Ammonium Ion Exchange Research Articles

Purification of Alcohol Dehydrogenase Enzyme from Chicken Liver and Immobilization Onto Florisil

The enzyme alcohol dehydrogenase (ADH) is a dimeric enzyme in which each of its subunits has a Zn2+ metal-containing catalytic domain and a cofactor binding domain. This enzyme converts alcohol into an aldehyde. In this article, the activity of the enzyme was investigated by applying the immobilization process directly to the alcohol dehydrogenase enzyme purified and activated florisil from the chicken liver. For this purpose, homogenization of chicken liver was achieved and its supernatants were separated by applying the ultracentrifugation process to the resulting homogenate. Then, % ammonium precipitation, dialysis, and ion exchange chromatography processes were performed, respectively. As a result of these processes, the hepatic alcohol dehydrogenase was purified 150.3 times compared to the coarse homogenate, and the specific activity of the enzyme was determined to be 0.631 U/mg protein. The activity of the enzyme directly immobilized was found to be 0.034 U/mg protein.

Three-Step Purification and Characterization of Organic Solvent-Tolerant and Alkali-Thermo-Tolerant Xylanase from Bacillus paramycoides T4 [MN370035

In the present study, an extracellular alkali-thermo-tolerant xylanase from Bacillus paramycoides was produced in the presence of an organic solvent. The enzyme was purified by ammonium sulphate precipitation, gel filtration, and ion exchange chromatography, with an overall recovery of 25.9%. The purified enzyme hada 70 kDa molecular weight (MW) confirmed by SDS-PAGE gel analysis. The maximum enzyme activity was reported at 55 °C and pH 7.0. Xylanase activity and stability were improved in the presence of 30% (v/v) n-dodecane, iso-octane, n-decane, and cyclohexane (7 days). The enzyme activity was improved by Co2+, EDTA, and Triton-X-100 while vigorously repressed by Hg2+ and Cu2+. The purified enzyme showed 1.473 mg/mL Km and 654.017 µg/mL/min Vmax values. The distinctive assets of the isolate verified the potential application in the field of biomass conversion into fuel and other industrial processes. Organic solvent-tolerant xylanases can be used for concurrent saccharification and bioethanol production, the amplification of intoxicating beverages, and the fermenting industry.

Biochemical Insights into the functionality of a novel thermostable β-amylase from Diocleareflexa

β-amylases are exohydrolases that catalyze the hydrolysis of α-1,4 glycosidic linkages in polysaccharides to produce maltose. Despite various applications of plant β-amylases, thermolability of the enzyme has been a major challenge that continuously prompts the search for thermostable β-amylases. In this study, β-amylase was isolated from an underutilized legume, marble vine (Dioclea reflexa) and purified to apparent homogeneity, using a combination of 30–80% ammonium sulfate precipitation, ion exchange and gel filtration chromatography. It was characterized for its physicochemical properties. The enzyme gives a purification fold and specific activity of 12.25 and 9.43 U/mg respectively, it has a molecular weight of 56.23 kDa using 12% SDS-PAGE. The kinetic parameters Km and Kcat of the enzyme for p-nitrophenyl-maltopentaoside were 0.22 mM and 1340 s−1. The enzyme had an optimum pH of 6.0 while the optimum temperature was 60 °C. while the thermal inactivation rate constants (kd) value of the enzyme was 0.002, thermal inactivation (ΔG) was 99.1 kJ/mol, ΔH and ΔS were 27.7 kJ/mol and −305.80 J/mol.K respectively at 333 k respectively. The thermal inactivation of the enzyme followed first-order kinetics at 60 °C. The enzyme was relatively stable for 140 min retaining 70% of its initial activity at 60 °C and 67% of the activity at pH 6.0. The activity of purified D. reflexa β-amylase was enhanced in the presence of Zn2+, Ca2+ and Mg2+ and strongly inhibited by Cu2+ and Hg2+. Remarkably, the enzyme exhibited thermostable properties which increase its prospects as a veritable potential enzyme for various industrial and biotechnological applications.

