CO_(2) capture by modified clinoptilolite and its regeneration performance

This study focuses on CO_(2) capture by pressure swing adsorption(PSA),with modified clinoptilolite as the adsorbent.Natural clinoptilolite is modified by roasting,by acid pickling,by a combination of acid pickling and roasting,and by ion exchange.Modification by acid pickling-roasting and by ion exchange are found to give the highest CO_(2) adsorption capacities,of 730 mL/g and 876.7 mL/g,respectively.It is found that regeneration of clinoptilolite by a combination of vacuum desorption and heating enables recovery of as much as 89%of its previous CO_(2) adsorption capacity.To examine the CO_(2) adsorption capacity of clinoptilolite when applied to mixed gas,a simulated coking exhaust containing 12%CO_(2) and 4%O_(2) is used,and it is found that ion exchange modified clinoptilolite achieves a CO_(2) removal efficiency of 92.5%.A BET test reveals that acid pickling-roasting and Na^(+) modification enhance the porosity of clinoptilolite,thereby improving its adsorption capacity.This work demonstrates the feasibility of applying modified clinoptilolite as an effective adsorbent for COO_(2)capture,providing a promising tool for dealing with greenhouse gases.

Influence of Calcination on the Physical Characteristics and Nitrogen Removal Performance of Clinoptilolites

The influences of roasting activation on the particle morphology, microscopic structure, and adsorption properties of natural clinoptilolites were investigated. The experimental results show that the optimal modified conditions include a calcination temperature at 400 ℃, a roasting time of 0.5 h, and furnace cooling. The ammonia nitrogen removal rate from analog renewable water of the modified clinoptilolites reached 72% in the optimized conditions, which is 12% higher than that of natural ones. Scanning electron microscopy analysis showed that the surface morphology changed, the micro-hole size increased, and the surface became smoother and more uniform after calcination. The single-point total adsorption average pore width increased from 7.74 nm to 10.64 nm.

AMMONIUM TREATMENT OFNATURAL CLINOPTILOLITE AND ITS CHARACTER OF ION-EXCHANGE

Ammonium can change the type of natural clinoptilolite from Jinyun ofZhejiang Province of China. The character of exchange and selectivity of ammonium type clinoptilolite to the alkali and alkaline - earth metal were investigated, the heatresistance and nitric acid - resistance of natural clinoptilolitewere discussed. All types of clinoptilolite were researched by means of X - ray,IR spectroscopy, DTA analyses. The ion exchange was experimented by columnoperation, indicating that the valid amount of exchange capacity of NH+4 typeclinoptilolite is more than 25mg/g.

Photocatalytic Degradation of Ethylene Dichloride in Water Using Nano TiO₂Supported on Clinoptilolite as a Photocatalyst

In this article one of the advanced oxidation processes (AOP) combined methods, photocatalyst /H2O2, is utilized in order to study photodegradation of ethylene dichloride (EDC) in water. Nano Titanium (IV) Oxide, supported on Clinoptilolite (CP) (Iranian natural zeolite) using solid-state dispersion (SSD) method for improvement of its photocatalytic properties. The results show that the TiO2/Clinoptilolite (SSD) is an active photocatalyst. The effects of five important photocatalytic reaction parameters including the initial concentration of ethylene dichloride, the ratio of TiO2/Clinoptilolite, the catalyst concentration, H2O2 concentration and pH in photodegradation of ethylene dichloride were examined. In this experiments, the design and also the optimum parameters were obtained by Taguchi Method, using Design Expert8®software. Taguchi's L27 (5^3) orthogonal array design was employed for the experimental plan. Four parameters were found to be significant whereas, pH was found to be an insignificant parameter after conducting experiments. A first order reaction with K = 0.007 min-1 was observed for the photocatalytic degradation reaction.

