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Efficient removal of phosphate (PI) and nitrate ions (NI) from aqueous phases is crucial for securing drinking water sources. This study firstly explored the surface modification of ground coffee waste biochars (GCWB) via co-thermal decomposition of ground coffee wastes (GCWs) and oyster shells (OSs), focusing on their differences in the physicochemical properties and adsorption mechanisms of PI and NI related to the selectivity and adsorption capacity. OSs-doped GCWB (OS@GCWB) exhibited the higher adsorption capacities of PI (106.5 µg/g) and NI (57.9 µg/g) ions compared to GCWB (PI = 12.2 µg/g; NI = 35.2 µg/g) owing to its enriched calcium hydroxides and improved surface charge properties through co-thermal decomposition of GCWs and OSs. From the assessed kinetic, intra-particle diffusion, and isotherm parameters, physisorption and intra-particle diffusion were primarily responsible for the elimination of PI and NI by GCWB and OS@GCWB. Moreover, the obtained thermodynamic parameters revealed that the adsorptive removal of PI and NI using GCWB and OS@GCWB showed spontaneous and endothermic natures over the tested temperature ranges. The shifts in the dominant adsorptive removal mechanisms of GCWB toward PI and NI from the ligand exchanges to the electrostatic surface complexations supported that its improved surface characteristics through co-thermal decomposition of GCWs and OSs could improve the selectivity and adsorption capacities of PI and NI in the co-presence of Cl-, HCO 3 -, and SO 4 2- ions. Based on these observations, OS@GCWB derived from co-thermal decomposition of GCWs and OSs may be a promising adsorbent for the elimination of PI and NI. • OSs were used as alternatives to pure chemicals for surface modifications of GCWB. • OS@GCWB showed greater adsorption capacities of PI and NI than GCWB. • Co-pyrolysis of GCWs and OSs improved the selectivity of GCWB for PI and NI. • Adsorption of PI and NI by GCWB controlled by ligand exchanges. • Electrostatic surface complexations governed adsorption of PI and NI by OS@GCWB. [ABSTRACT FROM AUTHOR]

In this study, the feasibility of Mg/Al layered double hydroxides (LDH) functionalized coffee ground waste biochars (LDH MgAl @CWGB) as a potential adsorbent to selectively recover phosphate (PO 4 3−) and nitrate (NO 3 −) ions in aqueous phases and their consecutive uses as a slow-release fertilizer for stimulating the plant growth were identified. The higher adsorption capacity of PO 4 3− and NO 3 − ions by LDH MgAl @CWGB (PO 4 3− = 6.98 mgP/g, NO 3 − = 2.82 mgN/g) compared with pristine coffee ground waste biochars (CWGB; PO 4 3− = 0.19 mgP/g, NO 3 − = 0.32 mgN/g) was mainly due to the incorporation of Mg/Al mixed oxides and Cl contents. Chemisorption and intra-particle mainly controlled the adsorptive recovery of PO 4 3− and NO 3 − ions by CWGB and LDH MgAl @CWGB in aqueous phases and their adsorption toward CWGB and LDH MgAl @CWGB proceeded endothermically and spontaneously. The changes in the major adsorption mechanisms of PO 4 3− and NO 3 − ions from ligand exchange (CWGB) to electrostatic surface complexation and anion-exchange (LDH MgAl @CWGB) supported the conclusion that the alternation of the surface features through Mg/Al LDH functionalization might improve selectivity and adsorption capacity of PO 4 3− and NO 3 − ions onto CWGB under the co-existence of Cl−, SO 4 2−, and HCO 3 − ions. Since PO 4 3-- and NO 3 −-loaded LDH MgAl @CWGB exhibited much higher seed germination, root and shoot growth rates of garden cress seeds (Lepidium sativum L) than other liquid and solid matrices, including 5 mgP/L PO 4 3− and 5 mgN/L NO 3 −, 10 mgP/L PO 4 3− and 10 mgN/L NO 3 −, and LDH MgAl @CWGB, it can be postulated that PO 4 3-- and NO 3 −-loaded LDH MgAl @CWGB could be practically applicable to the agricultural field as a slow-release fertilizer to facilitate the seed germination, root and shoot growth of the plants. [Display omitted] • LDH MgAl @CWGB more efficiently captured PO 4 3− and NO 3 − ions than CWGB. • LE played a critical role in adsorption of PO 4 3− and NO 3 − ions onto CWGB. • Mg/Al LDH functionalization increased selectivity of CWGB for PO 4 3− and NO 3 − ions. • ESC and AE mainly governed adsorption of PO 4 3− and NO 3 − ions toward LDH MgAl @CWGB. • PO 4 3-- and NO 3 −-loaded LDH MgAl @CWGB promoted seed germination and plant growth. [ABSTRACT FROM AUTHOR]