Cuprous species distribution over CuCl/NaY dependent on acidity and their CO Adsorption/desorption performance study

• NaY zeolite was synthesized and its acidity was adjusted through NH 4 Cl exchange methods. • Three NaY-Cu samples with identical Cu loading presented different Cu + /Cu 2+ distribution dependent on their acidity. • NaY-Cu presented superior CO storage compared with NaY supports for strong Cu + CO bond. • Cu + cations located in site III and V dominated the CO adsorption compared to site I, II and IV. The impact of acidity on copper species distribution during solid exchange process of CuCl/NaY mixture and their CO storage performance were evaluated in this work. Firstly, the acidity of home-made Na form faujasite (NaY-10) was adjusted through ammonium ion exchange method to obtain its H from supports with different acidity. The bulk characterization results demonstrated the NaY-Cu structure collapsed in varying degrees during solid exchange process, but NaY-Cu samples exhibited superior CO storage ability compared with the corresponding NaY supports. DRIFTs of CO adsorption and simulation through first-principles calculations were further examined to reveal the CO adsorption sites and CO adsorption behaviors over hydroxyls, Na + cations and Cu + /Cu 2+ cations. Finally, the relation between faujasite acidity and CuCl distribution was systematically concluded and the CO adsorption/desorption difference between NaY supports and NaY-Cu samples was directly summarized to illustrate their industrial application potential.

PRODUCTION, PURIFICATION AND IMMOBILIZATION OF TRIACYLGLYCEROL LIPASE FROM INDIGENOUS LIPOLYTIC MICROORGANISMS

Triacylglycerol lipase was produced from locally isolated Aspergillus niger and Bacillus sp. using submerged fermentation. The process was optimized and lipase was purified and immobilized. Maximum lipase activity was obtained; with microorganisms cultured in medium containing 1% olive oil and 1% soybean meal as substrate, 72hrs incubation at 30°C, pH 6.0 and medium supplementation with 2% glucose, 1% peptone for A. niger, 72hrs incubation at 37°C, pH 8.0 and medium supplementation with 1% glucose, 1.5% peptone for Bacillus sp. The enzymes were purified using ammonium sulphate precipitation and ion exchange chromatography to achieve 13-14 fold purity with a yield ranging from 53-57%. Lewatite and Amberlite were found to be very good supports for the immoblization of bacterial and fungal lipases, respectively. The immobilization of lipase was proved to be an excellent tool for industrial applications of the enzyme.

Acidity and Stability of Brønsted Acid Sites in Green Clinoptilolite Catalysts and Catalytic Performance in the Etherification of Glycerol

Natural zeolite clinoptilolite CLIN with a framework ratio of Si/Al ≥ 4 containing mainly potassium and calcium ions in its internal channel system was used as a starting material. The acidic HCLIN catalysts were prepared under soft conditions avoiding the use of environmental less-benign mineral acids. The starting material was ion exchanged using a 0.2 M aqueous ammonium nitrate solution at a temperature 80 °C for 2 h. The obtained NH4CLIN was converted into the acid HCLIN catalyst by calcination at 300–600 °C. The obtained samples were characterized by XRD, FTIR, SEM/TEM, AAS, and EDX element mapping. The state of aluminium and silicon was studied by 27Al- and 29SiMAS NMR spectroscopy. The textural properties of the catalysts were investigated by nitrogen adsorption and desorption measurements. The Brønsted acidity of the HCLIN catalysts was studied by temperature-programmed decomposition of the exchanged ammonium ions releasing ammonia as well as 1H MAS NMR, {1H–27Al} Trapdor, and {1H–27Al} Redor experiments. The strongly agglomerated samples were crystalline and thermally stable up to >500 °C. Although a part of the clinoptilolite framework is maintained up to 600 °C, a loss of crystallinity is already observed starting from 450 °C. The specific surface areas of the starting CLIN and ammonium exchanged NH4CLIN are low with ca. 26 m2/g. The pores are nearly blocked by the exchangeable cations located in the zeolite pores. The thermal decomposition of the ammonium ions by calcination at 400 °C causes an opening of the pore entrances and a markable increase in the specific micropore area and micropore volume to ca. 163 m2/g and 0.07 cm3/g, respectively. It decreases with further rising calcination temperature indicating some structural loss. The catalysts show a broad distribution of Brønsted acid sites (BS) ranging from weak to strong sites as indicated the thermal decomposition of exchanged ammonium ions (TPDA). The ammonium ion decomposition leaving BS, i.e., H+ located at Al–O–Si framework bridges, starts at ≥250 °C. A part of the Brønsted sites is lost after calcination specifically at 500 °C. It is related to the formation of penta-coordinated aluminium at the expense of tetrahedral framework aluminium. The Brønsted sites are partially recreated after repeated ammonium ion exchange. The catalytic performance of the acidic HCLIN catalysts was tested in the etherification of glycerol as a green renewable resource with different C1-C4 alcohols. The catalysts are highly active in the etherification of glycerol, especially with alcohols containing the branched, tertiary alkyl groups. Highest activity is observed with the soft activated catalyst HCLIN300 (300 °C, temperature holding time: 1 min). A total of 78% conversion of glycerol to mono and di ether were achieved with tert-butanol at 140 °C after 4 h of reaction. The mono- and di-ether selectivity were 75% and 25%, respectively. The catalyst can be reused.

