Recoverable Solvent-Treated Poultry Feathers for Multi-Metal Biosorption of Oxyanions and Cations: Experimental and Modeling Insights

Modelling studies for remediation of Cr (VI) from wastewater by activated Mangifera indica bark

Synthesis, characterization of modified nanoadsorbents and its application in removal of Zn2+ ions from battery effluent

This study focuses on the design and application of calcium alginate/gum arabic/eggshell powder composite microbeads (CA/GA/ES10) for the removal of methylene blue dye from aqueous solutions through the adsorption method. The characterization of adsorbents was conducted utilizing ATR-FTIR, SEM, XRD, TGA, and pHpzc. The pHpzc value of CA/GA/ES10 composite microbeads was determined as 5.56. From optimization studies, the contact time, adsorbent dosage, and pH values were determined as 60 min, 0.1 g/50 mL, and ≅ 7, respectively. The adsorption raw data have been utilized in the non-linear Langmuir, Freundlich, Temkin, and Sips models. The maximum adsorption capacity of CA/GA/ES10 composite microbeads, as per the Sips, was determined to be 33.30 mg/g at 298 K. The high correlation coefficients ( $$r^{2}$$ r 2 = 0.9976) and low error functions ( $$\chi^{2}$$ χ 2 = 0.03) indicate that the non-linear Langmuir is the most appropriate isotherm for the adsorption process. From the Langmuir model, the maximum adsorption capacity was determined as 29.71 mg/g at 298 K. The adsorption process adheres to a non-linear pseudo-second-order ( $$r^{2}$$ r 2 = 0.9999) and Elovich ( $$r^{2}$$ r 2 = 0.9999) models. According to thermodynamic results, the adsorption process occurs exothermic ( $$\Delta H^{^\circ } = - 3.77\;{\text{kJ/mol}}$$ Δ H ∘ = - 3.77 kJ/mol ) and spontaneous ( $$\Delta G^{^\circ } = - 25.83\;{\text{kJ/mol}}\;{\text{at}}\;298\;{\text{K}}$$ Δ G ∘ = - 25.83 kJ/mol at 298 K ) in nature. The impact of varying salt concentrations on the adsorption process was assessed. According to the salt effect, the removal percentage decreased from 81.12 to 65.15% with the addition of NaCl, and from 81.12 to 58.78% with the addition of CaCl2. The reusability tests show that the composite microbeads created can be used repeatedly for up to 7 cycles. After the 7th cycle, the removal of MB dye decreased from 81.11 to 53.45%. All results showed that the prepared ternary composite microbeads are effective adsorbents for the removal of cationic dye from aqueous solutions. Graphical abstract

In this research paper, chemically activated Thuja Occidentalis leaves carbon (CATLC) is used as an adsorbent for the removal of calcium (Ca2+) ion from aqueous solution. CATLC is prepared and characterized by FTIR, SEM and EDX. The impact of pH, adsorbent dosage, contact period and initial concentration of Ca2+ on the adsorption performance of CATLC for Ca2+ removal are examined by batch studies. The results disclose that CATLC has a high potential to adsorb Ca2+ (91% removal) at pH 7.00. To know the equilibrium behaviour of Ca2+ adsorption, Freundlich and Langmuir models are investigated, and the data discloses that Langmuir model (maximum adsorption capacity ‘Qm’ obtained is of 51.28mg/g and R2= 0.9953) fits better than Freundlich model(R2 =0.8723). The Kinetic studies indicate that pseudo-second-order(R2= 0.9909) is the best fit rather than pseudo-first order, intra particle and Elovich models and chemisorptions are the rate-limiting steps for the Ca2+ adsorption using CATLC adsorbent. Regeneration studies showed that CATLC can be regenerated easily and reused for several adsorption cycles, with sodium chloride solution as a regenerating agent. The application of CATLC adsorbent is useful to reduce the hardness concentration in groundwater samples to meet the allowable limit according to WHO-2011 standards.

