Effluent Reclamation Research Articles

Performance improvement of triple-doped nanocomposite membrane towards hairwork dyeing effluent reclamation approaching zero liquid discharge

Performance improvement of triple-doped nanocomposite membrane towards hairwork dyeing effluent reclamation approaching zero liquid discharge

Bimetallic nanoparticles preparation from metallic organic frameworks, characterization and its applications in reclamation of textile effluents

Abstract Herein bimetallic nanoparticles of Co–Mn were prepared using metal-organic framework (CoMn2 (C2O4)3·6H2O) as a starting material. Initially, the bimetallic organic frame work was prepared which was then subjected to pyrolysis to get the desired product. Techniques like scanning electron microscopy (SEM), Energy-Dispersive X-ray spectroscopy (EDX), X-ray Diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FTIR) were used to characterize the bimetallic nanoparticles. These analyses revealed that the Co–Mn nanoparticles consisted of finely distributed Mn and Co, along with O in the composites. XRD data confirmed the presence of nano-scale ranges and alloy formation between Co–Mn. The nanoparticles were employed as adsorbent for methyl violet adsorption, with optimized conditions found to be pH 9, temperature 333 K, adsorbents dosage of 0.01 g, and 30 min of contact time. The pseudo-second-order kinetic model best described the adsorption kinetics data whereas Langmuir isotherm exhibited the closest fit, with a maximum adsorption capacity of 625 mg/g at 333 K. Thermodynamic parameters indicated endothermic processes, with ΔH° = 15.155 kJ mol−1, and the process to be spontaneous with negative ΔG° values −0.303, −0.831, and −1.886 (kJ mol−1) at 293 K, 313 K, and 333 K, respectively. The ΔS° value of 52.76 J mol−1K−1 suggested increased disorder at the solid-solution interface during adsorption. The adsorbent could be effectively used in reclamation of dyes loaded water as alternative of activated carbon.

Cause analysis for fouling mitigation, techno-economic and toxicity reduction assessments of hairwork dyeing effluent reclamation via membrane-based hybrid systems

Based on the continuous innovation of membrane materials and partnered reagents, it is necessary to timely evaluate the efficiency improvement of a package of relevant wastewater treatment processes and clarify the associated pivotal causes. For this purpose, the root-cause analysis for fouling mitigation derived from influent characteristics, the techno-economic and toxicity reduction assessments of hairwork dyeing effluent (HDE) reclamation via three membrane-based hybrid systems approaching zero discharge were systematically carried out. The experimental results showed that with the aid of a novel efficient and biodegradable flocculant, the lower fluorescence peak intensity, the more negative zeta potential and the quantitatively dominant hydrophobic components in feedwater all helped to mitigate the same-charged hydrophilic TFN-CQDs membrane fouling due to modification of itself. Accordingly, the optimal processing technology required the minimum amount and replacement frequency for membrane elements and less than 1/5 and 1/10 of the energy consumption and chemicals of their counterparts, respectively. Besides, it also decreased the waste (brine) stream volume fraction to 7%, and greatly increased B/C value of supernatant to 0.667, thus strengthening “intermediate control” of pollutants. Although the organic contaminant components in HDE basically transcend the aromatic/hydrophilic differences in producing biotoxicity, all schemes still had good performance in its elimination. Undoubtedly, the outcome of these evaluations will provide valuable technical guidance for scaling-up the prototype results and promoting the cleaner production of local wig enterprises.

Design of a bioaugmented soil aquifer treatment for efficient removal of p‐nitrophenol

AbstractSecondary effluent reclamation and reuse is an effective solution to the water shortage problem, and the safety of reused water is a matter of increasing concern. p‐Nitrophenol (PNP), a common secondary effluent pollutant, can be efficiently removed using the eco‐friendly bioaugmented soil aquifer treatment (SAT) system at the laboratory scale. In this study, a sewage treatment plant in Changchun was selected as a case study to apply the bioaugmented SAT system for field scenarios efficiently. The bioaugmented SAT system was simulated using HYDRUS‐1D code. Biodegradation and adsorption coefficient were conducted from the batch experiment. Based on the degradation experiments, the concentration of bacteria injected into SAT system was designed to be 6 × 1018 colony‐forming units (CFU) m−3. To enhance the efficiency of the bioaugmented SAT system, the key parameters were optimized based on the sensitivity analysis and the response surface methodology, which showed that the optimal operating conditions were an initial concentration of 86.11 mg L−1, a medium of 4.27‐m thickness, and a wet/dry ratio of 0.28. Specifically, alternated wetting–drying conditions and increasing the medium thickness reduced PNP within a specific range. This work demonstrates the performance and applicability of the bioaugmented SAT system for removal PNP in secondary sewage effluent.

