pH Pzc Research Articles

Chemical Characteristics of Chicken Litter Waste in Closed-House System

Waste from the broiler and layer farming industry with a closed-house system continues to increase without optimizing waste utilization and harms the environment. Potential chicken litter waste from the chicken farming industry in West Sumatra is 5 tons per harvest (40 days) from a chicken livestock capacity of 100,000 chickens. This research aims to assess the potential and utilization and study the biochemistry of chicken manure waste in closed-house systems as biosorbents and fertilizers through amelioration technology. Closed-house chicken coop bedding waste (CHCCW) in the form of sawdust has functional groups such as carboxyl that can absorb cations because it can increase the negative charge in the soil so that it can be utilized by plants. In addition, the CHCCW can also absorb cations (pollutants). Chemical characteristics from the analysis results prove the ability of the CHCCW. Chicken litter waste has chemical characteristics that have the potential as a biosorbent and are valid as fertilizer, which has a proximate composition (moisture 4.26%; volatile matter 74.20%; ash 6.78% and fixed carbon 14.76%); pH (pH H2O 8.37 and pH PZC 7.37); electrical conductivity (EC) >2 dS m-1 and cation exchange capacity (CEC) 182.67 Cmol(+)kg-1. The nutrient composition of chicken manure waste in closed-house systems has macro nutrients (6.88% C; 0.06% N; 5.89% P; 34.89% K; 36.28% Ca; 5.76% S) and micronutrients (2.49% Fe; 1.39% Mn; 1.22% Zn; 1.01% Cu; and 5.15% Cl). Chicken manure waste in closed-house systems also has functional groups such as O-H, N-H, C-H, C-OH, C=C, C=O, C-O-C, Si-O, and O-CH3, which play an active role in the absorption of pollutants and nutrients in the soil.

Removal of Chromium (VI) from Water Using Orange peel as the Biosorbent: Experimental, Modeling, and Kinetic Studies on Adsorption Isotherms and Chemical Structure

The present work aims to assess the effectiveness and efficiency of orange peels as a low-cost biosorbent for removing Cr(VI) from an aqueous solution by the biosorbent process. The orange peels as adsorbent was characterized using different methods, such as FTIR, pHpzc, equilibrium pH, TGA, XRD, SEM, and (BET). The tests were conducted in the batch mode, and the effects of different parameters, such as the pH, dosage of the bioadsorbent, influent Cr(VI), and time, on the biosorption of Cr(VI) were investigated. The adsorption kinetics proved that a contact time of 90 min resulted in the highest (approximately 97.8%) Cr(VI) removal, with an adsorption capacity of 4.96 mg/g. Moreover, the increase in the biosorbent dosage (from 1 to 10 g/L) resulted in the enhancement in the Cr(VI) removal effectiveness. Moreover, the pH of the solution also affected significantly the effectiveness of the removal. The tests were conducted under acidic pH solution conditions, and the prediction of the pH value at a zero charge (pH pzc) was confirmed experimentally. Furthermore, the results from the batch-mode assays were successfully tested by an experimental design (full factorial design). The biosorption of Cr(VI) on orange peels occurred mostly according to the pseudo-second-order kinetic model and the uptake of Cr(VI) was satisfactorily described by the Langmuir model.

MERCURY (II) ADSORPTION ON MINERALS OF MAIKOP SERIES ROCKS AND MUD VOLCANO CLAYS

The acid-base properties of the surface of the Maikop series clays and mud volcano clays, as well as their adsorption properties with respect to mercury (II) ions, were studied. It is shown that pH PZC for the former is 7.1 on average; for the second — 9.0. The pH PZC value for mud volcano clays is consistent with the pH values in the waters of mud volcanoes in the Kerch-Taman region. When the mass ratio of the sorbent and solution is 1:900, adsorption equilibrium occurs after 4 days with active stirring. Experimental data on mercury adsorption from NaCl–NaHCO 3 solution on natural sorbents are best described by the Redlich-Peterson and Toth equations. The process of mercury adsorption on clays of the Maikop series is more intense than on mud volcano clays.

