Efficient nitrate removal from water by biosorption onto a southern Mediterranean Sea native plant Posidonia oceanica (L.) powder

Dargai District Malakand, Pakistan, is a tax-free zone that attracts many industrialists to install their plants in this area. Along with other industries, a number of steel mills are polluting the natural environment of this locality. This study aimed to evaluate heavy metals levels in steel mills effluents and fabricate an efficient adsorbent from the leaves of plants growing on the banks of the drainage lines of the industries and having high phytoremediation capabilities, through chemical modifications. Initially, the effluents were analyzed for heavy metal concentrations, then the leaves of a plant (Pteris vittata) with better phytoremediation capability were chemically modified. The leaves of Pteris vittata were crushed into a fine powder, followed by chemical modification with HNO3, then washed with distilled water, neutralized with NaOH and finally activated through calcium chloride to enhance its biosorption ability, abbreviated as CMPVL. Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), surface area analyzer, energy dispersive X-ray spectroscopy (EDX), and thermal gravimetric analysis (TGA) were used to characterize the CMPVL. The modified leaves in the powdered form were then used for the reclamation of Fe(II) present in the effluents of the mentioned industries. Batch biosorption tests were performed under varied physicochemical conditions of pH (2–9), contact time (10–140 min), temperature (293–333 K), biosorbent dose (0.01–0.13 g), and initial metal concentration (20–300 mg L−1) to optimize the removal of the selected metal. Langmuir, Jovanovic, Freundlich, Temkin, and Harkins–Jura isotherm models were used to assess the equilibrium data. With a high R2 value of 0.977, the Langmuir model offered an excellent match to the equilibrium data. The pseudo-first order, pseudo-second order, power function, intraparticle diffusion, and Natarajan–Khalaf models were applied to experimental kinetics data. With R2 values of 0.999, the pseudo-second order model well fitted the obtained data. The Van’t Hoff equation was used to calculate ΔH°, ΔS° and ΔG° of Fe(II) sorption on CMPVL. The ∆H° and ∆G° were negative, whereas ΔS° was positive, suggesting that the biosorption process was exothermic, favorable, and spontaneous. The selected plant leaves were found to be efficient in the reclamation of iron from the industrial effluents (as the plant has a high natural capability for remediating the selected metal ion) after chemical modification and may be used as an alternative to activated carbon as being a low-cost material and a high phytoremediator of iron metal. Such natural phenomena of phytoremediation should be utilized in obtaining efficient adsorbents for other metals as well.

Batch and fixed bed column studies for the removal of Indosol Yellow BG dye by peanut husk

Biosorption of crystal violet onto cyperus rotundus in batch system: kinetic and equilibrium modeling

Dyes released into the environment have been posing a serious threat to natural ecosystems and aquatic life due to presence of heat, light, chemical and other exposures stable. In this study, the Pleurotus ostreatus (a macro-fungus) was used as a new biosorbent to study the biosorption of hazardous malachite green (MG) from aqueous solutions. The effective disposal of P. ostreatus is a meaningful work for environmental protection and maximum utilization of agricultural residues.The operational parameters such as biosorbent dose, pH, and ionic strength were investigated in a series of batch studies at 25°C. Freundlich isotherm model was described well for the biosorption equilibrium data. The biosorption process followed the pseudo-second-order kinetic model. Taguchi method was used to simplify the experimental number for determining the significance of factors and the optimum levels of experimental factors for MG biosorption. Biosorbent dose and initial MG concentration had significant influences on the percent removal and biosorption capacity. The highest percent removal reached 89.58% and the largest biosorption capacity reached 32.33 mg/g. The Fourier transform infrared spectroscopy (FTIR) showed that the functional groups such as, carboxyl, hydroxyl, amino and phosphonate groups on the biosorbent surface could be the potential adsorption sites for MG biosorption. P. ostreatus can be considered as an alternative biosorbent for the removal of dyes from aqueous solutions.

The present investigation explored the use of Citrus reticulata waste biomass (CWB) for the removal of Pb(II) and Co(II) from the aqueous solutions. The Pb(II) and Co(II) biosorption was found to be dependent on pH of the solution, biosorbent dose, biosorbent particle size, temperature, shaking speed, contact time and initial concentration of metal ions. A metal uptake capacity of 41.16 and 52.64 mg/g was observed at pH 5 and 7 for Pb(II) and Co(II), respectively. The biosorption data followed the Freundlich model for both metals. The overall biosorption process was best described by pseudo-second order kinetics. The effect of several pretreatments on the biosorption efficiency of CWB was also investigated. The results demonstrated that pretreatments influenced the biosorption capacity of the biomass for the both metals significantly. Maximum biosorption capacity of 83.77 and 95.55 mg/g was observed for Pb(II) and Co(II) with sodium hydroxide treated and simply heated biomass, respectively. FTIR spectrum indicated the presence of -OH, -NH, -COOH groups in the biomass. The surface structure of CWB was analyzed by JEOL JMT 300 scanning electron microscope (SEM), and the existence of metal ions on the surface of biosorbent was determined by energy dispersive X-ray (EDX) spectroscopy.

