Adsorption Media Research Articles

Distribution of Colloidal and Powdered Activated Carbon for the <i>in Situ</i> Treatment of Groundwater

The use of in situ technologies for the treatment of groundwater containing various compounds of concern are widely accepted. These technologies include chemical reduction, chemical oxidation, anaerobic and aerobic bioremediation, and adsorption, among others. One requirement for the successful application of these technologies is the delivery of the remedial reagent(s) to the compounds of concern. A rapidly evolving in situ technology is the injection of adsorptive media such as activated carbon and ion-exchange resin including powdered or colloidal activated carbon. Activated carbon has a long-demonstrated history of effectiveness for the removal of various organic and inorganic compounds in above ground water treatment systems. However, due to constraints related to the particle size and physical properties of the activated carbon, the in situ application of activated carbon has been limited. Recent developments in the manufacturing of activated carbon have created a smaller particle size allowing activated carbon to be applied in situ. To evaluate if powdered and colloidal activated carbon can be effectively distributed in aquifers, the two types of carbon were injected using direct push technology adjacent to each other at four sites with varying geology. Evaluation of distribution was completed by sampling the aquifer prior to and post-injection for total organic carbon. The results of the studies indicated that both forms of activated carbon were effectively delivered to the targeted injection zones with both carbon types being detected at least seven meters away from the point of injection. The colloidal form of the activated carbon showed good distribution throughout the four targeted zones of injection with 93 percent of the samples collected having colloidal activated carbon present within them whereas the powdered activated carbon cells were more susceptible to aquifer heterogeneity with only 67 percent of the samples collected having activated carbon present. Preferential accumulation of activated carbon was observed in high horizontal hydraulic conductivity seams, especially within the powdered activated carbon cells. These results suggested that the powdered form of activated carbon was more suspectable at the four sites to heterogeneity within the aquifer than the colloidal form of activated carbon. Sampling of monitoring well screens installed prior to the injection of the two forms of activated carbon showed preferential accumulation of powdered activated carbon within the sand pack, which could result in sampling bias.

Removal of Methylene Blue of Textile Industry Waste with Activated Carbon using Adsorption Method

The colorant that is often used in the textile industry is methylene blue which is a cationic heterocyclic aromatic compound. This compound is very stable and is difficult to decompose naturally leading to environment in large concentrations. Therefore, a waste treatment technology to reduce the concentration of dye waste in water becomes importannt. So far, adsorption method with activated carbon remains the most efficient and effective technique in removing dyes from liquid waste due to its relatively large adsorption capacity. Activated carbon is one of the non-metallic mineral commodities or multipurpose industrial minerals, one of which is as an adsorbent or adsorbent media. This study aims to determine the potential of activated carbon in adsorbing methylene blue with variations in the concentration of methylene blue and particle size of activated carbon. The procedures in this experiment include, the preparation of activated carbon with size variations (20-60, 60-100 and> 100 mesh) and variations in the concentration of methylene blue (15 ppm, 30 ppm and 45 ppm) with contact time (0 to 180 minutes). From the results of the study, it was found that the smaller the size of activated carbon used, the greater the adsorption capacity, ie at mesh size> 100 mesh, the adsorption capacity was 9.8%. Whereas, the smaller the concentration of methylene blue, the activated carbon could work optimally at a concentration of 15 ppm at 30 minutes with adsorption capacity as high as 100%.Keywords: adsorption; Methylene Blue; activated carbon; concentration; time; particle size

Application of Natural Zeolite in Methylene Blue Wastewater Treatment Process by Adsorption Method

