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Two sodium alginate-based Pb2+-imprinted thermosensitive hydrogels (SPIT (without ɛ-PL) and SPPIT (with ɛ-PL)) were synthesized, with sodium alginate and ɛ-polylysine (ɛ-PL) as the matrix, N-isopropylacrylamide as the monomer. Characterization with differential scanning calorimeter, Fourier transform infrared spectroscopy, thermogravimetric analyzer, scanning electron microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy confirmed the aimed structure of the hydrogels. The adsorption capacity of SPIT and SPPIT for Pb2+ was 98.64 mg/g and 153.49 mg/g, respectively. Washing the Pb2+-loaded adsorbent with 10 °C deionized water, SPIT and SPPIT achieved a desorption efficiency of 94.59 % and 97.51 %, respectively. After 10 cycles of adsorption-desorption process, the adsorption capacity and desorption efficiency remained at about 80–88 % of the original ones, expressing excellent reusability. In a mixture containing eight metal ions (Pb2+, Cu2+, Mg2+, Ca2+, Cd2+, Na+, K+, Fe3+), the adsorption capacity of SPIT to Pb2+ was 92.49 mg/g, and that of SPPIT was 102.49 mg/g, much higher than that to the other ions (1.50–11.38 mg/g on SPIT, 9.48–27.45 mg/g on SPPIT), showing excellent adsorption selectivity. The introduction of ɛ-PL enhanced the adsorption capacity, antibacterial ability and stability of the hydrogel, ensuring better application potential in real wastewater. • Two Pb2+-imprinted adsorbents were prepared with sodium alginate as the matrix. • The differential scanning calorimeter test confirmed the reversible thermosensitivity of the adsorbents. • Washing with cold water (5-10 °C) could regenerate the Pb2+-loaded adsorbents. • After 10 cycles of reuse, 80–88 % of the adsorption capacity was remained. • The adsorptive selectivity coefficient of adsorbent was up to 33.99. [ABSTRACT FROM AUTHOR]

The efficiency of saturated Activated Carbon (AC) electrochemical regeneration was evaluated. Reactor configurations in cathodic/anodic process, applied current effect on the properties of AC and Methylene Blue MB-AC interactions and adsorption/desorption mechanisms were studied. The efficiency was measured by adsorption capacity adsorption/regeneration cycles and changes in the adsorbent characteristic were analyzed through FTIR, BET, Optical Microscopy (OM) and SEM before and after the regeneration. The energy consumption was analyzed to assess the economic feasibility. It was found that the electrochemical treatment was efficient in returning the AC adsorption capacity, maximum efficiencies of approximately 79% and 84% were reached when the Carbon Fiber Cloth-AC electrode was subjected to anodic and cathodic currents, respectively, at a current of 0.1 A. In addition, the material demonstrated good stability through adsorption-regeneration cycles by cathodic process, with the material's adsorption capacity being almost totally recovered for 8 consecutive cycles. The removal percentage around 80% was kept after the cycles, with optimal conditions when the electrode was subjected to cathodic currents, NaCI as electrolyte at a current of 0.1 A for 2 h. The characterization techniques provided results that allow to explain the higher and prolonged efficiency of the cathodic current. Furthermore, these reactor configurations achieved an electrical energy consumption of 2.3 and 2.1 kWh kg-1 of material for cathodic and anodic, respectively. These results indicate that the electrochemical is an economical and environmental suitable technique capable of restore carbon adsorbents to be reusable for several water treatment cycles. [ABSTRACT FROM AUTHOR]