The present investigation explored the use of Citrus reticulata waste biomass (CWB) for the removal of Pb(II) and Co(II) from the aqueous solutions. The Pb(II) and Co(II) biosorption was found to be dependent on pH of the solution, biosorbent dose, biosorbent particle size, temperature, shaking speed, contact time and initial concentration of metal ions. A metal uptake capacity of 41.16 and 52.64 mg/g was observed at pH 5 and 7 for Pb(II) and Co(II), respectively. The biosorption data followed the Freundlich model for both metals. The overall biosorption process was best described by pseudo-second order kinetics. The effect of several pretreatments on the biosorption efficiency of CWB was also investigated. The results demonstrated that pretreatments influenced the biosorption capacity of the biomass for the both metals significantly. Maximum biosorption capacity of 83.77 and 95.55 mg/g was observed for Pb(II) and Co(II) with sodium hydroxide treated and simply heated biomass, respectively. FTIR spectrum indicated the presence of -OH, -NH, -COOH groups in the biomass. The surface structure of CWB was analyzed by JEOL JMT 300 scanning electron microscope (SEM), and the existence of metal ions on the surface of biosorbent was determined by energy dispersive X-ray (EDX) spectroscopy.

Cellular responses and phenol bioremoval by green alga Scenedesmus abundans: Equilibrium, kinetic and thermodynamic studies

The feasibility of alginate-immobilised Chlorella sorokiniana for nitrate and ammonium removal from drinking water in regard to carbon source effects was studied in this paper. Three different natural carbon sources were tested in batch experiments with nitrate as nitrogen source: sucrose, grape juice and acacia honey. The nitrate removal efficiencies achieved at 50 mg/L of initial nitrate concentration under sucrose, grape juice and acacia honey were 93, 99 and 94 %, respectively. At 100 mg/L of nitrate, comparable efficiencies were obtained after approximately 3 days, whilst for acacia honey at 50 mg/L, it took only 2 days of cultivation and 3 days for the other two carbon sources. Grape juice and acacia honey showed better performances than sucrose, which must be linked to their chemical compositions. The study of the impact of biosorbent quantity on nitrate removal efficiency showed that sufficient nitrate removal efficiencies could be achieved with a beads/water ratio of 1:6.7 (v/v) or smaller. In addition, the beads’ ages significantly impacted the nitrate removal. The removal of ammonium was studied in the presence of nitrate with acacia honey as carbon source. At the highest concentrations being tested (ammonium-30 mg/L and nitrate-50 mg/L), ammonium was completely removed in <3 days and nitrate by 81 % in 4 days, whereby the suitable beads/water ratio was 1:5. The priority of ammonium assimilation was noticed when compared to nitrate. According to the results, the alginate-immobilised C. sorokiniana represents a promising tool for the removal of nitrogen from drinking water sources.

Characterizing the capacity of hyporheic sediments to attenuate groundwater nitrate loads by adsorption

Many studies were undertaken on the biosorption potential of different kinds of biomaterials. However, there is a paucity of data regarding the biosorption mechanism of Cr (VI) using dried cells. In our study, the removal of Cr (VI) from aqueous solution was investigated in a batch system by the dried biomass of a chromium-resistant bacterium isolated from activated sludge samples. Equilibrium and kinetic experiments were undertaken at various initial metal concentration, pH, and biosorbent dosage. Bacillus cereus biomass was characterized using Energy-Dispersive X-ray (EDX), Scanning Electron Microscope (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). Biosorption process was found to be pH dependent. The optimum pH was found to be 2.0. The Langmuir and Freundlich were considered to identify the isotherm that could better describe the equilibrium adsorption of Cr (VI) onto the biomass. Langmuir and Freundlich models fitted our experimental data. The suitability of the pseudo-first order and pseudo-second order kinetic models for the biosorption of Cr (VI) onto Bacillus cereus was also performed. The mechanism for the adsorption was studied by fitting the kinetic data with the Boyd plot and intra-particle diffusion model. External mass transfer was found to be the rate-determining step. Based on the ionic nature of the metal, the intra-particle diffusion and extent of film diffusion varied.

Assessment of Cu (II) removal from an aqueous solution by raw Gundelia tournefortii as a new low-cost biosorbent: Experiments and modelling

ABSTRACTThe study explores the adsorption potential of Chrysanthemum indicum biomass for nickel ion removal from aqueous solution. C. indicum flowers in raw (CIF-I) and biochar (CIF-II) forms were used as adsorbents in this study. Batch experiments were conducted to ascertain the optimum conditions of solution pH, adsorbent dosage, contact time, and temperature for varying initial Ni(II) ion concentrations. Surface area, surface morphology, and functionality of the adsorbents were characterized by Brunauer, Emmett, and Teller (BET) surface analysis, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and Fourier transform infrared spectroscopy (FTIR). Adsorption kinetics were modeled using pseudo-first order, pseudo-second order, Elovich, intraparticle diffusion, Bangham's, and Boyd's plot. The equilibrium data were modeled using Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich (D-R) isotherm models. Experimental data provided the best fit to pseudo-second-order kinetic model and Langmuir isotherm model for the adsorption of Ni(II) ion on both CIF-I and CIF-II with maximum adsorption capacities of 23.97 and 44.02 mg g−1, respectively. Thermodynamic analysis of the data proved the process to be spontaneous and endothermic in nature. Desorption studies were conducted to evaluate the possibility of reusing the adsorbents. Findings of the present study provide substantial evidence for the use of C. indicum flower as an eco-friendly and potential adsorbent for the removal of Ni(II) ions from aqueous solution.