Removal of divalent cations and oxyanions by keratin-derived sorbents: Influence of process parameters and mechanistic studies

The presence of chromium in aquatic streams due to the discharge of industrial effluents is of great concern because of its toxic nature. Removal of Cr(VI) ion from wastewater is a necessary task. To enhance the adsorption capacity of sawdust for heavy metals, sawdust was modified with formaldehyde and used for the adsorption of heavy metal Cr(VI). The process of modifying was characterised by Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). The effects of various parameters such as pH, contact time, adsorbent dose and initial metal ion concentration on the adsorption process were investigated. The maximum removal of chromium (VI) was found to be 100% at pH 2.0, initial Cr(VI) concentration of 10 mg/L, and adsorbent dose of 4 g/L. Equilibrium isotherms for the removal of Cr(VI) were analysed by the Langmuir, Freundlich, and Temkin isotherm models and the experimental data were well explained by the Freundlich isotherm model. The maximum adsorption capacity was found to be 8.84 mg/g. Kinetic studies were performed by pseudo-first-order, pseudo-second-order, intraparticle diffusion and Elovich models. The R2 value of the pseudo-second-order model is higher than other kinetic models. Therefore, the obtained data were the best fit with the pseudo-second-order kinetic model. The thermodynamics indicated that the adsorption process of sawdust for Cr(VI) was endothermic and spontaneous in nature.

This study investigated the potential of Brazilian kaolin as a low-cost adsorbent for the removal of Malachite Green (MG) from colored effluents. The morphology, chemical structure and surface properties of the adsorbent were investigated by characterization techniques such as X-ray diffraction, N2 adsorption-desorption isotherms, Fourier transform infrared spectroscopy, X-ray fluorescence spectrometry, scanning electron microscopy, thermogravimetric analysis and particle size distribution. A possible technological application of raw kaolin is the MG removal from aqueous media, which was investigated using batch adsorption experiments. The adsorption kinetics was studied using the pseudo-first order, pseudo-second order and Elovich models. The adsorption isotherms were studied using the Langmuir, Freundlich and Sips models. The Elovich model was the more adequate to represent the adsorption kinetic, while the equilibrium was well represented by the Langmuir model. The maximum adsorption capacity, at pH of 6.3 and temperature of 25oC, was 128 mg g-1, and this satisfactory result may be associated with some adsorbent properties. Therefore, the results revealed that raw kaolin can be utilized as a promising low-cost adsorbent to remove MG from colored effluents.

Fabrication and characterization of novel macroporous Jeffamine/diamino hexane cryogels for enhanced Cu(II) metal uptake: Optimization, isotherms, kinetics and thermodynamic studies

Large amounts of highly heavy metals contaminated wastewater effluents are produced through the metal finishing and electroplating processes. In this study, mesoporous zeolite was prepared from Egyptian bentonite by alkali-hydrothermal method.The prepared zeolite was characterized by XRD technique showing the formation of crystalline phases corresponded to the zeolite structure. The adsorption performance of zeolite toward removal of copper (Cu+2) and nickel (Ni+2) ions was studied in relation to effect of contact time, concentrations of metal ions and the dose of adsorbent. The effect of Cu+2 and Ni+2 ions in treated wastewater on the corrosion behavior of steel pipelines was demonstrated. Elovich, Pseudo-first-order and Pseudo-second order kinetic models were applied. Kinetics models revealed that the adsorption of both Cu+2 and Ni+2on zeolite was controlled by pseudo-second order kinetic and the equilibrium achieved at 90 minutes. Langmuir, Freundlich and Dubinin–Kaganer–Radushkevich isotherms were investigated and the results showed that the adsorption of both cations well-satisfied with Langmuir model. The free energy (E) was 10.66 and 8.772 kJ/mol for the adsorption of Cu+2 and Ni+2 ions, respectively, confirming that the adsorption is a physical process.The effect of Cu+2 and Ni+2 on the corrosion behavior of steel pipelines revealed that the corrosion resistance of steel for treated anduntreated water is almost the same.

Fluoride related health issues such as dental and skeletal fluorosis have become a global concern in recent times. Adsorption is one of the affordable defluoridation techniques. This study reports the potentiometric determination of fluoride adsorbed onto Aluminium modified zeolite Na-LSX (AMZL) from aqueous solution at 25oC and various experimental conditions: pH (4.5-9), initial fluoride concentrations (3-15 mg/L), adsorbent dosage (2.5- 12.5 g/L) and contact time (4-6 days) in a batch system. The obtained adsorption data was fitted to Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherms. Error functions, χ2 , SSE, SAE were used in conjunction with R2 to ascertain the best fitted isotherm. The various kinetic models Lagergren’s pseudo-first-order, Ho’s pseudo-secondorder, Intra-particle Diffusion and Elovich models were used to evaluate the kinetics of fluoride adsorption. The maximum fluoride uptake unto AMZL occurred at pH 5.5 over a period of 360 min. An increase in adsorbent dosage and pH affected fluoride removal. The presence of bicarbonate ions had a negative effect on the adsorption of fluoride however, chloride and nitrate did not affect the adsorption of fluoride. By the use of error functions, χ 2 , SSE, SAE and the coefficient of regression, R2 values, Langmuir isotherm model gave the best description of fluoride adsorption onto AMZL. The maximum fluoride adsorption capacity of AMZL based on Langmuir model was found to be 4.122 mg/g. The Ho’s pseudo-second order kinetics best fitted the fluoride adsorption data obtained. The adsorption mechanism was found to be predominantly physisorption than chemisorption.

