Garden pruning waste is becoming a problem that intensifies the garbage siege. It is of great significance to purify polluted water using biochar prepared from garden pruning waste. Herein, the interaction mechanism between BPS and oriental plane tree biochar (TBC) with different surface functional groups was investigated by adsorption experiments, spectroscopic analysis and theoretical calculations. Adsorption kinetics and isotherm of BPS on TBC can be satisfactorily fitted into pseudo-second-order kinetic and Langmuir models, respectively. A rapid adsorption kinetic toward BPS was achieved by TBC in 15 min. As compared with TBC prepared at low temperature (300 °C) (LTBC), the maximum adsorption capacity of TBC prepared at high temperature (600 °C) (HTBC) can be significantly improved from 46.7 mg g⁻¹ to 72.9 mg g⁻¹. Besides, the microstructure and surface functional groups of HTBC were characterized using SEM, BET-N₂, and XPS analysis. According to density functional theory (DFT) theoretical calculations, the higher adsorption energy of HTBC for BPS was mainly attributed to π-π interaction rather than hydrogen bonding, which was further supported by the analysis of FTIR and Raman spectra as well as the adsorption thermodynamic parameters. These findings suggested that by improving π-π interaction through high pyrolysis temperature, BPS could be removed and adsorbed by biochar with high efficacy, cost-efficiency, easy availability, and carbon-negative in nature, contributing to global carbon neutrality.

The adsorption of radioactive iodine, which is capable of presenting high mobility in aquatic ecosystems and generating undesirable health effects in humans (e.g., thyroid gland dysfunction), was comprehensively examined using pristine spent coffee ground biochar (SCGB) and bismuth-impregnated spent coffee ground biochar (Bi@SCGB) to provide valuable insights into the variations in the adsorption capacity and mechanisms after pretreatment with Bi(NO₃)₃. The greater adsorption of radioactive iodine toward Bi@SCGB (adsorption capacity (Qₑ) = 253.71 μg/g) compared to that for SCGB (Qₑ = 23.32 μg/g) and its reduced adsorption capability at higher pH values provide evidence that the adsorption of radioactive iodine with SCGB and Bi@SCGB is strongly influenced by the presence of bismuth materials and the electrostatic repulsion between their negatively charged surfaces and negatively charged radioactive iodine (IO₃⁻). The calculated R² values for the adsorption kinetics and isotherms support that chemisorption plays a crucial role in the adsorption of radioactive iodine by SCGB and Bi@SCGB in aqueous phases. The adsorption of radioactive iodine onto SCGB was linearly correlated with the contact time (h¹/²), and the diffusion of intra-particle predominantly determined the adsorption rate of radioactive iodine onto Bi@SCGB (Cₛₜₐgₑ II (129.20) > Cₛₜₐgₑ I (42.33)). Thermodynamic studies revealed that the adsorption of radioactive iodine toward SCGB (ΔG° = −8.47 to −7.83 kJ/mol; ΔH° = −13.93 kJ/mol) occurred exothermically and that for Bi@SCGB (ΔG° = −15.90 to −13.89 kJ/mol; ΔH° = 5.88 kJ/mol) proceeded endothermically and spontaneously. The X-ray photoelectron spectroscopy (XPS) analysis of SCGB and Bi@SCGB before and after the adsorption of radioactive iodine suggest the conclusion that the change in the primary adsorption mechanism from electrostatic attraction to surface precipitation upon the impregnation of bismuth materials on the surfaces of spent coffee ground biochars is beneficial for the adsorption of radioactive iodine in aqueous phases.

Herein, activated carbon supported modified with bimetallic-platin ruthenium nano sorbent (PtRu@AC) was synthesized by a thermal decomposition process and used in the removal of methylene blue (MB) from aqueous solutions. The synthesized nano sorbents were characterized by X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), and X-ray Photoelectron Spectroscopy (XPS) spectroscopic techniques. The data obtained from characterization studies showed that PtRu@AC nano sorbent was highly crystalline and in a form of PtRu alloy with a monodispersed composition. The results indicated that the maximum adsorption capacity (qemax) for the removal of MB with PtRu@AC under optimum conditions was detected to be 1.788 mmol/g (569.4 mg/g). The experimental kinetic results of the study revealed that the adsorption of methylene blue was found to be more compatible with the false second-order model compared to some tested models. Calculations for thermodynamic functions including enthalpy change (ΔHo), entropy change (ΔSo), and Gibbs free energy change (ΔGo) values were performed to get an idea about the adsorption mechanism. As a result, the synthesized PtRu@AC nano adsorbent was detected as a highly effective adsorbent material in the removal of MB from aquatic mediums.