Ammonia pools in zeolites for direct fabrication of catalytic centers

Reduction process is a key step to fabricate metal-zeolite catalysts in catalytic synthesis. However, because of the strong interaction force, metal oxides in zeolites are very difficult to be reduced. Existing reduction technologies are always energy-intensive, and inevitably cause the agglomeration of metallic particles in metal-zeolite catalysts or destroy zeolite structure in severe cases. Herein, we disclose that zeolites after ion exchange of ammonium have an interesting and unexpected self-reducing feature. It can accurately control the reduction of metal-zeolite catalysts, via in situ ammonia production from ‘ammonia pools’, meanwhile, restrains the growth of the size of metals. Such new and reliable ammonia pool effect is not influenced by topological structures of zeolites, and works well on reducible metals. The ammonia pool effect is ultimately attributed to an atmosphere-confined self-regulation mechanism. This methodology will significantly promote the fabrication for metal-zeolite catalysts, and further facilitate design and development of low-cost and high-activity catalysts.

Phosphate Fixation and P Mineralogy on Natural and Ca-Modified Zeolites During Simultaneous Nutrient Removal

The recovery and recycling of nutrients (N&P) from wastewater are one of the major topics to save primary energy and resources, to raise the efficiency of wastewater treatment plants, and to foster a future circular economy. In the present study, the removal of ammonium (NH4+) and phosphate (PO43−) using natural and Ca-treated zeolite is investigated in detail. Special emphasis is put on the simultaneous removal of both species from model solutions followed by elaborate mineralogical analyses (XRD, EPMA, FEG-SEM) for zeolite characterization and in order to determine the type, structure, and crystal sizes of CaP-phases precipitating on the zeolites surface. The effectivity of the phosphate segregation and chemical composition and the crystalline structure of the CaP-phase precipitating on the surface of the zeolite depend on the physico chemical conditions in particular on pH, molar ratio of Ca and P (due to zeolite modification), and the presence of NH4+. Results of simultaneous removal experiments of N&P revealed that Ca pretreatment enhances P segregation and increases the obtainable P-loadings of Ca–zeolites. Maximum P-loadings of 25 mg g−1 Ca–zeolite in binary solutions containing both ammonium and phosphate were obtained. Simultaneous phosphate removal by surface precipitation of CaP-phases does not significantly influence ammonium ion exchange and the type of CaP-precipitates formed on the zeolite surface is assumed to be mainly brushite and apatite.

Enhanced nutrient removal from stormwater runoff by a compact on-site treatment system