Integrated photo-Fenton and membrane-based techniques for textile effluent reclamation

The complexity of textile effluents demands innovative treatment capable to promote the water reuse and by-products recovery. Taking this into account, an advanced oxidation process (AOP, photo-Fenton) was combined with microfiltration (MF) and nanofiltration (NF) in two distinctive processes: (1) MF-NF-AOP(c) and (2) MF-AOP-NF; aiming for the NF concentrate treatment in the first, and as a NF pre-treatment in the second. The MF was able to reject > 99.1% of the indigo blue, which can be reused in the dyeing process. The AOP applied to MF permeate had a higher COD degradation (78%, compared to 69% when applied to NF concentrate treatment), but the residual iron content resulted in a pronounced concentration polarization effect in the NF. Due to that fact, the NF in the second treatment systems had a higher fouling rate and lower permeate flux (average value: 19 L/m2h) compared to the first (average value: 38 L/m2h). In both cases, the residual iron concentration in the NF concentrate and in the AOP effluent prevented their reuse. However, the NF permeate from both treatment processes can be considered for yarn washing-off and equipment washing down. Furthermore, for the combination MF-NF-AOP(c), the NF permeate met the requirements to be recycled back to the process. The better performance of the first system (MF-NF-AOP(c)) in textile wastewater treatment was reassured by its lower operating expenditure (0.421 US$/m3) compared to MF-AOP-NF (0.736 US$/m3). Overall, the treatment combining MF-NF-AOP(c) was considered the most cost-effective alternative for textile wastewater treatment reuse.

Visible light-activated NGQD/nsC3N4/Bi2WO6 microsphere composite for effluent organic matter treatment

The diminishing availability of clean water resources has led to a high demand for advanced, effective wastewater effluent reclamation techniques. In this study, a new microsphere composite of nitrogen-doped graphene oxide quantum dots, nanosheet C3N4, and Bi2WO6 was synthesized and characterized to examine its feasibility as a visible light-activated photocatalyst for wastewater reclamation. At the optimal dose of 1 g•L−1 under 6 h of illumination, the composite exhibited a high removal capability for effluent organic matter (82.8 ± 1.6%). Its high performance and stability over multiple cycles are attributed to two factors: (1) its harvesting ability over a wide range of the visible light region and (2) its ability to separate photoinduced charge carriers effectively, which is driven by the efficient interfacial contact of the hosts and inclusion of the photosensitized nitrogen-doped graphene oxide quantum dots in the structural network. The complex effluent organic matter removal process of the compound was further examined by fluorescence spectroscopy and size exclusion chromatography. Fluorescence spectroscopy showed that humic-like components with a higher degree of aromatic condensation and greater molecular size were preferentially removed by photocatalysis. Protein-like components were removed more rapidly than the humic-like components due to the synergetic effects of OH and 1O2 on the rapid decomposition of low-molecular-weight compounds. Size exclusion chromatography revealed that the photocatalytic system preferentially removed larger molecules via adsorption and oxidation; however, smaller size fractions might be produced via the breakdown of biopolymer and humic substance fractions in effluent organic matter.

Technical and economic potential of high-temperature NF and DCMD for gold mining effluent reclamation

Direct contact membrane distillation (DCMD) and high-temperature nanofiltration (NF) were compared in terms of technical and economic aspects for the treatment of pressure oxidation process (POX) real effluent. Tests were carried out in bench scale and differences in fouling behavior and its impacts on NF and MD performance were evaluated. High pollutants rejection rates were observed for both systems (>92.4 %). However, DCMD had better permeate quality and lower energy requirement, which contributed significantly to its lower operational costs due to use of the effluent residual heat. CAPEX and OPEX were estimated at US$/m3 2.251 for NF and US$/m3 0.233 for DCMD. DCMD application represents a saving of US$ 45,138.3 annually supplying 250,768.3 m3 of high-quality reuse water. At the end, this research allowed for a better comprehension of these membrane technologies, preventing the production of waste and increasing efficiencies in the uses of energy, water, and resources.