In this study, NaOH-assisted H 2 O 2 post-modification was proposed as a novel strategy to enhance the adsorption of radioactive strontium (Sr) onto residual coffee waste biochars (RCWBs). To validate its viability, the adsorption capacities and mechanisms of Sr(II) using pristine (RCWB P), H 2 O 2 post-modified (RCWB HP), and NaOH-assisted H 2 O 2 post-modified residual coffee waste biochars (RCWB NHP) were experimentally and theoretically investigated. The highest adsorption capacity of Sr(II) for RCWB NHP (10.91 mg/g) compared to RCWB HP (5.57 mg/g) and RCWB P (5.07 mg/g) was primarily attributed to higher negative surface zeta potential (RCWB NHP = –5.66 → −30.97 mV; RCWB HP = –0.31 → −11.29 mV; RCWB P = 1.90 → −10.40 mV) and decoration of Na on the surfaces of RCWB P via NaOH-assisted H 2 O 2 post-modification. These findings agree entirely with the theoretical observations that the adsorption of Sr(II) onto RCWB P and RCWB HP was controlled by electrostatic interactions involving carbonyls whereas enriched carboxylic acids and decorated Na on the surfaces of RCWB NHP through the replacement of Mg and K by NaOH-assisted H 2 O 2 modification stimulated electrostatic interactions and cation exchanges governing the adsorption of Sr(II). Hence, NaOH-assisted H 2 O 2 post-modification seemed to be practically applicable for improving the adsorption capacity of Sr(II) using RCWB-based carbonaceous adsorbents in real water matrices. [Display omitted] • NaOH-assisted H 2 O 2 post-modification enhanced surface charge properties of RCWB P. • RCWB NHP showed highest Q e values of Sr(II) than RCWB P and RCWB HP. • Adsorption of Sr(II) by RCWB P , RCWB HP , and RCWB NHP was endothermic process. • Carbonyls were responsible for adsorption of Sr(II) by RCWB P and RCWB HP. • Carboxylic acids and Na played a key role in adsorption of Sr(II) by RCWB NHP. [ABSTRACT FROM AUTHOR]

The adsorption of ibuprofen (IBU) onto the pristine (CB), magnetic (MCB), and simultaneously magnetic activated waste coffee residue biochars (MACB) in groundwater and lake water was rigorously investigated in order to offer profound insights into the differences in their adsorption mechanisms and performances (i.e., adsorption capacity and separability). The higher adsorption capacity of IBU for MACB compared CB and MCB in groundwater and lake water was mainly attributed to the well-developed micropore structures of MACB via the simultaneous magnetization and activation. These phenomena were pronounced for groundwater than lake water due to its lower dissolved organic carbon concentrations. The calculated kinetic, intra-particle diffusion, isotherm, and thermodynamic parameters indicate that the adsorption of IBU onto CB, MCB, and MACB proceeded spontaneously and endothermically and their adsorption processes in groundwater and lake water were mainly governed by the physisorption (i.e., pore-filling effects, hydrogen bonding, and π-π electron donor-acceptor interactions), liquid film diffusion, and intra-particle diffusion. The noticeable increase of the X-ray photoelectron spectroscopy peak intensity related to the C O bond of the carbonyls in IBU-loaded MACB suggests that the accelerated pore-filling effects via the simultaneous magnetization and activation lead to the adsorption capacity improvement of IBU in groundwater and lake water. From the superior reusability of MACB in 3–4 adsorption-desorption cycles even under real water matrices (reuse efficiency > 60%), it can be postulated that the simultaneous magnetization and activation might provide a practicable way for enhancing the adsorption capacity of IBU toward waste coffee residue biochars and their separability in groundwater and lake water. [Display omitted] • Simulataneous magnetization and activation improved adsorption capacities of WCRBs. • Physisorption mainly controlled adsorption of IBU by CB, MCB, and MACB. • MACB exhibited highest adsorption capacity of IBU under real water matrices. • Enhanced pore-filling effects strongly contributed to adsorption of IBU onto MACB. • MACB had adequate resuabilities in 3 – 4 adsorption-desorption cyles (> 60%). [ABSTRACT FROM AUTHOR]