Surface Modification of Tea-Waste-Based Biochar Adsorbent: Synthesis, Characterization, and Batch Adsorption for the Removal of Zidovudine ARV Drug and Phenol

Domestic, agricultural, and industrial waste has been investigated as a substitute for activated carbon adsorbents. For instance, the transformation of tea waste to biochar can be utilized as a substitute for activated carbon adsorbents. In this study, tea waste-based biochar adsorbents (biochar, biochar/reduced graphene oxide (biochar/rGO), biochar/reduced graphene oxide/deep eutectic solvent-cetyltrimethylammonium bromide (biochar/rGO/DES-CTAB), and biochar/reduced graphene oxide/deep eutectic solvent-glycerol (biochar/rGO/DES-glycerol)) were synthesized by simple thermal treatment of tea waste and sucrose followed by modification with reduced graphene oxide and deep eutectic solvents. The obtained materials were characterized using a range of spectroscopy techniques, Fourier Transformed Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), Scanning Electron Microscopy–Energy-Dispersive X-ray Spectroscopy (SEM–EDS), Brunauer, Emmett, and Teller (BET) surface area analysis, and pH at point of zero charge (pH PZC). The obtained results showed that the principal material, i.e., biochar was modified, and FTIR results confirmed the presence of added functional groups. SEM images revealed surface structural changes, and BET showed a decrease in pore size from 10.16 nm to 6.87 nm. The synthesized materials were applied for the removal of ZDV and phenol from the aqueous medium. Batch adsorption studies were conducted to optimize operating parameters such as the adsorbent dose, solution pH, contact time, and initial concentration. Pseudo-first-order (PFO), Pseudo-second-order (PSO), and intraparticle diffusion (IPD) kinetic models were determined to investigate the mechanism of the adsorption process. The coefficient of correlation, R2, was used to determine the best fit of the kinetic models. The adsorption results showed that the DES-glycerol-modified adsorbent was more efficient in removing the pollutants ZDV and phenol than biochar, biochar/rGO, and biochar/rGO/DES-CTAB adsorbents. In addition, the results showed that an acidic medium of pH 2.00 and a contact time of 1 h 30 min and 30 min is sufficient for removing ZDV and phenol, respectively, from an aqueous medium.

Performance and mechanism of phosphorus adsorption removal from wastewater by a Ce-Zr-Al composite adsorbent.

With the increasingly serious eutrophication of global water bodies and the strict discharge standards of tail water in wastewater treatment plants (WWTPs), there is an urgent technology need for efficient deep phosphorus removal from wastewater. A composite cerium-based adsorbent (Ce-Zr-Al) was synthesized by coprecipitation method for the adsorption of low concentration phosphorus in water. The performance of the Ce-Zr-Al composite adsorbent was explored, and the mechanism was also revealed through the analyses including SEM, BET, XPS, and FT-IR. The results showed that the composite adsorbent had excellent phosphorus removal performance. The phosphorus removal rate reached up to 92.6%, and the phosphorus concentration in effluent was less than 0.074 mg/L. The phosphate adsorption capacity of saturation was 73.51 mg/g. The adsorption process of phosphate was in accordance with pseudo-second-order kinetic model and Langmuir model. In addition, the composite adsorbent had a high zero potential point (pH PZC= 8) and a wide range of pH application. After the repeated desorption for 10 times in NaOH solution, the composite adsorbent still maintained good adsorbability (adsorption rate > 94%). The ligand exchange and electrostatic adsorption played the main role for the phosphorus removal from water using the composite adsorbent.