Safety and efficacy of purified clinoptilolite-tuff treatment in patients with irritable bowel syndrome with diarrhea:Randomized controlled trial

BACKGROUND Irritable bowel syndrome(IBS)is a highly prevalent gastrointestinal disorder with poor response to treatment.IBS with predominant diarrhea(IBS-D)is accompanied by abdominal pain as well as high stool frequency and urgency.Purified clinoptilolite-tuff(PCT),which is approved by the Food and Drug Administration for use as a dietary supplement with the brand name G-PUR®,has previously shown therapeutic potential in other indications based on its physical adsorption capacity.AIM To assess whether symptoms of IBS-D can be ameliorated by oral treatment with PCT.METHODS In this randomized,placebo-controlled,double-blind pilot study,30 patients with IBS-D diagnosis based on Rome IV criteria were enrolled.Following a 4-wk run-in phase,14 patients were randomized to receive a 12-wk treatment with G-PUR®(2 g three times daily),and 16 patients received placebo.The relief from IBS-D symptoms as measured by the proportion of responders according to the Subject’s Global Assessment(SGA)of Relief was assessed as the primary outcome.For the secondary outcomes,validated IBS-D associated symptom questionnaires,exploratory biomarkers and microbiome data were collected.RESULTS The proportions of SGA of Relief responders after 12 wk were comparable in both groups,namely 21%in the G-PUR®group and 25%in the placebo group.After 4 wk of treatment,36%of patients in the G-PUR®group vs 0%in the placebo group reported complete or considerable relief.An improvement in daily abdominal pain was noted in 94%vs 83%(P=0.0353),and the median number of days with diarrhea per week decreased by 2.4 d vs 0.3 d in the G-PUR®and placebo groups,respectively.Positive trends were observed for 50%of responders in the Bristol Stool Form Scale.Positive trends were also noted for combined abdominal pain and stool consistency response and the Perceived Stress Questionnaire score.Only 64%in the G-PUR®group compared to 86%in the placebo group required rescue medication intake during the study.Stool microbiome studies showed a minor increase in diversity in the G-PUR®group but not in the placebo group.No PCT-related serious adverse events were reported.CONCLUSION In this randomized,double-blind,placebo-controlled study,the PCT product,G-PUR®,demonstrated safety and clinical benefit towards some symptoms of IBS-D,representing a promising novel treatment option for these patients.

Porosity on External Surface of H-Clinoptilolite Sorption of CCI4 and n-C6H14

CCl4 （carbon tetrachloride） and n-C6H14 （n-hexane） sorption studies have been carried out on natural and dealuminated clinoptilolite-type zeolites. External surface area of the materials has been assessed using the αs-plots method. The high resolution αs-plots show that the isotherms are divided into four parts corresponding to adsorption in ultramicropores, intersections, supermicropores and external surface area, respectively. The mineralogies of natural zeolites are determined by X-ray analysis. N： low-pressure hysteresis loops, displayed by some substrata, are related to the micropore structure and to the ion-exchange treatment at which the natural precursors were subjected. The adsorption behavior of these substrata was examined in the range of relative pressures between 10^-5-1. Natural samples were used as reference materials to carry out the sorption analyses of the dealuminated samples. The effect of narrow micropore constrictions on the adsorption behavior of clinoptilolites was explored. The occurrence of a low-pressure hysteresis loop on the sorption isotherm of a modified sample is associated to the strong adsorption of the adsorbate molecules at the entrance of the necked-shape micropores, which interfere with the diffusion of the adsorbate molecules inside the porous structure.

Experiment and Modeling of Low Coverage Uptake of N2 and 02 on H-Clinoptilolite Zeolite from Tehuacan, Puebla, Mexico

Adsorption isotherms of N2 and 02 on dealuminated clinoptilolite zeolites were measured by the inverse gas chromatography method at zero-coverage. This type of microporous solids such as natural （CLINA） and dealuminated clinoptilolite zeolites （CLIDA1-CLIDA5） were conditioned by means of acid treatment of the natural zeolitic precursor （CLINA） with HCI at different concentration. Adsorption of selected gases （N2 and 02） on clinoptilolite zeolites were studied in the temperature range from 398 K to 498 K. The Langmuir adsorption model was found to approximately fit the gases adsorption data, within the selected temperature range. The uptake amount of these gases by the diverse adsorbents was temperature dependent. Additionally, the energies of interaction between of these gases with clinoptilolite microporous walls were realized from the evaluation of the isosteric heats of adsorption （qst）. These isosteric heats were found to obey in the following decreasing order： qst （N2）： CLIDA1 〉 CLIDA3 〉 CLIDA2 〉 CLIDA4 〉 CLIDA5 〉 CLINA; while qst （02）： CLIDA3 〉 CLIDA2 〉 CL1DA1 〉 CLIDA5 〉 CLIDA4 〉 CLINA.

