Sorption of cobalt and zinc from single and binary metal solutions by Evernia prunastri

Non-living lichen Evernia prunastri was studied as biosorbent material for zinc and cobalt removal from single and binary metal solutions. Sorption equilibrium of Zn2+ and Co2+ ions was reached within 1 hour. Both cobalt and zinc biosorption was not pH dependent within the range pH 4-6 and negligible at pH 2. The experimental results were fitted to the Langmuir, Freundlich, Redlich-Peterson and Langmuir-Freundlich adsorption isotherms to obtain the characteristic parameters of each model. The Langmuir, Redlich-Peterson and Langmuir-Freundlich isotherms were found to well represent the measured sorption data. According to the evaluation using the Langmuir equation, the maximum sorption capacities of metal ions onto lichen biomass were 112 μmol/g Zn and 97.2 μmol/g Co from single metal solutions. E. prunastri exhibited preferential uptake of zinc from equimolar binary Zn2+ - Co2+ mixtures within the range 50 – 4000 μM. Even thought mutual interference was seen in all Co-Zn binary systems. To evaluate the two-metal sorption system, simple curves had to be replaced by three-dimensional sorption surface. These results can be used to elucidate the behavior of lichens as bioindicators of cobalt and zinc pollution in water and terrestrial ecosystems.

Removal of Excessive Nitrogen and Phosphorus from Urban Wastewater Using Local Microalgal Bloom

The organic content from urban wastewater is treated with various conventional processes efficiently. However, for biological treatment of secondary effluent containing excessive inorganic nitrogen and phosphorus, microalgae can be used. In this study, algal strains have been collected from locally available natural blooms and cultured in a BG-11 medium. Spirulina sp., the blue-green algae, dominant over the other species within the natural bloom, is applied in ten different dosages (0.2-2.5 g/L) to the synthetic wastewater with a 3-day hydraulic retention time. The removal efficiency of nitrate, ammonia, and phosphate have been observed to be about 60%, 30%, and 54% respectively. The highest removal efficiency has been found at 2.5 g/L of microalgae dose. Linear forms of Langmuir and Freundlich isotherms have been used for biosorption modeling, and both isotherms fit well with R2>60% and NRMSE<11% in all cases. Additionally, the separation factor and the adsorption intensity represent the favorability of the biosorption process. Journal of Engineering Science 12(3), 2021, 19-27

Adsorptive Removal of Arsenic by Synthetic Iron-loaded Goethite: Isotherms, Kinetics, and Mechanism

Arsenic contamination in the groundwater is a worldwide concern. Therefore, this study was designed to use synthetic iron-loaded goethite to remove arsenic. Adsorption was significantly pH-dependent; hence, pH values between 5.0 and 7.0 resulted in the highest removal of arsenate and arsenite. Langmuir and Freundlich isotherms were almost perfectly matched in terms of strong positive coefficient of determination “R2” arsenate – 0.941 and 0.992 and arsenite – 0.945 and 0.993. The adsorption intensity “n” resulted as arsenate – 2.542 and arsenite – 2.707; besides separation factor “RL” found as arsenate – 0.1 and arsenite – 0.5, respectively. However, both “n” and “RL” leads to a favourable adsorption process. Temkin isotherm yielded in equal binding energies “bt” showing as 0.004 (J/μg) for both arsenate and arsenite. Jovanovic monolayers isotherm was dominated by the Langmuir isotherm. This resulting in maximum adsorption capacity “Qmax” of arsenate – 1369.877 and arsenite – 1276.742 (μg/g), which approaches to the saturated binding sites. Kinetic data revealed that adsorption equilibrium was achieved in 240 – arsenate and 360 – arsenite (minutes), respectively. Chemisorption was found effective with high “R2” values 0.981 ­– arsenate and 0.994 – arsenite, respectively, with the best fitting of pseudo-second order. Moreover, Brunauer Emmett Teller (BET), Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FTIR) were used to determine the morphological content, surface area, crystalline structure, and chemical characteristics of the adsorbent. It is anticipated that optimal arsenic removal was achieved by the porosity, chemical bindings, and surface binding sites of the adsorbent.