Textile industry waste contains dyes that are difficult to decompose naturally and cause disruption of ecosystems in water. The colorant that is often used in the textile industry is methylene blue which is a cationic heterocyclic aromatic compound. This compound is so stable that it is difficult to decompose naturally and is harmful to the environment in large concentrations. Therefore, we need a waste treatment technology that can reduce the concentration of dye waste in water. So far, the adsorption method remains the most efficient and effective technique in removing dyes because of its relatively large adsorption capacity. One method that can be used is the adsorption method using natural zeolite. Zeolite is one of the non-metal mineral commodities or multipurpose industrial minerals, one of which is as an adsorbent or adsorbent media. This study aims to determine the potential of natural zeolite in absorbing methylene blue with variations in the concentration of methylene blue and various sizes of natural zeolite mesh. The procedures in this experiment include, the preparation of natural zeolite with size variations of 20-60 mesh, 60-100 mesh and> 100 mesh and variations in the concentration of methylene blue used 15 ppm, 30 ppm and 45 ppm with contact time from 0 to 180 minutes. From the results of the study it was found that the smaller the size of natural zeolite used, the greater the percentage of dye removal that is at mesh size> 100 mesh the percentage of dye removal was 32.11%. As for the variation of the concentration of methylene blue, the smaller the concentration, the natural zeolite can work optimally ie at a concentration of 15 ppm at 180 minutes the remaining methylene blue concentration of 0.145 ppm.

Heavy Metals Removal from Agricultural Drains using Rice Husk inside the Stream

With the stabilization in water amounts on earth and the population growth and the water use increase in human life with the progress of all facilities and industries, the need to reuse of all available water resources be the most important issue for the research specially the reuse of all wastewater types. For the agricultural wastewater is the huge amount of wastewater and also it is the main disposal for all other wastewater, so its treatment became the most easy way to get new water resource with big quantities and continuity. The most serious problem in the drain wastewater is industrial wastewater pollutants for its containing of heavy metals and toxic substances. The study concentrates on finding a low cost and easy treatment procedure to make the dream of the agricultural drain wastewater reuse possible. Several studies applied agricultural wastes as an adsorbent material for removing successfully heavy metals from wastewater. So, in this study rice husk was used by putting as a block across the steam to work as adsorbing filter to remove the existing zinc and chromium appears due to industrial wastewater direct disposal in agricultural drains wastewater. The obtained Zn+2 removal ratios was 94.33% and Cr (VI) removal ratio was 89.2%. The study illustrated that the removal ratio is proportional with the adsorption media length for the contact time increase. The rice husk waste achieved removal efficiency for zinc better than Cr (VI). The success of use the agricultural waste as cheap adsorbent in treatment of agricultural drains wastewater polluted from industrial wastewater open the door for the existing drains to be easily treated with minimum cost and no effect on their profiles and saving the environment from heavy metals harm pollution.

A novel low-cost multi-barrier system for drinking water treatment in rural and suburban areas

Abstract A low-cost multi-barrier drinking water system incorporating geotextile fabric for pre-filtration, silver-coated ceramic granular media (SCCGM) for filtration and disinfection, granular activated carbon (GAC) as an adsorption media and a safe storage compartment for treated water has been developed and tested. The developed system offers a novel concept of point-of-use drinking water treatment in rural and suburban areas of developing countries. The system is primarily aimed at bacterial and aesthetic improvement and has been optimised to produce >99.99% E. coli and fecal coliforms removal. Although particular emphasis was placed on the elimination of bacteria, improvement of the acceptability aspects of water was also given high priority so that users are not motivated to use more appealing but potentially unsafe sources. This paper discusses key system features and contaminant removal performance. A system using SCCGM only was also tested alongside the multi-barrier system. Strengths and weaknesses of the system are also presented. Both the developed and SCCGM-only systems consistently provided >99.99% E. coli and fecal coliforms removal at an optimum flow of 2 L/h. The developed system significantly recorded improvements of aesthetic aspects (turbidity, color, taste and odor). Average turbidity removals were 99.2% and 90.2% by the multi-barrier and SCCGM-only systems respectively.

