Preparation of tamarind fruit seed activated carbon by microwave heating for the adsorptive treatment of landfill leachate: A laboratory column evaluation

Removal of recalcitrant organic matter of landfill leachate by adsorption onto biochar from sewage sludge: A quali-quantitative analysis

Sewage sludge is a byproduct of sewage treatment, whereas landfill leachate is a complex wastewater generated by the decomposition of solid waste. These byproducts require adequate management, and one option for the sludge is the thermal treatment by pyrolysis to produce biochar. The resulting biosolid can be used as an adsorbent to treat landfill leachate. The main objective of this research was to remove recalcitrant organic matter from landfill leachate by adsorption onto biochar produced from sewage sludge. Aerobic and anaerobic sludges were pyrolyzed at 450, 650 and 850 °C, under residence times of 60, 90 and 120 min. Temperature had a positive and more significant impact on the characteristics of the biochars produced, and consequently on the adsorption of recalcitrant organic matter. However, the impact of residence time was less intense and, in some cases negative. Biochars produced from both aerobic and anaerobic sludge pyrolyzed at 850 °C for 120 and 60 min, respectively, showed higher specific surface areas (114.4 m2g-1 and 104.2 m2g-1, respectively) compared with those pyrolyzed at 450 °C and 650 °C. The biochar from anaerobic sludge produced at 850 °C and 60 min showed the best performance regarding the adsorption process, with chemical oxygen demand (COD), dissolved organic carbon (DOC), and color removals from the leachate of 32%, 36%, and 41%, respectively. The results of adsorption capacity for this biochar from anaerobic sludge were 26.1 mg g-1 for COD and 7.9 mg g-1 for DOC. The adsorption of recalcitrant organic matter from leachate was evidenced by the decrease in the UV-Vis absorbances and fluorescence intensities. It indicates that recalcitrant and humic substances were removed mainly by biochars pyrolyzed at 850 °C. Thus, the results allow to stress that the pyrolysis of sewage sludge to produce biochar is a promising alternative to sludge treatment, and the biochar may be applied as a pre-treatment of landfill leachate since it successfully removed the recalcitrant organic matter.

Development of Rice Straw-derived Biochar-Bentonite Composite and its Application for in situ Sequestration of Ammonium and Phosphate Ions in the Degraded Mine Soil

Nutrient pollution has a diverse impact on the environment and human health. The presence of nutrients, such as ammonium and phosphate, is ubiquitous in the environment due to their extensive use in agricultural land and leaching through non-point sources. In this context, biochar-based composites could play an essential role in improving the soil's nutrient retention capacity. The present study aims to develop bentonite-biochar composites (BNT@BC 400 and 600) and utilize them as an ameliorating material in the coal mine degraded soil to reduce the leaching of ammonium and phosphate ions. The bentonite-biochar composite (BNT@BC 400 and 600) was synthesized using the pristine rice straw-derived biochar using the solvothermal method. The biochar was produced at two different pyrolytic temperatures, 400 °C and 600 °C, and denoted as BC 400 and 600, respectively. Hence, the bentonite-biochar composite was denoted as BNT@BC 400 and 600. The BNT@BC 400 and 600 were characterized using the elemental, proximate, SEM, XRD, and FTIR analysis. Subsequently, the BNT@BC composites were evaluated for the adsorptive removal of NH₄⁺ and PO₄^3- ions using batch adsorption and column leaching studies. In the soil columns, the BNT@BC 400 and 600 were mixed with the soil at two different application rates, viz. 1 and 2.5% (w/w). The leaching characteristics data were fitted using three different fixed-bed models to predict the maximum adsorption capacity of the amended soil columns and the dominant mechanism of adsorption. Results indicated that the BNT@BC 600 showed the maximum adsorption capacity of 33.77 and 64.23 mg g^-1 for the adsorption of NH₄⁺ and PO₄^3- ions, respectively. The dominant adsorption mechanisms in the aqueous solution were the electrostatic attraction, complexation, ion exchange, and precipitation processes. In the soil columns, the sorption of NH₄⁺ and PO₄^3- ions was governed by diffusive mass transfer and electrostatic interaction. Findings of the study indicated that incorporating the BNT@BC composite in the soil can significantly reduce the leaching of the NH₄⁺ and PO₄^3- ions and increase the overall soil fertility.