Surface charge characteristics of Inceptisols ameliorated with biochar from young coconut waste

The colloidal surface of the soil contains an electric charge and various surface characteristics. The application of amelioration technology can increase the availability of nutrients and overcome contamination such as pesticides in the soils. This research aimed to study the surface charge characteristics of Inceptisols ameliorated with biochar from young coconut waste (YCW). The experiment was carried out using a completely randomized design with three replications each. The treatment was carried out in a pot with dose equivalent to biochar YCW: A = 0 (0.0g); B = 10 (2.5g); C = 20 (5.0g); D = 30 (7.5g), and (E) 40 t ha-1 (10g 500g-1 soil). The results showed amelioration technology with biochar from young coconut waste, at the application of 40 t ha-1 on Inceptisols, an increased soil surface charge through changes in chemical characteristics by increasing the pH (H2O), EC, CEC, and SOM. The reduction in transmittance in the H-O-H bending band of water and C=C alkene (aromatic) (from 88.95 to 88,83 %) and minerals (from 50.50 to 50.42 %), increased the adsorption capacity of Inceptisols. The relationship of surface charge with chemical properties of Inceptisols ameliorated with biochar from young coconut waste occurred at a correlation value of ΔpH with pH H2O > pH PZC > CEC > Mineral = SOM > EC > pH KCl.

Preparation and Characterization of an Invasive Plant-Derived Biochar-Supported Nano-Sized Lanthanum Composite and Its Application in Phosphate Capture from Aqueous Media.

Invasive plants pose a great threat to natural ecosystems owing to their rapid propagation and spreading ability in nature. Herein, a typical invasive plant, Solidago canadensis, was chosen as a novel feedstock for the preparation of nano-sized lanthanum-loaded S. canadensis-derived biochar (SCBC-La), and its adsorption performance for phosphate removal was evaluated by batch adsorption experiment. The composite was characterized by multiple techniques. Effects of parameters, such as the initial concentration of phosphate, time, pH, coexisting ions, and ionic strength, were studied on the phosphate removal. Adsorption kinetics and isotherms showed that SCBC-La shows a faster adsorption rate at a low concentration and SCBC-La exhibits good La utilization efficiency than some of the reported La-modified adsorbents. Phosphate can be effectively removed over a relatively wide pH of 3-9 because of the high pH pzc of SCBC-La. Furthermore, the SCBC-La shows a strong anti-interference capability in terms of pH value, coexisting ions, and ionic strength, exhibiting a highly selective capacity for phosphate removal. Additionally, Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) measurements reveal that hydroxyl groups on the surface of SCBC-La were replaced by phosphate and manifest the reversible transformation between La(OH)3 and LaPO4. Considering its high adsorption capacity and excellent selectivity, SCBC-La is a promising material for preventing eutrophication. This work gives a new method of pollution control with waste treatment since the invasive plant (S. canadensis) is converted into biochar-based nanocomposite for effective removal of phosphate to mitigate eutrophication.

Removal of methylene blue dye from aqueous solution using an efficient chitosan-pectin bio-adsorbent: kinetics and isotherm studies.

Wastewater contains organic compounds, including dyes, which have potential risks to the environment. Hence, these compound needs to be eliminated from the aqueous solution. In the present study, chitosan-pectin composite (Cs-Pc) was used as an adsorbent to remove methylene blue dye (MB) from synthetic wastewater. To evaluate the parameters affecting adsorption, including the initial MB concentration, solution pH, contact time, and Cs-Pc dose, batch experiments were carried out. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared (FTIR), and pH point of zero charges (pH pzc) were applied for characterizations of Cs-Pc. The optimum conditions were obtained with an initial MB concentration of 50mg L-1: solution pH ~ 11, Cs-Pc dose: 1.5g L-1 and 180min contact time, which caused 97.77% of MB removal. In addition, the removal efficiency of MB was more influenced by pH than by sorbate dose. Also, Cs-Pc had a higher ability to remove MB than chitosan and pectin, probably due to its highly porous structure and rough surfaces that provides active sites and facilitate MB adsorption. The maximum removal efficiency and the adsorption capacity of MB onto Cs-Pc at 500mg L-1 concentration under optimum conditions were 98.67% and 328.02mgg-1, respectively. The adsorption kinetics and isotherms were best described by pseudo-second-order and Freundlich equation, respectively. After four times of recycling, the removal efficiency of MB was above 96%. Electrostatic and pi-pi interactions are the main mechanisms for the removal of MB onto the adsorbent. So the application of Cs-Pc is promising for MB removal from polluted solutions not only due to its strong adsorbing capability but also due to its excellent ability to reuse.

