Adsorbent Dosage Research Articles

Adsorption of methyl orange and methylene blue on activated biocarbon derived from birchwood pellets

This study explored the adsorption capacity of a physically activated biocarbon derived from the pyrolysis of birchwood pellets (ABPB) towards two dyes - methyl orange (MO, anionic) and methylene blue (MB, cationic), at pH 2, 7 and 11. Compared to mineral commercial activated carbon (CACmineral), ABPB exhibited lower SSA, pores volume and surface; higher external surface and average pore diameter, similar ash content and aromaticity, and stronger hydrophilicity and polarity. The maximum adsorption capacity on ABPB was equal to 220 mg/g for MO and 91 mg/g for MB after 17 h. Batch tests with variable adsorbent amount (0.5–2.5 g/L) showed for both ABPB and CACmineral better results for lower adsorbent dose. Under all tested conditions, ABPB showed higher or analogous adsorption capacity compared to CACmineral. Based on the pKa of MB (3.80) and MO (3.46) and on the pHPZC of ABPB (5.3), the adsorption was favored at pH 2 for MO and at pH 11 for MB. Kinetics analysis and isotherm modelling revealed that, although many different physicochemical interactions occurred between ABPB and the dyes molecules, chemisorption is the rate-controlling step and prevalent mechanism. In conclusion, this study may provide support to further research aimed at exploring the effect of ABPB's physicochemical properties on the efficiency and mechanisms of dyes adsorption.

Facile Preparation of Cross-Linked Moringa oleifera Seed Hulls Powder/Hydroxyapatite Framework Composite for Efficient Removal of Toluidine Blue and Methyl Violet 2B from Aqueous Solution

AbstractIn this study, adsorption of two cationic dyes, Toluidine Blue (TB) and Methyl violet 2B (MV 2B) from an aqueous solution was achieved by using multifunctional composite material. The formulation of the composite (MO@HA) was obtained by using Moringa oleifera seed hull powder, calcium chloride (CaCl2), and ammonium hydrogenophosphate (NH4)2HPO4 salts. Surface morphology, functional groups, specific surface area, and surface charge of the composite were explored using Scanning electron microscopy (SEM), Fourier Transform infrared spectroscopy (FTIR), BET analysis, and point of zero charge (PZC), respectively. The composite material resulted in a structural change in the surface of the adsorbents, increased oxygen vacancies, enhancement of active sites, and a specific surface area of 735.55 m2 g−1. Different adsorption parameters such as pH, contact time, adsorbent dosage, and initial concentration were evaluated. The adsorption study showed that equilibrium was reached after 60 min, and the optimum adsorption pH for both dyes (TB and MV 2B) was 6. Langmuir, Freundlich, Liu, and Temkin were fitted to describe the adsorption isotherm, both TB and MV 2B had best correlation with Liu isotherm. The maximum adsorption capacity of TB and MV 2B were 341.488 and 182.453 mg g−1, respectively. Adsorption-desorption cycling studies on the adsorbent confirmed its regeneration and reusability after 5 cycles. A possible adsorption mechanism involving electrostatic interactions, n-π bonding, and hydrogen bonding was suggested. These findings highlight a new direction in the development of efficient and sustainable adsorbent in environmental remediation, specifically in the removal of dyes from aqueous solution.

Preparation, characterization and application of polymeric ultra-permeable biodegradable ferromagnetic nanocomposite adsorbent for removal of Cr(VI) from synthetic wastewater: kinetics, isotherms and thermodynamics