Efficient and space-saving technologies for on-site treatment of stormwater runoff are required to control water pollution in the urban surface. The intermittent nature of stormwater runoff and extremely limited land available greatly hindered the application of current wastewater treatment technologies, and thus synchronous removal of multiple contaminants (especially for nutrient) efficiently was failed by current processes. In this study, a new compact CFFA treatment system, consisting of coagulation, flocculation, filtration and ammonium ion exchange units, was constructed for on-site treatment of stormwater runoff based on batch test optimization and pilot-scale test verification. The coagulation process effectively aggregated particles and precipitated phosphorus by dosing Al2(SO4)3, while flocculation using anionic polyacrylamide further enlarged particle size for efficient micromesh filtration. The dynamic micromesh filtration obtained turbidity and phosphorus removal efficiencies comparable to 30 min gravity settling with greatly smaller footprint. Ion exchange by zeolite showed higher exchange capacity owing to lower initial ammonium nitrogen concentration in the stormwater runoff. The pilot-scale experiments with treatment capacity of 1 L/s showed that the CFFA treatment system achieved synchronous removal of particles (97.2%), nitrogen (79.7%), phosphorus (95.0%) and organic matters (83.3%) efficiently within short hydraulic retention time of 0.35 h, yielding effluent with chemical oxygen demand, suspended solids, total phosphorus and total nitrogen of 38.7, 7.80, 0.22 and 2.80 mg/L, respectively. The CFFA treatment system had the highest pollutant removal loads compared to reported runoff treatment processes in literatures, and was well suited to on-site treatment of stormwater runoff with high space utilization efficiency.

A thermostable extracellular α-amylase from Aspergillus flavus S2-OY: Purification, characterisation and application in raw starch hydrolysis

An amylolytic fungus was isolated locally from the soil of a cassava waste dumpsite. It was identified as Aspergillus flavus S2-OY using 18S rRNA gene sequencing with gene bank accession number MZ267053.1. α-Amylase was produced from the fungus through solid substrate fermentation of potato (Solanum tuberosum L.) peel, a cheap and renewable substrate. The fungal enzyme was purified 13.41-fold by ammonium sulphate and ion exchange chromatography (CM Sephadex C-50), with final yield of 13.41%. Apparent molecular weight of 55.0 kDa was obtained for the purified enzyme, using SDS-PAGE. Optima pH (6.0) and temperature (70 °C) of α-amylase activity were determined for the enzyme which also showed thermal stability up to 70 °C, with 80% residual activity after 120 min. The enzyme exhibited a wide range of pH stability (4.0 to 7.0). Kinetic parameters Km and Vmax values obtained with soluble starch were 158 µg/ml/min and 1.51 mg/ml, respectively. The enzyme was slightly inhibited by Mg2+. Mn2+, Zn2+, Na+, K+, Hg2+ and the chelating agent, EDTA, at 5.0 mM concentration. However, it was activated by Sn2+. The enzyme hydrolysed gelatinised and ungelatinized raw yam, corn, rice and millet starches strongly but cassava starch moderately. These results revealed that cost-effective α-amylase production from Aspergillus flavus S2-OY could be realised with the use of potato peel as a cheap substrate, under solid substrate fermentation condition. Also, the fungal α-amylase is a raw starch-hydrolysing, acid to neutral and thermostable enzyme with potential for broad biotechnological applications.

English

In this experiment, effect of lead (Pb) + chromium (Cr) mixture on superoxide dismutase (SOD) in the liver of Labeo rohita at a concentration of 11.1 mgL-1 was observed. The ammonium sulphate precipitation and ion exchange chromatography techniques were successfully used to purify SOD. After purification, SOD activity of control and Pb+Cr treated fish was noted as 581.00 and 645.45 UmL-1, respectively while the specific activity was 1383.33 and 1613.62 Umg-1, respectively. The fold purification value of SOD was 2.75 and 2.45 for control and stressed fish, respectively. The recovery was calculated as 77.06 and 57.43% for control and stressed fish, respectively. The results of kinetic characterization showed that SOD form control and exposed fish had maximum activity at pH 6.5 and 7.0. Temperature also had a significant effect on activity of SOD. The SOD activity was measured maximum at 30°C for both control and Pb+Cr exposed fish. The Km value of liver SOD for control and Pb+Cr treated L. rohita was calculated as 1.48 and 0.62 mM, respectively. The value of Vmax for SOD from liver of control and Pb+Cr exposed fish was 1000 and 570 U mL-1, respectively. The enthalpy of denaturation (∆H*) for liver SOD from control and Pb+Cr exposed L. rohita was computed as 3.492 and 2.802 KJ mol-1 at 40°C, respectively and these values were dropped off with increasing the temperature until it remains 3.251 and 2.561 KJ mol-1 at 70°C, respectively. The free energy of thermal denaturation (ΔGº) of liver SOD was slightly increased with increasing temperature until 75°C which shows its resistance against heat. The values of ΔGº was observed as 58.03 and 57.95 KJ mol-1 for control and exposed fish at 40°C, respectively while the same was increased upto 62.37 and 62.00 KJ mol-1 at 70°C, respectively. It was concluded from negative value of ΔS* (entropy of inactivation) that the SOD is stable thermodynamically.