Fluoride adsorption enhancement of Calcined-Kaolin/Hydroxyapatite composite

The use of waste or natural resources is an interesting approach to preparing adsorbent materials. Most adsorption materials are powder-based, making them impractical for a variety of applications. In this work, the natural kaolin clay and hydroxyapatite synthesized from biogenic waste were studied as defluoridation materials. The point of zero charge (pH PZC ), the fluoride adsorption capability and the adsorption isotherm of calcined kaolin and mixed calcined kaolin/hydroxyapatite in both powdered and moulded forms were investigated. The hardness of the moulded (post-formed) samples was tested before and after in immersion in a fluoride solution. The maximum hardness was 15.8 kilo-pounds for the post-formed calcined kaolin sample. Sample hardness values slightly decreased after immersion in a fluoride solution due to the formation of micro-cracks. Most samples presented high pH PZC values, implying that these materials are suitable for the capture of fluoride anions. The adsorption properties varied with the ratio of calcined kaolin to hydroxyapatite. These properties for post-formed samples were different from those in powdered form. Post-formed samples showed higher fluoride adsorption. The maximum fluoride adsorption capacity and efficiency of the post-formed samples (calcined kaolin) at pH 3 were 1.74 F − mg/g and 87%, respectively. The sorption of fluoride of hydroxyapatite and mixed calcined kaolin/hydroxyapatite powders was found to have the form of the Langmuir isotherm, which indicates a monolayer adsorption on the adsorbent surface. Isotherms of calcined kaolin powder, post-formed calcined kaolin and mixed calcined kaolin/hydroxyapatite samples followed the Freundlich isotherm, which indicates multilayer adsorption on a heterogenous adsorbent surface.

Sequential modifications of chitosan biopolymer for enhanced confiscation of Cr(VI)

• Chitosan was successively modified with oxalic acid and biochar. • The adsorption capacity was found to improve from 2.062 mg g −1 for Ch to 383.8 mg g −1 for ChOxBC. • Equilibrium, isotherm, kinetics and thermodynamics studies have been carried out. • The adsorbents could be regenerated and reused in multiple cycles. Chitosan was successively modified by crosslinking with oxalic acid and forming its composite with cotton-straw-derived biochar. Cotton straw is a huge agricultural waste in central India region where cotton is a major agriculture product while chitosan is the second largest available biopolymer. Native chitosan (Ch), oxalate crosslinked chitosan (ChOx) and the Chitosan-Oxalate-Biochar composite (ChOxBC) were synthesized and characterized by FT-IR, SEM, EDX, XRD, BET surface area analysis and pH pzc etc. In batch adsorption studies for Cr(VI) removal, all three materials showed increased adsorption capacities from 2.062 mg g −1 for Ch, 348.3 mg g −1 for ChOx, and 383.8 mg g −1 for ChOxBC after just 60 min of adsorption. The enhancement in the adsorption capacities have been attributed to better stability of crosslinked chitosan, stronger ionic interaction with hydrogen chromate at pH 3.0 and enhanced surface area of the composite. In thermodynamic studies, the spontaneity of processes was assessed across the three materials. The experimental data from kinetics studies revealed that the Cr(VI) adsorption followed pseudo-second order kinetics. A study of columns confirmed that adsorbents can be applied to large volumes of samples. The adsorbents can be regenerated and reused, which makes the study more environmentally friendly.

An optimized sono-heterogeneous Fenton degradation of olive-oil mill wastewater organic matter by new magnetic glutarlaldehyde-crosslinked developed cellulose.