Hexavalent chromium (Cr(VI)) contamination in drinking water due to industrial activities is a growing worldwide concern. Cr(VI) concentrations exceeding a few parts per billion (ppb) can cause serious health problems such as asthma, blood cancer, kidney-related diseases, liver and spleen damage, as well as neurological system, immunological deficiencies, and reproductive issues. This study, thus, explored the feasibility of employing a novel polymeric ferromagnetic nanocomposite adsorbent made of low-cost, biodegradable, and ultra-permeable materials from pulp and paper sludge for adsorptive removal of hexavalent chromium (Cr6+) from synthetic wastewater. Vibrating-sample magnetometer (VSM), X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer-Emmet-Teller surface area (BET), and Fourier transform infrared (FTIR) were used to analyze the produced nanocomposite adsorbent. The Fourier transform infrared results confirmed the presence of adsorptive peaks attributed to −OH, −NH2, and FeO. Scanning electron microscopy micrographs revealed a porous adsorbent surface. XRD revealed the existence of the crystalline spinel-structured magnetite (Fe3O4) phase of iron oxide, while the saturation magnetization was established to be 26.90 emu/g. The Brunauer–Emmett–Teller analysis confirmed a slight decrease in the surface area of the nanocomposite adsorbent to 6.693 m2.g−1, compared to Fe3O4 (7.591 m2.g−1). The optimum conditions for Cr6+ removal were pH 2.0, 1.0 g/L adsorbent dose, room temperature (25°C), 120 min contact time, and 20 mg/L pollutant concentration. During removal, the Cr(VI) was adsorbed by electrostatic attraction and/or reduced to trivalent chromium Cr(III). At low starting Cr(VI) concentrations, chemisorption dominated the removal process, but as concentrations increased, physisorption became more significant. The prepared nanocomposite adsorbent presented exceptional removal efficiency of up to 92.23%, indicating that it may be useful for the adsorption of metal ions from industrial and household wastewater.

High-performance activated carbon from coconut shells for dye removal: study of isotherm and thermodynamics.

This study investigates the production of high-performance activated carbon (AC) from coconut shells (CS) through acid and base activation processes, along with pre- and post-functionalization of the biochar, aiming to effectively remove dyes from aqueous solutions. The resulting AC exhibited outstanding adsorption capabilities, with the Langmuir model providing a good fit to the experimental data. Maximum adsorption capacities were observed at different temperatures: 805 mg g-1 at 298 K, 904 mg g-1 at 318 K, and 1000 mg g-1 at 338 K for NaOH-activated AC, and 252 mg g-1 at 298 K, 295 mg g-1 at 318 K, and 305 mg g-1 at 338 K for H2SO4-activated AC. The presence of active sites and functional groups on the surface of AC facilitated dye adsorption. The influence of various parameters, including adsorbent dosage, dye concentration, pH, and temperature, on the adsorption process were also examined, identifying the ideal conditions for dye removal. Thermodynamic analysis confirmed the endothermic nature of the adsorption process, with higher temperatures leading to increased adsorption capacities. Overall, the research highlights the potential of various activation routes for the production of high-value AC as a sustainable and effective adsorbent for dye removal from wastewater.

Enhancing Selenium Removal Using Pre-Treated Natural Clay: Experimental Investigation and Predictive Modeling

Abstract A heat treatment methodology was adopted as a pretreatment strategy, altering the porous structure of the clay to minimize leaching for selenium adsorption in an aqueous system. Rigorous experiments were carried out in batch mode to determine optimal parameters across various variables, including contact time, adsorbent dosages, selenium concentrations, pH, temperature, and stirring speed during selenium removal using natural clay. Investigating several kinetic and isotherm models revealed the best fitting for the pseudo-second-order and the Langmuir isotherm. Endothermic and spontaneous characteristics of the adsorption process were shown during thermodynamic analysis. In this study, a predictive model for the efficiency of selenium separation was established using Response Surface Methodology (RSM). Additionally, an Artificial Neural Network (ANN), a data-driven model, was employed for comparative analysis. The predictive model exhibited a high degree of agreement with experimental data, demonstrated by a low relative error of <0.10, a high regression coefficient of >0.97), and a substantial Willmott-d index of >0.95. Moreover, the efficacy of pre-activated clay in selenium removal was assessed, revealing the superior performance of ANN models over RSM models in forecasting the efficiency of the adsorption process. This research significantly advances an effective and sustainable material for selenium removal, providing valuable insights into predictive modeling techniques applicable to similar contexts to boost scale-up confidence during industrial implementation in affected regions.

