (CFA) as stabilizer featuring superior carbonation characteristics, stable CO2 cyclic uptake and high thermochemical energy storage density over multiple operation cycles. The optimal sorbent (CCS–H-G-CFA-D) exhibited a high initial CO2 uptake of 0.38 gCO2/gsorbent, superior cyclic stability with an average decay rate of 1.05% per cycle and remarkably stable energy storage density of 1375 kJ/kg, retaining 89.5% after 10 repeated cycles. Thereby, the simultaneously enhanced cyclic CO2 capture and thermochemical energy storage are attributed to adding CFA stabilizers in CS-derived CaO-based sorbents, forming stable skeleton to alleviate sintering, improving the uniform mixing degree between sorbent particles and promoting the carbonation reaction via synergistic effect. This simple and eco-friendly approach of cost-effective sorbents totally derived from industrial solid wastes provides a new avenue for large-scale practical CO2 capture and energy storage processes.

Enhanced removal of methylene blue and procion deep red H-EXL dyes from aqueous environments by modified-bentonite: Isotherm, kinetic, and thermodynamic

This study aims to enhance local bentonite's effectiveness in removing methylene blue and procion deep red dyes from aqueous media through organic modification with cetyltrimethylammonium bromide surfactant. Raw and modified bentonites were analyzed using XRF, XRD, FTIR, BET/BJH, and DSC techniques. The modified bentonite showed a crystalline structure and mesoporous morphology with a heterogeneous surface. Optimal adsorption conditions for MB dye were 0.2 g adsorbent dose, 60 min contact time, 60 mg/L initial concentration, and pH 8, achieving a maximum sorption capacity of 6.418 mg/g. For PDR dye, optimal conditions were a 0.125 g adsorbent dose, 40 mg/L initial concentration, 30 min contact time, and acidic pH, with a maximum adsorption capacity of 8.503 mg/g. Isotherm analysis indicated the Langmuir model best fits the adsorption data, suggesting a mono-layer adsorption process. Kinetic investigations revealed that the adsorption follows a pseudo-second-order model, indicating a chemisorption mechanism. Thermodynamic results showed exothermic adsorption for MB and endothermic adsorption for PDR. This work highlights the potential of surfactant-modified bentonite as a cost-effective sorbent for treating polluted aqueous systems, effectively removing both cationic and anionic dyes.

Performance evaluation and mechanism of Al2O3/TiO2 sorbents for fluoride remediation in groundwater

Excessive fluoride levels in drinking water are problematic in several countries, particularly those which are relatively poor. Thus, there is a need to create cost effective sorbents which can easily be applied to make the water safe to use. Therefore, this study focussed on Al2O3/TiO2 sorbents which appear to address issues with commercially available alumina such as aluminium dissolution. Adjusting the alumina/titania ratio significantly influenced not only the fluoride uptake capacity but also the uptake of a wide range of contaminants found in groundwater. The exchange kinetics were relatively fast regardless of mixed oxide composition with equilibrium obtained within 6 h. Equilibrium isotherms were unfavourable for fluoride removal where titania compositions were dominant. In contrast, favourable isotherms were noted when alumina was the dominant oxide present. Barium, calcium, strontium, boron, iron, manganese, zinc, potassium, lithium, and silica were all substantially removed by varying the alumina/silica ratio in the sorbent. This behaviour may be valuable for broader remediation of dissolved species in groundwater (not just fluoride). Based upon the tests data a 70% Al2O3 – 30% TiO2 material was recommended to be the preferred composition for comprehensive treatment of groundwater. The sorbents appeared to comprise of alumina and titania with surface areas between 129 and 255 m2/g. There was no evidence for new oxide phases nor for a relationship between surface area and performance. Mechanistically both ion exchange and surface complexation may occur when treating groundwater.