Isolation, Purify and Characterization of Lectin from the Seeds of Artocarpus Species

Aim: To isolate, partially purify and characterize lectin from the seeds of Artocarpus species - using ammonium sulphate, gel-filtration and ion exchange chromatography. 
 Methodology: ABO blood groups were screened for the assay of hemagglutinating property with seed lectins of both. heterophyllus and A. hirsutus. The seed lectins were extracted using suitable buffer system pH 7.0 and partially purified by gel filtration and ion exchange chromatographic techniques.
 Results and Discussion: Lectins were extracted from the defatted seed powders of A. heterophyllus and A. hirsutus. The extracts were used for optimization of assay buffer for hemagglutination activity and 50 mM Tris-HCl buffer, pH 8.8 containing 1 mM CaCl2 and 1 mM MnCl2 showed greater hemagglutinating property. Screening for optimum concentration of RBCs from different blood group (A, B, AB and O groups) indicated O group at 10 % concentration as ideal for the assay of hemagglutinating property with seed lectins of both A. heterophyllus and A. hirsutus.
 Conclusion: In this study, lectin from the seeds of Artocarpus heterophyllus and Artocarpus hirsutus were isolated and partially purified. The isolated lectins were characterized for their heamagglutination activity. Among the human blood types (A+, B+, AB+ and O+) used, all the blood groups showed agglutination while greater agglutination was observed with O+ blood group.

Production, Purification and Characterization of Xylanase Enzyme from <i>Bacillus sp</i> in Solid State Fermentation

Xylanases are extensively applied in paper and pulp industries as well as during preparation of baked products to improve their quality. Additionally, it is also used in coffee, oil and starch industries in order to increase their nutritional values. Soil samples were collected near saw mills in various localities of Bangalore urban to isolate organisms for the production of xylanase using solid state fermentation. Six organisms were isolated using selective media based on their morphological characters. Among them one organism showed maximum production of xylanase enzyme identified as Bacillus sp based on their biochemical test and 16s RNA sequencing. Solid substrate fermentation was carried out using various agro wastes such as sugar cane bagasse, saw dust, paddy husk, wheat straw and orange peel powder. Sugarcane bagasse showed maximum production of enzyme compared to other substrates with different physical parameters such as pH 8, temperature at 35 °C after 72 hrs of incubation. Trace element such as Mg++ enhances the production of enzyme more than 22 % compared with other metal ions like Ca++, Mn++ and Fe++. After production, enzyme purified by using three step methods such ammonium sulphate precipitation, dialysis, ion exchange and gel filtration. Fold purification was increased up to 12 fold, yield 36 % and molecular weight of enzyme was 62 KDa determined using SDS PAGE.

Biochemical properties of extracellular protease from Staphylococcus epidermidis isolated from Harbin dry sausages and its hydrolysis of meat protein

This study aimed to explore biochemical properties of extracellular protease from Staphylococcus (S.) epidermidis BP9 isolated from Harbin dry sausages and its future potential application in Harbin dry sausages. The protease was purified by 80% ammonium sulfate, ion exchange, and gel filtration chromatography to obtain a 24 kDa extracellular protease. The protease reached maximal activity at pH 6.0 and 50 °C and was stable at pH 4.0–9.0 and 20–40 °C. Its protease activity was inhibited in the presence of Fe2+. The enzymatic characterization of the protease revealed a Vmax 62.5 U/mL·min, Km 11.76 mg/mL, and the half-life = 62.44 min, ΔH*d = 72.11 kJ/mol, ΔG*d = 91.40 kJ/mol, and ΔS*d = −59.60 J/mol·K at 50 °C. In addition, the protease hydrolysed myofibrillar protein into small particles and produced soluble peptides. This study provides a basis for understanding the biochemical characteristics of the S. epidermidis BP9 protease and its future application for Harbin dry sausages.