Recent Developments in the Adsorption of Heavy Metal Ions from Aqueous Solutions Using Various Nanomaterials.

Water pollution is caused by heavy metals, minerals, and dyes. It has become a global environmental problem. There are numerous methods for removing different types of pollutants from wastewater. Adsorption is viewed as the most promising and financially viable option. Nanostructured materials are used as effective materials for adsorption techniques to extract metal ions from wastewater. Many types of nanomaterials, such as zero-valent metals, metal oxides, carbon nanomaterials, and magnetic nanocomposites, are used as adsorbents. Magnetic nanocomposites as adsorbents have magnetic properties and abundant active functional groups, and unique nanomaterials endow them with better properties than nonmagnetic materials (classic adsorbents). Nonmagnetic materials (classic adsorbents) typically have limitations such as limited adsorption capacity, adsorbent recovery, poor selective adsorption, and secondary treatment. Magnetic nanocomposites are easy to recover, have strong selectivity and high adsorption capacity, are safe and economical, and have always been a hotspot for research. A large amount of data has been collected in this review, which is based on an extensive study of the synthesis, characterization, and adsorption capacity for the elimination of ions from wastewater and their separation from water. The effects of several experimental parameters on metal ion removal, including contact duration, temperature, adsorbent dose, pH, starting ion concentration, and ionic strength, have also been investigated. In addition, a variety of illustrations are used to describe the various adsorption kinetics and adsorption isotherm models, providing insight into the adsorption process.

Sulfonate-Bonded Conjugated Microporous Polymer Hollowed-Out Spheres to Capture Fluoroquinolone Antibiotics and Cationic Dyes from Wastewater.

Developing adsorbent materials for the efficient removal of multiple organic pollutants in water is of importance technological significance. In the present work, a kind of conjugated microporous polymer (CMP) with a hollow sphere structure was constructed by applying SiO2 nanoparticles as a template and 1,3,5-triethynylbenzene (TEB) and 2,7-dibromocarbazole (27-DBCZ) as building blocks via the Sonogashira-Hagihara cross-coupling reaction. In order to further improve the dispersibility of the as-resulting CMPs in water, hydrophilic CMPs (H-S-CMPs) were obtained by a sulfonation modification. The adsorption performance of H-S-CMPs on dyes and antibiotics was investigated, which was based on different experimental parameters such as the initial concentration, contact time, temperature, pH, and adsorbent dose. The adsorption isotherm, kinetics, and thermodynamics were also studied, and the possible adsorption mechanism of H-S-CMPs was discussed. The experimental results illustrated that the adsorption process of H-S-CMPs on dyes and antibiotics is more consistent with the Langmuir isotherm model and the pseudo-second-order kinetic model. The maximum adsorption capacities of H-S-CMPs for rhodamine B (RhB), methylene blue (MB), ciprofloxacin, and norfloxacin were 206.2, 324.7, 222.2, and 216.9 mg/g, respectively, which were determined according to the Langmuir isothern model. In addition, the adsorption mechanism of H-S-CMPs may be attributed to the synergistic effects of hydrogen bonding, electrostatic attraction, π-π stacking, and pore filling. After 5 cycles, H-S-CMPs still maintained good stability, and their removal rate of dyes could reach more than 70%. Notably, this polymeric hollow microsphere has been less extensively investigated as an adsorbent for the removal of dyes and antibiotics. As a result, based on the designable flexibility of CMPs and the unique structure of hollow microspheres, the material holds great promise for wastewater treatment in the presence of multiple pollutants.

