Utilization of carbon-coated ZrO2/Mn-Mg-Zn ferrites nanostructures for the adsorption of Cs (I) and Sr (II) from the binary system: kinetic and equilibrium studies

Carbon-coated ZrO2/Mn-Mg-Zn ferrites nanostructures (CZ-FN) have been prepared as a new inorganic sorbent to remove Cs (I) and Sr (II) from a waste stream. Adsorption of Cs (I) and Sr (II) has been implemented considering different noteworthy parameters, for example, shaking time and the optimum time achieved high adsorption capacity of both ions [103 and 41 mg/g for Sr (II) and Cs (I)] was found 30 min. Also, the impact of pH values was studied; the best pH value for the adsorption process is pH 6. The adsorption saturation capacity of CZ-FN is 420.22 and 250.45 mg/g for strontium and cesium, respectively. The solubility percentage of CZ-FN was calculated utilizing diverse molarities from HNO3, HCl, and NaOH as eluents, the obtained data reveals an increase in the solubility percentage with more increase in the molarity of the eluents. The elevation in the solubility percentage follows the following order; HNO3 < HCl < NaOH. The kinetic studies were applied using the nanolinear form of different kinetic models; it was found that the adsorption process obeys the nonlinear pseudo-second-order. According to equilibrium studies, the Langmuir model has been more accurate than the Freundlich model for adsorption in the case of binary systems. The values of Di for the strontium and cesium are 10-10 m2/s, which displays the chemisorption nature of this process. The greatest values of the desorption process for the strontium and cesium are 96.87% and 94.43 by 0.3 M of HNO3. This indicated that the carbon-coated ZrO2/Mn-Mg-Zn ferrites could be regenerated and recycled to remove strontium and cesium ions from waste streams.

Metal tolerance and biosorption of Pb ions by Bacillus cereus RMN 1 (MK521259) isolated from metal contaminated sites

Recent years, metal pollution is an alarming factor to know about protects the environmental ecosystem due to the toxic, persistent and abundant in nature. Metals are present everywhere in the biotic and abiotic samples including soil, water, and microbes. The rate of bioaccumulation and biotransformation are very high. The excess concentration of the metals causes heavy metal pollution or contamination. Due to these defects, the removal of metals using biological sources is heightened in the current research. In this current investigation, the biosorption potential ability of the metal tolerable Bacillus cereus on Pb and Cu rich environment was chosen and thoroughly monitored. The 16s rRNA of the Bacillus cereus was sequenced, and named as Bacillus cereus RMN 1 (MK521259). The various test concentration (10-60 mg/mL) of Pb and Cu was exhibited the maximum removal percentages of 85.2% and 60.2%. The result of bisorption factors exhibited, 300 mg/mL of the biosorbent potency, 60 min contact time and pH 7, and they found to be optimal to remove the maximum of Pb ion from the solution. In the regression coefficients, the Freundlich and Langmuir isotherm models were used to study the adsorption kinetics of metal ions. In addition, the isotherm model confirmed that the of B. cereus biomass medicated metal adsorption was more favourable reaction for metal degradation. With the above evidences, the results of the present investigation proved that B. cereus derived biomass was actively adsorbing the metals ions. Thus we are recommending for the implementation of effective waste water treatment.

Facile synthesis of Zr4+ incorporated chitosan/gelatin composite for the sequestration of Chromium(VI) and fluoride from water

The development of industrialization and agricultural activities have carried various negative impacts to living organisms in recent decades and also, the frequent problem of inorganic pollution have been environmental anxiety to the community. Among these, Cr⁶⁺ and F^- are priority poisonous pollutants from many industries. In this work, we present a low-cost synthesis procedure to obtain biocompatible zirconium incorporated chitosan-gelatin composite (CS-Zr-GEL) were fabricated and explored for the adsorptive removal of toxic Cr⁶⁺ and F^- from water. The adsorption mechanism of toxic Cr⁶⁺ and F^- was done by batch mode as a function of contact time, solution pH and co-existing ions. The obtained materials were extensively studied by several physico-chemical techniques to access their properties by X-ray diffraction (XRD), scanning electron microscopy with Energy Dispersive X-ray Spectroscopy (SEM-EDX), Fourier-transform infrared spectroscopy (FTIR), Brunauer-Emmett-Teller (BET), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) analysis. Additionally, the fabricated adsorbent is highly dependent on solution pH. The kinetic and isotherm data were fitted using pseudo-second-order kinetic and Langmuir isotherm models. The maximum adsorption capacity for CS-Zr-GEL is 138.89 and 12.13 mg/g at 323K for Cr⁶⁺ and F^- respectively. These findings demonstrate that the CS-Zr-GEL adsorbent represents a promising candidate that would have a practical influence on water/wastewater treatments.

