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.

Combined Treatment (Alkali + Thermal) of Calotropis procera Fiber for Removal of Petroleum Hydrocarbons in Cases of Oil Spill

The objective of this study was to evaluate the Calotropis procera fiber treated with NaOH combined with heat treatment as sorbent material for removal of petroleum and derivatives in cases of oil spill. The effects of oil viscosity, fiber/oil contact time, and the type of sorption system (oil and oil/water) were evaluated by experimental planning. The fiber obtained was characterized by Fourier transform infrared spectroscopy (FTIR), field-emission scanning electron microscopy (SEM-FEG), thermogravimetric analysis (TG/DTG), contact angle, and wettability. The fiber treated by combining NaOH and heat treatment (CPNaOHT) exhibited a large structure with an internal diameter of 42.99 ± 3.98 μm, roughness, and hydrophobicity on the surface with a contact angle of 101 ± 2°. The sorption capacity of oil ranged from 190.32 g/g to 98.9 g/g. After five cycles of recycling, the fiber still maintains about 70% of its initial sorption capacity and presented low liquid desorption (0.25 g). In this way, it can be used as an efficient sorbent to clean up spills of oil and oil products.

Continuous Fixed-Bed Column Study Using Carbon Nano-Adsorbent Made Through Pyrolysis of Garbage Leachate on the Sand Particles for Removal of 4-Nonylphenol from Surface Water

The potential of carbon nanorods (NRs) derived from garbage leachate was assessed in a fixed-bed and batch system replacing the present costly approaches to treat surface water polluted by 4-Nonylphenol. First, the waste leachate was coated on silica particles and then pyrolysis was performed at 300 to 800℃. The optimum temperature for the production of nano-adsorbent was determined by analyses such as scanning electron microscopy (SEM) for adsorbent morphological characterization, X-ray energy dispersive spectrometry (EDS), and Raman test. Next, Freundlich, Langmuir, and UT isotherm models were used to analyze the batch equilibrium data. The impact of inlet 4-NP concentration (0.5, 1, and 2 mgL-1), feed flow rate (5, 10, and 20 mLmin-1), bed height (5, 10, and 15 cm), and bottom-up flow on the breakthrough features of the sorption system with a fixed bed was examined. The adsorption data were fitted using the well-known column models (i.e., Thomas, Yoon-Nelson, and Adams-Bohart). For all circumstances, the best fitting was obtained for the attained results using Yoon-Nelson and Thomas models, but not the Adams-Bohart model. The experimental data confirmed that increasing the inlet concentration and bed depth resulted in an increase in the adsorption capacity and a decrease in flow rate. After applying a different regeneration process, the results showed the effectiveness of the novel engineered substance as a reusable adsorbent for water treatment.

An innovative dual-column system for heavy metallic ion sorption by natural zeolite

This study investigates the design and performance of a novel sorption system containing natural zeolite. The apparatus consists of packed, fixed-bed, dual-columns with custom automated controls and sampling chambers, connected in series and stock fed by a metering pump at a controlled adjustable distribution. The purpose of the system is to remove heavy metallic ions predominately found in acid mine drainage, including lead (Pb2+), copper (Cu2+), iron (Fe3+), nickel (Ni2+) and zinc (Zn2+), combined in equal equivalence to form an acidified total 10 meq/L aqueous solution. Reported trends on the zeolite’s preference to these heavy metallic ions is established in the system breakthrough curve, as Pb2+ >> Fe3+ > Cu2+ > Zn2+ >> Ni2+. Within a 3-h contact period, Pb2+ is completely removed from both columns. Insufficient Ni2+ removal is achieved by either column with the promptest breakthrough attained, as zeolite demonstrates the least affinity towards it; however, a 48.97% removal is observed in the cumulative collection at the completion of the analysis period. The empty bed contact times for the first and second columns are 20 and 30 min, respectively; indicating a higher bed capacity at breakthrough and a lower usage rate of the zeolite mineral in the second column. This sorption system experimentally demonstrates the potential for industrial wastewater treatment technology development. Keywords: zeolite; sorption; packed fixed-bed columns; heavy metallic ions; automated sampling design

An innovative dual-column system for heavy metallic ion sorption by natural zeolite

