Pollutants In Aqueous Media Research Articles

Synthesis of hydrotalcite and titanium dioxide (HT-TiO2) composite for application in heterogeneous photocatalytics processes

The objective of the study was to synthesize a composite of hydrotalcite and titanium dioxide (HT-TiO2) for application in heterogeneous photocatalytic processes to the degradation of organic pollutants in aqueous media. The composites were characterized by X-ray diffraction and surface area, then an experimental design was carried out to evaluate the influence of pH and temperature on the adsorption capacity of pollutants against the anionic dye indigo carmine using a kinetic study. Photocatalytic tests were carried out in a chamber equipped with a UV lamp and hydrogen peroxide as an auxiliary oxidant in degradation. The adsorption results corroborated with the order of surface areas obtained, where the adsorption capacity followed the order of HT, HT-TiO2 5 %, HT-TiO2 10 %, and TiO2, respectively, obtaining removals up to 96.94 %. For the heterogeneous photocatalytic tests, the best conditions of the experimental design were used for each semiconductor, with a removal of up to 99.96 % being observed in 2 h. The use of hydrogen peroxide as an auxiliary oxidant reduced the reaction time to 45 min, demonstrating how joint effluent treatment techniques can increase the speed and efficiency of the process.

High-carbon-content biochar from chemical manufacturing plant sludge for effective removal of ciprofloxacin from aqueous media

Biochar is considered a promising biosorbent for harmful organic pollutants in aqueous media. However, only a limited number of biochars derived from industrial sludges have been utilized due to their problematic high ash content and heavy metal leaching. In this study, a highly effective biochar was prepared as a superabsorbent for ciprofloxacin (CIP) from chemical manufacturing plant sludge via K2CO3-activated pyrolysis, and its CIP removal behavior was evaluated. Unlike sewage sludge, chemical manufacturing plant sludge contains low SiO2, resulting in an ultra-pure carbon (95.4%) based biochar with almost negligible ash content. As the pyrolysis temperature increased from 400 to 800 °C, the ordered graphitic carbon structure transformed into an amorphous carbon phase, and most oxygen-containing groups disappeared. However, the pore size significantly decreased to ∼4.5 nm due to the corrosive carbon volatilization caused by K2CO3, resulting in an extremely large surface area of 2331.8 m2/g. Based on its large surface area and porous carbon structure, the activated biochar at 800 °C (CAB-800) exhibited an outstanding CIP adsorption capacity of 555.56 mg/g. The CIP adsorption isotherm, kinetic, and thermodynamic studies were systematically investigated. The CIP adsorption on CAB-800 was mainly attributed to π-π interactions and hydrogen bond formation, with electrostatic interactions partially contributing to the adsorption reaction. From pH 2 to 12, CAB-800 showed an excellent CIP adsorption capacity of over 316.7 mg/g, with adsorption favored under acidic conditions. Except for HCO3− and CO32−, the presence of anions and humic acids did not significantly affect CIP adsorption capacity. These results demonstrate that biochar produced from chemical manufacturing industry sludge via K2CO3 activation is a highly feasible material for the removal of CIP from aqueous media.

Activated Periodates and Sodium Percarbonate in Advanced Oxidation Processes of Organic Pollutants in Aqueous Media: A Review

The methods of periodates and sodium percarbonate activation are considered for planning strategic approaches to increasing the efficiency and intensity of oxidative degradation of organic pollutants in aquatic environments. A classification of periodate activation methods is proposed, including activation methods by external energy effects, catalytic activation methods, and other activation methods (e.g., by hydrogen peroxide, by hydroxylamine, activation in alkaline medium). Activation methods for sodium percarbonate were divided into homogeneous and heterogeneous activation methods.