Post-treatment of matured landfill leachate: Synthesis and evaluation of chitosan biomaterial based derivatives as adsorbents

Matured landfill leachate is complex in nature, hence, a single conventional treatment unit is insufficient to remove the contaminants of the leachate to achieve the discharge standards. Furthermore, high levels of organic matter, colour compounds, and iron-based materials form a dark black/brown colour in leachate which is not removed by the biological treatment units. Hence, an Anoxic-Oxic Membrane Bioreactor coupled with a tertiary adsorption unit composed of crosslinked-protonated chitosan was tested for effective removal of the colour of the permeate. Several operational parameters such a pH, contact time, and adsorbent dosage on the adsorptive removal of colour were quantified using sorption-desorption experiments. Furthermore, the biosorbent was characterized using FTIR, SEM, XRD, BET-specific surface area, and pH_ZPC. Response Surface analysis confirmed the optimization of operational parameters conducted through traditional batch experiments. Langmuir isotherm model fitted with equilibrium data (R² = 0.979) indicating a monolayer homogeneous adsorption. Kinetic data followed the Pseudo-Second-Order model (R² = 0.9861), showing that the adsorbent material has abundant active sites. The percentage removal values show that the colour removal increases with time of contact and dosage of adsorbent, but removal is mainly influenced by the solution pH levels. The experimental results manifested a colour removal efficiency of 96 ± 3.8% obtained at optimum conditions (pH = 2, adsorbent dosage = 20 g/L, contact time = 48 h) along with an adsorption capacity of 123.8 Pt-Co/g suggesting that the studied adsorbent can be used as an environmentally friendly biosorbent in a tertiary unit for colour removal in a treatment system which is used to treat matured landfill leachate.

Fixed-bed column dynamics of ultrasound and Na-functionalized diatomite to remove phosphate from water

A continuous fixed-bed column study was used to evaluate phosphate adsorption performance of U-D-Na which was functionalized by the cheap NaCl reagent after simple ultrasonic purification of diatomite. In this work, various effect factors, including flow rate, initial phosphate concentration, and the bed height, on breakthrough performance of fixed column were investigated. Experimental results demonstrated that the breakthrough time declined with the increase of inlet phosphate concentration and feed rate, whereas the increase of bed height turned out to significantly extend the breakthrough time. The dynamic adsorption process could be well fitted by the Thomas model, with a correlation coefficient R² > 0.9000 under main operating conditions. A thrice loop of effective regeneration was achieved with 0.1 M hydrochloric acid eluent and deionized water. The maximum removal rate for phosphate was more than 95% in the column adsorption process. The results proved that U-D-Na could be used as a better alternative phosphate adsorbent for wastewater in a continuous column sorption process.

Biochar application in organics and ultra-violet quenching substances removal from sludge dewatering leachate for algae production

Algae production in nutrient rich sludge dewatering leachate after biogas production is a promising option for wastewater treatment plants. However, the ultra-violet (UV) absorbing characteristic of UV-quenching substances (UVQS) existing in these waters can notably reduce the light transmission within the liquid body. The present work demonstrates a comparative adsorptive removal of UVQS, and other organic substances (expressed as COD and TOC) onto the "acid catalyst" functionalised adsorbent (PPhA) and commercial activated carbon (CAC) from leachate originating from leftover sludge dewatering after biogas production. Laboratory scale column studies were performed to investigate the adsorption performance of selected parameters. The PPhA increased the UV transmittance of leachate more than 4 times and outperformed CAC. Bed Depth Service Time and Yan models were used on the experimental data in order to estimate the maximum adsorption capacity and evaluate the characteristics of the fixed-bed. The PPhA equilibrium uptake of COD and TOC amounted to 5.7 mg/g and 0.9 mg/g, respectively. The postulated removal mechanism in environmentally relevant conditions (e.g., pH neutral) suggested a complex interaction between the biochar and organic macromolecules. Diluted phosphoric acid solution (0.01 mol/L) was successfully used for the column regeneration. Beside the UVQS, PPhA showed affinity towards toxic heavy metals (e.g., Pb, Ni, Co) pointing out the rich surface chemistry of the PPhA. Based on the obtained results and successfully implemented scale-up methodology, the low-cost PPhA adsorbent might effectively compete with the CAC as a highly efficient platform in wastewaters leachate processing.