Porous Aromatic Melamine Schiff Bases as Highly Efficient Media for Carbon Dioxide Storage

High energy demand has led to excessive fuel consumption and high-concentration CO2 production. CO2 release causes serious environmental problems such as the rise in the Earth’s temperature, leading to global warming. Thus, chemical industries are under severe pressure to provide a solution to the problems associated with fuel consumption and to reduce CO2 emission at the source. To this effect, herein, four highly porous aromatic Schiff bases derived from melamine were investigated as potential media for CO2 capture. Since these Schiff bases are highly aromatic, porous, and have a high content of heteroatoms (nitrogen and oxygen), they can serve as CO2 storage media. The surface morphology of the Schiff bases was investigated through field emission scanning electron microscopy, and their physical properties were determined by gas adsorption experiments. The Schiff bases had a pore volume of 0.005–0.036 cm3/g, an average pore diameter of 1.69–3.363 nm, and a small Brunauer–Emmett–Teller surface area (5.2–11.6 m2/g). The Schiff bases showed remarkable CO2 uptake (up to 2.33 mmol/g; 10.0 wt%) at 323 K and 40 bars. The Schiff base containing the 4-nitrophenyl substituent was the most efficient medium for CO2 adsorption and, therefore, can be used as a gas sorbent.

Kinetic Study of Adsorption of Some Azo Dyes On A Thermally Catalyzed Local Bentonite Clay

The research is included studying the kinetic of the adsorption of two azo dyes synthesized in our laboratories on a local bentonite thermally activated .The efficiency and capacity of adsorption are calculated at the optimal conditions of adsorption. Such as the effect of dose , contact time ,pH of adsorption medium and temperature . Four kinetic models of adsorption namely ,pseudo first and second order ,Elovich , and intraparticle diffusion have been applied on the experimental data of the adsorption system under consideration . The results showed that ,the studied systems are fitted to the pseudo second order model ,and the adsorption process occurs in more than one mechanism. The activation energy of adsorption of the studied system in addition to the thermodynamic functions of activation of adsorption are estimated from studying the effect of temperature on the rate constant of adsorption .

Use of rice straw-based biochar for batch sorption of barium/strontium from saline water: Protection against scale formation in petroleum/desalination industries

The formation of hard mineral scale deposits (e.g., celestite (SrSO4) and barite (BaSO4)) is the most common problem that hinders sustainable operations of water-flooded oilfield and desalination systems (i.e., membrane fouling) when using poor quality water contaminated with barium (Ba(II)) and strontium (Sr(II)) ions. In this work, nanoscale biochar (∼53–712 nm) was synthesized from waste rice straw (cost = 380 to 560 ± 27 US$/Ton; n = 9) and applied as a protective approach against the formation of mineral scale deposits via adsorptive removal of Ba(II)/Sr(II) contaminants from 30,000 ppm saline wastewater. Adsorption of Ba(II)/Sr(II) ions onto biochar was investigated and optimized as a function of biochar amount, water pH, contact time, temperature, and Sr(II)/Ba(II) ratio using response surface methodology. Based on kinetic and isotherm analyses, the biochar exhibited enhanced potential to capture Sr(II)/Ba(II) ions via weak ion-exchange or pore-filling mechanisms (sorption energy (E)≈ 0.61–0.89 kJ/mol). A comparison of partition coefficient (PC) values verified that sorption of Sr(II) onto biochar is far superior to that of Ba(II) (PCs of 10.1 and 2.5 μmol g−1 μM−1, respectively). Sorption selectivity was mainly dependent on solution pH and the metallic properties of Ba(II)/Sr(II)(e.g., metal size, speciation, and mobility). Quantitative analysis of treated saline water using electrical conductivity and ion chromatography confirmed the ability of biochar sorbent to remove Ba(II) and Sr(II) ions (97.5%) with pre-desalination (e.g., total salts reduction of 25.7% after 48 h). It is thus recommended to utilize the prepared biochar as a promising pre-desalinating adsorptive medium to inhibit mineral scale formation before oilfield water flooding in the petroleum field and membrane desalination systems.