Adsorption Dynamics of Agricultural Waste Activated Carbon in Water Quality Improvement

This study investigated the removal of Lead and Cadmium ions from aqueous solution using activated carbons from agricultural wastes. Activated carbons prepared by chemical activation using Phosphoric acid were characterized by Fourier Transform Infrared (FTIR), Scanning Electron Microscopy (SEM) and Brunauer-Emmett-Teller (BET) analysis. The influence of contact time, initial concentration and adsorbent dose which governed the efficiency of the process was ascertained through batch adsorption studies. Adsorption isotherms were determined by correlating with Langmuir and Freundlich isotherms and the kinetic studies were correlated with pseudo first order and pseudo second order equations. The results showed that the amount of Lead and Cadmium adsorbed decreased as the adsorbent dose increased while the adsorption capacity increased with increased in contact time and initial concentration. Activated carbons prepared from Coconut shell and palm kernel (shell and cake) competed favorably with the commercial activated carbon in percentage removal of the metal ions as all the activated carbons had over 90 % removal within 60 minutes when 1g of adsorbent was used. The equilibrium data fitted best into Freundlich isotherms for both metal ions. The rate of adsorption could be described by pseudo second order for all the adsorbents except Coconut shell activated carbon in the adsorption of Lead while intra-particle diffusion was the limiting step for Cadmium adsorption. Therefore, the agricultural by-products can be used as effective, low-cost, and environmentally friendly adsorbents for domestic water treatment in many parts of the world.

Activated Carbons for Arsenic Removal from Natural Waters and Wastewaters: A Review

The arsenic pollution of waters and wastewaters is concerning many countries across the world, and because of the effects of arsenic on human health, its removal from waters is of great importance. Adsorption using functionalized activated carbons as a technique for the removal of arsenic from water streams has gained great attention. In the present review, we summarize synthesis technologies, the characterization of materials and arsenic removal capacity, and we clarify the parameters which play a critical role in the removal of arsenic, such as the pH value of the water, the active group in the functionalization and temperature. The review article concludes that most of the experimental data fit both Langmuir and Freundlich isotherms. In this review, the recyclability and reuse of the materials are also reported, and the findings show that for both arsenite and arsenate, even after several adsorption cycles, the material can be further used as an efficient adsorbent for arsenic removal.

Copper and Zinc Removal Efficiency of Two Reactive Filter Media Treating Motorway Runoff—Model for Service Life Estimation

The predominant techniques used for road runoff treatment are sedimentation and filtration. In filtration systems, the ability of the media to adsorb the contaminants is a finite process. Consequently, construction, operation and maintenance managers of such systems should know in advance the service life, i.e., when the used medium should be replaced, and associated costs of operation and maintenance. A batch experiment followed by a packed bed reactor (PBR) experiment addressed the kinetics of the studied media argon oxygen decarburization slag (AOD) and Polonite, followed by the development of a 1D-model to describe the change of concentration of Cu and Zn within time. The batch test results showed that Cu and Zn adsorption followed the Freundlich isotherms for AOD and Polonite. Those results coupled with the linear driving force model and the developed model resulted in good agreement between the PBR results and the simulation. The model was capable to predict (i), the service life at the hydraulic load of 0.18 m/h for AOD (Cu: 395 d; Zn: 479 d) and Polonite (Cu: 445 d; Zn: 910 d), to show (ii) the profile concentration in the PBR within time and the gradient of the concentration along the height of the reactor.