The single adsorption of radioactive barium (Ba(II)), cobalt (Co(II)), and strontium (Sr(II)) ions using pristine (SCWB–P) and chemically activated spent coffee waste biochars with NaOH (SCWB-A) were thoroughly explored in order to provide deeper insights into the changes in their adsorption mechanisms through alkaline chemical activation. The greater removal efficiencies of SCWB-A (76.6–97.3%) than SCWB-P (45.6–75.2%) and the consistency between the adsorptive removal patterns (Ba(II) > Sr(II) > Co(II)) and oxygen bond dissociation enthalpies (BaO (562 kJ/mol) > SrO (426 kJ/mol) > CoO (397 kJ/mol)) of radioactive species supported the assumption that the adsorption removal of radioactive species with spent coffee waste biochars highly depended on the abundances of O-containing functional groups. The calculated R2 values of the pseudo-first-order (SCWB–P = 0.998–0.999; SCWB-A = 0.850–0.921) and pseudo-second-order kinetic models (SCWB–P = 0.988–0.998; SCWB-A = 0.935–0.966) are evident that the physisorption mainly controlled the adsorption of radioactive species toward SCWB-P and the chemisorption played a crucial role in their adsorptive removal with SCWB-A. From the calculated intra-particle diffusion, isotherm, thermodynamic parameters, it can be concluded that the intra-particle diffusion and monolayer adsorption primarily governed the adsorption of radioactive species using SCWB-P and SCWB-A, and their adsorption processes occurred spontaneously and endothermically. The dominant adsorption mechanism of spent coffee waste biochars was changed from physisorption (ΔH° of SCWB-P = 21.6–29.8 kJ/mol) to chemisorption (ΔH° of SCWB-A = 42.4–81.3 kJ/mol) through alkaline chemical activation. The distinctive M-OH peak in the O1s XPS spectra of SCWB-A directly corresponding to the decrease in the abundances of O-containing functional groups confirms again that the enrichment of O-containing functional groups markedly facilitated the adsorption removal of radioactive species by chemisorption occurred at the inner and outer surfaces of spent coffee waste biochars. [Display omitted] • Alkaline chemical activation improves physicochemical properties of SCWB-A. • Enriched O-containing functional groups enhance removal of radioactive ions. • Adsorption rates of radioactive species are controlled by intra-particle diffusion. • Physisorption plays a key role in adsorption of radioactive species toward SCWB-P. • Chemisorption mainly governs adsorptive removal of radioactive ions using SCWB-A. [ABSTRACT FROM AUTHOR]

This study investigated the competitive adsorption mechanisms of pharmaceuticals (i.e., naproxen, diclofenac, and ibuprofen) toward the pristine and NaOH-activated biochars from spent coffee wastes (SCW) in lake water and wastewater effluent. The kinetic and isotherm studies revealed that the improved physicochemical characteristics and physically homogenized surfaces of the pristine SCW biochar through the chemical activation with NaOH were beneficial to the adsorption of pharmaceuticals (competitive equilibrium adsorption capacity (Q e, exp): NaOH-activated SCW biochar (61.25–192.07 μmol/g) > pristine SCW biochar (14.81–20.65 μmol/g)). The adsorptive removal of naproxen (Q e, exp = 14.81–18.81 μmol/g), diclofenac (Q e, exp = 15.73–20.00 μmol/g), and ibuprofen (Q e, exp = 16.20–20.65 μmol/g) for the pristine SCW biochar showed linear correlations with their hydrophobicity (log D at pH 7.0: ibuprofen (1.71) > diclofenac (1.37) > naproxen (0.25)). However, their Q e, exp values for the NaOH-activated SCW biochar (naproxen (176.39–192.07 μmol/g) > diclofenac (78.44–98.74 μmol/g) > ibuprofen (61.25–80.02 μmol/g)) were inversely correlated to the order of their log D values. These results suggest that the reinforced aromatic structure of the NaOH-activated SCW biochar facilitated the π-π interaction. The calculated thermodynamic parameters demonstrated that the competitive adsorption of pharmaceuticals on the NaOH-activated SCW biochar compared to pristine SCW biochar occurred more spontaneously over the entire pH (5.0–11.0) and ionic strength (NaCl: 0–0.125 M) ranges. These observations imply that the NaOH-activated SCW biochar might be potentially applicable for the removal of pharmaceuticals in lake water and wastewater effluent. Image 1 • Competitive adsorption of pharmaceuticals investigated under real water matrices. • NaOH-activated SCW biochar has high specific surface area and total pore volume. • NaOH-activated SCW biochar eliminates NPX, DCF, and IBU more effectively. • Adsorption of pristine SCW biochar corresponds to Log D values of micropollutants. • Increased aromaticity of NaOH-activated SCW biochar stimulates π-π interaction. [ABSTRACT FROM AUTHOR]