[Display omitted] The efficiency of saturated Activated Carbon (AC) electrochemical regeneration was evaluated. Reactor configurations in cathodic/anodic process, applied current effect on the properties of AC and Methylene Blue MB-AC interactions and adsorption/desorption mechanisms were studied. The efficiency was measured by adsorption capacity adsorption/regeneration cycles and changes in the adsorbent characteristic were analyzed through FTIR, BET, Optical Microscopy (OM) and SEM before and after the regeneration. The energy consumption was analyzed to assess the economic feasibility. It was found that the electrochemical treatment was efficient in returning the AC adsorption capacity, maximum efficiencies of approximately 79% and 84% were reached when the Carbon Fiber Cloth-AC electrode was subjected to anodic and cathodic currents, respectively, at a current of 0.1 A. In addition, the material demonstrated good stability through adsorption-regeneration cycles by cathodic process, with the material's adsorption capacity being almost totally recovered for 8 consecutive cycles. The removal percentage around 80% was kept after the cycles, with optimal conditions when the electrode was subjected to cathodic currents, NaCl as electrolyte at a current of 0.1 A for 2 h. The characterization techniques provided results that allow to explain the higher and prolonged efficiency of the cathodic current. Furthermore, these reactor configurations achieved an electrical energy consumption of 2.3 and 2.1 kWh kg −1 of material for cathodic and anodic, respectively. These results indicate that the electrochemical is an economical and environmental suitable technique capable of restore carbon adsorbents to be reusable for several water treatment cycles. [ABSTRACT FROM AUTHOR]

Polysaccharide-based hydrogel adsorbents become popular because of their high adsorption capacity and fast adsorption rate, but their low removal rate and poor pH resistance have always been fatal shortcomings. Herein, a feasible strategy was proposed to strengthen the ability of hydrogel adsorbent to remove organic pollutants (i.e., dye) by incorporating natural rectorite (REC) into chitosan- g -poly (2-acrylamido-2-methyl-propane-sulfonic-acid) hydrogel network to form a rectorite-in-polymer network structure. The introduction of less dosage of REC (1.2 wt%) into the hydrogel facilitates to improve its adsorption capacities toward methylene blue (MB) in deionized water, tap water, seawater, Yangtze River water, and Yellow River water (1083.39–1303.49 mg/g); while incorporating higher content of REC (15.8 wt% REC) helps to improve the removal rate (99.6% for MB in real waters), which are greatly superior to commercial activated carbons. The adsorbent keeps high adsorption efficiency in a broad pH range (2–11), and can be reused for >4 times. [Display omitted] • Synthesized chitosan-based hydrogel has a rectorite-in-polymer composite network. • The hydrogel shows high adsorption capacity (1303.49 mg/g) and removal rate (99.6 %). • Removal efficiency keeps high in real waters (Yangtze River, Yellow River, seawater). • The hydrogel's adsorption capacity far exceeds that of commercial activated carbon. • This method is universal to enhance the removal efficiency of hydrogel adsorbent. [ABSTRACT FROM AUTHOR]

Six water-tolerable metal-organic frameworks (MIL-101(Cr), MIL-100(Fe), MIL-100(Cr), MIL-53(Cr), MIL-96(Al), and UiO-66) were employed for the adsorptive removal of acetic acid from water. UiO-66 exhibited more potential as an acetic acid adsorbent than other five MOFs. UiO-66 was further investigated in the view of adsorption kinetics, isotherm, thermodynamics, and regeneration of the adsorbent. The analysis of film diffusion and intraparticle diffusion model suggested that larger acetic acid concentrations would cause higher effects of boundary layer, and the adsorption process was multiple steps. The kinetic results show that adsorption of acetic acid on UiO-66 fitted to pseudo-second-order model and was controlled by chemical adsorption. The adsorption isotherm of acetic acid on UiO-66 followed Freundlich isotherm, which indicated the presence of heterogeneous surface on UiO-66. The thermodynamic parameters (Δ G , Δ H and Δ S ) were also calculated, confirming that the adsorption of acetic acid on UiO-66 was spontaneously exothermic and decrease of disorder. The regeneration of UiO-66 was also demonstrated by washing with deionized water and ethanol. The adsorption capacity and XRD of UiO-66 did not change significantly even after three cycles. Therefore, UiO-66 can be a promising adsorbent for adsorptive removal of acetic acid from wastewater. [ABSTRACT FROM AUTHOR]