The present study highlights the olive mill wastewater (OMW) treatment characteristics through a sono-heterogeneous Fenton process using new designed [GTA-(PDA-g-DAC) @Fe3O4] and characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), magnetic properties measurements, and point of zero charge (pH pzc) analysis. A preliminary removal study showed significant degradation efficiency (75%) occurred combining the magnetic synthesized catalyst [GTA-(PDA-g-DAC)@Fe3O4] ([catalyst] = 2 g/L) with US /H2O2 and maintaining 500WL-1 ultrasonic power (US). The values obtained by US only were (13%), H2O2/US (18%), US/Fe3O4 (28%), and US /Fe3O4/H2O2(35%). The catalytic findings have shown that [GTA-(PDA-g-DAC)@Fe3O4] exhibited good properties for OMW compound's degradation. The sonocatalytic process coupling and extra oxidant addition resulted in the degradation substantial levels. For instance, the concomitant effect of degradation optimized parameters; H2O2 10 mM, [GTA-(PDA-g-DAC) @Fe3O4] nanocomposites 2.5 g/L, at pH 3, and T 35 °C for 70 min resulted in an almost complete mineralization of aqueous OMW solution followed by a significant decolorization. Oxidation results exhibited efficient degradation rates in total phenolic compounds (TPC), total amino compounds (TAC), and chemical oxygen demand (COD) oxidation rate were 89.88, 92.75, and 95.66 respectively following the optimized sono-heterogeneous catalytic Fenton process. The prepared magnetic catalyst exhibited a good stability during repeated cycles. The gathered findings gave the evidence that sono-heterogeneous catalytic Fenton process is a promising treatment technology for OMW effluents.

Evaluation of the mechanisms of adsorption of microcystins and nodularin-R onto rice husk-based biochar

• Non-electrostatic and electrostatic interactions govern cyanotoxin adsorption onto RH. • Charge-neutral MC-RR displays high adsorption onto RH at different concentrations. • MC-LR and NOD-R at low concentrations experience attractive interactions with RH surface. • MCs with net negative charge and NOD-R show less adsorption onto RH than MC-RR. • Lateral electrostatic repulsions are more pronounced for MC-LA than for MC-LW and MC-LF. Adsorption mechanisms of individual and collective sorption of microcystins (MCs) and nodularin-R (NOD-R) onto heat-treated rice husk (RH) at neutral pH were evaluated. The functional groups on cyanotoxin standards and RH surface as well as their charge indicate that non-electrostatic and electrostatic interactions are present. Surface area and porosity of RH were determined indicating that MCs and NOD-R can be adsorbed in secondary micropores and mesopores of RH. Positively charged guanidinium ion in arginine-containing MCs and NOD-R created attractive electrostatic forces with the negatively charged RH surface (pH PZC ∼3.3). MCs and NOD-R experience electrostatic repulsion with the surface due to the presence of negatively charged carboxylate groups. MC-RR, even at significantly high toxin concentrations, could be removed by RH as it had a strong attraction to the surface due to two arginines and its neutral charge. Other congeners adsorbed on RH experienced lateral intermolecular repulsion and repulsion with molecules in solution. At low sorbate concentrations, MC-LR and NOD-R had electrostatic attraction to the RH surface and MC-LA, MC-LW, and MC-LF experienced electrostatic repulsion with the surface at all concentrations. Non-electrostatic forces govern the adsorption process of MC-LA, MC-LW, and MC-LF, and electrostatic forces are significant for the adsorption of MC-LR, MC-RR and NOD-R at low concentrations (1-100 ng/mL) as well as the adsorption of MC-RR at high concentrations (1000 ng/mL). The presence of 0.3 M NaCl increases the adsorption of MC-LA and MC-LF proving that those molecules undergo repulsive interactions with RH. The adsorption of MCs and NOD-R onto RH is pH dependent, and it appears to be improved at pH values < pH PZC . Overall, the adsorption of MCs and NOD-R onto RH biochar depends on congener concentration, structure, and charge, and can be modified through optimization of structural properties of RH sorbent and sorption conditions, such as ionic strength and pH.