Arsenate (As(V)) oxyanion removal was achieved utilizing diverse chitosan-containing adsorbents, such as chitosan beads, protonated chitosan flakes, chitosan powder, and chitosan functionalized with meso-2,3-dimercapto succinic acid (DMSA), and glutaraldehyde (GLA). Protonated Chitosan Flakes (PCF) showed to be the more effective adsorbent for the removal of As(V) oxyanion from aqueous solutions, removing 97% at the initial concentration of 0.500 mg/L. As(V) adsorption was favored by the Langmuir model, with a maximum adsorption capacity (Q°) of 5.43 mg/g. The results showed that the PCF is an excellent non-toxic and inexpensive adsorbent for As(V) oxyanion removal in level traces from aqueous solution.

In this paper, the isotherm, kinetic, and thermodynamic of cationic dye removal onto inorganic adsorbent (Feldspar) were investigated in single and binary systems. Basic Red 18 (BR18) and Basic Blue 41 (BB41) were used as cationic dyes. The characterization of the Feldspar was carried out using X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) techniques. The effect of operational parameters such as adsorbent dosage, initial dye concentration, pH, ionic strength, and temperature on dye removal was studied. It was found that the adsorption of BR18 and BB41 onto Feldspar followed with Langmuir and extended Langmuir isotherms in single and binary systems, respectively. Adsorption kinetic of dyes was found to conform to pseudo-second order kinetic in single and binary system. The thermodynamic data showed that dye adsorption onto Feldspar was spontaneous, endothermic, and physisorption reaction. Based on the data of the present investigation, one could conclude that the Feldspar as an eco-friendly and low-cost adsorbent might be a suitable alternative to remove dyes from colored aqueous solutions containing cationic dyes.

The adsorption of indigo carmine dye onto Activated Pomegranate Peels (APP) from aqueous solutions was followed in a batch system. The adsorbent was characterized by the BET method (specific surface area SBET: 51.0674 m2/g) and point of zero charge (pHpz = 5.2). However, some examined factors were found to have significant impacts on the adsorption capacity of pomegranate peels (APP) such as the initial dye concentration (10–60 mg/L), solution pH (2–12), adsorbent dose (1–10 g/L), agitation speed (100–600 rpm), and temperature (298–308 K). The best adsorption capacity was found at pH 2 with an adsorbent dose 1 g/L, an agitation speed 300 rpm and a contact time of 45 min. The adsorption mechanism of IC onto (APP) was studied by using the first-pseudo order, second-pseudo order, Elovich, and Webber-Morris diffusion models. The adsorptions kinetic were found to follow rather a pseudo-second order kinetic model with a determination coefficient ( R2) of 0.999. The equilibrium adsorption data for IC onto (APP) were analyzed by the Langmuir, Freundlich, Elovich, and Temkin models. The results indicate that the Langmuir model provides the best correlation with capacities ( qmax of 158.73 mg/g at 298 K). The adsorption isotherms at different temperatures have been used for the determination of thermodynamic parameters like the free energy; enthalpy and entropy to predict the nature of adsorption process. The negative values Δ G° and Δ H° indicate that the overall adsorption is spontaneous and exothermic with a physisorption process. The adsorbent elaborated from pomegranate peels material was found to very effective and suitable for the removal of reactive dyes from aqueous solutions, due to its availability, low cost preparation, and good adsorption capacity.

Gelatin-bentonite composite as reusable adsorbent for the removal of lead from aqueous solutions: Kinetic and equilibrium studies

The biosorption of cyanide ions from aqueous solution by bagasse was studied in a batch adsorption system with pH, contact time, cyanide ion concentration, metal ion concentration, and adsorbent dosage as variables. XRD, FT-IR spectroscopy, CHN, proximate, ultimate, and TG/DTG thermal analyses were used for the characterization of bagasse. The biosorption capacities and rates of biosorption of cyanide ions onto bagasse were evaluated. The Langmuir and Freundlich adsorption models were applied to describe the isotherms and isotherm constants. Biosorption isothermal data were interpreted by the Langmuir model followed by the Freundlich model with maximum adsorption capacity of 98% of cyanide ion on bagasse. The kinetic experimental data were properly correlated with the first- and second-order kinetic model.