• A porous nanofiber membrane with dense distribution of La nanorods was prepared. • Exceptional high utilization ratio of La (0.98). • LPS was easily separated from solution. • The LPS can reduce total phosphorus to less than 10 μg/L in natural lake water. • Phosphate was effectively captured in a wide pH range of 4–10. As phosphate is one of the key causes of water eutrophication, its removal from aquatic ecosystems is essential. Adsorption methods have been widely used to remove phosphate from water bodies. However, most of the adsorbents are unstable and difficult to separate from solution. In this paper, we used a simple electrospinning method to prepare a new, well-dispersed, lanthanum (La)-based porous polyacrylonitrile nanofiber (LPS) with more active sites, which improve its phosphate removal efficiency. The maximum phosphate adsorption capacity on LPS was 218.5 mg P/g (La) (50.4 mg P/g). After complete adsorption, the P/La molar ratio on LPS was 0.98. After 48 h of oscillation, the leakage of La from LPS in deionized water was only 74 μg/L, effectively ruling out secondary pollution of the water-body. Moreover, unlike most adsorbents, LPS has the advantage that it can be readily isolated from water. After treatment with LPS, the total phosphorus (TP) of a water sample from Yangzonghai Lake (Yunnan, China) was reduced to 4.2 μg/L, a value lower than the concentration threshold of eutrophication (10 μg/L) set by the United States Environmental Protection Agency (USEPA) and the first category of the surface water environmental quality standard (10 μg/L) set by China for lakes and reservoirs. [ABSTRACT FROM AUTHOR]

• The adsorption of diclofenac potassium onto modified soybean hulls was evaluated. • The thermal treatment was studied by thermogravimetric analysis and residence time. • The experimental data fitted pseudo-first order and Sips models. • The adsorption mechanism occurs through hydrogen bonds and π-π interactions. • The modified soybean hulls presented a maximum adsorption capacity of 96.88 mg g−1. Because Diclofenac potassium (DCF-p) is a drug that is easily accessible and widely consumed worldwide, it is often identified in water monitoring samples. Wastewater treatment has not been able to remove it completely, and for this reason traces reach the surface and groundwater, causing an impact on non-target organisms. In this sense, adsorption is highlighted as a simple and usually efficient process. Soybean hulls are residues generated in large quantities, often disposed of in landfills. For this reason, their use as adsorbent becomes interesting. However, no study to date has evaluated modifications of such residue in order to remove drugs from water. Thus, the objective of this study was to evaluate the adsorption capacity of the soybean hulls after chemical and thermal treatment in the removal of DCF-p. In the adsorption tests, it was found that the increase in pH from 5 to 9 caused a small reduction in the adsorption capacity, however the effect of the ionic strength showed that the dissolved salt ions acted as co-adsorbents, favoring adsorption. Kinetic data demonstrated rapid adsorption, with equilibrium at 180 min and adsorption capacity of 17.27 mg g−1. The experimental data adjusted to the pseudo-first-order model, and the intraparticle diffusion model suggested a multi-stage process. The adsorption isotherms were adjusted to the Sips model, revealing a maximum adsorption capacity of 96.88 mg g−1 at 308 K. The thermodynamic parameters indicated a spontaneous and favorable process for all temperatures studied, with an exothermic reaction controlled by physisorption. Lastly, it was found that the adsorption of DCF-p occurred by π-π interaction and hydrogen bonds. [ABSTRACT FROM AUTHOR]

Pb2+ adsorption onto activated carbon was studied as a function of the different liquid medium during batch adsorption process without shaking/agitation of flasks (where adsorbate and adsorbent coexist). As liquid medium deionized water (DW) enhanced with gases bulk nanobubbles (bNBs) was used. The adsorbent material used was activated carbon from potato peels. The maximum Pb2+ adsorption capacity (Q m) was 9 mg/g in the case of adsorption process in DW without agitation, whereas the respective Q m was 94 mg/g by using DW-bNBs as medium without agitation. It was also found that Q m increased to 171 mg/g in the adsorption process with DW-bNBs and agitation (150 rpm). This finding was the start point of a new experimental design where after re-agitation (intense shaking of 225 rpm) of the respective experimental case (94 mg/g), the final Q m was 163 mg/g i.e. very close to the one corresponding to simultaneous adsorption and agitation from the beginning. The results are analyzed and discussed intensively to lead in several important implications on the influence of bNBs to the bulk solute mass transfer. Based on our experimental equilibrium data a modified-Langmuir equation was developed, applied and proposed so as to better simulate the whole (complicated) process. [ABSTRACT FROM AUTHOR]