Fixed-Bed Column Technique for the Removal of Phosphate from Water Using Leftover Coal

The excessive discharge of phosphate from anthropogenic activities is a primary cause for the eutrophication of aquatic habitats. Several methodologies have been tested for the removal of phosphate from aqueous solutions, and adsorption in a flow-through reactor is an effective mechanism to reduce the nutrient loading of water. This research aimed to investigate the adsorption potential of leftover coal material to remove phosphate from a solution by using continuous flow fixed-bed column, and analyzes the obtained breakthrough curves. A series of column tests were performed to determine the phosphorus breakthrough characteristics by varying operational design parameters such as adsorbent bed height (5 to 8 cm), influent phosphate concentration (10–25 mg/L), and influent flow rate (1–2 mL/min). The amorphous and crystalline property of leftover coal material was studied using XRD technology. The FT-IR spectrum confirmed the interaction of adsorption sites with phosphate ions. Breakthrough time decreased with increasing flow rate and influent phosphate concentration, but increased with increasing adsorbent bed height. Breakthrough-curve analysis showed that phosphate adsorption onto the leftover coal material was most effective at a flow rate of 1 mL/min, influent phosphate concentration of 25 mg/L, and at a bed height of 8 cm. The maximal total phosphate adsorbed onto the coal material’s surface was 243 mg/kg adsorbent. The Adams–Bohart model depicted the experimental breakthrough curve well, and overall performed better than the Thomas and Yoon–Nelson models did, with correlation values (R²) ranging from 0.92 to 0.98. Lastly, leftover coal could be used in the purification of phosphorus-laden water, and the Adams–Bohart model can be employed to design filter units at a technical scale.

Circular economy based landfill leachate treatment with sulphur-doped microporous biochar

There is now increasing interest in the creation of a more 'circular economy', with a particular aim to eliminate waste - by design, within which products are optimised to be reused, restored or returned. Here, a sulphur functionalised microporous biochar was synthesised from an abundant biomass waste material (cherry kernels), for the selective removal of Pb(II) from landfill leachate as a representative heavy metal. The production process utilises renewable waste material and removes toxic chemicals. Characterisation of the biochar showed that pyrolysis and functionalisation formed an adsorbent with a microporous structure and rich surface chemical functionality. The adsorption process was optimised using a 'response surface methodology - Box-Behnken Design'. Lead removal efficiency approached 99.9% under optimised experimental conditions, i.e., where the solution pH was 6.0, the biochar dose was 4.0 g/L and the contact time was 47 min. The adsorption process was best described using a Freundlich model. The maximum amount of Pb(II) adsorbed was 44.92 mg/g. The main adsorption mechanisms occurred through outer-sphere (electrostatic attraction) and inner-sphere complexation. Desorption studies showed that three successful regeneration cycles (with acidic deionised water) could be used post pyrolysis. The biochar removed 97% of Pb(II) from landfill leachate samples, as compared to 9.4%, and 7.6% for two commercial activated carbon adsorbents. These findings demonstrate the high selectivity of this biochar towards Pb(II) and its applicability even in the presence of high concentrations of many potentially interfering inorganic and organic ions and compounds.