Experimental results are presented for the electrolytic ChemDen (Chemical-Denitrification) process which was designed to investigate the effect of operational parameters on the nitrate (NO 3 − ) removal from metal-finishing wastewater. The parameters included electrode materials, electrode gap, reducing agent, hydraulic retention time (HRT) and recycle ratio in the single electrolytic ChemDen reactor for lab-scale tests. The removal efficiency of nitrate is based upon a non-biological process which consists of chemical and electrolytic treatment. Results showed that removal efficiency of nitrate was highest when the zinc (Zn) electrodes were used for both anode and cathode. In the case of insoluble electrode, combining Pt anode with Ti cathode provided great improvement of nitrate removal. For the Pt-Ti electrode combination, increasing electrode gap tended to increase removal efficiency of nitrate significantly. However, no further increase in the nitrate removal was observed when the electrode gap was longer than 10mm. Using sulfamic acid and Zn metal powder as reducing agents for the electrolytic ChemDen reaction, highest nitrate removal was achieved when the mole ratio of Zn: sulfamic acid: nitrate was 1.2: 1: 1. Remarkable improvement in the nitrate removal was also observed with increasing HRT from 10 to 30 min, while the effectiveness was limited when HRT was increased to 60 min. Recycling in electrolytic ChemDen reactor affected nitrate removal positively because it could improve both dispersion and reuse of Zn metal powder as reducing agent in the reactor. Recycling effects were thought to be associated with increasing surface reactivity of the Zn metal powder in the electrolytic ChemDen reactor.

Biosorption properties of a CaCl2-modified Sargassum oligocystum algae biomass for removal of Cr(VI) from aqueous solutions were investigated. Experimental parameters affecting the biosorption process such as pH, contact time, biosorbent dosage, and temperature were studied. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), mapping test, energy-dispersive X-ray spectroscopy (EDX), and specific surface area were used to assess the physico-chemical properties the biosorbent. The surface area of biosorbent was found to be 35.64 m2/g. FTIR test revealed that the active groups of -OH, -NH2, -C-H, C-O, -C-N, and S=O were present on the surface of CaCl2-modified S. oligocystum biomass. The kinetic behavior of the chromium biosorption by modified S. oligocystum biomass followed well pseudo-second order kinetic (R2>0.999). The biosorption equilibrium occurred at 100th min of contact time. The Langmuir, Freundlich, and Dubinin-Radushkevich models were applied to describe the biosorption isotherm of Cr(VI) onto modified S. oligocystum biomass. According to the RL and n parameters of the studied isotherms, the Cr(VI) biosorption process was physical and desirable. The chromium biosorption capacity of modified S. oligocystum biomass was found to be 34.46mg/g. The calculated thermodynamic parameters (ΔG o , ΔH o , and ΔS o ) indicated that the biosorption of Cr(VI) onto modified S. oligocystum biomass algae was feasible, spontaneous, and exothermic under examined conditions.

Yeast biomass is considered a low-cost material that can be successfully used for the biosorption of metal ions from aqueous solution, due to its structural characteristics. This study evaluates the biosorptive performance of Saccharomyces cerevisiae in the biosorption of Co(II), Zn(II) and Cu(II) ions from aqueous media in batch mono-component systems. The influence of solution pH, biosorbent dose, contact time, temperature and initial metal ions concentration was examined step by step, to obtain the optimal conditions for biosorption experiments. Maximum uptake efficiency for all metal ions on this biosorbent was obtained at: pH = 5.0, 4.0 g biosorbent/L, room temperature of 23 °C, and a contact time of 60 min, and these were considered optimal. The equilibrium results were analyzed using Langmuir, Freundlich and Dubinin–Radushkevich isotherm models, while for the modeling of the kinetics data, three models (pseudo-first order, pseudo-second order and intra-particle diffusion) were used. Dubinin–Radushkevich isotherm model and the pseudo-second order model showed the best fit with the experimental data obtained at biosorption of Co(II), Zn(II) and Cu(II) ions on Saccharomyces cerevisiae. Both maximum biosorption capacities and pseudo-second rate constants follow the order: Co(II) &gt; Zn(II) &gt; Cu(II), suggesting that the structural particularities of metal ions are important in the biosorption processes. Based on the obtained equilibrium and kinetic parameters, the biosorption mechanism is analyzed and the possible applications are emphasized.