Advanced degradation of organic pollutants using sonophotocatalytic peroxymonosulfate activation with CoFe2O4/Cu- and Ce-doped SnO2 composites

The rampant upsurge of organic pollutants in aqueous media has become one of the major concerns nowadays. Finding non-specific catalysts that can target a wide range of organic pollutants is a key challenge. Eco-friendly oxidative radicals, such as promoted by peroxymonosulfate (PMS), are necessary for efficient water decontamination. We propose a multicomponent composite catalyst for activating PMS using a dual strategy of sonophotocatalysis. The composite integrates cobalt ferrite and Cu- or Ce-doped SnO2, with the at. % of doping metal and the mixture ratio carefully balanced. The top-performing architectures were able to decompose rhodamine B (20 ppm), a representative pollutant, in under 3 min and achieve over 70% mineralization in just 5 min. The synthesized nanocomposites demonstrated exceptional sonophotocatalytic performance, even when treating complex and diverse multipollutant solutions (80 ppm), achieving over 75% mineralization after 150 min. Considering their high stability and reusability, the proposed CoFe2O4/Cu- and Ce-doped SnO2 materials are among the state-of-the-art heterogeneous catalysts for mineralizing organic pollutants through PMS activation.

Removal of malachite green from water: Comparison of adsorption in a residue-derived AC versus photocatalytic oxidation with TiO2 and study of the adsorption-photocatalysis synergy

The literature rarely compiles studies devoted to the removal of pollutants in aqueous media comparing adsorption and photocatalytic degradation, and does not pay enough attention to the analysis of combined adsorption-photocatalytic oxidation processes. In the present manuscript, the removal of malachite green (MG) from aqueous solutions has been investigated in three different sustainable scenarios: i) adsorption on activated carbon (AC) derived from a residue, luffa cylindrica, ii) photocatalytic oxidation under simulated solar light using titanium dioxide (TP) and iii) combined adsorption-photocatalytic oxidation using TP-AC (70/30 wt./wt.) under simulated solar light. The study has revealed that in the three scenarios and studied conditions, the total removal of this endocrine-disrupting dye from the solution takes place in the assayed time, 2 h, in some cases just in a few minutes. MG adsorption in the AC is a very fast and efficient removal method. MG photocatalytic oxidation with TP also occurs efficiently, although the oxidized MG is not totally mineralized. MG removal using the TP-AC composite under simulated solar light occurs only slightly faster to the MG adsorption in the AC, being adsorption the dominating MG removal mechanism for TP-AC. Thus, more than 90% of the removed MG with TP-AC under simulated solar light is adsorbed in this carbon-containing composite. The obtained results highlight the interest in adsorption, being the selection of the most suitable removal method dependent on several factors (i.e., the cost of the AC regeneration, for adsorption, or the toxicity of the intermediate oxidation species, for photooxidation).Paying attention to MG photooxidation with TiO2, comparison of two working photodegradation schemes shows that the direct photodegradation of MG from solution, avoiding any initial dark equilibrium period, is more efficient from a time perspective. The use of scavengers has proved that MG photodegradation occurs via an oxidation mechanism dominated by superoxide anion radicals.

A new perspective for surface modifying TiO2 to effectively enhance its visible light photocatalytic activity

In this study, a new perspective was proposed to regulate the photocatalytic properties of TiO2 and a novel TiO2-based composite (BA@TiO2) with nitrogen-containing surface layer was obtained by surface modifying TiO2 with an organic molecular (3,3′-Diaminobenzidine, BA). The composite (BA@TiO2) exhibited high responsiveness to visible light and great photocatalytic activity, which could remove 92% of tetracycline hydrochloride (TC), and also maintained a high ability to photodegrade low concentrations of TC. The free radical trapping experiments showed that h+ and •O2- were the most dominant active species in the degradation process. The possible degradation pathways of TC were deduced with the help of HPLC-MS and fuikui index. QSAR was used to perform toxicity analysis of the degradation intermediates. In addition, the composites demonstrated good recyclable stability and removal efficiency of TC in real water samples, indicating BA@TiO2 is a purifying agent with great efficiency and sustainability for practical treatment of organic pollutants in aqueous media.