A review of the application of adsorbents for landfill leachate treatment: Focus on magnetic adsorption

Landfill leachate is a significant environmental threat due to the complexity and variety of its pollutants. There are various physical, chemical, and biological treatment methods proposed for leachate treatment. Adsorption with conventional adsorbents such as activated carbon is a process which has been widely employed with relative success. Magnetic adsorbents are a special type of adsorbents with favorable stability, high adsorption capacities, and excellent recycling and reuse capabilities when compared to conventional sorbents. Research regarding the synthesis and use of magnetic adsorbents has been growing at a rapid pace, exhibiting >8-fold increase in publications in the decade of 2010 to 2020. In the current study, both conventional and magnetic adsorbents for landfill leachate treatment have been comprehensively reviewed and discussed. The application of magnetic adsorbents for landfill leachate treatment is relatively new, with numerous avenues of research open to study. Although the production of magnetic adsorbents is significantly more expensive than conventional adsorbents, when taking into consideration all life cycle costs, they are much more competitive than it initially appears. If environmental impacts are of concern, research should shift towards the use of greener chemicals and processes for magnetic adsorbent synthesis, because preliminary analysis of the current synthesis processes shows a much higher environmental impact compared to conventional adsorbents, in particular in terms of global warming potential and energy use.

Influence of the Natural Zeolite Particle Size Toward the Ammonia Adsorption Activity in Ceramic Hollow Fiber Membrane

Natural zeolite is widely used in removing ammonia via adsorption process because of its superior ion-exchange properties. Ceramic particle size affects the adsorptivity of particles toward ammonia. In this study, hollow fiber ceramic membrane (HFCM) was fabricated from natural zeolite via phase inversion. The effect of natural zeolite particle size toward the properties and performance of HFCM was evaluated. The results show that the HFCM with smaller particle sizes exhibited a more compact morphological structure with better mechanical strength. The adsorption performance of HFCM was significantly improved with smaller particle sizes because of longer residence time, as proven by the lower water permeability. A high adsorption performance of 96.67% was achieved for HFCM with the smallest particle size (36 μm). These findings provide a new perspective on the promising properties of the natural zeolite-derived HFCM for ammonia removal.

Adsorptive nanocomposite membranes for heavy metal remediation: Recent progresses and challenges

Heavy metal contamination in aqueous system has attracted global attention due to the toxicity and carcinogenicity effects towards living bodies. Among available removal techniques, adsorptive removal by nanosized materials such as metal oxide, metal organic frameworks, zeolite and carbon-based materials has attracted much attention due to the large active surface area, large number of functional groups, high chemical and thermal stability which led to outstanding adsorption performance. However, the usage of nanosized materials is restricted by the difficulty in separating the spent adsorbent from aqueous solution. The shift towards the use of adsorptive composite membrane for heavy metal ions removal has attracted much attention due to the synergistic properties of adsorption and filtration approaches in a same chamber. Thus, this review critically discusses the development of nanoadsorbents and adsorptive nanocomposite membranes for heavy metal removal over the last decade. The adsorption mechanism of heavy metal ions by the advanced nanoadsorbents is also discussed using kinetic and isotherm models. The challenges and future prospect of adsorptive membrane technology for heavy metal removal is presented at the end of this review.

Continuous column adsorption of naphthenic acids from synthetic and real oil sands process-affected water (OSPW) using carbon-based adsorbents

In this study, activated petroleum coke (APC) and commercial activated carbon (CAC) were used in a continuous adsorption column for removal of model naphthenic acids and organics from real oil sands process-affected water (OSPW). Diphenylacetic acid and 2-naphthoic acid, two model naphthenic acid (NA) compounds, were removed completely by the APC in a continuous column operation. Due to the complex nature of organics in OSPW, total organic carbon (TOC) was measured to determine the effectiveness of OSPW treatment by APC. The removal of TOC from OSPW at its natural pH 8 by APC was only 25%, whereas acidification at pH 4 followed by APC adsorption removed 96% of the initial TOC. When compared to a commercial activated carbon, the APC showed an average of 20% higher organics removal. The experimental breakthrough curves were better fitted by Thomas model in comparison to Adams-Bohart and Yoon-Nelson models. The regeneration of APC was conducted using methanol with 0.01 wt% NaOH (pH = 11.7) and a total of four cycles of adsorption and regeneration were conducted with marginal loss of adsorption sites.

