A novel, eco-friendly and green synthesis of PPAC-ZnO and PPAC-nZVI nanocomposite using pomegranate peel: Cephalexin adsorption experiments, mechanisms, isotherms and kinetics

In the present work, powdered activated carbon coated by nanoparticles ZnO and nZVI was derived from pomegranate peel extracts and finally applied for removal of cephalexin (CEX (from aqueous solutions. This experimental research was conducted discontinuously. The effects of pH of solution, reaction time, PPAC-nZVI and PPAC-ZnO composites dose, and initial concentration of cephalexin and composite recovery on process efficiency were investigated. The removal efficiency in optimal conditions for cephalexin with PPAC-nZVI and PPAC-ZnO (CEX = 50 mg L�1, composite dose = 1.25 g L�1, reaction time = 45 min and pH = 5) was obtained 96.06 and 94.17, respectively. The results of the study of isotherm and absorption kinetics for both composites showed that the absorption process follows Langmuir isotherm and pseudo second-order kinetics. The present study showed that the composites could be used as an effective and bio-friendly absorbent to remove cephalexin from aqueous solutions. © 2020 The Society of Powder Technology Japa

Keeping thinning-derived deadwood logs on forest floor improves soil organic carbon, microbial biomass, and enzyme activity in a temperate spruce forest

Deadwood is a key component of forest ecosystems, but there is limited information on how it influences forest soils. Moreover, studies on the effect of thinning-derived deadwood logs on forest soil properties are lacking. This study aimed to investigate the impact of thinning-derived deadwood logs on the soil chemical and microbial properties of a managed spruce forest on a loamy sand Podzol in Bavaria, Germany, after about 15 years. Deadwood increased the soil organic carbon contents by 59% and 56% at 0–4 cm and 8–12 cm depths, respectively. Under deadwood, the soil dissolved organic carbon and carbon to nitrogen ratio increased by 66% and 15% at 0–4 cm depth and by 55% and 28% at 8–12 cm depth, respectively. Deadwood also induced 71% and 92% higher microbial biomass carbon, 106% and 125% higher microbial biomass nitrogen, and 136% and 44% higher β-glucosidase activity in the soil at 0–4 cm and 8–12 cm depths, respectively. Many of the measured variables significantly correlated with soil organic carbon suggesting that deadwood modified the soil biochemical processes by altering soil carbon storage. Our results indicate the potential of thinned spruce deadwood logs to sequester carbon and improve the fertility of Podzol soils. This could be associated with the slow decay rate of spruce deadwood logs and low biological activity of Podzols that promote the accumulation of soil carbon. We propose that leaving thinning-derived deadwood on the forest floor can support soil and forest sustainability as well as carbon sequestration

Potential of using green adsorbent of humic acid removal from aqueous solutions: equilibrium, kinetics, thermodynamic and regeneration studies

The natural organic matter in water resources poses many problems, such as unpleasant taste and colour in the water, and is one of the most important precursors to the formation of disinfection byproducts (DBPs) during water treatment. This study was performed to evaluate the efficiency of activated carbon (AC) and activated carbon coated with nZVI nanoparticles (AC-nZVI) to remove humic acid from aqueous solutions. To end this, the effect of some operational factors including pH, contact time, humic acid concentration and adsorbent dose was studied in removal of humic acid from aqueous solutions in the presence of AC and AC-nZVI. The structure of the adsorbents and their morphology were characterized by FTIR, BET, SEM and XRD analyzes. The adsorption isotherm was determined using Langmuir, Freundlich and kinetic adsorption models by studying quasi-first-order and quasi-second-order models. The thermodynamic parameters of the adsorption system such as changes in enthalpy (ΔH0), entropy (ΔS0) and free energy of Gibbs (ΔG0) were also measured and evaluated. The results showed that the removal efficiency is directly associated with the dose of adsorbent and has a reverse association with pH and humic acid concentration. The optimal removal of humic acid at the adsorbent dosage of 1.6 g/L, the humic acid concentration of 50 mg/L and the contact time of 45 min was found 84.7% and 95.68% for AC and AC-nZVI, respectively. The SBET and total pure volume for the AC-nZVI were 821.52 m2/g and 0.631 cm3/g respectively. The removal rate by AC-nZVI as significantly high, indicating the effective role of nanoparticle stabilisation on activated carbon. As a result, it is possible to find an effective and highly efficient adsorbent by stabilising the nanoparticles on activated carbon that can be used to remove humic acid

Efficiency of Zeolite Coated with Zero-Valent Iron Nanoparticles for Removal of Humic Acid from Aqueous Solutions