Modeling and optimization of direct dyes removal from aqueous solutions using activated carbon produced from sesame shell waste

Today, there is a significant concern in the industry regarding the disposal of wastewater containing dyes into the environment, so the management and appropriate disposal of these wastes in the environment are considerable. The main aim of this study is to assess the efficiency of activated carbon (AC) prepared from sesame shells to remove direct dyes from aqueous solutions. According to the results, AC prepared from sesame shell had a high specific surface area (525 m2/g) and porous structure. The results demonstrated that the adsorbent had high potential to remove direct dyes as 84.5% of direct brown 103 (DB103), 93.08% of direct red 80 (DR80), 93.37% of direct blue 21 (DB21) and 98.39% of direct blue 199 (DB199) under the optimal conditions of adsorbent dose 4.8 g/L, contact time 19 min, pH 3 and initial dye concentration 12 mg/L. The experimental results showed that kinetic data were best described by the pseudo-second-order model (R2 = 0.989) while isotherm data were best fitted by the Freundlich model (R2 = 0.994). In the present study, not only was the produced waste used as a useful and economically valuable material, but it was also applied as an effective adsorbent to remove direct dyes from industrial effluents and reduce environmental pollution.

Efficacy of white rot fungal biomass of Phanerochaete chrysosporium for adsorption and removal of reactive red and reactive blue dyes from water

Water pollution has become a worldwide issue, particularly in developing countries. This study aimed to cleanse water contaminated with reactive red (RR-198) and reactive blue (RB-19) dyes via adsorption onto nonliving white rot fungal biomass Phanerochaete chrysosporium under different operational conditions. It was found that P. chrysosporium removed more of RB-19 than RB-198. The conditions of pH 3, temperature 50 °C, adsorbent dosage 0.6 g, particle sizes of adsorbent (0.25 mm), and contact time (30 min) were optimum for removal of the dyes. RR-198 and RB-19 were removed with levels of 78.4% and 86.4%, respectively at pH 3; 79.6% and 90.0%, respectively using 0.6 g of adsorbent dosage; 82.0% and 87.0%, respectively at 30 min; and 82.0% and 87.2%, respectively at 50 °C. Thus, dead P. chrysosporium biomass was shown to be a biosorbent for the uptake of RB-19 and RR-198 dyes.

Sugarcane Bagasse Based Adsorbents and their Adsorption Efficacy on Removal of Heavy Metals from Nakuru Industrial Wastewater: Optimization, Kinetic and Thermodynamic Aspects

Currently, researchers are seeking to reduce heavy metal contamination from the environment, using agricultural waste materials like rice husk, groundnuts shells among others. The study focused on the removal of Cu(II), Pb(II), Cd(II), Ni(II), and Cr(III) ions from aqueous solutions and Nakuru industrial wastewater using sugarcane bagasse (NSCB) and valorised bagasse ash (VSCB), as alternative low-cost agricultural waste bio-sorbents. To achieve this goal, sugarcane bagasse was collected from Nzoia sugar industry in western Kenya, while the valorised bagasse was obtained by heating sugarcane bagasse sample in a muffle furnace at 300°C for three hours. Furthermore, batch adsorption studies were performed, and the effects of several factors, i.e. adsorbent particle size, pH, contact time, initial heavy metal ions concentration and temperature were investigated to optimise the removal efficiency of Pb, Cu, Cd, Ni, and Cr. The optimal adsorption conditions were pH of 5.0, adsorbent dosage of 0.1 g and ≤ 150µm particle size, equilibrium time of 60 minutes and at 25 degrees Celcius. The removal kinetics of the metal ions onto both adsorbents fitted well with the pseudo-second-order model. The removal kinetics of the metal ions onto both adsorbents fitted well with the pseudo-second-order model. The adsorption of Pb2+ and Ni2+ onto NSCB fitted better with the Freundlich isotherm model, while Cd2+, Cu2+ and Cr3+ showed better fit for the Langmuir isotherm model. As for VSCB adsorbent, Cr3+ has a better fit with the Langmuir isotherm model whereas Pb2+, Ni2+, Cd2+, and Cu2+ fitted well on the Freundlich isotherm model. Freundlich constant’s (1/n) values and the separation factor (RL) from the Langmuir isotherm model indicate that the metal ions were favourably adsorbed onto the adsorbents. Langmuir isotherm model was used to estimate the maximum adsorption capacities (qmax) for Cu(II), Pb(II), Ni(II), Cd(II), and Cr(III). The negative free energy change (∆G) values revealed that adsorption process of the metal ions onto NSCB and VSCB was spontaneous. Fourier Transform Infrared Spectroscopy (FTIR) was used for characterization studies. Interactions with metal ions caused the frequencies of the active functional groups, –OH, C=O and C=C, on the bio-sorbent surfaces to shift to higher values. Therefore, sugarcane bagasse and valorised bagasse have demonstrated higher potential to remove relatively all selected heavy metals in the industrial wastewater at controlled pH.