The adsorptive removal of chromium (VI) in aqueous solution by novel natural zeolite based hollow fibre ceramic membrane

Adsorption is one of the most efficient ways to remove heavy metal from wastewater. In this study, the adsorptive removal of hexavalent chromium, Cr (VI) from aqueous solution was investigated using natural zeolite, clinoptilolite, in the form of hollow fibre ceramic membrane (HFCM). The HFCM sample was prepared using phase inversion-based extrusion technique and followed by sintering process at different sintering temperatures in the range of 900-1050 °C. The fabricated HFCM was characterised using scanning electron microscopy (SEM), contact angle, water permeability, and mechanical strength for all HFCMs sintered at different temperatures. The adsorption and filtration test of Cr (VI) were performed using an in-house water permeation set up with a dead-end cross-flow permeation test. An asymmetric structure with sponge- and finger-like structures across the cross-section of HFCM was observed using SEM. Based on the characterisation data, 1050 °C was chosen to be the best sintering temperature as the water permeability and mechanical strength of this HFCM were 29.14 L/m²∙h and 50.92 MPa, respectively. The performance of the HFCM in adsorption/filtration was 44% of Cr (VI) removal at the Cr (VI) concentration of 40 mg/L and pH 4. In addition, the mathematical model was also performed in simulating the experimental data obtained from this study. All in all, the natural zeolite-based HFCM has a potential as a single-step Cr (VI) removal by membrane adsorption for the wastewater treatment.

Conversion of solid waste to activated carbon to improve landfill sustainability

Heterogeneous composite wastes from landfills were evaluated as precursors for the generation of activated carbon (AC). A single-step chemical activation process was applied involving irradiation with microwave energy and impregnation with KOH. The average percentage yield of AC from active landfill precursor was higher than that from closed landfill for all depths sampled. Increase in impregnation ratio and irradiation power decreased the average percentage yield for both landfill precursors (active: 38.1 to 33.1%; closed: 42.1 to 33.3%). The optimum pH range for adsorption of methylene blue was pH 6-7, while adsorption increased with increase in temperature over the range 30 to 50°C. Carbonyl and hydroxyl groups were the major functional groups on the surface of AC. The properties of the AC are potentially suitable for the removal of cationic dyes and pollutants. AC generated from the landfill composite was comparable to that from other biomass being managed through AC generation. This is the first report to demonstrate the possible reuse of landfill composite as AC. The reuse option of landfill composite could provide a means of sustainable management of landfilled municipal waste.

Adsorption of phosphate from aqueous solution using electrochemically modified biochar calcium-alginate beads: Batch and fixed-bed column performance

Batch and continuous fixed-bed column studies were investigated using electrochemically modified biochar calcium-alginate beads (EMB-CABs) as an adsorbent for the removal of phosphate from aqueous solutions. Batch experiments revealed that the phosphate adsorption behavior of EMB-CABs and its structural characteristics were highly dependent on pH condition. Also, kinetics and equilibrium isotherms studies demonstrated that the experimental data correlated well with the pseudo-second-order and Sips isotherm models, respectively. The effects of different operating parameters such as bed height, initial phosphate concentration, and flow rate were investigated in a continuous fixed-bed column, and the experimental data were fitted to three different breakthrough models, the Adams-Bohart, Thomas, and Yoon-Nelson models. The results suggested that the Yoon-Nelson model showed better agreement with the breakthrough curves than other models. Lastly, the design parameters for a large-scale column were calculated via the scale-up approach using the breakthrough parameters obtained from lab-scale column tests.