Design and synthesis of a new coordination polymer of zinc (II): Crystal structure and evaluation for its adsorption studies in removing perilous organic dye pollutants in aqueous medium

The contamination of aqueous environments by hazardous organic dye pollutants has become a pressing global concern, necessitating innovative strategies for effective water purification. In this research, we present the design, synthesis, and comprehensive evaluation of a new zinc(II) coordination polymer, formulated as [Zn(HIPA)(HIZ)2]n⋅H2O (CP-1), specifically tailored for adsorption studies aimed at the removal of hazardous organic dye pollutants from aqueous mediums. The CP-1 was effectively synthesized using a hydrothermal synthesis approach and incorporates two distinct organic ligands, namely, 5‑hydroxy isophthalic acid, and imidazole, along with a water molecule within the crystal lattice. The structural and morphological attributes of the synthesized coordination polymer (CP-1) are elucidated through a comprehensive characterization process, including SCXRD, PXRD, FTIR, UV–VIS spectroscopy, TGA, SEM, and BET analysis. Single-crystal diffraction of CP-1 confirms that Zn is coordinated in a tetrahedral environment. The CP-1 was systematically examined for dye adsorption of four hazardous organic dyes namely methylene blue (MB), methyl orange (MO), crystal violet (CV) and congo red (CR). Batch adsorption experiments were conducted, probing the influence of variables such as contact time, pH, temperature, the effect of dosage and initial dye concentration on the adsorption efficiency of CP-1. The CP-1 shows the best adsorption efficiency for MB followed by MO, CV, and CR. The CP-1 exhibits high selectivity and efficient MB and MO dyes adsorption at room temperature and neutral pH. Moreover, three different kinetic models were utilized to attain a deeper comprehension of the reaction mechanism involved in the adsorption of MB and MO. Amongst these models, the pseudo-second-order kinetic model demonstrated the best fit for both cases. Furthermore, the density functional theory with the dispersion correction (Grimme's DFT-D3) was utilized to support the dye's adsorption mechanism with the CP-1. To study this, the dispersion corrected interaction energies were computed for the dye-complex systems at B3LYP-D3/6–31G(d,p)/LANL2DZ level of theory. The efficient adsorption performance, coupled with its structural and chemical stability, suggests that CP-1 holds great potential for practical applications in water treatment processes aimed at addressing the pressing challenge of organic dyes pollutant contamination. Further research and exploration of its adsorption properties can unveil its full potential for future applications as a dye adsorbent.

Dual phase zirconium-based metal-organic gel (Zr-MOG) as chromium (VI) removal via photoreduction

Given the widespread production of Cr(VI) from numerous industrial processes, as well as its harmful toxicity as a carcinogenic agent, it is critical to explore stable and efficient adsorbents with quick performance for Cr(VI). Recently, environmentally friendly adsorbents have been employed to reduce metallic pollutants in aqueous media called zirconium-containing metal-organic frameworks (Zr-MOFs) or UiO-66. UiO-66 are favourable because of their nontoxic metal sources, outstanding stabilities, and distinctive physicochemical characteristics. Despite the benefits of using MOFs, overcoming their poor macro-shaping and hydro-stability to be used as commercial adsorbents and catalysts remains a significant problem. Zirconium-based metal-organic gel (Zr-MOG) xerogel is widely known as a new nanomaterial to overcome metal-organic framework (MOFs) disadvantage as microcrystalline powder. This research is an effort to investigate green ZrMOG as a potential photocatalyst for reducing Cr(VI) to Cr(III) ions. The behaviour of ZrMOG in dark adsorption and photocatalysis, with and without a scavenger, as well as its reusability were studied. Besides that, synthesised Zr-MOG xerogel exhibited three different X-ray diffraction (XRD) pattern categories: fully amorphous, 1:1 ratio and 1:4 ratio of amorphous and crystalline structure. The performance of pure amorphous MOG, pure crystalline MOG and dual-phase MOG as photocatalysts were compared. The dualphase structure Zr-MOG 5 exhibits the greatest Cr(VI) ion reduction, with an 87% removal rate in 120 minutes.

