Optimization of the metakaolin geopolymer preparation for maximized ammonium adsorption capacity

The surface water of Sanjiang Plain generally contained 0.04 to 2.50 mg L-1 of dissolved Fe ion, while the groundwater contained 0.03 to 21.00 mg L-1, which is relative high in comparison with other regions. The purpose of this study was to investigate the effect of dissolved Fe in the irrigation water on the adsorption of ammonium. Soil samples were collected from topsoil of a paddy field. Fe2+concentration in either surface water (0.70 mg L-1) or groundwater (15.0 mg L-1) were simulated to employ batch experiments in lab. The results show that when Fe2+ concentration was 0.70 mg L-1, it might slightly increase ammonium adsorption on the albic black soil. However, when Fe2+ concentration increased to 15.0 mg L-1, it may increase or decrease ammonium adsorption on the albic albic black soil, depending on ammonium concentration in the soil solution. In details, ammonium adsorption capacity decreased when ammonium concentration is less than 30.77 mg L-1, while increased when it’s more than 30.77mg L-1. Long-term irrigated soils with groundwater might increase content of iron oxides in the paddy soils and thus increase ammonium adsorption capacity. However, Fe2+ in the irrigating water might also lead to desorption and leaching of ammonium in each flooding event.

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Impact of steel slag on the ammonium adsorption by zeolite and a new configuration of zeolite-steel slag substrate for constructed wetlands

Water Science & Technology ◽

10.2166/wst.2017.232 ◽

2017 ◽

Vol 76 (3) ◽

pp. 584-593 ◽

Cited By ~ 3

Author(s):

Pengbo Shi ◽

Yingbo Jiang ◽

Hongtao Zhu ◽

Dezhi Sun

Keyword(s):

Adsorption Capacity ◽

Ph Value ◽

Molecular Form ◽

Steel Slag ◽

Order Reaction ◽

Drastic Reduction ◽

Pseudo First Order Reaction ◽

Ammonium Adsorption ◽

Pseudo Second Order ◽

The One

The CaO dissolution from slag, as well as the effects of influencing parameters (i.e. pH and Ca2+ concentration) on the ammonium adsorption onto zeolite, was systematically studied in this paper. Modeling results of Ca2+ and OH− release from slag indicated that pseudo-second-order reaction had a better fitness than pseudo-first-order reaction. Changing pH value from 7 to 12 resulted in a drastic reduction of the ammonium adsorption capacity on zeolite, from the peak adsorption capacity at pH 7. High Ca2+ concentration in solution also inhibited the adsorption of ammonium onto zeolite. There are two proposed mechanisms for steel slag inhibiting the ammonium adsorption capacity of zeolite. On the one hand, OH− released from steel slag can react with ammonium ions to produce the molecular form of ammonia (NH3·H2O), which would cause the dissociation of NH4+ from zeolite. On the other hand, Ca2+ could replace the NH4+ ions to adhere onto the surface of zeolite. An innovative substrate filling configuration with zeolite placed upstream of the steel slag was then proposed to eliminate the disadvantageous effects of steel slag. Experimental results showed that this novel filling configuration was superior to two other filling configurations in terms of ammonium removal.

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Effects of fresh and aged biochars from pyrolysis and hydrothermal carbonization on nutrient sorption in agricultural soils

SOIL Discussions ◽

10.5194/soild-2-29-2015 ◽

2015 ◽

Vol 2 (1) ◽

pp. 29-65 ◽

Cited By ~ 2

Author(s):

M. Gronwald ◽

A. Don ◽

B. Tiemeyer ◽

M. Helfrich

Keyword(s):

Adsorption Capacity ◽

Agricultural Soils ◽

Sandy Loam ◽

Nutrient Retention ◽

Hydrothermal Carbonization ◽

Field Application ◽

Retention Capacity ◽

Phosphate Retention ◽

Ammonium Adsorption ◽

Phosphate Leaching

Abstract. Leaching of nutrients from agricultural soils causes major environmental problems that may be reduced with biochar amendments to the soils. Biochars are characterised by a high adsorption capacity, i.e., they may retain nutrients such nitrate and ammonium. However, biochar properties strongly depend on feedstock and the production process. We investigated the nutrient retention capacity of biochars derived from pyrolysis (pyrochar) as well as from hydrothermal carbonization (hydrochar; produced at 200 and 250 °C) from three different feedstocks (digestates, Miscanthus, woodchips) mixed into different soil substrates (sandy loam and silty loam). Moreover, we investigated the influence of biochar degradation on its nutrient retention capacity using a seven-month in-situ field incubation of pyrochar and hydrochar. Pyrochars showed the highest ability to retain nitrate, ammonium and phosphate, with pyrochar from woodchips being particularly efficient in nitrate adsorption. Ammonium adsorption of pyrochars was controlled by the soil type of the soil-biochar mixture. We found some ammonium retention on sandy soils, but no pyrochar effect or even ammonium leaching from the loamy soil. The phosphate retention capacity of pyrochars strongly depended on the pyrochar feedstock with large phosphate leaching from digestate-derived pyrochar and some adsorption capacity from woodchip-derived pyrochar. Application of hydrochars to agricultural soils caused small, and often not significant, effects on nutrient retention. In contrast, some hydrochars did increase the leaching of nutrients compared to the non-amended control soil. We found a surprisingly rapid loss of the biochars' adsorption capacity after field application of the biochars. For all sites and for hydrochar and pyrochar, the adsorption capacity was reduced by 60–80% to less or no nitrate and ammonium adsorption. Thus, our results cast doubt on the efficiency of biochar applications to temperate zone soils to minimize nutrient losses via leaching.