Low-molecular-weight organic acids may significantly influence the mobility of metal in environment, but the kinetics are not fully understood and have not been quantified. In this study, the thermodynamic and kinetic effects of citric acid (CA) on the adsorption of Cd(II) and Ni(II) on goethite were investigated using batch-adsorption and stirred-flow experiments. A charge distribution and multisite complexation model (CD-MUSIC) and a thermodynamically based multi-rate kinetic model were employed to describe the adsorption behaviors. Two ternary surface complexes, (≡FeO)₂CitMe and (≡FeOH)₂MeCit²⁻, were involved in the adsorption. In addition, CA differed in its effects on Cd(II) and Ni(II) adsorption, enhancing Cd(II) adsorption but inhibiting Ni(II) adsorption at high levels. Kinetically, in the presence of CA, the adsorption of Cd(II) was faster than that of Ni(II). Increasing CA concentration led to faster Cd(II) adsorption, but resulted in the dissolution of the adsorbed Ni(II), possibly due to the much higher complexation constants of Ni-CA than of Cd-CA in aqueous phase. This finding implied that, in the rhizosphere, high level of CA may lead to more dissolution of Ni(II) than Cd(II); while in acidic ferrosol, CA may alleviate Cd(II) mobility and toxicity. The proposed mechanistic model sheds light on ion partition in the soil environment and may improve predictions thereof.

This study investigated the hourly inorganic aerosol chemistry and its impact on atmospheric visibility over an urban area in Central Taiwan, by relying on measurements of aerosol light extinction, inorganic gases, and PM₂.₅ water-soluble ions (WSIs), and simulations from a thermodynamic equilibrium model. On average, the sulfate (SO₄²⁻), nitrate (NO₃⁻), and ammonium (NH₄⁺) components (SNA) contributed ∼90% of WSI concentrations, which in turn made up about 50% of the PM₂.₅ mass. During the entire observation period, PM₂.₅ and SNA concentrations, aerosol pH, aerosol liquid water content (ALWC), and sulfur and nitrogen conversion ratios all increased with decreasing visibility. In particular, the NO₃⁻ contribution to PM₂.₅ increased, whereas the SO₄²⁻ contribution decreased, with decreasing visibility. The diurnal variations of the above parameters indicate that the interaction and likely mutual promotion between NO₃⁻ and ALWC enhanced the hygroscopicity and aqueous-phase reactions conducive for NO₃⁻ formation, thus led to severely impaired visibility. The high relative humidity (RH) at the study area (average 70.7%) was a necessary but not sole factor leading to enhanced NO₃⁻ formation, which was more directly associated with elevated ALWC and aerosol pH. Simulations from the thermodynamic model depict that the inorganic aerosol system in the study area was characterized by fully neutralized SO₄²⁻ (i.e. a saturated factor in visibility reduction) and excess NH₄⁺ amidst a NH₃-rich environment. As a result, PM₂.₅ composition was most sensitive to gas-phase HNO₃, and hence NOx, and relatively insensitive to NH₃. Consequently, a reduction of NOx would result in instantaneous cuts of NO₃⁻, PM₂.₅, and ALWC, and hence improved visibility. On the other hand, a substantial amount of NH₃ reduction (>70%) would be required to lower the aerosol pH, driving more than 50% of the particulate phase NO₃⁻ to the gas phase, thereby making NH₃ a limiting factor in shifting PM₂.₅ composition.

The emergence and continual accumulation of industrial micropollutants such as dyes, heavy metals, organic matters, and pharmaceutical active compounds (PhACs) in the ecosystem pose an alarming hazard to human health and the general wellbeing of global flora and fauna. To offer eco-friendly solutions, living and non-living algae have lately been identified and broadly practiced as promising agents in the bioremediation of micropollutants. The approach is promoted by recent findings seeing better removal performance, higher efficiency, surface area, and binding affinity of algae in various remediation events compared to bacteria and fungi. To give a proper and significant insight into this technology, this paper comprehensively reviews its current applications, removal mechanisms, comparative efficacies, as well as future outlooks and recommendations. In conducting the review, the secondary data of micropollutants removal have been gathered from numerous sources, from which their removal performances are analyzed and presented in terms of strengths, weaknesses, opportunities, and threats (SWOT), to specifically examine their suitability for selected micropollutants remediation. Based on kinetic, isotherm, thermodynamic, and SWOT analysis, non-living algae are generally more suitable for dyes and heavy metals removal, meanwhile living algae are appropriate for removal of organic matters and PhACs. Moreover, parametric effects on micropollutants removal are evaluated, highlighting that pH is critical for biodegradation activity. For selective pollutants, living and non-living algae show recommendable prospects as agents for the efficient cleaning of industrial wastewaters while awaiting further supporting discoveries in encouraging technology assurance and extensive applications.