Continuous biosorption of nickel from aqueous solution using Chrysanthemum indicum derived biochar in a fixed-bed column

The biosorption capability of Chrysanthemum indicum to remove nickel ions from aqueous solution in a fixed-bed column was examined in this study. Native C. indicum flower waste was improved for its biosorptive potential by pyrolysis to obtain its biochar form and, thereby, both raw (CIF-R) and biochar (CIF-BC) forms of the flower were used for Ni(II) removal. Fixed bed column studies were conducted to examine the influence of bed height (1.0-3.0 cm), flow rate (1.0-5.0 mL min^-1) and initial metal ion concentration (25-75 mg L^-1). The breakthrough curves (C_out/C_in vs time) were modelled using different dynamic adsorption models, viz. Adams-Bohart, Thomas and Yoon-Nelson model. Interpretation of the data revealed a favorable correlation with the Thomas model with higher R² values and closer model-predicted and experimental biosorption capacity values. The equilibrium uptake capacity of CIF-R and CIF-BC for Ni(II) were found to be 14.02 and 29.44 mg g^-1, respectively. Further, the column was regenerated using HCl as eluent, to desorb the adsorbed Ni(II) ions. The experimental results implied and affirmed the suitability of the biosorbents for nickel ion biosorption with its nature being favorable, efficient, and environmentally friendly.

Removal of phosphorus from water by using volcanic ash soil (VAS): batch and column experiments

Using low-cost and naturally available materials is considered an optimal adsorbent for removing phosphorus (P) from water due to its simplicity and economic efficiency. This study examined the removal of P from water using volcanic ash soil (VAS) by batch and column experiments. The maximum adsorption capacity of P was 2.94 mg g^-1, estimated from the batch experiment according to a Langmuir isotherm. The column study showed a higher adsorption capacity of 5.57 mg g^-1. The breakthrough curve showed that influent water containing 2 mg L^-1 P was completely purified by VAS within 1,230 pore volumes (PV). The breakthrough and saturation points of the curves were 3,100 PV and 14,875 PV, respectively. After an adsorption column was loaded with 20,508 PV, a regeneration procedure was developed to determine whether an ion exchange of P with chloride occurred or adsorbed P in the columns could be eluted. Approximately 20% of P was recovered from columns by desorption tests, regardless of NaCl solution or deionized water. Specific surface area and mineral concentrations are both important characteristics that improve the adsorption capacity of VAS. The present study suggests that VAS is a promising adsorbent to remove P in water.

Characterization and Properties of Activated Carbon Prepared from Tamarind Seeds by KOH Activation for Fe(III) Adsorption from Aqueous Solution

This research studies the characterization of activated carbon from tamarind seed with KOH activation. The effects of 0.5 : 1–1.5 : 1 KOH : tamarind seed charcoal ratios and 500–700°C activation temperatures were studied. FTIR, SEM-EDS, XRD, and BET were used to characterize tamarind seed and the activated carbon prepared from them. Proximate analysis, percent yield, iodine number, methylene blue number, and preliminary test of Fe(III) adsorption were also studied. Fe(III) adsorption was carried out by 30 mL column with 5–20 ppm Fe(III) initial concentrations. The percent yield of activated carbon prepared from tamarind seed with KOH activation decreased with increasing activation temperature and impregnation ratios, which were in the range from 54.09 to 82.03 wt%. The surface functional groups of activated carbon are O–H, C=O, C–O, –CO₃, C–H, and Si–H. The XRD result showed high crystallinity coming from a potassium compound in the activated carbon. The main elements found in the activated carbon by EDS are C, O, Si, and K. The results of iodine and methylene blue adsorption indicate that the pore size of the activated carbon is mostly in the range of mesopore and macropore. The average BET pore size and BET surface area of activated carbon are 67.9764 Å and 2.7167 m²/g, respectively. Finally, the tamarind seed based activated carbon produced with 500°C activation temperature and 1.0 : 1 KOH : tamarind seed charcoal ratio was used for Fe(III) adsorption test. It was shown that Fe(III) was adsorbed in alkaline conditions and adsorption increased with increasing Fe(III) initial concentration from 5 to 20 ppm with capacity adsorption of 0.0069–0.019 mg/g.