Utilization of Nanochitosan as Adsorbent of Mercury (Hg) in Gold Ore Processing Waste

Mercury pollution in gold ore processing wastewater can cause environmental and health problems. A large amount of mercury pollution causes neurological disease, paralysis, loss of sense of taste, irregular speech, and death. One effective method to reduce mercury amount in the environment is adsorption. Adsorption performance is affected by several factors such as surface area of material, deacetylation degree (DD), and adsorption condition, which is indicated by contact time and mercury concentration. Nanochitosan is used in this research. Effect of deacetylation degree (85%; 87%; 95%), contact time (30;60;90;120 minutes), and variation of mercury concentration (5;10;15;20;25;30 ppm) on adsorption performance was investigated in this research. Nanochitosan in this research is characterized by FTIR, SEM-EDX, BET-BJH, and pH PZC. AAS measures adsorption performance in this research. The result shows that nanochitosan, which has the best adsorption performance, is nanochitosan with a deacetylation degree of 95%, at a contact time of 60 minutes, and mercury concentration is 15 ppm.

Heavy metals migration and antibiotics removal in anaerobic digestion of swine manure with biochar addition

Anaerobic digestion (AD) is a key technology for the utilization of swine manure, but the complex pollution of heavy metals and antibiotics in manure is catching more attentions. In this study, AD of swine manure loading with four types of biochar was performed in a 1 L-frosted jar with the total fresh weight of 840 g, in which the effects of biochar on the AD stability and methane yields were focused, and the removal of antibiotics and migration of heavy metals were investigated as well. The results showed that the removal efficiencies of sulfadimidine and tylosin were remarkable, which were up to around 70% and 100%, respectively. The maximum methane yield of 146.98 mL/ (g VS) was noted in the digester added with the biochar derived from paper mill sludge (BPMS) which contained 87.35% of ash, having a high pH PZC of 8.95 and more mesopores and macropores. In this reactor, 12.40% of Cu was moved to the solid phase, and 70.26% of Zn and 82.80% of As were migrated to the solid digestate. Compared to the control, the content of the acid soluble Cu in the digester loaded with BPMS was decreased to 7.99%, and no acid soluble Zn was found along with a drop of 29.20% for the reducible Zn, and the residual As content was increased by 16.60%. It revealed that BPMS had a great potentiality to remove As and Zn in wastewater and synchronously mitigate the bioavailability of Cu/Zn/As in the digestate. Herein, applying BPMS in the AD of swine manure could reduce the complex pollution of heavy metals and antibiotics, and obtain a higher methane yield simultaneously. • Paper mill sludge biochar had high pH PZC and was rich of ash, macropores and mesopores. • Around 70% of SDM and 100% of TYL were degraded in AD. • Highest methane yield was noted in the digester loaded with paper mill sludge biochar. • 70.26% Zn and 82.80% As migrated to solid digestate via paper mill sludge biochar adsorption. • Paper mill sludge biochar could reduce the eco-toxicity of Cu, Zn, As in the digestate.

Preparation and Characterization of Modified Clay - Application to the Adsorption of an Industrial Dye

The objective of this work is the valorization of certain local clays by their use in the treatment of waste water. For this, we have improved the surface properties of a natural Algerian Clay from the west of Algeria from the deposit of ghousel (Maghnia). The treatments carried out are the following: physical and chemical. The prepared material (calcined and activated) was characterized by infrared spectroscopy, measurement of the cation exchange capacity, specific surface and by measuring the pH (pzc). Then, the clay used is applied to the adsorption of an industrial dye (yellow bemacid) in aqueous solution. The quantitative analysis of the dye was followed by UV-Visible spectrophotometer, this analysis allows to determine the best conditions that favor the adsorption such as contact time, adsorbate concentration, adsorbent mass, solution pH and temperature.