The present work compared both the bioaccumulation of trace elements and the values of ecophysiological parameters measured in thalli of the lichen Pseudevernia furfuracea (L.) Zopf in two monitoring campaigns performed before and after improvement measures put in place by a 15 MW biomass power plant (BPP): the activation of a concentrated solar thermodynamic plant and the increasing percentage of exhausted olive pomace used as fuel. The cases of no enrichment and moderate enrichment change from 49 and 17% in 2013 to 68 and 4.2% in 2019, respectively. Several metals in 2019, show a Delta (difference between exposed and not exposed lichen thalli concentration) that is significantly lower than in 2013. The spatial pattern of contamination is comparable between the two years. However, the BPP affects the spatial variation of Ti, Al, V and Co in both 2019 and 2013, but only in the latter year also that of Cu, Cr and As which, in some monitoring sites, developed extremely high levels of enrichment. Traffic, whose rate increased over time, constantly influences the bioaccumulation of Cu, Sb and Mo. In 2019, the lichen oxidative stress is significantly reduced as well as the number of correlations between malondialdehyde levels and those of trace elements. Pigment values never differ (p > 0.05) from pre-exposure levels. Our results suggest that the development of hybrid plants, as well as a better fuel selection can reduce the environmental impact due to the combustion of biomass contributing to make this type of energy source more sustainable.

The synthesis of new high-performance and low-cost nanomaterials in the adsorption process that meets the requirements of green chemistry is still a major challenge for the removal of dyes in the textile industry. In this sense, hydrogen titanate nanotubes (H-TiNTs) were synthesized, characterized, and used in the adsorption process to remove methyl violet (MV) dye from water. For the characterization, the H-TiNTs showed a high surface area of 309.304 m² g⁻¹ and a point of zero charge of 6.4. The density functional theory (DFT) study was performed, which showed that the adsorption occurred especially for the weak dispersion interactions C – H…O and – H…Ti. More intense attractive interactions were also identified in the H-TiNTs, such as intramolecular hydrogen bondings O–H…O. For the kinetic adsorption studies, the equilibrium was reached after 180 min, with an 88% MV removal. The best fit occurred for the pseudo-second-order model (R² = 0.99), compared to the pseudo-first-order and intraparticle diffusion models, which were also used. Both Langmuir (R² = 0.99) and Freundlich (R² = 0.93) isotherm models showed a good fit; however, the Langmuir model best described the adsorption process of MV dye in H-TiNTs with a qₘₐₓ = 106 mg g⁻¹. The thermodynamic parameters ΔG°, ΔH°, and ΔS° indicated that the adsorption process was spontaneous and endothermic. Due to the high efficiency of the removal of MV dye using H-TiNTs, this material can be a promising and low-cost alternative, compared to other adsorbents used for dye removal in textile industry wastewater.

Desulfurization of liquid fuels mitigates the amount of noxious sulfur oxides and particulates released during fuel combustion. Existing literature on oxidative-adsorptive desulfurization technologies focus on sulfur-in-fuel removal by various materials, but very little information is presented about their desorption kinetics and thermodynamics. Herein, we report for the first time, the mechanism of sulfur desorption from neutral activated alumina saturated with dibenzothiophene sulfone. Batch experiments were conducted to examine the effects of agitation rate, desorption temperature, sulfur content, and eluent type on sulfur desorption efficiencies. Results show enhanced desorption capacities at higher agitation rate, desorption temperature, and initial sulfur content. Desorption efficiency and capacity of acetone were found to be remarkably superior to ethanol, acetone:ethanol (1:1), and acetone:isopropanol (1:1). Desorption kinetics reveal excellent fit of the nonlinear pseudo-second-order equation on desorption data, indicating chemisorption as the rate-determining step. Results of the thermodynamics study show the spontaneous (ΔG° ≤ −2.08 kJ mol⁻¹) and endothermic (ΔH° = 32.35 kJ mol⁻¹) nature of sulfur desorption using acetone as eluent. Maximum regeneration efficiency was attained at 93% after washing the spent adsorbent with acetone followed by oven-drying. Scanning electron microscopy, Fourier transform infrared, and X-ray diffraction spectroscopy analyses reveal the intact and undamaged structure of neutral activated alumina even after adsorbent regeneration. Overall, the present work demonstrates the viability of neutral activated alumina as an efficient and reusable adsorbent for the removal of sulfur compounds from liquid fossil fuels.

In this work, four kinds of covalent organic framework (COF) materials (TpPa-1, TpBD, TpDT, and TFBBD) with different pore sizes or functional groups were synthesized by an ultrasonic method for the adsorption of five sulfonamides. Optimization experiments regarding the adsorption time, vortex speed, and pH were carried out to improve adsorption efficiency. In addition, kinetic and thermodynamic experiments were conducted to explore the adsorption mechanism of the sulfonamides on the different COFs. The adsorption processes of the five sulfonamides on the four COFs fit the pseudo-second-order kinetic model and Langmuir adsorption isotherm model. Additionally, pore filling, hydrogen bond interactions, and electrostatic attraction were found to be the main adsorption mechanisms.