Influence of Intercropping Maize with Cowpea and Fertilization with Clinoptilolite on Forage Yield and Quality

Maize forage is poor in protein content which leads to low quality and nutritive value.Regarding the high feed costs of protein supplementations,legumes can be used in livestock nutrition for their high protein content,and thus,provide cost savings.In this study,maize(Zea mays L.)and cowpea(Vigna unguiculata L.)were intercropped in different sowing densities and fertilization with clinoptilolite and their monocropping equivalents were tested to determine the best intercropping system on forage yield and quality.Maize was cultivated alone(75,000 plants·ha^-1)and intercropped with cowpea as follows:75,000 plants·ha-1 of maize and 37,500 plants·ha^-1 of cowpea(MC1),75,000 plants·ha^-1 of maize and 50,000 plants·ha-1 of cowpea(MC2)and 75,000 plants·ha^-1 of maize and 75,000 plants·ha^-1 of cowpea(MC3),in rows alternating with maize.The highest dry matter yield was produced by MC3(23.8 t·ha^-1),and the lowest by SM(20.7 t·ha^-1)in fertilization with clinoptilolite.All intercropped systems had higher crude protein contents,MC1(101 g·kg^-1 DM),MC2(108 g·kg^-1 DM)and MC3(117 g·kg^-1 DM),than the monocrop maize(84 g·kg^-1 DM)in fertilization with clinoptilolite.Intercropping of maize with cowpea and fertilization with clinoptilolite reduced neutral detergent fiber,resulting in increased forage digestibility.Therefore,maize intercropping with cowpea and fertilization with clinoptilolite could substantially increase forage quantity and quality,and decrease requirements for protein supplements as compared with maize monocrop.

Fertcel Clinoptilolite Natural Product to Optimize the Fertilization and Reduce Environmental Pollution

The shortages of chemical fertilizers in Cuba in 90s caused the introduction of different research results obtained on this time for the implementation of natural zeolites in the fertilizer industry. It＇s known as the high capacity of cation exchange of the natural Cuban clinoptilolite, which contributes to reducing nutrient losses, such as ammonia, and keeping the potassium and phosphorus cations available. Extensive tests were done on the field with the objective to evaluate the agronomic effect of incorporating this mineral in fertilizer. The results obtained in this experiment contributed to almost all Cuban chemical fertilizers, which has been incorporated around 15%-20% of natural zeolite clinoptilolite in its composition by Cuban agriculture consumes, reducing the chemical carriers of the fertilizers and decreasing the contamination of the environment. Also this mineral contributes for increases in agricultural income more than 15% in all cases; additionally, a trend can be observed towards gradual recovery of some soil fertility indicators, in which the chemical fertilizers with Fertcel was applied.

Removal of Ag(I) from Aqueous Solution by Japanese Natural Clinoptilolite

The present study examined the adsorption of silver ion in aqueous solution onto natural clinoptilolite zeolite from Futatsui Mine, Akita Prefecture, Japan. The effects of various parameters, i.e., solution pH, adsorbent dosage, adsorption time, silver ion solution concentration, and temperature, on silver ion adsorption process onto clinoptilolite were examined. Additionally, the thermodynamics of the silver ion adsorption process was investigated. The optimum pH for silver adsorption was determined to be around 4.0. The adsorption process could be well described by the Langmuir isotherm model. The calculated maximum adsorption capacity was 0.64 mmol/g. Adsorption kinetics studies were also conducted. The results showed that the adsorption process preferentially followed the pseudo-second-order kinetics model over the pseudo-first-order model. Furthermore, with decreasing aqueous solution temperatures, the adsorption kinetics became slower and the amount of silver ion adsorbed increased. The thermodynamic values, ΔG0, ΔH0, and ΔS0, indicated that adsorption was an exo-thermic and spontaneous process.