Evaluation of photocatalytic activity of heterojunctions between bismuth oxyhalides and hematite in the degradation of organic compounds in liquid phases under visible light

Photocatalysts were synthesized by constructing p-n type heterojunctions between bismuth oxyhalides BiOX (X = I or Br) and hematite (α-Fe2O3) for enhanced visible light photodegradation of pollutants in aqueous medium. BiOX, in this text called precursors, were synthesized using a modified solvothermal method and by coprecipitation. Hematite was added using hydrothermal treatment. Herein the materials prepared using precursors and hematite are being called catalysts. All materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), diffuse reflectance spectroscopy (DRS) and adsorption assays with N2. The characterization of BiOX revealed that the solvothermal methods synthesized precursors with greater surface area and structural uniformity than those obtained by coprecipitation. The BiOI precursors, had observed reaction rate constant, kap, values for rhodamine between 0.0054 and 0.0167 min−1. The BiOBr precursors provided values between 0.1016, and 0.0515 min−1. In order to synthesizing the catalysts, an experimental planning was carried out. It showed that Fe/Bi ratio was the variable with the greatest impact on activity, followed by temperature. The BiOI catalysts had kap maximum values for rhodamine between 0.0419, and 0.0213 min−1, while BiOBr catalysts between 0.1144 and 0.1082 min−1. BiOI and BiOBr catalysts provided kap at least 2.0 and 1.12 times greater than their precursors, respectively. Also, successfully degraded phenol, confirming photocatalytic activity of the catalyst surface.

Hydrothermal carbonization of vegetable-tanned leather shavings (HTC-VTS) for environmental remediation: optimization of process conditions.

Herein, the response surface methodology (RSM) has been used to study simultaneously the effects of carbonization temperature, residence time and moisture content on the activated hydrochar preparation-based vegetable-tanned leather shavings (VTS) using hydrothermal carbonization method (HTC). Owing to the desirability chosen, three responses were analysed, namely: the hydrochar yield, iodine and methylene blue numbers. The analysis of experimental results revealed that the hydrochar yield was decreased with increase in carbonization temperature which led to micropores formation inside the hydrochar network. The optimal preparation conditions retained were: 83.10%, 390.44 mg g-1 and 259.63 mg g-1 for the hydrochar yield, iodine and methylene blue number respectively. The hydrochar micrograph showed the presence of external pores, whereas the FTIR analysis recorded the presence of acidic functional groups found on hydrochar surface. The findings revealed that the VTS is a good precursor for the hydrochar preparation useful in the removal of organic and inorganic pollutants in aqueous media.

Application of the general rate law model to the sonolytic degradation of nonvolatile organic pollutants in aqueous media

The pseudo-first and pseudo-second order equations have been the most commonly used models to characterize the sonolytic disappearance kinetics of nonvolatile pollutants in aqueous media. In this work, the general rate law model, i.e., pseudo-nth order kinetics equation, was applied for the first time to the sono-decomposition of different nonvolatile organic pollutants, naphthol blue black (NBB), furosemide (FSM), 4-isopropylphenol (4-IPP), and rhodamine B (RhB), in water. It was shown that the general rate law for a chemical reaction would apply to the kinetics of sonochemical decomposition. It is not feasible to set the order of ultrasonic pollutant degradation kinetics to pseudo-first or pseudo-second, as is typically used in numerous studies. The sonochemical oxidation reaction has a fractional order, the order is often non-integer, which frequently indicates a complex sonolytic decomposition reaction mechanism. The degradation mechanism of NBB and RhB does not change with the initial substrate concentration. They are ultrasonically degraded by hydroxyl radicals both in the bulk liquid solution and at the liquid/bubble interfacial layer. The destruction mechanism of FSM and 4-IPP changes as the initial contaminant concentration changes. At low initial substrate concentrations, these pollutants are oxidized mainly by reaction with hydroxyl radicals in the bulk liquid solution and at the interfacial shell of the cavitation bubbles. At high initial substrate concentrations, FSM and 4-IPP are degraded by thermal destruction in the liquid/bubble interfacial layer and by •OH radicals both in the bulk liquid solution and at the liquid/bubble interfacial layer. Additionally, the pseudo-nth order model predicts very well the sonolytic degradation at various sonication frequencies and intensities. The general rate law expression should be used to assess the real kinetics order of the sonolytic destruction process without any predetermined assumptions or constraints.