SORPTION OF INDAZIFLAM IN BRAZILIAN SOILS WITH DIFFERENT pH VALUES

ABSTRACT Pre-emergence herbicides, such as indaziflam, have agronomic efficiency when available in the soil solution, mainly in the superficial layer (0-10 cm), the region with the highest concentration of weed seed bank. However, information about the sorption of indaziflam in Brazilian soils still is scarce, since most studies available in the literature were conducted in soils of temperate regions. The objective of this study was to estimate the sorption of indaziflam using high-performance liquid chromatography (HPLC) and bioassay in a Latossolo Vermelho-Amarelo (Oxisol) and in a Cambissolo (Inceptisol), at pH values of 5.1 and 6.1. In the biossay, Sorghum bicolor was used as an indicator plant. Quantitative indaziflam data were obtained by HPLC, and the sorption and desorption coefficients were determined in the soils using Freundlich isotherms. Increasing the pH of the two soils from 5.1 to 6.1 resulted in reductions of C50 and sorption coefficient values. Desorption, a parameter estimated only by HPLC, showed an inverse behavior to that of sorption, that is, the lowest desorption was observed in the condition of highest sorption. It is concluded that the increase in pH of the studied soils reduces indaziflam sorption, influencing the recommendations of this herbicide, from both the agronomic and the environmental points of view. When the goal is to verify the presence or absence of indaziflam in the studied soils, the bioassay technique has satisfactory efficiency. Chromatographic assay is necessary when quantifying the concentration of this herbicide in the soil.

Comparative between different Natural Sources of Activated Carbon for the Removal Reactive Green Dye from Aqueous Solution

Water pollution is one of the biggest problems facing us, so it requires the need to develop a very high-efficiency and inexpensive absorbent material from natural surfaces and compare it with expensive commercial sorbents. Where in this study an absorbent substance was prepared from the natural surfaces of Syzgium Aromaticum Flower Bud (SAFB), Nigella Sativa (NS) Converted to activated carbon to activated carbon Activated (SAFB), and Activated (NS), as these surfaces are characterized by high porosity, cheap price and very high efficiency in removing dye. The composite was illustrated via different analysis apparatus included FTIR, and FE-SEM, The adsorption result were fitted with Freundlich isotherms. The experimental kinetic result at different primary reactive green dye concentrations, were also analyzed through first model, second model and Elovich model. The obtained data appear that the model pseudo-first model fits the adsorption kinetic result through R2 0.96028, R2 0.9486, R2 0.9016 and R2 0.9620 of SAFB and ACTIVE-SAFB and Nigella Sativa (NS) and Activated (NS) in the same order.

Removal of phenol from aqueous solution using biochar produced from Araucaria Columnaris Bark

Abstract This work investigates the removal of phenol from aqueous solution using Araucaria Columnaris bark (ACB) as biochar. Five different types of biochars were developed through pyrolysis at different temp from 300 to 500°C. The effects of initial concentration, contact time, pH and temperature on adsorption behavior were studied in batch mode for each biochar. The optimum contact time observed for equilibrium condition was 60 mins for every biochar. And, the maximum adsorption followed the order 298 K > 308 K > 318 K. Adsorption equilibrium data were fitted to Langmuir and Freundlich isotherms by non-linear regression method and kinetic data by linear regression method, and fitted to pseudo-first order, pseudo-second order and Intraparticle diffusion models. Adsorption kinetics was reasonably described by pseudo-second order model with R 2 value 0.99. Thermodynamic parameters were also estimated that implied, the adsorption process was spontaneous and exothermic in nature. Study further showed that the acidic pH increased adsorption capacity of biochar but decreases continuously towards basic side. The removal of phenol with prepared biochar was achieved as high as 100 % for ACB-500. The maximum iodine adsorption value of prepared biochar was found to be 453.3 mg/g.

Phosphorus removal in domestic wastewater treatment plant by calcined eggshell

Recovery of phosphorus (P) from wastewater is a topic of great interest. Besides being a non-renewable resource, P discharge in receiving waters can trigger algae blooms. The present study aimed to quantify the removal of P from two sites at a wastewater treatment plant using calcined eggshell (CES) as adsorbent. CES was prepared from raw shells calcined at 600 °C (CES600) and 800 °C (CES800). Calcined eggshells at 800 °C proved to be an efficient material for P removal. Efficiencies greater than 70% were achieved using CES800 concentrations of 0.1 g L−1 for synthetic sample, 0.3 g L−1 for preliminary treated wastewater and 20 g L−1 for supernatant from sludge anaerobic digester. The adsorption process was fast, occurring mostly in the first 30 minutes. Both Langmuir and Freundlich isotherms fitted the experimental data on adsorption. In kinetic experiments, a pseudo-second order model fitted P adsorption from synthetic, preliminary effluent and digester supernatant. Thermogravimetric analysis showed a 54% eggshell mass loss at 800 °C. Calcination increased calcium and reduced carbon fractions in the eggshells, while increasing the surface area.