Purification, Characterization and Bioefficacy of Legume Lectins against Mustard Aphid

Background: Lectins are carbohydrate binding proteins which perform diverse roles in plants. One important role is in plant defense. These proteins hold great potential as entomotoxic proteins as a part of integrated pest management. Methods: Lectins were purified and characterized from seeds of two legumes, Glycine max-Soybean and Lens culinaris-Lentil, employing ammonium sulfate fractionation and ion exchange chromatography. Bioefficacy of the purified lectins was evaluated against mustard aphid.Result: Lectins isolated from seeds of soybean (Glycine max agglutinin GMA-I, II) and lentil (Lens culinaris agglutinin LCA-I) were purified upto 9.30 (GMA-I), 4.60 (GMA-II) and 8.70 (LCA-I) fold, respectively. Lectin characterization revealed that soybean agglutinin and lentil agglutinin were specific towards D-Galactose and D-mannose, respectively. Insect bioassay was carried out with five different concentrations (10, 20, 30, 40, 50 µg/ml) of purified lectins of soybean and lentil against mustard aphid. The lethal concentration LC50 value for GMA-I was obtained as 32.1 µg/ml with a 95% confidential interval of 18.2 to 40.5 µg/ml and that of LCA-I was 19.1 µg/ml with a 95% confidential interval of 9.3 to 26.8 µg/ml. Lentil lectin (LCA-I) with lower LC50 value, was found to be the potential candidate for integrated pest management.

Biochemical properties of extracellular protease from Staphylococcus carnosus RT6 isolated from Harbin dry sausages, and its hydrolysis of meat proteins

The characteristics of the extracellular protease, produced by Staphylococcus carnosus RT6 isolated from Harbin dry sausages, and its hydrolysis of meat proteins were investigated. The protease was purified by ammonium sulfate, ion exchange, and gel filtration chromatography to obtain a 20.0kDa extracellular protease. The protease reached maximal activity at pH 9.0 and 50 °C and was stable at pH 7.0 to 11.0 and 20 to 40 °C. Its protease activity was easily inhibited in the presence of Zn2+ , Fe2+ , and Fe3+ . The enzymatic characterization of the protease revealed a Vmax 49.50 U/ml·min, Km 8.19mg/ml, and the half-life=28.06min, ΔH* d =114.11kJ/mol, ΔG* d =89.24kJ/mol, and ΔS* d =77.00 J/mol·K at 50 °C. In addition, the protease hydrolyzed meat protein into small particles and produced soluble peptides. This study provides a basis for understanding the biochemical characteristics of the S. carnosus RT6 protease and its future application for fermented meat products.

Purification of Wickerhamomyces anomalus Keratinase and Its Prospective Application in Poultry Feed Industries

Animal wastes emanating from cow horns, hooves and feathers are keratinous in nature which can only be degraded by keratinolytic microorganisms. Consequently, the pollution resulting from the accumulation of these wastes in response to growing livestock demand is posing a significant threat to human health and the environment. This study was carried out using cow hooves as the substrate for the production of keratinase from fungal identified as Wickerhamomyces anomalus 9 (18S rDNA gene sequencing) was isolated from soil rich hooves using basal salt agar medium and potato dextrose agar. The keratinase of the isolate was assessed using skim milk agar and the enzyme was produced by solid-state fermentation. The crude enzyme was purified using ammonium sulphate precipitation, ion exchange and gel-filtration chromatography. The specific activity of the enzyme was 0.29 U/mg with a yield of 45% and a 7.25 purification fold. The optimal pH and temperature of the enzyme were 8.0 and 60 oC respectively. The enzyme was observed to be thermo-stable at 50oC between for 30 minutes. The kinetics revealed that the Vmax was 0.384U/min with Km 86.95mg/ml. The native molecular weight of the enzyme was found to be 34KDa. There were significant differences at 95% confidence with poultry feed treated with Wickerhamomyces anomalus keratinase in moisture, ash content, crude fibre, crude fat, nitrogen content, crude protein and carbohydrate compare to the untreated feed. These results suggest an environment-friendly approach for biodegradation of cow hooves wastes for the production of keratinases, animal waste management as well as a promising tool for chicken feed additives. Keywords: Biodegradation, Chromatography, Cow hooves, Keratinase, Pollution