水热法合成超细斜发沸石试验研究

斜发沸石具有较强的吸附和离子交换能力,在重金属和油污废水去除、制糖、造纸净化、抗菌抗癌药物助剂制备、石油化工催化裂化、国防以及CO_(2)脱除等领域应用广泛。为了获得纯度较高的斜发沸石,以NaOH、KOH、Al(OH)_(3)、Na_(2)O·nSiO_(2)、H_(2)O为原料,采用水热法制备了斜发沸石,并通过XRD和晶面分析,研究了斜发沸石的合成条件,结果表明:合成斜发沸石的最佳条件为n(SiO_(2))/n(Al_(2)O_(3))=11、n(OH-)/n(SiO_(2))=0.55、n(H_(2)O)/n(SiO_(2))=25~55、温度150℃、时间6 d,合成的斜发沸石呈片状结构,特征峰完整,纯度较高,其晶胞组成为Na_(0.36)K_(6.58)[(AlO_(2))6(SiO_(2))_(25.26)]·6.71H_(2)O,n(SiO_(2))/n(Al_(2)O_(3))约为8.5,属中硅铝比沸石。SEM分析结果显示,其粒径在1.3μm以下,表明粒度非常细;其静态水吸附量为34.3%,达到了HG/T 2690-2012《13X分子筛》中的一等品指标要求。研究成果可为高纯度细粒斜发沸石的精准合成提供借鉴。

改性天然斜发沸石去除氨氮的工艺

氨氮污染对环境和生态系统的重大影响使水处理领域氨氮污染的去除一直是人们关注的重点。为了更有效地去除污水中的氨氮污染,研究采用酸、碱、盐及热处理等方法对海林斜发沸石改性,并进行沸石的形貌分析和吸附容量的测定,研究了天然及改性后的斜发沸石对污水中氨氮的吸附效果。试验结果表明,4种改性处理均会对斜发沸石的交换性能产生影响,其中盐改性的效果最好,且更容易实际操作,改性后的斜发沸石仍符合Lagmuir型平衡关系式。根据钠、钾、钙3种盐的离子交换等温线可知,三者对NH^(+)_(4)的交换等温线均为d型曲线,三者选择性交换能力钠沸石>钙沸石>钾沸石。斜发沸石可有效再生,且经过盐处理改性后的斜发沸石能够更有效地吸附污水中的氨氮。

改性沸石(Na-Y型)对Ni^(2+)的吸附行为

将天然沸石熔融制得新型改性沸石(Na-Y型),研究Na-Y型沸石对N i2+的吸附行为.结果表明,对N i2+的饱和吸附量,Na-Y型沸石为31.04mg.g-1,而天然斜发沸石和Na型沸石(NaC l改性)仅为3.60mg.g-1和7.64 mg.g-1.Na-Y型沸石对N i2+的等温吸附行为符合Freund lich方程.对溶液中N i2+的吸附量在初始阶段(0—5h)快速上升,而后趋于平缓.共存阳离子对Na-Y型沸石吸附N i2+的影响为:Co2+>Ca2+>Fe3+>K+.