Poly(p-phenylenediamine)/maghemite composite as highly effective adsorbent for anionic dye removal

Poly(p-phenylenediamine)/maghemite (PPDA/γ-Fe2O3) composites were prepared by the oxidative polymerization of p-phenylenediamine with ammonium peroxodisulfate as an oxidizing agent in the presence of γ-Fe2O3 nanoparticles. Morphology of the prepared composites was examined by the scanning and transmission electron microscopies. X-ray diffraction and EDX were used to study crystallinity and chemical composition, respectively. TGA demonstrated that only 7 and 45 wt% of γ-Fe2O3 were incorporated into PPDA prepared with 25 and 50 wt% of γ-Fe2O3, respectively. Adsorption property of the composites was examined towards the anionic dye, Reactive Black 5. The adsorption results were fitted to different kinetics and isotherm models. The highest adsorption capacity (Qmax) was estimated to be 223 mg g−1 in case of PPDA with the highest specific surface area (70.6 m2 g–1) prepared with 25 wt% of γ-Fe2O3. Qmax of neat PPDA was estimated to be 185.2 mg g−1 and 123.2 mg g−1 for PPDA prepared with 50 wt% of γ-Fe2O3. In addition to the enhancing of the adsorption capacity, the incorporation of γ-Fe2O3 particles provided an easy separation of the composites from the adsorption medium.

Influence of gas migration on permeability of soft coalbed methane reservoirs under true triaxial stress conditions.

The permeability of the coal body is the key parameter restricting the efficient extraction of coalbed methane, and scholars have analysed it from two angles of the change of stress state and porosity of the coal body. However, there is still a lack of study on the mechanism of gas migration and movement in soft coalbed methane reservoir under the coupling between the true triaxial stress field (maximum principal stress σ1 > intermediate principal stress σ2 > minimum principal stress σ3) and the gas pressure field. In this paper, the coal gas adsorption and seepage experiments are conducted through the self-developed true triaxial ‘gas–solid’ coupled coal mass seepage system with gas as the adsorption and seepage medium and coal briquette taking the place of soft coalbed methane reservoirs. Furthermore, the coal gas adsorption deformation model and the permeability evolution model taking gas adsorption into account are developed. Through analysis of both experimental and theoretic results, the main conclusions are drawn as follows: (i) With the increase in gas pressure, the adsorption deformation variation of coal mass is divided into a slow growth zone, a stable growth zone and a rapid growth zone. (ii) The gas adsorption deformation model developed can predict the variation trend of coal mass adsorption volumetric strains for different types of soft coalbeds, and the fitting variance of experimental and theoretical volumetric strains is above 98%. (iii) With the increase in maximum principal stress difference, the coal permeability variation curve shows two obvious turning points, which can be divided into a slow reduction zone, a rapid reduction zone and a steady reduction zone. (iv) The permeability model of coal mass considering the gas adsorption effect can reflect the variation characteristics of permeability in the rapid reduction zone, and the overall fitting variance of experimental and theoretical permeabilities is above 91%. The above results could provide a reliable experimental and theoretical basis for improving coalbed methane extraction rates.

Application of Activated Carbon Fibers for Removal of Iron and Lead Salts from Waste water

In this study, the adsorption characteristics and performance of activated carbon fibers (ACF) were prepared from Polyacrylonitrile (PAN) waste, for removal of heavy metals was investigated. The effects of heavy metals concentration, adsorption temperature, pH of adsorption solution and contact time for removal of iron sulfate and lead acetate were studied to determine the best performance properties. The surface of ACF before and after adsorption process was investigated by scanning electron microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDX). The adsorption characteristics were mainly affected by pH of adsorption media and the adsorption temperature. The pH 4.0 was the optimum one for the adsorption processes of iron sulfate and lead acetate. Increasing the adsorption temperature from 30 - 80°C improved the removal efficiency of Fe(Ⅱ) from 71 % to 94 % and for Pb(II) increased from 57 % to 83 % . The surface of ACF after adsorptions is characterized by the formation of some precipitations on the surface of ACF. These precipitations and granulation are noticed. EDX analysis confirms the presence of Fe(II) and Pb(II) onto ACF after adsorptions.