The performance of iron-silicate-based biochar as a sorbent material towards 133Ba retention from radioactive liquid waste

Abstract The application of Phalaris seed peel (PSP) for the production of biochar involves the pyrolysis process in an N2 environment, resulting in the creation of a cost-effective sorbent. Two distinct modifications were conducted on the existing biochar (BC), employing just silicate (BC/SiO2) and in combination with iron-silicate (BC/SiO2/Fe). Several analytical methods were used to look at the modified biochar’s physical and chemical properties. These included scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis-differential thermal analysis (TGA-DTA), and surface area analysis. Based on the initial investigations, it has been revealed that the use of silica and iron as the second modification is a more suitable approach for effectively retaining 133Ba from liquid radioactive waste streams. The investigation of sorption kinetics and isotherms was conducted to enhance our understanding of the process. The Langmuir isotherm model demonstrates the most optimal correlation for sorption, yielding a maximum sorption capacity (Q max) of 31 mg/g. Furthermore, an evaluation was performed on the BC/SiO2/Fe sorbent material by subjecting it to a mixture of simulated radioactive liquid waste, which included 133Ba, 60Co, and 137Cs.The experimental results indicate that BC/SiO2/Fe exhibits a comparatively higher sorption capacity for 133Ba when compared to 60Co and 137Cs as competing ions.

A comprehensive understanding of the role of sodium sulfate in calcium looping via in-situ experiments and DFT studies: Performance and mechanism

Adding alkali metal salt promoters to calcium-based materials can influence the cycling performance of CaO-based sorbents. So far, most research on alkali metal salts focus on carbonate and chloride salts, while little attention is paid to sulfates. In this paper, we present an in-depth study of the role of Na2SO4 in calcium looping via in-situ experiments and DFT simulations. The results show that the effective conversion rate of Na2SO4-CaO after one cycle is 0.779 with the energy storage density of 2476.1 kJ/kg, while the effective conversion rate of CaO is 0.562 with the energy storage density of 1786.4 kJ/kg. After 80 cycles, the effective conversion and energy storage density of Na2SO4-CaO are lower than CaO, which is attributed to Na+ reducing the surface energy and accelerating the sintering. Moreover, an optimization strategy based on coordination effect among Na2SO4, CaO and inert oxides is proposed to slow down the sintering problems. Among them, Na2SO4-(CaO + ZnO) has the best adsorption performance and energy storage performance and ZnO is cheap, which can be considered a cost-effective sorbent. This work provides a new approach for developing efficient, simple and cost-effective calcium-based materials by simultaneously achieving fast reaction rates and good cycling stability of CaL.

The Application of Aluminium Powder as an Accumulation Medium of Mercury from Air

A gaseous elemental mercury (Hg0) sampler was developed for the assessment of mercury (Hg) pollution from the air and utilised aluminium (Al) powder as the accumulation medium. The Hg sampler is presented as an alternative cost-effective sorbent that can be used for the assessment of Hg pollution in atmospheric air in areas where natural bio-indicators such as lichens and moss do not grow, including the urban environments. The chemical treatment of Al materials was necessary to weaken the aluminium oxide (Al2O3) layer to increase the adsorption capability of Al material. Treated Al samples were exposed to Hg vapours for one hour to two weeks in a Hg atmosphere chamber. Other Al powder samples were exposed to the ambient air at areas of the Tshwane Metropolitan Municipality for six to ten months. The analysis of samples by an RA-915+ Zeeman mercury analyser showed that the limit of detection (LOD) and limit of quantification (LOQ) for the determination of Hg in Al powder with a mass of 100 mg were found to be 0.31 ng g−1 and 1.0 ng g−1, respectively. The content of Hg that accumulated on Al powder was linear from 0.1 to 25 ng g−1, thus enabling the measurement of Hg accumulation from air at the global average concentration level. Mercury from air that accumulated on Al powder in the Tshwane Metropolitan Municipality ranged between 70 ng g−1 and 155 ng g−1.