Techno-economic analysis of single disinfection units and integrated disinfection systems for sewage effluent reclamation

This study aimed to evaluate several potential candidates of single disinfection/disinfectant units and integrated disinfection systems in treating sewage effluent to obtain non-potable water, within a techno-economic analysis framework. Eight candidates of commercially available disinfection units and integrated disinfection systems were selected to be examined under the techno-economic analysis by comparison amongst the sewerage effluent. There were 4 types of treatment processes represented amongst the single disinfection units (Single): ultraviolet (UV), chlorination, microfiltration (MF), and ultrafiltration (UF). Within these processes, MF and UF both were represented twice by HVLP00010 and PVDF021 M (MF membranes); and by PVDF1001 M and PES20kDa (UF membranes). Whereas, for integrated disinfection systems (Integrated), UV disinfection and chlorination act as the primary disinfection unit, with MF/UF, Enviromulti-media (EMM) adsorption, or granular activated carbon (GAC) adsorption integrated as the pre-treatment unit. Two design capacities for water recovery - 100 m³/day (to represent a pilot-scale reproduction) and 5000 m3/day (to represent an industrial-scale reproduction) were defined to analyze and compare the cost effectiveness between single disinfection units and integrated disinfection systems chosen in this study. Amongst the studied setups, single chlorination unit and EMM-UV integrated disinfection system were the two most economical configurations to regenerate treated water for restricted applications. Whereas, the single PVDF1001 M UF membrane filtration unit was ultimately suggested as the most economic and viable technology for unrestricted water reuse purpose at both design capacities, considering the estimated cost at Malaysia currency, RM 0.50/m³ and RM 0.10/m³ for 100 m³/day and 5000 m³/day design capacity, respectively.

Membrane selection for the Gold mining pressure-oxidation process (POX) effluent reclamation using integrated UF-NF-RO processes

Abstract The UF-NF-RO integrated route has emerged as a reclamation alternative for mine effluent from the pressure-oxidation processing (POX), producing concentrate metals stream, recover acid and water for reuse. Despite the route potentiality, it is still necessary to seek for more chemically stable membranes to increase the process sustainability, particularly because the membranes are exposed to aggressive conditions (acid effluent) and a high rejection is desired. Thus, in this study, commercial NF membranes (NF90, NF270, MPF34, DK, and Duracid) and RO membranes (BW30, LP, TFC-HR, XN45, and SG) were evaluated in terms of key performance parameters, such as permeate flux, metals rejection, acid recovery, fouling potential, maximum permeate recovery (RR), and chemical stability. The DK and SG, as NF and RO membranes respectively, showed the highest potential for POX effluent treatment application. In the NF process, an average concentration factor of 2 was observed for metals concentration retentate at 50 % permeate RR. For metals, particularly for cobalt, nickel, and copper, this concentration was favorable to subsequent recovery processes. The RO generated a retentate with sulfuric acid 2.5 times more concentrated and low impurity content (0.00058 g L−1) and 40 % RR was chosen for the process considering the permeate quality, which can be used as reuse water. Besides that, the amount of lime demanded for neutralization in the proposed route is approximately 41 % lower compared to regular process. The results showed that for the designing system the membrane selection is a critical part, mainly due the effluent characteristics.

Advanced reclamation of hairwork dyeing effluent using tree-shaped cellulose flocculants and subsequent optimization of dual-membrane performance and fouling behavior

The purpose of this study is to prepare eco-friendly cationic tree-shaped cellulose-based flocculants (CLFs) through ultrasonic modification as the primary pretreatment, and then realize advanced hairwork dyeing effluent (HDE) reclamation by coupling with dual membrane process. The results showed that the optimal CLF-10 could be obtained by extra ultrasonic processing with a certain conservative time to tune its microstructure appearing in a well-veined and fluffy tree-shaped morphology with relatively uniform particle size distribution. The excellent flocculation performance of CLF-10 in terms of turbidity, total organic carbon (TOC) and dissolved organic carbon (DOC) removal rates reached up to 99.1%, 72.1% and 70.5% at the dosage of 100 mg L−1, and the largest and most dense flocs (Amean of 269 900 μm2 and Df of 1.80) were formed accordingly. This is precisely because the above mentioned microstructure properties enable it to have smaller steric hindrance effect and more active sites, thus effectively clustering the largest amount of target contaminants. Consequently, the bench-scale test employed CLF-10 agent achieved a higher HDE recovery rate of 80.3% under the circumstance of lower operating pressure and significantly mitigated membrane fouling, and the final cleaner reuse water only contained 76.2 mg⋅L−1 of total dissolved solids (TDS), 23.9 mg CaCO3·L−1 of total hardness and 1.85 mg·L−1 of DOC.