斜发沸石对干湿交替条件下水稻产量和氮素累积的影响

【目的】斜发沸石作为一种优良的土壤改良剂,因其具有改善土壤养分、提高水稻产量、减少氮素流失等积极作用而广泛用于水稻生产中。通过田间定位试验,探究干湿交替灌溉条件下斜发沸石对水稻氮素吸收利用和产量的长期影响。【方法】在2017—2021年连续5年进行原位大田试验。试验设计为随机区组试验,设置常规淹灌条件下不施斜发沸石(I_(CF)Z_(0)),干湿交替灌溉下不施斜发沸石(I_(AWD)Z_(0))和干湿交替灌溉下施加10 t/hm^(2)斜发沸石(I_(AWD)Z_(10))3个处理,斜发沸石于2017年施入土壤,之后4年(2018—2021)不再施用。水稻生育期内定期取0—30 cm土壤样品用于测定无机氮含量,每年水稻成熟期,调查籽粒产量量及主要产量构成因子,计算地上部氮累积量、氮肥偏生产力。【结果】I_(CF)Z_(0)和I_(AWD)Z_(0)处理的水稻产量、地上部氮累积量和氮肥偏生产力差异均不显著。与I_(CF)Z_(0)和I_(AWD)Z_(0)处理相比,I_(AWD)Z_(10)处理连续5年均显著提高了地上部氮累积量和产量,但增长率随定位试验的延长有所下降。I_(AWD)Z_(10)处理氮肥偏生产力较I_(CF)Z_(0)和I_(AWD)Z_(0)处理分别增加了9.67~13.44和5.53~9.55 kg/kg,产量分别增加了1.26~2.42和1.00~1.72 t/hm^(2)。与I_(AWD)Z_(0)相比,I_(AWD)Z_(10)处理地上部干物质累积量在拔节孕穗期、抽穗开花期、乳熟期和成熟期分别增加了20.96%~31.24%、16.89%~30.44%、17.87%~25.45%和13.43%~21.12%,地上部氮累积量分别增加了19.92%~47.14%、14.90%~43.88%、21.68%~31.37%和7.18%~30.27%。I_(AWD)Z_(0)与I_(CF)Z_(0)处理土壤无机氮含量差异不显著,I_(AWD)Z_(10)处理土壤无机氮含量最高,较I_(AWD)Z_(0)处理增加了19.88%~40.96%。在分蘖—穗肥阶段,5年间I_(AWD)Z_(10)处理的土壤NH_(4)^(+)-N含量较I_(CF)Z_(0)和I_(AWD)Z_(0)处理分别增加了31.83%~48.84%和28.35%~52.80%。I_(AWD)Z_(0)和I_(CF)Z_(0)处理收获后土壤全氮含量差异不显著,I_(AWD)Z_(10)较I_(CF)Z_(0)处理显著提高了收获期土壤全氮含量,提升幅度为9.27%~11.41%,这表明随着时间的延长,斜发沸石并不会对土壤养分产生负面影响,反而对土壤养分具有长期改善的作用。【结论】在干湿交替灌溉条件下,一次性施用斜发沸石可连续多年提高水稻生育期土壤铵态氮含量、增加土壤全氮,进而促进水稻氮吸收,提高氮肥偏生产力和产量。因此,斜发沸石可用于新型灌溉技术下提高水稻产量,实现稻田可持续利用。

基于海绵铁-斜发沸石组合系统的模拟农村黑臭水体脱氮除磷研究

农村水体黑臭污染现象仍不容忽视。研究以海绵铁及斜发沸石为基质,分别按0/1、1/10、1/5及1/1的填充体积配比构建了四组柱反应器(Device-Ⅰ~Device-Ⅳ),考察了各反应器在连续流及潮汐流进水方式下对低C/N模拟农村黑臭水体中氮磷等污染物的脱除表现,并对作用前后的填料进行表征,分析了反应器内微生物的自然生长情况。结果表明,海绵铁可强化系统NO_(3)^(-)-N及TP的去除效果,并在潮汐流下利于COD的去除。潮汐进水方式下,具海绵铁反应器的NO_(3)^(-)-N及TP去除率均可分别超过98%及95%,Device-Ⅱ平均NO_(3)^(-)-N及TP去除率分别可达99.66%及99.36%,COD最高去除率可达93.38%。系统NH_(4)^(+)-N的脱除依赖于斜发沸石的作用,潮汐进水促进了沸石系统的生物再生,可弥补连续流下氧缺乏及微生物作用低下对系统NH4+-N脱除的限制。

天然沸石改性方法及改性条件的研究

通过对预处理后的天然斜发沸石进行HCl、NaCl、NH_(4)Cl、H_(2)SO_(4)、HDTMA、CH_(3)COOH、NaOH 7种不同方法改性,寻求最佳的改性方法,制得不同类型的改性沸石。实验结果表明,HDTMA改性后的沸石对重金属Cd^(2+)的去除率最高,因此选用HDTMA作为改性剂制备改性沸石,同时研究了HDTMA改性剂溶液的浓度、浸泡时间、体积质量比、焙烧温度等影响改性沸石品质的潜在因素。得出最佳的改性沸石吸附剂的制备条件是:HDTMA溶液的质量浓度5 g/L,浸泡时间12 h,体积质量比10(mL∶g),最佳焙烧温度500℃。