Mitigation of Fluoride Contamination in Drinking Water Supply Sources by Adsorption Using Bone Char: Effects of Mineral and Organic Matrix

This study focused on fluoride (F−) contamination of water sources in Bahimi village, Cameroon. After the first investigation, results revealed that all water samples collected had elevated concentrations of fluoride ions (2.3 ± 0.1) mg/L to (4.5 ± 0.2) mg/L above the WHO guidelines (less than 1.5 mg/L). To mitigate the F− levels, the use of bone char (BC) as an adsorbent material was proposed and its performance was tested. BC was prepared from bovine bones at different calcination temperatures (350 °C, 450 °C, 550 °C and 650 °C) and residence times (1 h and 2 h). The prepared materials were characterized in detail by SEM/EDS, BET, FTIR, and XRD. The BET findings indicated that the surface area of BC samples decreased with increasing calcination temperature and residence time. At a lower heating temperature and holding time (350 °C, 1 h), the prepared BC exhibited a higher specific surface area (112.3 ± 0.3) m2/g and adsorption capacity for F− in the sampled water. Also, the batch adsorption experiments showed that the optimized adsorbent dose of 8 g/L facilitates the reduction in the F− level of the sampled water below the acceptable limit level (1.5 mg/L) within 5 min of treatment. The presence of Ca2+ and Mg2+ in natural water has a positive effect on the removal of F− in BC resulting in a high adsorption performance range of (72.5 ± 1.4)% to (80.3 ± 0.6)%. It was found that the adsorption of Ca2+ on the BC surface occurs via cation exchange with Na+. However, an increase in dissolved organic carbon (DOC) in the treated water limited the application of BC. Overall, the study presented a cost-effective adsorbent for the removal of this recalcitrant ion in the water source.

Sol-gel synthesis, structure and adsorption properties of LiMgxMn(2-x)O4 (0 ≤ x ≤ 0.7) Oxides

Lithium manganese оxides with a spinel structure LiMgxMn(2–x)O4, doped with Mg2+ ions in the range 0 ≤ x ≤ 0.7, were obtained by sol-gel synthesis. Phase composition and morphology of obtained оxides were studied by using X-ray phase analysis and scanning electron microscopy. It is shown, that in the studied range 0 ≤ x ≤ 0.7 Mg-doped lithium manganese оxides saved the structure of the original cubic spinel LiMn2O4, while an increase in parameter a was observed from 8.175 to 8.309 Å and average crystallite size practically unchanged (30–36 nm). Samples of the initial LiMn2O4 and Mg-doped spinels were represented by prismatic particles of submicron (0.1–0.2 µm) and micron (1.0–3.0 µm) sizes, respectively. The effect of the adsorbent dose (0.05–0.3 g/l) and pH (3.0–13.0) of the solution on the adsorption efficiency was studied. The adsorption isotherms of the LiMg0.3Mn1.7O4 samples were described by the Langmuir monomolecular adsorption equation. An increase in the temperature of the model solution from 25 to 45°C was accompanied by an increase in the maximum adsorption of the LiMg0.3Mn1.7O4 samples from 10.50 to 10.98 mmol/g, which indicates the endothermic nature of the adsorption process. The kinetics of adsorption was well described by a pseudo-second order equation, which indicates the occurrence of chemical interaction during the adsorption process.