Rapid and de-centralized model for municipal effluent reclamation using microalgae

Abstract Microalgal bioremediation is currently being venerated for its potential in municipal liquid waste (MLW) treatment. Algae-based water treatment with retention time competitive to the conventional water treatment processes is a challenge. The present study investigated the role of algal biomass concentration to improve treatment efficiency to reduce the time required for water treatment. Eighty percent removal of pollutants (in terms of chemical oxygen demand (COD), ammonia, phosphate and fecal coliforms) was obtained in 12 hours at a biomass concentration of 1 gL−1. Further, continuous treatment of MLW using membrane-assisted photobioreactor was established. The treatment led to >95% removal of ammonia, >75% removal of COD and 100% removal of fecal coliforms within 12 hours. Physiological assessment of the algal culture showed that the cells did not manifest symptoms of stress throughout the reactor cycle, a consequence of continuous availability of the nutrients, maintaining the culture in continuous growth state.

Pretreatment for the reclamation of rendering plant secondary effluent with NF/RO: UF flat sheet versus UF hollow fiber membranes

Rendering plants produce large amounts of wastewater that could be reused at the plant with adequate treatment. Membrane fouling is the main problem during the treatment of this type of wastewater by nanofiltration (NF) and reverse osmosis (RO). In order to reduce membrane fouling, the rendering plant secondary effluent was pretreated with two types of ultrafiltration (UF) membranes: MW as a flat sheet and ZW-1 as a hollow fiber membrane. The fouling on NF/RO flat sheet membranes (NF90, NF270, and XLE) was evaluated with the resistance-in-series model, while the fouling mechanisms were assessed with crossflow models. The UF, NF, and RO permeates were characterized to determine its suitability for reuse in the rendering plant. ZW-1 reduced the flux decline by 67.0% for NF270, 1.6% for NF90, and 38.0% for XLE; while MW reduced the flux decline by 72.4% for NF270, 50.1% for NF90, and 68.1% for XLE. The pretreatment with MW resulted in higher fouling reduction and a permeate that is appropriate for industrial reuse (washing purposes in the rendering plant). In terms of fouling resistance, NF270 and XLE membranes showed less fouling resistance during the treatment compared to NF90. The highest quality of permeate was obtained with XLE membrane, satisfying the water requirements for steam generation. The predominant fouling mechanisms for NF/RO were partial and complete pore blocking. The best combination for rendering plant secondary effluent reclamation was UF with MW membrane and RO with XLE membrane.

Reclamation of real oil refinery effluent as makeup water in cooling towers using ultrafiltration, ion exchange and multioxidant disinfectant

The refining industry is one of the most water consuming industries. Hence, reclamation of effluents can be useful as a sustainable, permanent, and available source of water for refineries. Therefore, this research was conducted aimed to evaluate the efficiency of integrated processes of ultrafiltration, mixed bed ion exchange and multioxidant disinfectant (MOX) as an advanced treatment of oil refinery effluent in order to provide makeup water in cooling towers. Integrated pilot including polysulfone membrane, two types of strong acid cationic resin and strong base anionic resin were used for real effluent reclamation. Finally, the treated effluent was disinfected using on site generated solution of MOX disinfectant. In the optimum Trans Membrane Pressure of 1 bar, removal efficiency of COD (57%), TDS (80%), Turbidity (94%), SiO2 (67%), Oil (88%), HPC (99%) was achieved. Integrated processes was efficient in reclamation of oily effluents in order to provide makeup water in cooling towers.

The feasibility of UF-RO integrated membrane system combined with coagulation/flocculation for hairwork dyeing effluent reclamation.