PENGARUH UKURAN SERBUK ARANG KAYU ULIN TERHADAP EFEKTIVITAS PEMURNIAN BIOGAS

This study aims to determine the effect of ironwood charcoal powder size on the effectiveness of biogas purification and generator-set performance. This research was carried out by flowing biogas from sanitary landfill to biogas purification insulator containing adsorption media with charcoal varying charcoal size variations, namely size 20, 30 and 40 mesh, then biogas stored in a storage tube then flowed to the chamber for CO2 level reading and CH4 uses a gas analyzer. From this study the following results were obtained: Biogas without charcoal (CO2 26514.66 ppm and CH4 101.07 ppm), Biogas with a size of 20 mesh (CO2 20270.08 ppm, CH4 458.35 ppm and effectiveness of 23.55%), with a size of 30 mesh (CO2 14273.31 ppm, CH4 658.75 ppm and effectiveness of 46.16%), with a size of 40 mesh (CO2 12092.66 ppm, CH4 3161.04 ppm and effectiveness of 54.39%). For the results of testing the performance of generator sets using biogas fuel which has been purified with ironwood charcoal with a size of 40 mesh, ie for no load, rotation is obtained at 3465.0 rpm, temperature 102 0C, and voltage 240 V (stable), with load 350 W obtained rotation 3203.8 rpm, temperature 236 0C, and voltage 150-240 V (unstable), with a load of 700 W obtained rotation 3360.9 rpm, temperature 220 0C, and voltage 100-200 V (unstable). Keywords: Biogas Purification, Variation in Mesh Size, Ironwood Charcoal. Keywords: Purification of Biogas, Mesh Size Variations, Ulin Wood Charcoal

RETRACTED: A Sugarcane-Bagasse-Based Adsorbent Employed for Mitigating Eutrophication Threats and Producing Biodiesel Simultaneously

Eutrophication is an inevitable phenomenon, and it has recently become an unabated threat. As a positive, the thriving microalgal biomass in eutrophic water is conventionally perceived to be loaded with myriad valuable biochemical compounds. Therefore, a sugarcane-bagasse-based adsorbent was proposed in this study to harvest the microalgal biomass for producing biodiesel. By activating the sugarcane-bagasse-based adsorbent with 1.5 M of H2SO4, a highest adsorption capacity of 108.9 ± 0.3 mg/g was attained. This was fundamentally due to the surface potential of the 1.5 M H2SO4 acid-modified sugarcane-bagasse-based adsorbent possessing the lowest surface positivity value as calculated from its point of zero charge. The adsorption capacity was then improved to 192.9 ± 0.1 mg/g by stepwise optimizing the adsorbent size to 6.7–8.0 mm, adsorption medium pH to 2–4, and adsorbent dosage to 0.4 g per 100 mL of adsorption medium. This resulted in 91.5% microalgae removal efficiency. Excellent-quality biodiesel was also obtained as reflected by the fatty acid methyl ester (FAME) profile, showing the dominant species of C16–C18 encompassing 71% of the overall FAMEs. The sustainability of harvesting microalgal biomass via an adsorption-enhanced flocculation processes was also evidenced by the potentiality to reuse the spent acid-modified adsorbent.

Separation processes for carbon dioxide capture with semi-clathrate hydrate slurry based on phase equilibria of CO2 + N2 + tetra-n-butylammonium bromide + water systems

The objective of this work was to assess multi-stage separation processes for CO2 capture based on semi-clathrate hydrate (SCH) adsorption media. Phase equilibria were determined for CO2+tetra-n-butyl ammonium bromide (TBAB), N2+TBAB and CO2+N2+TBAB SCH and correlated with a modified van der Waals–Platteeuw model. Experimental CO2 separation factors ranged from 5 to 10, whereas calculated values were all around 18 implying inhomogeneous absorption in the slurries. For simulation conditions, hydrate mass fractions less than 0.09 were estimated to prevent aggregation of the hydrate solids. A two-stage batch separation process allowed enrichment of CO2 to more than 90mol% from a 20mol% CO2 feed. A three-stage continuous countercurrent separation process allowed a CO2 recovery of about 90%. Separation performance of semi-clathrate hydrates ranked favorably among the CO2 separation methods, showing that SCH adsorption media have excellent potential for carbon capture applications.