Adsorption effect for removing fluoride with species of nitrogen by using La-BDC-NH2/C3N4: Experiments and mechanism

Fluoride contamination has emerged as a significant global environmental concern, with prolonged consumption of fluoride-rich groundwater being a primary contributor to fluorosis. Nitrogen sites play an important role in the process of fluoride removal, but the influence of different nitrogen species on fluoride adsorption has not been clearly clarified. In this study, a lanthanide organic framework adsorbent La-MOF-NH2 was prepared by solvothermal method, and a new adsorbent La-MOF-NH2@g-C3N4 was synthesized by adding g-C3N4 rich in various nitrogen sources. The effects of adsorbent dosage, pH, temperature and co-existing anions on the adsorption of fluorine were systematically studied. Optimal conditions were identified at a dosage of 2 g/L and a pH of 3, achieving theoretical maximum adsorption capacities of 219.4406 mg/g and 63.1401 mg/g, respectively. The results of five regeneration experiments shown that La-MOF-NH2 and La-MOF-NH2@g-C3N4 have strong recovery capacity. According to the adsorption isotherm and kinetic model, the adsorption mechanism of fluoride ions is mainly hydrogen bonding and chemisorption. In addition, through the experimental characterization and mechanism study, it was proved that amino group > pyridinic nitrogen > graphitic nitrogen. It provides a good guide for designing adsorbents containing nitrogen sites.

Modification of steel slag and its application for phosphate and ammonia removal in aquatic products processing wastewater

ABSTRACT This study aims to modify different types of steel slag by heating, characterise the material and test its ability for adsorption of phosphate and ammonia from aquatic products processing wastewater. The materials were characterised by SEM, EDS, BET and FT-IR analyses. The effects of the type of steel slag, calcination temperature in steel slag modification, pH, contact time, adsorbent mass and initial pollutant concentration were investigated using the one-factor-at-a-time approach. The results show that the adsorption kinetic of the samples followed the pseudo-second-order model, whereas their adsorption isotherm fitted well with the monomolecular adsorptive Langmuir with a maximum phosphate adsorption capacity of 45.045 mgPO43-/g. Optimisation using Response Surface Methodology was conducted with the independent factors (adsorbent doses, contact time and calcination temperature of steel slag) and response (removal efficiency of phosphate). The temperature and dosage of the material significantly affected phosphate removal efficiency and optimisation conditions were suggested. Validation of one optimum condition at the calcination temperature of 801°C, the adsorbent dosage of 11.9 g/L and the contact time of 72 min using real aquatic products processing wastewater resulted in the removal efficiencies of 86.93, 87.59, 7.76 and 7.58% for phosphate, total phosphorus, ammonia and total nitrogen, respectively.

Exploiting RSM and ANN modeling methods to optimize phosphate ions removal using LDH/alginate composite beads

In the present work, layered double hydroxide (MgAl) and alginate composite beads (LDH/alginate) were developed and used as low-cost and environmentally friendly adsorbent for phosphate ions removal. The successful incorporation of sodium alginate into the LDH structure was confirmed through SEM analysis. The dried beads exhibited a notably rough surface, which promotes molecular movement and potentially enhances pollutant adsorption. The pH of zero charge point (pHPZC) of the composite was found to be 7.41. This result implies that negative ions have a tendency to draw positive charges on the adsorbent surface via electrostatic interaction forces when the pH is lower than the pHPZC. On the other hand, a surface that has a pH higher than pHPZC mostly has a negative charge. The percentage removal and adsorption capacity were investigated as a function of contact time.Experiments were carried out by simultaneously varying three factors, in order to evaluate and compare the predictive capabilities of the response surface methodology (RSM) and the artificial neural network approach (ANN) for the adsorption process. Both methods demonstrated a strong ability to accurately predict the adsorption process. However, the response surface methodology exhibited a lower prediction error compared to the artificial neural network approach.The central composite design within response surface methodology (CCD-RSM) was employed to optimize the experimental conditions for the adsorption process. The model, which considers three factors: adsorbent dose (A), initial concentration (B), and contact time (C), proved to be significant. Among these, the quadratic term (B2) had the most substantial impact on the phosphate ion adsorption rate. The analysis yielded an R2 value of 0.94, indicating an excellent fit to the data. The findings suggest that increasing contact time and reducing the initial concentration improve phosphate ion removal efficiency, while the adsorbent dose has little to no effect. The Artificial Neural Network (ANN) model effectively predicted the adsorptive remediation of phosphate ions onto LDH/alginate composite beads, achieving a high coefficient of determination (R2 = 0.984) between the model outputs and the experimental data. The study highlights the significant potential of LDH/alginate composite beads as a natural adsorbent for the removal of phosphate ions from aqueous solutions. These results underscore the environmental friendliness and efficiency of the adsorbent used for phosphate adsorption.