Application of an Fe-TAML/H2O2 system for rapid degradation of organic matter

Combining iron with the tetra-amido macrocyclic ligand (Fe-TAML) results in an efficient catalytic complex that, in the presence of an oxidant such as hydrogen peroxide (H2O2), efficiently promotes the degradation of organic pollutants via oxidants. To date, various synthesis methods have been employed, resulting in seven different Fe-TAML/H2O2 compounds (i.e., generations) that have many applications. Nevertheless, the catalytic activity of each generation depends on the pH of the medium; while the first generation has been the most used for water treatment purposes and has achieved efficiencies of over 90% in alkaline pH, the potential applications of the other generations are still under investigation. Thus, this mini-review summarizes the synthesis methods of the different Fe-TAML generations, presents the mechanism of action of the Fe-TAML/H2O2 compound in pollutant degradation, and analyzes the most recent studies on applying this compound to degrade different pollutants in aqueous media.

Green synthesis of a mesoporous hyper-cross-linked polyamide/polyamine 3D network through Michael addition for the treatment of heavy metals and organic dyes contaminated wastewater

Environmental pollution is the greatest challenge of the modern age due to unprecedented industrialization and urbanization that has led to the contamination of water resources with a wide range of pollutants. The release of untreated industrial and municipal wastewater to water bodies further intensifies the problem. The presence of heavy metals and organic contaminants in water poses significant threats to humans, aquatic life, and the environment. Adsorption is one of the famous water treatment technologies due to its simplicity, low cost, efficiency, and minimal secondary pollution. The selection or synthesis of an effective adsorbent is key to the success of the adsorptive removal of pollutants. In this work, we synthesized an adsorbent consisting of a mesoporous hyper-cross-linked polyamide/polyamine 3D network through a single-step Michael addition reaction. The adsorbent was characterized by FTIR, PXRD, TGA, SEM, and TEM to investigate its functional moieties, material nature, thermal, morphological, and internal structural features, respectively. Due to its mesoporous structure, presence of functional groups, and 3D hyper-cross-linked network, it efficiently removed heavy metals (Cd, Cr, and Pb) from aqueous media. The effect of various parameters such as sample pH, adsorbent dosage, contact time, and adsorbate concentrations was thoroughly investigated. The experimental data were analyzed by a variety of isotherm models wherein Langmuir was found to be the best fit for explaining the adsorption of all the metals. The adsorption kinetics was best explained by the pseudo-second-order model. The maximum adsorption capacities for Cd, Cr, and Pb were 60.98 mg g−1, 119 mg g−1, and 9.302 mg g−1, respectively. The synthesized adsorbent was also tested for removal of organic dyes, and it showed selective and fast removal of Eriochrome Black T. Polymeric resins can be promising materials for adsorptive remediation of pollutants in aqueous media.

Photochemistry of the Fe(III)-iminodiacetic acid complex under UVA and UV/Vis irradiation: synthesis and characterisation

ABSTRACT The photochemistry of Fe(III)-Iminodiacetic acid complex (Fe(III)-IDA) was studied under UVA and UV/Vis irradiation. The synthesis was realised via molar ratio method modified by reaction of IDA as ligand with Fe(III) as metal. The interaction of Fe(III) with IDA was characterised using Fourier-transform infrared (FTIR) and spectroscopy UV–visible. The results confirmed the stability of the complex at pH > 5; with constant of stability (Log β = 10.02) and stoichiometry Fe(III): IDA = 1:1. In addition, the redox potential was calculated at 521 mV, which is significantly lower than E° for the Fe(III)/Fe(II) couple. The photolysis of this complex in the presence of UVA light and UV/Vis light at different pHs was carried out. This photolysis was followed by several assay Fe(II) and •OH. The results show that the Fe(III)-IDA complex present a photo-reactivities under either light source and the phenomenon is faster when the UV/Vis was used. The initial conversion rate (r0) decreased with increasing of initial pH. The formation of hydroxyl radicals via the Fenton reaction was improved at pH = 2.12 for both irradiation sources used. Reduction of total organic carbon was also studied using the total organic carbon (TOC). The feasibility of amino iron complexes to improve the Fenton process under irradiation was confirmed. Additionally, our research also evidenced the optimal conditions for the formation of hydroxyl radicals; which are the key factor in remove pharmaceuticals pollutants in aqueous media. Based on the results obtained, the Fe(III)-IDA complex could be efficiently photolysis under UV/Vis light.