Butea monosperma leaf as an adsorbent of methylene blue: recovery of the dye and reuse of the adsorbent

Butea monosperma leaf powder was used as an adsorbent to remove methylene blue dye from aqueous solution. Different parameters that affect on adsorption such as dye concentration, adsorbent dose, contact time and pH of the solution were analyzed. The suitable dye concentration was found to be 100 mg/l for adsorption experiments. The adsorbent dose and optimum contact time were standardized as 0.5 g/l and 120 min, respectively. The acceptable pH of the medium for adsorption was found as pH = 8. At the standardized environment, the maximum adsorption efficiency of the adsorbent was recorded as 98.70%. The ultra-morphological structure disclosed that the adsorbent had originally rugged surface with empty spaces on it, and after adsorption of the dye, these pores and spaces were filled up with the dye. Fourier transformed infrared spectroscopy chromatogram of the adsorbent shows many downward peaks which can be attributed to the existence of functional groups like C=O, –OH and –NH, etc. The suitably studied isotherm model was the Freundlich model having the correlation coefficient (r2) value of 0.9810. The adsorbent was transferred to the acidic environment (pH 6). At the pH, about 80% adsorbed dye was exuded. The adsorbent can be used for maximum two times for removal of the dye. Therefore, it can be concluded that Butea monosperma leaf powder has potential to remove methylene blue in aqueous solution. The absorbed dye can easily be recovered from adsorbent for reuse purposes.

An optimized configuration of adsorptive wells for the remediation of an aquifer contaminated by multiple aromatic hydrocarbon pollutants

Adsorptive wells arrays are an innovative outline of Permeable Reactive Barrier (PRBs) made of a definite number of passive deep wells opportunely distributed in the aquifer, known as PAB-D (Discontinuous Permeable Adsorptive Barrier). They are generally located downstream the contaminated groundwater flow and perpendicularly to the groundwater flow direction. Being PAB-D wells filled with adsorbing media, whose hydraulic permeability is higher than the surrounding media, the array will create a targeted capture zone, which will force the contaminated water to pass through the whole PAB-D, allowing for both the interception of the contaminant plume and its treatment. In this work, an optimized configuration of PAB-D is presented, for the in situ-remediation of an aquifer simultaneously contaminated by benzene and toluene. The design optimization of the PAB-D was performed by using COMSOL Multiphysics®, in which numerical simulations reproduced the transport and the adsorptive phenomena occurring inside the aquifer and the barrier itself. The proposed technique was applied to the remediation of an aquifer located in an urban area in the north of Naples (Italy), in proximity of numerous landfills, where the contamination was spread over an area of 0.10 km2. Simulation results confirm the effectiveness of the PAB-D, being both pollutant plumes intercepted and their concentrations reduced below their correspondent Italian regulatory threshold values. The best array configuration of PAB-D resulted made of 741 wells, each having a diameter of 0.6 m, which was also compared with a continuous barrier (PABC) showing a reduction of about 49% of the volume and 35% of the overall remediation cost.

Post-treatment of landfill leachate using rice husk ash as adsorbent medium

Sanitary landfill is the most disposal method for urban solid waste. However, in the process of organic matter degradation, a dark-colored liquid with high potential for polluting is produced, necessitating an efficient treatment before its discharge into watercourses. Several technologies can be used in the treatment, such as biological and physico-chemical systems. The activated carbon produced from agricultural residues - rice husk ash (RHA), appears as an alternative treatment, mainly for color reduction in landfill leachate. This study determined the best operational condition for the slurry treatment using a fixed-bed column. The column was filled with activated RHA and support material (sand). The column heights studied were 5 cm (C1) and 20 cm (C2) of adsorbent. The column with 20 cm of RHA and sand intercalated with the coal layer showed better efficiency in removal of the chemical oxygen demand (COD), with COD removal efficiency of 88.91% and rupture time of 120 min. The removal of apparent color was 87.40% with the rupture time of 40 min and true color removal of 86.64% with rupture time of 50 min. Activated rice husk ash was shown to be promising for post-treatment of the leachate with substantial efficiency.