Amidoxime-functionalized corn straw for efficient Cr(VI) adsorption from water: Waste utilization, affinity character and DFT simulation

To endow the added value of agricultural waste straw resources, we introduced amidoxime groups onto corn straw to fabricate amidoxime-functionalized corn straw sorbents (AO-CS) capable of efficiently adsorbing Cr(VI). The presence of surface-anchored functional moieties significantly accelerated the adsorption rate, achieving equilibrium in just 10 min. The Langmuir isotherm model and experimental data agreed well, with the maximum adsorption capacity reaching 199.7 mg/g at pH = 2.0, 303 K. Experiments with various temperatures were used to obtain the thermodynamic parameters (ΔG, ΔH, and ΔS). The Cr(VI) adsorption mechanism on AO-CS was found to involve electrostatic attraction, hydrogen bonding, redox reactions, and complexation, as confirmed by DFT calculations, FT-IR, and XPS analysis results. Under conditions of coexisting anions (Cl-, NO3-, SO42-, and PO43-), AO-CS exhibited a high selectivity for Cr(VI) due to the establishment of a more stable complex between amidoxime groups and Cr2O72-. Moreover, AO-CS could be easily regenerated using EDTA, with only a slight decrease in adsorption capacity even after four cycles. In conclusion, these cost-effective sorbents with rapid adsorption toward Cr(VI) held great promise for practical applications in wastewater treatment.

Highly efficient capture of iodine vapor by [Mo3S13]2− intercalated layered double hydroxides

From the swollen LDH, bulky [Mo3S13]2− anions are facilely introduced into the LDH interlayers to assemble the Mo3S13-LDH composite, which exhibits excellent iodine capture performance and good irradiation resistance. The positive-charged LDH layers may disperse the [Mo3S13]2− uniformly within the interlayers, providing abundant adsorption sites for effectively trapping iodine. The Mo-S bond serving as a soft Lewis base has strong affinity to I2 with soft Lewis acidic characteristic, which is conducive to improvement of iodine capture via physical sorption. Besides, chemisorption has a significant contribution to the iodine adsorption. The S22−/S2− in [Mo3S13]2− can reduce the I2 to [I3]− ions, which are facilely fixed within the LDH gallery in virtue of electrostatic attraction. Meanwhile, the S22−/S2− themselves are oxidized to S8 and SO42−, while Mo4+ is oxidized (by O2 in air) to Mo6+, which combines with SO42− forming amorphous Mo(SO4)3. With the collective interactions of chemical and physical adsorption, the Mo3S13-LDH demonstrates an extremely large iodine adsorption capacity of 1580 mg/g. Under γ radiation, the structure of Mo3S13-LDH well maintains and iodine adsorption capability does not deteriorate, indicating the good irradiation resistance. This work provides an important reference to tailor cost-effective sorbents for trapping iodine from radioactive nuclear wastes.

Efficient selective uptake of mercury ions using inverse vulcanization-synthesized sulfur-rich adsorbents

Mercury abatement from complex environmental sources remains a significant challenge for environmental protection due to the lack of cost-effective sorbents. Sulfur-based adsorbents have been traditionally used for selective uptake of Hg(II) ions, necessitating the creation of effective sulfur adsorption sites. Herein, we propose a sulfur-rich material synthesized method via inverse vulcanization for mercury removal from solutions. Mercury exhibits an affinity for sulfur, and highly active sulfur sites enhance its adsorption efficiency. Inert elemental sulfur can be activated by aliphatic diamine through a ring-opening process, converting sulfur and polyvinyl chloride (PVC) into functional sulfur-rich materials at a mild temperature of 50 °C. The cross-linked structure of PVC enhances the dispersion of active sulfur sites. This sulfur and nitrogen-containing material demonstrates excellent mercury removal capabilities, exhibiting high selectivity even in complex ionic environments, with a maximum adsorption capacity of 309.2 mg/g. Our results highlight the efficiency of this sulfur-rich material as a mercury sorbent. The inverse vulcanization method enables the efficient utilization of two abundant resources, sulfur and waste PVC. This research has been submitted for publication in a scientific journal, and we have provided a concise and polished version for your consideration.