Assessment of surface and electrical properties of the TiO2@zeolite hybrid materials

Degradation of pollutants in aqueous medium is of high interest due to the impact on environment and human health, therefore, design and study of the physico-chemical properties of photocatalysts for water remediation are of major significance. Among properties of photocatalyst, those related to the surface and electrical mechanism are crucial to the photocatalyst´s performance. Here we report the chemical and morphological characteristics of TiO2@zeolite photocatalyst by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) respectively, and a coherent electrical conduction mechanism was proposed based on data obtained from assisted laser impedance spectroscopy (ALIS), in which the zeolite was synthesized from recycled coal fly ash. The results obtained by SEM and XPS verified the presence of spherical particles of TiO2 anatase with presence of Ti3+ state. ALIS results showed that impedance of the entire system increases when the amount of TiO2 increases and the samples with lower capacitive performance allowed a larger transfer of the charges between the solid–liquid interface. All results showed that higher photocatalytic performance of TiO2 growth over hydroxysodalite with 8.7 wt% and 25 wt% of TiO2 can be explained in terms of the morphology of TiO2 and the interactions between substrate-TiO2 mainly.

Amino decorated adenine based metal-organic framework for multi-faceted applications.

Multifunctional metal-organic frameworks with luminescence properties are promising materials for the detection and treatment of toxic pollutants in aqueous media. Herein, an adenine-based multifunctional Zn-MOF {[Zn3.5(AIPA)2(Ade)3(H2O)2]n using linkers adenine (Ade) and 5-aminoisophthalic acid (AIPA)} was prepared that could selectively detect particular classes of explosives and antibiotics, namely, nitrophenols, tetracyclines and nitrofurans. Moreover, the as-synthesized Zn-MOF displayed a remarkable efficiency for the treatment of antibiotics in water through adsorption and photocatalytic degradation. A subtle balance between photoinduced electron transfer (PET), resonance energy transfer (RET) and competitive excitation energy absorption enabled detection selectivity towards the pollutants. On the other hand, intermolecular interactions of free functional groups assisted the treatment process and thereby highlighted the crucial role of the linkers in furnishing multifunctional behavior without the need for any postsynthetic modifications.

Construction of Z-scheme heterojunction based on BiOBr-nanoflakes embedded sulfonic-acid-functionalized g-C3N4 for enhanced photocatalytic removal of hazardous pollutants in aqueous media

BackgroundEnvironmental remediation and energy production via semiconductor photocatalysis has attracted great interest in the research field because of their enormous physicochemical properties and ease of modification through forming various heterojunctions. MethodsIn this work, the nanoflakes-like bismuth oxybromide embedded sulfonic acid-functionalized graphitic carbon nitride (BiOBr-NFs/g-C3N4-SAF) were prepared by hydrothermal and wet-impregnation methods. The FT-IR, XPS, and TGA studies confirm the presence of surface sulfonic groups. Meanwhile, PL, EIS, M-S, and transient photocurrent analyses indicate the suppressed recombination rate, interfacial charge transfer, band-edge potentials, and photoexcitation phenomena. Significant findingsThe surface modification and the heterojunction formation of BiOBr-NFs/g-C3N4-SAF enable adequate band-edge potentials for photooxidation and photoreduction reactions. Among the as-synthesized photocatalysts, the 20 wt.% BiOBr-NFs/g-C3N4-SAF resulted in 98.39% of Cr(VI) photoreduction and 99.88% of RhB photooxidation within 15 min and 30 min, respectively. The rate constant (k’) for the photooxidation of RhB (0.6615 min–1) is about 11.7 and 11.4 folds than g-C3N4-SAF and BiOBr-NFs, respectively. Meanwhile, the k’ for the photoreduction of Cr(VI) (0.6243 min–1) is around 30.1 and 15.8 folds than g-C3N4-SAF and BiOBr-NFs, respectively. This enhanced photocatalytic activity is ascribed to the strongly associated BiOBr-NFs/g-C3N4-SAF Z-scheme heterojunction interface, assuring effective photogenerated charge transport and high redox band-edge potentials and reduced recombination rates.