Adsorption properties of kaolinite-based nanocomposites for Fe and Mn pollutants from aqueous solutions and raw ground water: kinetics and equilibrium studies

Raw kaolinite was used in the synthesis of metakaolinite/carbon nanotubes (K/CNTs) and kaolinite/starch (K/starch) nanocomposites. Raw kaolinite and the synthetic composites were characterized using XRD, SEM, and TEM techniques. The synthetic composites were used as adsorbents for Fe and Mn ions from aqueous solutions and natural underground water. The adsorption by the both composites is highly pH dependent and achieves high efficiency within the neutral pH range. The experimental adsorption data for the uptake of Fe and Mn ions by K/CNTs were found to be well represented by the pseudo-second-order kinetic model rather than the intra-particle diffusion model or Elovich model. For the adsorption using K/starch, the uptake results of Fe ions was well fitted by the second-order model, whereas the uptake of Mn ions fitted well to the Elovich model rather than pseudo-second-order and intra-particle diffusion models The equilibrium studies revealed the excellent fitting of the removal of Fe and Mn ions by K/CNTs and Fe using K/starch with the Langmuir isotherm model rather than with Freundlich and Temkin models. But the adsorption of Mn ions by K/starch is well fitted with Freundlich rather than Temkin and Langmuir isotherm models. The thermodynamic studies reflected the endothermic nature and the exothermic nature for the adsorption by K/CNTs and K/starch nanocomposites, respectively. Natural ground water contaminated by 0.4 mg/L Fe and 0.5 mg/L Mn was treated at the optimum conditions of pH 6 and 120 min contact time. Under these conditions, 92.5 and 72.5% Fe removal efficiencies were achieved using 20 mg of K/CNTs and K/starch nanocomposites, respectively. Also, K/CNTs nanocomposite shows higher efficiency in the removal of Mn ions as compared to K/starch nanocomposite.

Upgraded modified forms of bituminous coal for the removal of safranin-T dye from aqueous solution

Natural bituminous coal was used as a precursor in the synthesis of different modified products. The modification of coal was performed by treating it with nitric acid (N-coal), coating its surface by zinc oxide nanoparticles (Z-coal), and converting it into porous graphite (PG). The effect of modification processes on the structures, morphologies, and optical properties was followed by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectrum (FT-IR), and UV/VIS spectrophotometer analysis. The surface of N-coal grains becomes smoother than the surface of raw coal grains due to the removal of the associated impurities and the formation of nitrogen function groups. For Z-coal, the whole surface of coal grains appears to be completely covered by agglomerated ZnO nanoparticles of massive density and irregular shapes. The average crystallite size of the formed ZnO is ~22.2 nm and density of dislocations is 2.029 × 10^-3 dislocation/nm². Also, the removal of safranin-T dye by natural bituminous coal and its modified forms was investigated as a function of contact time, adsorbent mass, initial dye concentration, and pH value. At pH 8, the PG showed higher efficiency (96%) than Z-coal (93.5%), N-coal (74.5%), and natural coal (62%) after 2 h for 0.1 g on 100 mg/L dye. The obtained results are well fitted by pseudo-second-order kinetic than by intraparticle diffusion and Elovich kinetic models for the adsorption by N-coal, Z-coal, and PG, whereas the adsorption by raw coal is well fitted with both pseudo-second-order and Elovich kinetic models. The Langmuir isotherm model fits well the equilibrium adsorption isotherm of safranin by raw coal and its modified forms. The values of maximum adsorption capacity were calculated for raw coal, N-coal, Z-coal, and PG to be 21.3, 27.4, 32.46, and 33.67 mg/g, respectively. A monolayer model with one energy and a monolayer model with two energies as advanced equilibrium models were investigated for more physical interpretation of the adsorption process. The calculated parameters (number of adsorbed molecules per site and number of receptor sites per unit mass) reflected the role of modification processes in the adsorption behavior of safranin. Graphical abstract High volatile bituminous coal and its modified forms have been used for the removal of Safranin-T dye from aqueous solution.