This paper aims to validate the feasibility of hairwork dyeing effluent (HDE) reclamation using an ultrafiltration (UF)-reverse osmosis (RO) integrated membrane system combined with coagulation-flocculation and sedimentation acquiring the highest possible product water recovery rate along with both satisfactory separation performance and well controlled membrane fouling. Under the circumstance of only physical cleaning involved, the laboratory-scale test yielded a higher and satisfactory reuse ratio of 76% for HDE, and the corresponding RO product as reclaimed water contained only 223 mg·L-1 of TDS, 3.87 mg·mL-1 of DOC and 10.3 mg·mL-1 of total hardness, which was obviously better than the quality of existing feedwater in hairwork dyeing process. After each processing unit, the distributions of fulvic (region III) and humic (region V) organics decreased continuously, while an overall rising trend in distribution of protein-like organics (regions I and II) was observed. Contact angle for the fouled UF and RO membranes significantly increased by 19.5° and decreased by 19.7°, respectively, which suggested that different polarity of organic or inorganic adsorption rather than membrane roughness was the main factors affecting wetting properties of the fouled employed membranes. Both ATR-FTIR and XPS spectra indicated that organic fouling on UF membrane surface under harsh condition (RUF = 90%) was mild and tolerable, whereas a surprising amount of hydrophilic micromolecular organics riched in carboxyl and hydroxyl functional groups were absorbed on RO membrane surface after permeation.

Membrane capacitive deionization for low-salinity desalination in the reclamation of domestic wastewater effluents

This study aims to investigate the feasibility of desalinating secondary effluent from a domestic wastewater treatment plant (DWTP) using membrane capacitive deionization (MCDI) for reclamation purposes. The desalination performance of a MCDI stack with 10 pairs of 20 cm × 20 cm activated carbon electrodes was evaluated in single-pass mode. As evidenced, the MCDI stack outperformed the capacitive deionization stack. The water quality characteristics of the inflows and product water were also analyzed. Our results revealed that MCDI can effectively remove undesired ions such as calcium and nitrate from the DWTP effluent for water reclamation. In particular, the solution conductivity of the product water was observed to be as low as 1.27 μS/cm. Removal of the ions was easily performed by the electrostatic field-assisted deionization process. The use of MCDI for low-salinity wastewater reclamation demonstrated favorable energy performance with a low volumetric energy input and a molar energy input of 0.12 kWh/m3 and 0.03 kWh/mole, respectively; and the energy efficiency of this system is expected to be further improved by energy recovery or incorporation of energy-producing processes. These results are indicative of the benefits of using MCDI as part of the treatment processes for the reclamation of wastewater with low salinity.

Assessing potential of nanofiltration for sulfuric acid plant effluent reclamation: Operational and economic aspects

Sulfuric acid plant wastewater is characterized by low pH and high concentrations of sulfate and metals, including arsenic, which is a toxic element that requires specific treatment. This study aimed to investigate the sulfuric acid plant wastewater treatment using NF by evaluating the main NF operational conditions (feed pH, applied pressure and permeate recovery rate) and the preliminary capital and operational cost. The results showed the NF potential to treat the wastewater. The retention of higher valence counterions to balance the retained co-ion loads was the most important mechanism observed. By combining the best operational conditions (feed pH = 2, applied pressure = 10 bar and permeate recovery rate = 45%), retention of 94% of sulfate, 98% of calcium, 85% of As III and 75% of As V was achieved and permeate could be reused in industry. The NF system had its CapEx estimated at US$ 551.250,00 and the OpEx ranged from 0.364 to 0.446 US dollars per cubic meter of wastewater for estimated membrane lifespan of 5–1 year. Savings of more than US$ 99,000 year−1 could be achieved with the industrial reuse of the permeate, which could reduce the water consumption by approximately 551,880 m3 year−1.

Agricultural Irrigation with Effluent – What should we be Worried About?