Application of breakthrough curve analysis and response surface methodology for optimization of a hybrid separation system consisting of fixed-bed column adsorption and dead-end depth filtration

This work investigates the performance and optimization of a hybrid process consisting of a fixed-bed adsorption (FBA) column and a dead-end filtration (DEF) cell for the removal of methylene blue (MB) from water. Granular activated carbon and cellulose acetate depth filter sheets were used as adsorbent and filter medium, respectively. Effects of four operation parameters (initial concentration, feed flowrate, bed length, and filter type) on the MB removal rate (RR) were investigated using breakthrough data analysis and response surface methodology. This RR (mass of MB removed per second) captures the removal capacity and separation rate, simultaneously. The maximum RR was found theoretically equal to 3.875 s−1 at the optimized conditions of initial concentration =39.86 mg/L, flowrate = 1.15 L/min, bed length =29.95 cm, and filter type = OS100, and validated with the experimental data with 99% agreement. The performance of the hybrid process operating at the optimal operation conditions was found to be superior to those of the individual FBA column and DEF cell. After 100 s from the process commencement, the RR obtained with the hybrid process was about 64% higher than that obtained with the FBA column and 30% higher than that obtained with the DEF cell.

Physico-chemical characterization of carbonized apricot kernel shell as precursor for activated carbon preparation in clean technology utilization

This paper investigates the ability of waste apricot (Prunus armeniaca) kernel shells (AKS) bio-char prepared by single-step carbonization process at 850 °C (residence time of 1 h) for possible removal of toxic elements and organic micro-pollutants. The experiment that was performed as well as parameters used proved to be optimal for bio-char production as adsorbing medium, where last issue is validated by multiform material characterization techniques. It has been shown that the produced bio-char possess highly-porous morphology features, with large specific surface area (328.570 m2 g−1). The obtained product was characterized by various pore sizes (including super-micropores and mesopores with maximum pore size of 2.24 nm) structures. Preliminary results are indicated that obtained bio-char can shows increased affinity to possible adsorption of the small organic molecule contaminants upgraded by its physico-chemical properties. Cost estimation of AKS bio-char production substantiated its cost effectiveness and its good physical and chemical properties for future design in batch adsorption and regeneration tests. It was established that AKS produced bio-char was 2.5 times cheaper than the commercially available activated carbon. Bio-char exhibits promising removal performances for potential adsorption of heavy metal and organic micro-pollutants from wastewaters systems, as indicated by material textures and spectroscopy measurements.

Metal adsorption in aqueous media using Moringa oleifera Lam. seeds produced in Ecuador as an alternative method for water treatment

This work explores the technical viability in the use ofMoringa oleifera Lam. seeds produced in Ecuador as an adsorbent medium for copper (Cu), nickel (Ni) and chromium (Cr) present in water that could be implemented in future Water Resource Recovery Facilities in Ecuador. The seeds were prepared following a sequence of washing, drying, crushing, sieving, rewashing, and final drying. Two treatments were performed based on particle size. Treatment 1 consisted on a mixture of 70% of particles larger than 2 mm and 30% of particles between 1 and 2 mm; while Treatment 2 consisted only on 1 - 2 mm particles. Batch experiments were performed with metal concentrations ranging from 10 to 150 ppm, a dose of 1.00 g of MO per liter, and mechanical stirring for 1 hour. Treatment 2 showed to be more favorable to metal removal and the Langmuir model better characterized adsorption of the three metals.The best kinetic description of the three metals is that of a pseudo first-order reaction where the adsorption capacities are 50.93 mg Cu/g MO, 30.14 mg Ni/g MO, and 40.98 mg Cr/g MO, with removal percentage of 37 - 53 %, 39 - 76%, and 11 - 33%, respectively.