Fe(III)–Chitosan Microbeads for Adsorptive Removal of Cr(VI) and Phosphate Ions

Fe(III)–chitosan microbeads (Fe–CTB) were prepared using a chemical coprecipitation method. SEM–EDX, FTIR, XRD, TGA, BET, and pH pzc were performed for the characterization of the adsorbent. Various parameters were optimized as pH, adsorption time, adsorbent dose, initial Cr(VI), and PO43− ion concentration and the effect of assorted ions for adsorption studies. Fe–CTB microbeads revealed more than 80% detoxification for a 100 mg L−1 initial concentration at pH 3 with 60 min stirring of Cr(VI) and PO43− ion having adsorption capacities of 34.15 and 32.27 mg g−1, respectively. The adsorption process for Cr(VI) and PO43− ion followed the monolayer adsorption as they favored the Langmuir isotherm model. Kinetic and thermodynamic studies’ emphasis on the adsorption process was spontaneous and exothermic with pseudo-second-order kinetics for both adsorbates. The microbeads were found to be reusable in multiple cycles.

African almond (Terminalia catappa L) leaves biochar prepared through pyrolysis using H3PO4 as chemical activator for sequestration of methylene blue dye

African almond leaves (ALs) were used for the preparation of sustainable and eco-friendly adsorbent through chemical activation, followed by pyrolysis at 700 oC for adsorption of methylene blue (MB) dye from aqueous solution. Phosphoric acid activated African almond leaves biochar (PALB) was characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET), pH point zero charge (pH pzc) and X-ray diffraction (XRD) techniques. The influence of various adsorption parameters was investigated for determination of optimum conditions for sequestration of MB dye. Equilibrium adsorption isotherm and kinetic models were equally assessed. Mesoporous PALB with surface area 816 m2/g and radius 1 nm has excellent removal efficiency due to removal of >98% MB dye from aqueous solution at room temperature 303 K, pH 8, initial dye concentration of 50 mg/L, adsorption dose of 0.2 g/L and contact time 30 min. Adsorption isotherm and kinetic were best fitted with Freundlich and pseudo-first order (PFO) kinetic models. Positive value of enthalpy (ΔHo) showed that the adsorption process was endothermic, while the negative value of free energy (ΔGo) suggested that the process was spontaneous and the positive value of entropy (ΔSo) indicated increase in randomness at adsorbate/adsorbent interface. PALB displayed a good monolayer adsorption capacity (Q max) of 263.95 mg/g when compared to those of other adsorbents reported in the literature for removal of MB dye from aqueous solution. This study established potential ability of PALB as eco-friendly adsorbent for adsorption of MB dye from aqueous solution.

Manganese containing oxides catalytic ozonation in aqueous solution: Catalytic mechanism on acid sites

• Protonation of hydroxyl groups on acid sites is a necessary condition for electron transfer reaction. • Solution pH is a significant variable in the linear sweep voltammetry test. • Electron transfer ability of acid sites in MgMn x O y is positively related to Mg content. Transition metal oxides and transition metal containing oxides have been extensively researched in heterogeneous catalytic ozonation for water treatment. However, catalytic mechanism for typical transition metal oxide – manganese oxide (MnO 2 ) in catalytic ozonation is still ambiguous. Herein, MnO 2 and magnesium manganese oxides (MgMn x O y ) with different molar ratios of Mg to Mn were analysed by linear sweep voltammetry (LSV) test to explore a necessary condition for electron transfer reaction between ozone and acid sites of the catalysts in aqueous solution. And their catalytic performances were investigated in ozonation of acetic acid aqueous solution at a neutral pH. It is found that electron transfer reaction occurs in manganese containing oxides catalytic ozonation when ozone is adsorbed on protonated surface hydroxyl groups of acid sites (Mn 2+ /Mn 3+ in the lattice). But ozone that is absorbed on protonated hydroxyl groups of Mg 2+ in the lattice cannot react with acid sites to generate reactive oxygen species in MgMn x O y catalytic ozonation. Protonation of hydroxyl groups on acid sites can be achieved by enhancement in point of zero charge (pH PZC ) of the catalysts or decrease in initial pH of aqueous solution. Protonation ability of hydroxyl groups on acid sites and electron transfer ability of acid sites are positively related to Mg content in MgMn x O y . MgMn x O y with 2:1 molar ratio of Mg to Mn (Mg 2 MnO y ) exhibits the highest catalytic activity and good stability in ozonation of acetic acid. On basis of catalytic mechanism on acid sites of manganese containing oxides, modification and application of manganese containing oxides would be further developed in heterogeneous catalytic ozonation for water treatment.