Enhanced lead adsorption by eco-hydroxyapatite derived from marble sludge: Optimization and kinetic study

In this study, eco-hydroxyapatite (e-HAP) was synthesized from marble sludge via a hydrothermal process for utilization as an adsorbent in the removal of Pb2+ ions from wastewater. X-ray powder diffraction (XRD) and thermal field emission scanning electron microscope (FE-SEM) revealed that increasing the Ca/P molar ratio (CPMR) and hydrothermal temperature (HT) increased crystallinity and that the influence of HT was more apparent. An increase in crystallinity, crystal length, and peak intensity was observed following an increase in the CPMR. Adsorption studies show that when the HT was 393 K, the CPMR was 0.67, the initial Pb2+ ion concentration was 100 mg/L, the equilibrium time was 20 min, and the adsorbent dosage was 0.6 g/L. The resulting removal efficiency (99.99 %) and maximum adsorption capacity (166.65 mg/g) are both very high. Adsorption kinetics are well described using a pseudo-second-order kinetic model. This paper presents a facile and economically sustainable approach to the synthesis of e-HAP from marble sludge for use in removing of Pb2+ from wastewater.

Removal of the nalidixic acid antibiotic from aqueous solutions using bovine serum albumin nanoparticles

The presence of antibiotic pollutants in water and wastewater can cause significant risks to the environment in different aspects. Therefore, antibiotics need to be removed from water. This study investigates the adsorption of nalidixic acid (NA), a common antibiotic, using bovine serum albumin nanoparticles (BSA NPs). These NPs were synthesized via desolvation technique and characterized using SEM, DLS, FT-IR, and UV-Vis spectroscopy. The effects of adsorbent dosage (0.02–0.9 mg), initial NA concentration (30–80 mg L− 1) and contact time (0.5–24 h) on adsorption efficiency were considered. Adsorption isotherms and kinetics were determined experimentally. The Freundlich isotherm best described the adsorption equilibrium, while the pseudo-second-order kinetic model accurately represented the adsorption process. Thermodynamic parameters confirmed the spontaneous and exothermic nature of NA adsorption onto BSA NPs. Under optimal conditions, BSA NPs achieved a removal efficiency of 75% for NA with a maximum adsorption capacity of 240 mg g− 1. These results demonstrate the potential of BSA NPs as an effective adsorbent for removing NA from aqueous solutions.

Investigation of Cephalexin Removal Using Biochar Derived from Nephelium lappaceum Seeds