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Effect of pyrolysis temperature on characteristics of biochars derived from different feedstocks: A case study on ammonium adsorption capacity

Waste Management ◽

10.1016/j.wasman.2019.02.049 ◽

2019 ◽

Vol 87 ◽

pp. 652-660 ◽

Cited By ~ 26

Author(s):

Defu Xu ◽

Junmin Cao ◽

Yingxue Li ◽

Alan Howard ◽

Kewei Yu

Keyword(s):

Adsorption Capacity ◽

Pyrolysis Temperature ◽

Ammonium Adsorption

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Effects of fresh and aged chars from pyrolysis and hydrothermal carbonization on nutrient sorption in agricultural soils

SOIL ◽

10.5194/soil-1-475-2015 ◽

2015 ◽

Vol 1 (1) ◽

pp. 475-489 ◽

Cited By ~ 25

Author(s):

M. Gronwald ◽

A. Don ◽

B. Tiemeyer ◽

M. Helfrich

Keyword(s):

Adsorption Capacity ◽

Agricultural Soils ◽

Sandy Loam ◽

Nutrient Retention ◽

Hydrothermal Carbonization ◽

Field Application ◽

Retention Capacity ◽

Phosphate Retention ◽

Ammonium Adsorption ◽

Phosphate Leaching

Abstract. Leaching of nutrients from agricultural soils causes major environmental problems that may be reduced with amendments of chars derived from pyrolysis (pyrochars) or hydrothermal carbonization (hydrochars). Chars are characterized by a high adsorption capacity – i.e. they may retain nutrients such as nitrate and ammonium. However, the physicochemical properties of the chars and hence their sorption capacity likely depend on feedstock and the production process. We investigated the nutrient retention capacity of pyrochars and hydrochars from three different feedstocks (digestates, Miscanthus, woodchips) mixed into different soil substrates (sandy loam and silty loam). Moreover, we investigated the influence of char degradation on its nutrient retention capacity using a 7-month in situ field incubation of pyrochar and hydrochar mixed into soils at three different field sites. Pyrochars showed the highest ability to retain nitrate, ammonium and phosphate, with pyrochar from woodchips being particularly efficient in nitrate adsorption. Ammonium adsorption of pyrochars was controlled by the soil type of the soil–char mixture. We found some ammonium retention on sandy soils, but no pyrochar effect or even ammonium leaching from the loamy soil. The phosphate retention capacity of pyrochars strongly depended on the pyrochar feedstock with large phosphate leaching from digestate-derived pyrochar and some adsorption capacity from woodchip-derived pyrochar. Application of hydrochars to agricultural soils caused small, and often not significant, effects on nutrient retention. In contrast, some hydrochars did increase the leaching of nutrients compared to the non-amended control soil. We found a surprisingly rapid loss of the chars' adsorption capacity after field application of the chars. For all sites and for hydrochar and pyrochar, the adsorption capacity was reduced by 60–80 % to less or no nitrate and ammonium adsorption. Thus, our results cast doubt on the efficiency of char applications to temperate zone soils to minimize nutrient losses via leaching.

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The investigation into the adsorption removal of ammonium by natural and modified zeolites: kinetics, isotherms, and thermodynamics

Water SA ◽

10.17159/wsa/2019.v45.i4.7546 ◽

2019 ◽

Vol 45 (4 October) ◽

Cited By ~ 1

Author(s):

Min Pan ◽

Mingchuan Zhang ◽

Xuehua Zou ◽

Xuetong Zhao ◽

Tianran Deng ◽

...

Keyword(s):

Adsorption Capacity ◽

Adsorption Process ◽

Low Cost ◽

Kinetic Studies ◽

Order Kinetic ◽

Regeneration Rate ◽

Ammonium Removal ◽

Ammonium Adsorption ◽

Order Kinetic Model ◽

Pseudo Second Order

The objectives of this study were to modify Chinese natural zeolite by NaCl and to investigate its suitability as a low-cost clay adsorbent to remove ammonium from aqueous solution. The effect of Ph on ammonium removal was investigated by batch experiments. The findings indicated that Ph has a significant effect on the removal of ammonium by M-Zeo and maximum adsorption occurred at Ph 8. Ion exchange dominated the ammonium adsorption process at neutral Ph, with the order of exchange selectivity being Na+ > Ca2+ > K+ > Mg2+. The Freundlich model provided a better description of the adsorption process than the Langmuir model. The maximum ammonium adsorption capacity was 17.83 mg/g for M-Zeo at 293K. Considering the adsorption isotherms and thermodynamic studies, the adsorption of ammonium by M-Zeo was endothermic and spontaneous chemisorption. Kinetic studies indicated that the adsorption of ammonium onto M-Zeo is well fitted by the pseudo-second-order kinetic model. Ea in the Arrhenius equation suggested the adsorption of ammonium on M-Zeo was a fast and diffusion-controlled process. The regeneration rate was 90.61% after 5 cycles. The removal of ammonium from real wastewater was carried out, and the removal efficiency was up to 99.13%. Thus, due to its cost-effectiveness and high adsorption capacity, M-Zeo has potential for use in ammonium removal from aqueous solutions.

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