This study investigates the design and performance of a novel sorption system containing natural zeolite. The apparatus consists of packed, fixed-bed, dual-columns with custom automated controls and sampling chambers, connected in series and stock fed by a metering pump at a controlled adjustable distribution. The purpose of the system is to remove heavy metallic ions predominately found in acid mine drainage, including lead (Pb2+), copper (Cu2+), iron (Fe3+), nickel (Ni2+) and zinc (Zn2+), combined in equal equivalence to form an acidified total 10 meq/L aqueous solution. Reported trends on the zeolite’s preference to these heavy metallic ions is established in the system breakthrough curve, as Pb2+ >> Fe3+ > Cu2+ > Zn2+ >> Ni2+. Within a 3-h contact period, Pb2+ is completely removed from both columns. Insufficient Ni2+ removal is achieved by either column with the promptest breakthrough attained, as zeolite demonstrates the least affinity towards it; however, a 48.97% removal is observed in the cumulative collection at the completion of the analysis period. The empty bed contact times for the first and second columns are 20 and 30 min, respectively; indicating a higher bed capacity at breakthrough and a lower usage rate of the zeolite mineral in the second column. This sorption system experimentally demonstrates the potential for industrial wastewater treatment technology development. Keywords: zeolite; sorption; packed fixed-bed columns; heavy metallic ions; automated sampling design

Nickel Sorption onto Chitosan - Silica Hybrid Aerogel from Aqueous Solution

The utilization and efficiency of agricultural waste-derived chitosan-silica hybrid aerogel “(CS)hA” on nickel removal from aqueous solution was examined and optimum parameters for pH, contact time, and initial ion concentration were determined during batch sorption system studies. Metal recovery was performed on the adsorbent using separately dilute concentrations of hydrochloric acid, acetic acid, ammonia, and sodium hydroxide solutions as eluents. The results generated were analyzed from kinetic and isotherm studies. The maximum Ni2+ adsorption of 99.78 % was established at 60 min and pH 3 in this study. The batch studies revealed that the percentage of nickel ion removal by the adsorbent decreased along with an increase in the initial Ni2+ ions concentration. The pseudo-second-order, the best fit of the kinetic model, has the values of its correlation coefficient “R2” ranging from 0.9 to 1, whereas the Langmuir model which had the maximum monolayer adsorption capacity of 85.84 mg g-1, was the best isotherm in interpreting the sorption process and the calculated separation factor was higher than 0 but less than 1. Dilute hydrochloric acid (0.1 M) was the best eluent in removing bound nickel ions (55.63 %) from (CS)hA.

Searching for optimum adsorption curve for metal sorption on soils: comparison of various isotherm models fitted by different error functions

Studies comparing numerous sorption curve models and different error functions are lacking completely for soil-metal adsorption systems. We aimed to fill this gap by studying several isotherm models and error functions on soil-metal systems with different sorption curve types. The combination of fifteen sorption curve models and seven error functions were studied for Cd, Cu, Pb, and Zn in competitive systems in four soils with different geochemical properties. Statistical calculations were carried out to compare the results of the minimizing procedures and the fit of the sorption curve models. Although different sorption models and error functions may provide some variation in fitting the models to the experimental data, these differences are mostly not significant statistically. Several sorption models showed very good performances (Brouers-Sotolongo, Sips, Hill, Langmuir-Freundlich) for varying sorption curve types in the studied soil-metal systems, and further models can be suggested for certain sorption curve types. The ERRSQ error function exhibited the lowest error distribution between the experimental data and predicted sorption curves for almost each studied cases. Consequently, their combined use could be suggested for the study of metal sorption in the studied soils. Besides testing more than one sorption isotherm model and error function combination, evaluating the shape of the sorption curve and excluding non-adsorption processes could be advised for reliable data evaluation in soil-metal sorption system.

Removal of Organic Pollutantsfrom Produced Water by Batch Adsorption Treatment

This paper investigates the adsorption of oil, chemical oxygen demand (COD) and turbidity of the produced water (PW) which accompanies the oil exploration and production after treatment by using powdered activated carbon (PAC), clinoptilolite natural zeolite (CNZ) and synthetic zeolite type X (XSZ). Moreover, the paper deals with the comparison of pollutant removal over different adsorbents. Sorption was carried out in batch sorption system. The operating factors including adsorbent dosage, time, pH, oil concentration and temperature were investigated to determine the optimum operational conditions. Three adsorption isotherm models (Langmuir, Freundlich and Temkin models) were applied. The kinetics of the oil sorption and the change in COD content over on PAC and CNZ were studied by using pseudo-first order and pseudo-second order kinetics models. Maximum oil removal efficiencies (99.57, 95.87 and 99.84%), COD and total petroleum hydrocarbon (TPH), respectively were found at PAC adsorbent dose of 0.25 g/100 mL. However, maximum turbidity removal efficiency (99.97%) was obtained when zeolite X was used at 0.25g/100 mL concentration. It is not very different from that obtained over PAC (99.65%). The results proved that adsorption over PAC is most effective compared to zeolites in the removal of organic pollutants from PW. Also, regeneration of the consumed adsorbents was carried out in this work to find out the possibility of reusing the adsorbents. The consumed powdered activated carbon and zeolites can be effectively regenerated and reused by chemical treatment and thermal treatment respectively.