Magnetic clay\zeolitic imidazole framework nanocomposite (ZIF-8@Fe3O4@BNT) for reactive orange 16 removal from liquid media

This study was performed to evaluate the removal from wastewater of reactive orange 16 (RO16) with magnetically separable zeolitic imidazole frameworks coated magnetic bentonite nanocomposites (ZIF-8@Fe 3 O 4 @BNT). Various microscopic and spectroscopic analyses were carried out to reveal the surface characteristics of the nanocomposite. Point of zero charging (pH PZC ) of ZIF-8@Fe 3 O 4 @BNT was obtained as 8.84. The dependence of RO16 removal yield on initial pH, initial dye concentration (C o ), adsorbent dose and contact time was investigated using the central composite design (CCD) included in response surface methodology (RSM). With the obtained quadratic model equation from CCD, the optimum values were determined as initial pH of 3.9, initial concentration (C o ) of 19.76 mg/L, adsorbent amount of 12 mg (480 mg/L), and contact time of 150 min. The maximum removal efficiency of 98.5% and the maximum adsorption capacity of 40.5 mg/g were reached at these optimal points. Adsorption kinetic analysis and equilibrium experiments showed that the best fit was reached with the pseudo-second-order and Langmuir isotherm models, respectively. Also, thermodynamic parameter changes for RO16 removal were calculated, and the results showed that the adsorption was favorable, spontaneous, and exothermic. With all of these, the fact that ZIF-8@Fe 3 O 4 @BNT has high recovery efficiency for RO16 removal, fast kinetics and can be separated easily and quickly with the help of a magnet before and after treatment provide significant advantages for wastewater treatment.

Preparation and characterization of different zeolites from andesite rock: Product evaluation for efficient dye removal

Synthetic Zeolite mixture (ZM) containing Analcime (ANA), Wairakite (W), and Phillipsite (PHI) was produced by alkali activation of andesite rock (AR) under hydrothermal conditions of 1.0&3.0 M NaOH, 100 °C, and duration of 1–5 days. The main affecting parameters for ZM phase crystallization were alkalinity, solution chemistry, parent rock dissolution rate, and reaction duration. The low alkali concentration was advantageous for ANA formation, and the hetero cationic slurry environment containing sodium and calcium resulted in co-crystallization of ANA-W zeolite series in the same pot. High alkalinity unfavored ANA persistence but was more suitable for PHI domination. The FT-IR results confirmed the conversion of the precursor rock into zeolites, whereas the measured surface area indicated the enlargement of the BET of the rock from 2.62 into 91.4 m2/g after zeolitization. The rock and synthetic product were identified using the X-Ray Diffraction (XRD), X-Ray Fluorescence (XRF), specific surface area (BET), and the structural groups for AR and ZM were tested using the FT-IR technique. The phase internal structures and microanalysis are monitored by the Scanning Electron Microscopy- Energy Dispersive X-ray Spectroscopy (SEM-EDS). Zeta potential of samples was measured using a particle size analyzer. For economic aspect, ZM formed at low alkali content of 1.0 M NaOH, 100 °C, and 5 days was evaluated for methylene blue dye removal as a model of textile wastewater. The effect of pH, contact time, initial concentration and zeolite dose on adsorption has been investigated. Zeta potential measurements revealed that, the pH pzc was 1.9. The maximum sorption performance was found to be 95.7% at 10 pH within 240 min and 1.5 g/L zeolite dosage. Furthermore, the application of the zeolitic product on a synthetic simulated effluent composed of different dyes and salts implied a removal efficiency of 92.63%. The isothermal investigation of Langmuir and Freundlich models at different temperatures revealed that, MB adsorption using the formed zeolite was adapted to the Freundlich isotherm. The dye removal was matched with the pseudo-first kinetic model. Also, the high efficiencies in the removal of dye molecules through 5 consecutive cycles were demonstrated in the regeneration experiments.