<p class="MsoNormal" style="line-height:200%;margin-bottom:0cm;mso-layout-grid-align:none;text-align:justify;text-autospace:none;"><span style="font-family:"Times New Roman",serif;font-size:12.0pt;line-height:200%;" lang="EN-US">The improper disposal of drugs into bodies of water has become a severe environmental and health issue. Biochar synthesized from different agro residues could be a potential material for the adsorption of pollutants in aqueous environments. </span><em><i style="mso-bidi-font-style:normal;"><span style="font-family:"Times New Roman",serif;font-size:12.0pt;line-height:200%;" lang="EN-US">Nephelium lappaceum</span></i></em><span style="font-family:"Times New Roman",serif;font-size:12.0pt;line-height:200%;" lang="EN-US"> seeds were pyrolyzed at 600 °C in a pyrolysis reactor incorporating a slow pyrolysis process for carbonization. Fourier-Transform Infrared (FTIR), Scanning Electron Microscope (SEM), and X-ray diffraction (XRD) were used to characterize the biochar before and after adsorption of the pharmaceutical pollutant cephalexin. The effects of several factors, including initial cephalexin concentration, time of contact, dosage of adsorbent, and pH, were considered for the sorption. The findings showed that the Freundlich model offered the greatest fit for adsorption. The better-fitted kinetic model was the pseudo-second-order kinetic. Based on Langmuir isotherm model, the maximum adsorption capacity of cephalexin was obtained as 63.69 mg/g. The adsorption process involves hydrogen bonding, surface complexation, electrostatic and π−π EDA interactions. The current study offers a feasible and optimistic method for using agricultural waste and an alternative adsorbent substance for recovering highly concentrated cephalexin from water-based solutions.<o:p></o:p></span></p>

Adsorption isotherms and removal of lead (II) and cadmium (II) from aqueous media using nanobiochar and rice husk

Removal of Cd(II) and Pb(II) from aqueous solutions is a challenging task and the search for novel adsorbents is underway. This study examined the efficiency of nanobiochar (NB) and rice husk (RH) in the adsorption and removal of Cd(II) and Pb(II) from water. The effect of various physicochemical parameters such as initial pH, initial Cd and Pb concentration, adsorbent dosage, and contact time were tested. SEM/EDX images confirmed the adsorption of Pb and Cd with surface physical and chemical changes. The maximum Pb removal was noted at pH 6 using NB (96%) and at pH 8 for RH (90%), and the maximum Cd removal by NB was recorded at 8 pH (91%) and by RH at pH 6 (87%). The decline in adsorption intensity at lower pH suggested protonation of the adsorbent surface causing cation-cation repulsion. Most of the adsorption occurred within the initial 60 min. A continuous gradual increase in the adsorption with time suggested multilayer formation. Of the three isotherms, the Freundlich model fits the present data best, implying an infinite surface coverage and indicating the potential for multilayer adsorption of Pb and Cd on the surfaces of RH and NB adsorbents. In conclusion, this study highlights the promising potential of NB as a cost-effective adsorbent for the removal of Cd and Pb ions from aqueous solutions.

Improving the adsorption properties of low surface area hardwood biochar for the removal of Fe+ and PO₄3- from aqueous solution.

Biochar produced from wood residues may provide a new method and material for managing the environment, particularly in terms of carbon sequestration and contaminant remediation. Additionally, biochar produced from wood residues is free of chemical fertilizers, likewise in rice straw, wheat straw, corn straw, etc. This study investigated the removal of iron from aqueous solutions by a novel low-cost and eco-friendly biochar made from hardwood trees and modified by adding MgCl2 for effective phosphate removal. Optimal adsorption conditions were determined through studies of adsorption time, pH, and adsorbent dosage. Batch equilibrium isotherm and kinetic experiments and pre/post-adsorption characterizations using FESEM-EDS, XRD, and FTIR suggested that the presence of carboxyl group elements and colloidal and nano-sized MgO (periclase) particles on the biochar surface were the main adsorption sites for aqueous iron and phosphate respectively. In this study, the HW and MgO-HW biochar showed excellent Dubinin-Radushkevich isotherm (D-R) maximum adsorption capacities of 289.45 and 828.82mg/g for iron and phosphate. The kinetic study for iron and phosphate adsorption was described well by pseudo second-order model and pseudo second-order model respectively. The HW biochar and the prepared MgO-HW biochar exhibited commendable iron adsorption (98.25%) performance at 10 pH units and phosphate (96.22%) at pH 6 respectively. Thus, this research reveals a waste-to-wealth strategy by converting hardwood waste into mineral-biomass biochar with excellent Fe and P adsorption capabilities and environmental adaptability.