A comparative study on the efficiency of ozonation and coagulation-flocculation as pretreatment to activated carbon adsorption of biologically stabilized landfill leachate

The present work investigates the potential of coagulation-flocculation and ozonation to pretreat biologically stabilized landfill leachate before granular activated carbon (GAC) adsorption. Both iron (III) chloride (FeCl3) and polyaluminium chloride (PACl) are investigated as coagulants. Better organic matter removal is observed when leachate was treated with FeCl3. At a dose of 1mg FeCl3/mg CODo (CODo: initial COD content), the COD and α254 removal was 66% and 88%, respectively. Dosing 1mg PACl/mg CODo resulted in 44% COD and 72% α254 removal. The settle-ability of sludge generated by PACl leveled off at 252mL/g, while a better settle-ability of 154mL/g was obtained for FeCl3 after dosing 1mg coagulant/mg CODo. For ozonation, the percentage of COD and α254 removal increased as the initial COD concentration decreased. Respectively 44% COD and 77% α254 removal was observed at 112mg COD/L compared to 5% COD and 26% α254 removal at 1846mg COD/L. Subsequent activated carbon adsorption of ozonated, coagulated and untreated leachate resulted in 77%, 53% and 8% total COD removal after treatment of 6 bed volumes. Clearly showing the benefit of treating the leachate before GAC adsorption. Mathematical modeling of the experimental GAC adsorption data with Thomas and Yoon-Nelson models show that ozonation increases the adsorption capacity and breakthrough time of GAC by a factor of 2.5 compared to coagulation-flocculation.

Adsorption of phosphate from aqueous solutions and sewage using zirconium loaded okara (ZLO): Fixed-bed column study

This study explores the potential of removing phosphorus from aqueous solutions and sewage by Zr(IV)-loaded okara (ZLO) in the fixed-bed column. Soybean residue (okara) was impregnated with 0.25M Zr(IV) solution to prepare active binding sites for phosphate. The effect of several factors, including flow rate, bed height, initial phosphorus concentration, pH and adsorbent particle size on the performance of ZLO was examined. The maximum dynamic adsorption capacity of ZLO for phosphorus was estimated to be 16.43mg/g. Breakthrough curve modeling indicated that Adams-Bohart model and Thomas model fitted the experimental data better than Yoon-Nelson model. After treatment with ZLO packed bed column, the effluent could meet the discharge standard for phosphorus in Australia. Successful desorption and regeneration were achieved with 0.2 NaOH and 0.1 HCl, respectively. The results prove that ZLO can be used as a promising phosphorus adsorbent in the dynamic adsorption system.

Effect of the ionic liquid group in novel interpenetrating polymer networks on the adsorption properties for oleuropein from aqueous solutions

Combining the advantages of ionic liquids with interpenetrating polymer networks, a novel ionic liquid modified adsorbent (PS/PVIm) was prepared and then used to enrich oleuropein to investigate the interactive forces between the adsorbent and oleuropein.

Preparation of activated carbon from sugarcane bagasse by microwave assisted activation for the remediation of semi-aerobic landfill leachate

This study evaluates the sugarcane bagasse derived activated carbon (SBAC) prepared by microwave heating for the adsorptive removal of ammonical nitrogen and orthophosphate from the semi-aerobic landfill leachate. The physical and chemical properties of SBAC were examined by pore structural analysis, scanning electron microscopy, Fourier transform infrared spectroscopy and elemental analysis. The effects of adsorbent dosage, contact time and solution pH on the adsorption performance were investigated in a batch mode study at 30°C. Equilibrium data were favorably described by the Langmuir isotherm model, with a maximum monolayer adsorption capacity for ammonical nitrogen and orthophosphate of 138.46 and 12.81 mg/g, respectively, while the adsorption kinetic was best fitted to the pseudo-second-order kinetic model. The results illustrated the potential of sugarcane bagasse derived activated carbon for the adsorptive treatment of semi-aerobic landfill leachate.