Policy regarding effluent water and reclamation aims to prevent environmental pollution while proposing an alternative water resource. Water makes up 99–99.9% of raw wastewater. Thus extracting organic and inorganic matter from water is a must. Worldwide, but especially in developed countries, great effort has been made to reuse wastewater, and it is becoming a reliable alternative source. Israel is the world leader in water reuse, allocating 85% of effluent water for agricultural irrigation. As such, it constitutes a “living laboratory” in which to study the implications of the intensive use of treated wastewater for agricultural irrigation, leading to research and legislation regarding effluent quality and regulation. Effluent produced in Israel is subject to severe regulations and standards and is considered suitable for every use except drinking water. It is mostly allocated for agricultural irrigation with no restrictions. The irrigated lands are close to natural water sources, and therefore water leaching from the fields infiltrate those sources, becoming part of the water cycle. A group of persistent and toxic nano- and micro-organic contaminants, including pharmaceutical residues, flows to water-treatment plants from hospitals, industry, agriculture and especially the domestic sector. These contaminants' chemical structure, characterized by aromatic rings and double bonds, makes them especially persistent; they are resistant to conventional biological treatment, used as a secondary treatment. As a result, the effluent that leaves the treatment plants, which is considered to be of high quality, actually contains pharmaceutical residues. After secondary and tertiary treatment, these persistent chemical residues can still be found in surface water, groundwater and agricultural products. Pharmaceutical residues in effluent allocated for agricultural irrigation are undesirable. Expansion of the monitoring system for those contaminants, improvement of the tertiary treatment, and implementation of advanced technologies for decomposition and removal of pharmaceutical contaminants are thus needed.

On-line construction of electrodialyzer with mono-cation permselectivity and its application in reclamation of high salinity wastewater

Electrodialysis (ED) technology has been paid special attention in reclamation of high salinity effluents. Therein, the attempts on how to separate out scale-forming cations are never ending. Different from a conventional scheme, an on-line endowment of mono-cation permselectivity to a conventional ED stack was put forward in this work by electro-deposition of branched polyethyleneimine with an optimized molecular weight. Subsequently, series of work performances, including limiting current, mono-cation permselectivity, permselectivity between specific anions, water transport behavior, current efficiency and energy consumption, were investigated in reclamation of a typical saline wastewater. The pilot-scale ED experiments showed that the modified ED stack displayed a significant mono-cation permselectivity, for examples, PNa+Ca2+ and PNa+Mg2+ were reduced from 0.36 and 0.81 to 0.11 and 0.12, respectively. Interestingly, a certain permeability priority for SO42- was also achieved at the same time. Moreover, the five-month service life tests indicated the ED stack can maintain a stable separation performance. On the other hand, some problems induced by the modification were also revealed, such as the facilitated water transport and the increase of energy consumption. Anyway, it is reasonable to believe that the scheme should have broad and promising application perspectives due to its effectiveness, economy and simplicity.

Comparison of Nanofiltration and Direct Contact Membrane Distillation as an alternative for gold mining effluent reclamation

Effluent reuse is becoming an environmentally-economically viable option for industries that have been struggling with environmental/legislative pressure and high costs of water supply and effluents discharge. Mining effluents are promising for reuse, but for this, (hazardous) metals and ions such as sulfate must be removed efficiently. This study aimed to compare the technical-economic performance of Nanofiltration (NF) and Direct Contact Membrane Distillation (DCMD) on gold mining effluent treatment. The results showed that both technologies are promising for mining effluent reclamation as high pollutants removal rates were observed (rejection >73% and >96% for NF and DCMD, respectively). DCMD showed lower flux than NF and was limited to operate up to permeate recovery rate (RR) of 40% due to severe fouling (CaSO4 precipitation), but produced a higher quality permeate with no reuse restriction, low energy requirement and lower associated costs due to use of the effluent residual heat. Capex and Opex (for membrane lifespan of 1–5 years) were estimated at US$ 575,490.30 and 2.00–2.10 US$/m3 for NF and US$ 305,483.85 and 0.13 to 0.27 US$/m3 for DCMD systems. The permeate reuse would reduce water consumption in 490,560 m3 year−1, which represents almost 50% of the industrial water demand.

Influence of ultrasonic waves on preparation of active carbon from coffee waste for the reclamation of effluents containing Cr(VI) ions

Present work explored the feasibility of using coffee waste based carbons for the removal of Cr(VI) ions from aqueous solution under different experimental conditions. Characteristics of active carbons resulted in maximum carbon yield and adsorption uptake. A narrow particle size distribution providing significant operating benefits through sonication has studied for fine-size dispersion of active carbons. Langmuir adsorption capacity was measured as 156.7mgg−1. Adsorption process was best obeyed with Freundlich and pseudo-second order models. Thermodynamic properties for the present system was found to be exothermic and spontaneous. The potentiality of carbon particles showed as an effective sorbent for Cr(VI) ions.