Temperature-swing adsorption of 4-isopropylphenol and bisphenol A onto a poly(N-isopropylacrylamide)/silica gel composite

Poly( N -isopropylacrylamide) (poly(NIPA)) is a thermosensitive polymer, with a lower critical solution temperature (LCST) of ~33 °C in water. Herein, a poly(NIPA)/silica gel composite was developed as an adsorbent for the temperature-swing adsorption (TSA) of organic pollutants in aqueous media. Poly(NIPA) was grafted onto a millimeter-sized silica gel by silane coupling, followed by free radical polymerization. The composite reversibly adsorbed/desorbed organic pollutants such as bisphenol A and 4-isopropylphenol by changing the temperature across the LCST range to modulate the hydrophilicity/hydrophobicity of poly(NIPA). The adsorption isotherms and kinetics were evaluated through a batch experiment. A continuous TSA process using a fixed-bed column with adsorption at 40 °C followed by desorption at 20 °C was demonstrated. The associated breakthrough curve was predicted by a mathematical analysis involving the Henry constant and effective diffusivity. The composite overcomes drawbacks such as a low mechanical strength and thermosensitive volume change of conventional poly(NIPA) gels. Thus, this study provides a strategy for preparing an environmentally friendly adsorbent and designing an adsorption process for wastewater treatment and conservation of water environments. • A thermosensitive poly( N -isopropylacrylamide)/silica gel composite was developed. • The composite adsorbed/desorbed organic pollutants with a change in temperature. • The adsorption isotherms and kinetics were investigated. • A continuous temperature-swing adsorption process was demonstrated and designed. • It is an environment-friendly way for wastewater treatment and water conservation.

Dye‐Sensitization‐Enhanced Photocatalytic Activity of BiOCl/Sulfur Quantum Dot Heterojunction under Visible‐Light Irradiation

AbstractHerein, we report a novel narrow band gap sulfur quantum dots (SQDs)‐modified BiOCl heterojunction (BOC/SQDs) for the photo‐degradation of hazardous organic pollutants via rhodamine B (RhB)‐sensitization. Such a high photocatalytic activity of RhB‐sensitized BOC/SQDs heterojunction derives not only from the improved visible‐light response capacity, high surface area/pore volume, suitable band structure for efficient electron transfer, but also from the surge of the number of electrons via RhB‐sensitization for reactive oxygen species (ROS) generation. Superoxide radicals (⋅O2−), holes (h+), and hydrogen peroxide (H2O2) play the important roles in the photo‐degradation. A possible mechanism for RhB‐sensitization enhanced degradation performance for treating organic pollutants by BOC/SQDs is proposed. The combination of dye‐sensitization with BOC/SQDs heterojunction can explore a greener, energy saving, and efficient photo‐induced nanoplatform for treating organic pollutants in aqueous media.

Effective adsorption of diclofenac sodium from aqueous solution using cationic surfactant modified Cuminum cyminum agri-waste: kinetic, equilibrium, and thermodynamic studies

The occurrence of pharmaceutical pollutants in aqueous media has increased where significant research is being conducted to eliminate these toxic compounds. In the present study, Tetradecyltrimethylammonium bromide (TTAB) modified Cuminum cyminum agri-waste (CCW) was prepared to investigate the removal of diclofenac sodium (DCF) from aqueous solution in the batch process for the first time. Physical and chemical characterizations of as-prepared adsorbent were conducted using field emission scanning electron microscopy, Fourier-transform infrared spectroscopy, N2 adsorption-desorption, and point of zero charge analysis. Besides, the effect of the main parameters that affect the adsorption process, i.e., adsorbent dosage (0.25–6 g/L), contact time (0–300 min), initial DCF concentration (10–500 mg/L), and pH of the solution, were investigated. Furthermore, the resulted data were analyzed using various kinetic and isotherm models. The Pseudo-second-order model with R 2 = 0.9981 showed the highest agreement with kinetic behavior. Also, the maximum adsorption capacity of DCF is 93.65 mg/g, according to the Langmuir isotherm. In acidic media, the adsorption capacity reached the highest value (44.69 mg/g). As a result, this study revealed that the agri-waste material could be modified and, as a low-cost adsorbent, have promising adsorption potential to remove pharmaceutical contaminants from the aqueous solution.