La‐H‐zeolites: efficient catalysts for acetic acid ketonic decarboxylation and esterification

AbstractBACKGROUNDCyclohexyl acetate and acetone are used as environmentally friendly solvents, while isobutene acts as an intermediate in the production of methacrolein, ethers, plastics and pharmaceuticals. Two La‐zeolite catalysts have been studied for converting acetic acid to cyclohexyl acetate, acetone and isobutene.RESULTSLa‐based zeolites were synthesized from Na‐nFAU zeolites by ammonium ion exchange, followed by lanthanum ion exchange. The influence of Brønsted and Lewis acid sites on the activity in acetic acid esterification with cyclohexanol and in ketonic decarboxylation of acetic acid was studied. Fourier transform infrared (FTIR) spectroscopy of pyridine adsorption has been used for acid site evaluation. The presence of Brønsted acid sites on the surface leads to an increase in cyclohexyl acetate and acetone selectivity, while the presence of Lewis acidity favors further transformation of acetone in isobutene.CONCLUSIONThe sample with the highest Brønsted acidity and the highest content in both La and Al, namely La‐H‐13X, showed the highest activity for both acetic acid esterification and ketonic decarboxylation – an indication that Brønsted acidity is very important for the studied reactions. © 2021 Society of Chemical Industry (SCI).

Compact wastewater treatment process based on abiotic nitrogen management achieved high-rate and facile pollutants removal

Chemically enhanced primary treatment (CEPT), ammonium ion exchange and regeneration (AIR) and membrane bioreactor (MBR) were coupled as CAIRM to treat domestic wastewater compactly and efficiently. CAIRM achieved efficient removal of chemical oxygen demand, ammonia nitrogen, total nitrogen (TN) and total phosphorus with total hydraulic retention time of 4.6 h, and obtained 2.3 ± 0.9 mg/L TN in the effluent. CEPT removed phosphate and impurities and prevented AIR from pollution. AIR maintained excellent nitrogen removal with a slight decrease in the exchange capacity of ion exchangers. MBR polished the effluent from AIR, and the larger particle size and better dewaterability of sludge mitigated the membrane fouling. Many heterotrophic genera, such as Rhodobacter and Defluviimonas, were enriched in the oligotrophic MBR. This study demonstrates the viability and stability of CAIRM in efficient wastewater treatment, which will address critical challenges in insufficient nitrogen removal and high land occupancy of current processes.

Sustainable ammonium recovery from wastewater: Improved synthesis and performance of zeolite N made from kaolin

Abstract Although zeolite N ( K 12 A l 10 S i 10 O 40 C l 2 . 8 H 2 O ) is used commercially for the removal and recovery of ammoniacal nitrogen from wastewater, it has received limited attention in academic literature. The hypothesis was that if an improved understanding of zeolite N synthesis and resultant physical parameters and performance can be acquired, then the application of this material may be accelerated. This study successfully addressed existing research challenges including: maximizing the cation exchange capacity (CEC); selection of preferred synthesis conditions; control of the size, shape, and dispersion of zeolite N crystals; and improvement of ion exchange properties. Zeolite N was hydrothermally synthesised from kaolin clay added to solutions of potassium hydroxide and potassium chloride in a “one pot” process. CEC values increased to 563 meq/100 g (c.f. 528 meq/100 g in previous literature). Reaction between 120 and 140 °C for 2–4 h under static conditions was preferred as higher temperatures (180 °C) produced kalsilite. The KOH molarity (1.2–4.3 M) controlled the average zeolite crystal size, dispersion, and crystal shape; with highest molarity values optimal. Whereas, added KCl acted as a template which promoted zeolite N formation. Removal of KCl resulted in creation of zeolite F ( K 13 ( O H ) 3 A l 10 S i 10 O 40 . 13 H 2 O ) which also belonged to the EDI structural type. Ammonium ion exchange from aqueous solution was improved when diffusion restrictions were eased; as evidenced by using smaller zeolite crystals which were highly dispersed and not agglomerated. Not only was a greater cation capacity recorded but also the time to reach equilibrium was decreased.