改性斜发沸石吸附矿井水中氟离子的研究

氟化物含量超标已成为限制矿井水利用的巨大挑战之一,研究了天然斜发沸石及H_(2)SO_(4)改性、Al_(2)(SO_(4))_(3)改性、NaOH溶液预处理后Al_(2)(SO_(4))_(3)改性、FeCl_(3)改性沸石对矿井水氟离子的吸附效果。结果表明,与天然斜发沸石相比,NaOH溶液预处理后Al_(2)(SO_(4))_(3)改性沸石MZ、FeCl_(3)改性沸石FZ对矿井水中氟离子的去除率提高了10.2倍和11.7倍,MZ及FZ的对氟离子的吸附符合Lagergren准二级动力学方程,理论平衡吸附容量分别达到0.428 mg/g及0.508 mg/g。改性沸石MZ及FZ对矿井水中氟离子去除率可达80%以上,为低浓度含氟矿井水的大规模低成本处理提供了科学依据。

几种天然斜发沸石矿的组成结构及性质对比研究

我国天然斜发沸石矿分布较广且储量丰富,具有巨大的开发利用价值。但由于成矿条件的差异,不同产地甚至同一产地不同区块天然斜发沸石的组成结构及诸多性质存在一定的差异,使其实际应用受到影响。因此,开展天然斜发沸石矿组成结构及性质的对比研究很有必要。选取河北一处(Z1)和辽宁两处(Z2和Z3)天然斜发沸石矿,研究并对比其组成、结构、pH值、阳离子交换容量以及重金属离子、水蒸气和甲醛的吸附效果。结果表明:三种天然沸石矿主要由斜发沸石、石英及少量方解石等矿物组成,含有SiO_(2)、Al_(2)O_(3)、K_(2)O、Na_(2)O、Fe_(2)O_(3)、MgO、TiO_(2)、CaO及少量重金属等成分,三者的矿物和化学组成存在一定差异。Z2样品表现出相对较好的重金属离子、水蒸气和甲醛气体吸附效果,其对Cd^(2+)、Cr^(3+)、水蒸气和甲醛气体的吸附容量分别为14.89 mg/g、6.65 mg/g、21.33 mg/g和7.12 mg/g,这与其具有更高的比表面积、介孔体积以及阳离子交换容量有关。该研究可为天然斜发沸石矿的评价、高效利用及环境应用提供一定的支持。

不同改性方法对天然斜发沸石组成结构及气体吸附性的影响研究

天然斜发沸石是储量最大且最具工业利用价值的天然沸石之一,然而受自身组成结构的限制,其吸附性能和环境应用效果欠佳,大规模应用进程迟缓。尽管通过对天然斜发沸石进行改性处理可在一定程度上解决上述问题,但目前关于不同改性方法对其组成结构及吸附性能的影响差异尚不完全明确,缺乏系统的对比研究。以河北承德围场地区天然斜发沸石为研究对象,考察并对比酸、碱、水热和热处理对其组成结构以及水蒸气、甲醛和甲苯气体吸附性的影响。结果表明:几种改性方法对天然斜发沸石的组成结构和气体吸附性的影响程度存在较大差异。酸、碱处理使得斜发沸石的结晶度有所降低,400℃热处理可破坏斜发沸石的晶体结构,水热处理使得天然斜发沸石转变为方沸石和P型沸石。天然沸石样品的比表面积和硅铝比分别为13 m^(2)/g和5.2,对水蒸气、甲醛和甲苯气体的吸附量分别为7.5 mg/g、8.5 mg/g和7.5 mg/g;而酸、碱、水热和热处理后沸石样品的比表面积分别为147 m^(2)/g、30 m^(2)/g、27 m^(2)/g和11 m^(2)/g,硅铝比分别为14.9、4.8、3.2和5.2,对水蒸气的吸附量分别为16.5 mg/g、8.0 mg/g、15.0 mg/g和8.5 mg/g,对甲醛的吸附量分别为27.0 mg/g、14.5 mg/g、9.0 mg/g和7.5 mg/g,对甲苯的吸附量分别为26.0 mg/g、8.5 mg/g、6.5 mg/g和5.0 mg/g。不同改性沸石气体吸附性能的差异与其比表面积和孔体积、硅铝比等特征密切相关。酸处理沸石具有相对更高的比表面积和孔体积,表现出优异的气体吸附性能。该研究对于天然斜发沸石的高效利用具有一定促进作用。