NixSy/NF composites assembled by sulfidation of nickel foam (NF) for highly effective capture of iodine

Under a facile one-step hydrothermal reaction by changing thiourea dosage to regulate sulfidation degree of nickel foam (NF), a variety of nickel sulfide composites of n-NixSy/NF (1-Ni3S2/NF, 3-Ni3S2 and 6-Ni3S2/Ni9S8) were prepared and utilized to capture iodine for the first time. The compositions and structures of the composites and their influence on iodine adsorption performance were elaborated in detail. During adsorption, Ni0 in NF and Ni0/S2− in Ni3S2/Ni9S8 both served as reducing agents to achieve the chemisorption for iodine, where the Ni0 and S2− were oxidized to Ni2+ and elemental S0 (S8), and the I2 molecules were reduced to I− which then reacted with the Ni2+ to form NiI2. The 1-Ni3S2/NF, 3-Ni3S2 and 6-Ni3S2/Ni9S8 exhibited different iodine adsorption capacities (qmI) of 1442, 1109 and 420 mg/g for iodine vapor, and 1191, 869 and 296 mg/g for iodine in solutions, respectively, giving the largest qmI of 1442 (for I2 vapor) and 1191 mg/g (for I2 in solution) by 1-Ni3S2/NF. The capture mechanism for iodine in solution was mainly by chemisorption, while for iodine vapor, profiting from the three-dimensional skeleton of NF, besides the chemisorption, physical sorption also played a role. After γ irradiation, the structures of n-NixSy/NF were well-maintained and iodine adsorption performance did not deteriorate, indicating the good radiation resistance. This work provides an important reference for tailoring new kinds of cost-effective sorbents to trap iodine from radioactive nuclear wastes.

In situ activation synthesis of tire-derived sorbents for efficient immobilization of elemental mercury from flue gas

Mercury removal from coal combustion flue gas remains a daunting challenge because of the lack of cost-effective sorbents. In this study, the in situ activation synthesis of tire chars was realized through SO2 induction and the tire-derived sorbents were used for elemental mercury (Hg0) removal from the simulated flue gas. Therein the sulfur species in tire chars are regulated. The results indicated that the specific surface area of tire chars was slightly decreased whereas more micropores were generated after SO2 activation. Compared with raw tire char, the sulfur content of tire-derived sorbents was obviously increased. The tire-derived sorbents also contained more sulfur- and oxygen-containing functional groups. For this reason, the Hg0 removal performance of tire-derived sorbents was dramatically increased after SO2 activation. The optimum pyrolysis temperature for the synthesis of tire-derived sorbents was 600 °C. The SO2 concentration in activation atmosphere had little effect on the Hg0 removal performance of tire-derived sorbents. The presence of SO2, NO and O2 was beneficial for Hg0 removal·H2O had little effect on Hg0 removal. The Hg0 adsorption capacity of tire-derived sorbents was further compared with the previously reported sorbents through adsorption dynamic simulations. Furthermore, the mechanism of Hg0 removal over tire-derived sorbents was revealed through XPS analysis and mercury temperature programmed desorption. It was found that the Hg0 removal process was mainly dominated by chemisorption, where organic sulfur species, CO group and COOH/C(O)–O–C group served as active sites for Hg0 capture.

Complex Agent for Phosphate Sequestration from Digested Sludge Liquor: Performances and Economic Cost Analysis

Phosphorus (P) management in the “water-energy-resource-nexus” in wastewater treatment plants (WWTPs) remains a longstanding challenge. P adsorption from the P-enriched digested sludge liquor (DSL) is a comparatively more practical and economically viable approach for P recovery in WWTPs. However, high concentrations of impurities in DSL might pose a negative and interferential effect on P adsorption, hindering the application of sorbents or precipitation methods. Given such a situation, highly efficient and cost-effective sorbent towards P reclamation from DSL is highly needed. Therefore, this study aims to develop a novel complex agent containing aluminum coagulant and superparamagnetic nano-sorbent (SNS) that can be used in magnetic seeding coagulation for P recovery. The complex agents with different PACl: SNS ratios showed varied turbidity removal rates and P recovery efficiencies and the optimal ratio was 15 mg PACl: 15 g SNS. PAC and SNS showed significant interaction because PAC could enhance P adsorption by shielding the interferential effect of colloidal impurities. In addition, the complex is highly regenerative, with turbidity and P removal rate stably maintained at 70–80% after 10 adsorption/regeneration cycles. The cost–benefit analysis of the dosing complex agent showed a dosing cost of 0.154 EUR/m3, admittedly much higher than the conventional magnetic seeding coagulation, which could probably be covered by the profit if the expensive and rare P product is reclaimed. This work indicated that the complex agent was superior due to its high adsorption capacity, easy separation, and repeated dosing, and therefore had the potential for P recovery from DSL.