The most important effect of natural organic materials in water is reacting with disinfectants and creating disinfectant by-products that are mostly carcinogenic. The aim of this study was to determine the optimum conditions for removal of humic acid (HA) by zeolite coated with nZVI nanoparticles (Zeolite/nZVI) from aqueous solutions. In this study, after synthesis of zeolite/nZVI, its structure and morphology were examined using FTIR, BET, XRF, and FESEM techniques. The effects of HA concentration, composite content, pH, and reaction time were evaluated. The experimental data were analyzed by Langmuir and Freundlich isotherm and pseudo-first-order and second-order kinetic models. Finally, the thermodynamic parameters of enthalpy (ΔΗ°), entropy (ΔS°), and Gibbs free energy (ΔG°) were calculated. The results of the analyses confirmed the accuracy of the composite structure. Its specific surface area by using BET method was 203.43 m2/g. The HA removal efficiency was obtained at 92.98% in optimum conditions of 50 mg/L concentration, 2 g/L composite dose, pH = 3, and reaction time of 60 min. The results of the isotherm and kinetic study showed that the HA adsorption process follows the Langmuir isotherm (R2 = 0.9707) and pseudo-second-order kinetic. The maximum adsorption capacity of the composite was determined at 23.36 mg/g by Langmuir model. Thermodynamic parameters indicate that the adsorption of HA endothermic and the reaction cannot be done spontaneously. Zeolite/nZVI composite had good removal efficiency after five times of recycling. The present study showed that zeolite/nZVI can be used as an effective adsorbent for removal of HA from aqueous solutions

Green preparation of activated carbon from pomegranate peel coated with zero-valent iron nanoparticles (nZVI) and isotherm and kinetic studies of amoxicillin removal in water

In present research, the activated carbon was prepared by a green approach from pomegranate peel coated with zero-valent iron nanoparticles (AC-nZVI) and developed as adsorbent for the removal of amoxicillin from aqueous solution. The physicochemical properties of the AC-nZVI were investigated using XRD, FTIR, and FESEM techniques. The optimal values of the parameters for the best efficiency (97.9) were amoxicillin concentration of 10 mg/L, adsorbent dose of 1.5 g/L, time of 30 min, and pH of 5, respectively. The adsorption equilibrium and kinetic data were fitted with the Langmuir monolayer isotherm model (qmax 40.282 mg/g, R2 0. 0.999) and pseudo-first order kinetics (R2 0.961). The reusability of the adsorbent also revealed that the adsorption efficiency decreased from 83.54 to 50.79 after five consecutive repetitions. Overall, taking into account the excellent efficiency, availability, environmental friendliness, and good regeneration, AC-nZVI can be introduced as a promising absorbent for amoxicillin from aquatic environments. © 2020, Springer-Verlag GmbH Germany, part of Springer Nature

Removal of acid blue 113 from aqueous solutions using low-cost adsorbent: adsorption isotherms, thermodynamics, kinetics and regeneration studies

Drainage of untreated wastewater from the textile industry due to the use of toxic compounds in it causes pollution in aquatic environments and major environmental and health problems. Therefore, the aim of the present study is to compare the performance of activated carbon coated with AC-ZnO composite as an adsorbent to remove the AB-113 from the aqueous solution. The present study is an experimental-laboratory study in which the effect of independent parameters has been investigated. FTIR and XRD analyzes were performed to determine the composition of the composite. Isothermal and kinetic adsorption at different concentrations were evaluated to evaluate the process. The results of physical-chemical analysis confirmed the correctness of the composite structure. Optimal conditions for AB-113 (with a concentration of 100 mg/L, a composite dose of 0.5 g/L, a reaction time of 15 minutes and pH = 3) 98.2% were obtained. The results of the study of isothermal and kinetic adsorption for dye showed that the adsorption process follows the isotherm of Freundlich (R2 = 0.9859) and Pseudo-second-order. The maximum adsorption capacity of AC-ZnO composite was determined using Langmuir model 333.33 mg/g. Thermodynamic parameters showed the non-spontaneity and endothermic in nature of adsorption process. The present study showed that nanoparticle stabilization technology can be used on activated carbon as an effective and efficient adsorbent to remove dye from aqueous solutions

Green synthesis of zero-valent iron nanoparticles and loading effect on activated carbon for furfural adsorption

The adsorption techniques are extensively used in dyes, metronidazole, aniline, wastewater treatment methods to remove certain pollutants. Furfural is organic in nature, considered a pollutant having a toxic effect on humans and their environment and especially aquatic species. Due to distinct characteristics of the adsorption technique, this technique can be utilized to adsorb furfural efficiently. As an environmentally friendly technique, the pomegranate peel was used to synthesized activated carbon and nanostructure of zerovalent iron impregnated on the synthesized activated carbon. The physicochemical and crystallinity characterization was done using Fourier transmission infrared spectroscopy (FTIR), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), and Field emission scanning electron microscopy (FESEM). The nanoparticles are porous in structure having 821.74 m2/g specified surface area. The maximum amount of the adsorbent pores in the range of 3.08 nm shows the microporous structure and enhancement in adsorption capacity. The effects of increment in concentration of adsorbent, pH, reaction contact time and adsorbent dose, isothermal and kinetic behaviour were investigated. At the UV wavelength of 227 nm furfural adsorption was detected. The separation of the furfural from the aqueous solution was calculated at the 1 h reaction time at the composite dosage of 4 g/L, 250 mg/L adsorbent concentration and pH kept at 7. The 81.87% is the maximum removal attained by the nanocomposite in comparison to the activated carbon is 62.06%. Furfural adsorption was also analyzed by using the equations of isothermal and kinetics models. The adsorption process analysis depends on the Freundlich isotherm and Intra-particle diffusion than the other models. The maximum adsorbent of the composite was determined by the Langmuir model which is 222.22 mg/g. The furfural removal enhances as the adsorbent dose enhances. The developed zerovalent iron nanoparticles incorporated on activated carbon (AC/nZVI) from pomegranate peel extract are feasible as an efficient and inexpensive adsorbent to eliminate furfural from a liquid solution