Template-assisted synthesis of molecularly imprinted polymers for the removal of methyl red from aqueous media

This study entails the synthesis of molecularly imprinted polymers (MIPs) with good selectivity coefficients for azo dye as a potential sorbent material to extract azo dye from polluted aqueous media. A series of MIPs for methyl red (MR) as a template, were synthesized by changing the molar ratio of functional monomers, via precipitation polymerization format of non-covalent approach. Water-soluble functional monomer; acrylic acid (AA) was used to weave the frame work of polymers while ethylene glycol dimethacrylate (EGDMA) was utilized as crosslinking monomer. The impact of different experimental parameters, such as mole ratio of monomer (functional) to crosslinking monomer on the molecular recognition was investigated. The highly efficient and selective MR-MIP was used for the removal of spiked MR dye from different water samples. The selected imprinted polymer, MR1-MIP was able to selectively remove the MR molecules from aqueous media. A significant amount of dye was removed by MR1-MIP from the river water samples with a high degree of removal efficiency i.e. 92.25%. The imprinting factor of 3.75 for MR1-MIP indicated that the high selectivity in terms of adsorption for MR. A minimum loss of only ~ 3.35% in the removal efficiency within ten sequential cycles of adsorption–desorption study evidenced that MR-MIPs could be used as the most cost effective and best sorbent for the removal of MR from polluted water. Furthermore, the structural properties of MR-MIPs were characterized by FTIR and EDX, whereas TGA, SEM and BET were used to describe the thermal, morphological and surface structures of the particles, respectively.Graphical

Hybrid CaO@MgO@g-C3N4 nanostructure as a cost-effective sorbent for hazardous organic dyes activated by additives

Hybrid CaO@MgO@g-C3N4 nanostructure as a cost-effective sorbent for hazardous organic dyes activated by additives

Smart in-line cleanup cartridge modules and floating sorbent systems for BrO3- removal from natural water sources – An innovative approach

Functionalized montmorillonite–chitosan hybrid systems were developed as novel and cost-effective sorbent materials for the quantitative removal of carcinogenic bromate from natural water sources. The developed materials were custom fabricated via two facile and innovative approaches viz. reusable cartridge as a ‘point of use’ clean up modules and carbon cloth based “floating sorbents”, as a removal strategy at the ‘point of entry’. The packing density and flow rate of inline clean up cartridges as well as the sorbent coating and drying procedure of floating sorbent systems were sequentially optimized and validated. The application potential of the fabricated materials was subsequently explored and the studies revealed excellent removal efficiencies of > 99% for batch and flow based systems. The developed modules could successfully remove bromate levels in spiked natural water samples such as drinking, well and river water, down to 10 µgL−1 with more than 97% efficiency. The findings were substantiated through characterisation studies and detailed mechanistic investigation was carried out to understand the better adsorption characteristics of hybrid functionalized clay-chitosan composite. Consequently, the studies implied that a modular inline clean up cartridge packed with 600 g Mt-H-CTS sorbent connected to a water purification system is sufficient to quantitatively remove as high as 100 µgL−1 bromate for a middle class household on a monthly basis. Furthermore, the rapid and efficient regeneration of the material could improve the longevity and makes it an ideal candidate for post disinfection treatment applications at drinking water outlets such as taps (point of use) as well as for large reservoirs in the form of ‘floating sorbents.