scholarly journals Adsorption of nitrate onto biochar derived from agricultural residuals

2017 ◽  
Vol 77 (2) ◽  
pp. 548-554 ◽  
Author(s):  
Haihua Zhao ◽  
Yingwen Xue ◽  
Li Long ◽  
Xiaolan Hu

Abstract To develop low-cost adsorbents for aqueous nitrate, biochars were prepared from three types of agricultural residuals at different pyrolysis temperatures (300 °C, 450 °C, and 600 °C). The corncob biochar produced at 600 °C (CC600) was the best nitrate adsorbent of all the tested biochars. Characterization results showed that CC600 had good thermal stability, porous structure, and abundant surface functional groups. Findings from batch adsorption experiments demonstrated that CC600 showed relatively fast adsorption kinetics to nitrate in aqueous solutions. In addition, the Langmuir adsorption capacity of CC600 to nitrate was 14.46 mg/g, comparable to that of other biochar-based adsorbents. Therefore, CC600 showed promising potential to be used as a low-cost adsorbent for the treatment of nitrate in water.

2021 ◽  
Vol 13 (16) ◽  
pp. 8994
Author(s):  
Eliana Contreras-López ◽  
Victor Miyashiro Kiyan ◽  
Jaime Porras Cerrón ◽  
Ana María Muñoz ◽  
Fernando Ramos-Escudero ◽  
...  

This study aimed to evaluate the adsorption capacity of an adsorbent obtained using sanky peel for the removal of phosphate from aqueous solutions. The study was conducted in two stages: (1) adsorbent preparation considering yield, phosphate removal, adsorption capacity, and textural characteristics; (2) an assessment of the effectiveness of using sanky peel as an adsorbent for removing phosphates from aqueous solutions. Batch adsorption was studied in aqueous solutions containing phosphate and calcium ions with the selected adsorbent. Adsorption kinetics and equilibrium isotherms were studied using mathematical models. The adsorption kinetics followed the pseudo-second-order, Elovich, and Weber–Morris models, thus demonstrating that adsorption rates were not controlled by multiple processes. Adsorption equilibrium data fitted best with the Dubinin–Radushkevich model. Finally, a Fourier transform infrared spectroscopy analysis revealed the presence of brushite spectra bands after adsorption. The results of this study can help better understand the use of sanky peel as an adsorbent and good alternative for aqueous phosphate adsorption.


2019 ◽  
Vol 146 ◽  
pp. 1043-1053 ◽  
Author(s):  
Mohammad Hadi Dehghani ◽  
Mohammad Sarmadi ◽  
Mohammad Reza Alipour ◽  
Daryoush Sanaei ◽  
Hamid Abdolmaleki ◽  
...  

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1312
Author(s):  
Dereje Tadesse Mekonnen ◽  
Esayas Alemayehu ◽  
Bernd Lennartz

The contamination of surface and groundwater with phosphate originating from industrial and household wastewater remains a serious environmental issue in low-income countries. Herein, phosphate removal from aqueous solutions was studied using low-cost volcanic rocks such as pumice (VPum) and scoria (VSco), obtained from the Ethiopian Great Rift Valley. Batch adsorption experiments were conducted using phosphate solutions with concentrations of 0.5 to 25 mg·L−1 to examine the adsorption kinetic as well as equilibrium conditions. The experimental adsorption data were tested by employing various equilibrium adsorption models, and the Freundlich and Dubinin-Radushkevich (D-R) isotherms best depicted the observations. The maximum phosphate adsorption capacities of VPum and VSco were calculated and found to be 294 mg·kg−1 and 169 mg·kg−1, respectively. A pseudo-second-order kinetic model best described the experimental data with a coefficient of correlation of R2 > 0.99 for both VPum and VSco; however, VPum showed a slightly better selectivity for phosphate removal than VSco. The presence of competitive anions markedly reduced the removal efficiency of phosphate from the aqueous solution. The adsorptive removal of phosphate was affected by competitive anions in the order: HCO3− >F− > SO4−2 > NO3− > Cl− for VPum and HCO3− > F− > Cl− > SO4−2 > NO3− for VSco. The results indicate that the readily available volcanic rocks have a good adsorptive capacity for phosphate and shall be considered in future studies as test materials for phosphate removal from water in technical-scale experiments.


2020 ◽  
Vol 11 (4) ◽  
pp. 11891-11904

In the present study, batch mode adsorption was carried out to investigate the adsorption capacity of dried bael flowers (Aegle marmelos) for the adsorptive removal of Cu(II) ions from aqueous solutions by varying agitation time, initial metal concentration, the dose of adsorbent, temperature, and initial pH of the Cu(II) ion solution. The percentage removal of 98.7% was observed at 50 ppm initial metal ion concentration, 0.5 g/100.00 cm3 adsorbent dosage, within the contact time of 120 minutes at 30 ºC in the pH range of 4 – 7. The sorption processes of Cu(II) ions was best described by pseudo-second-order kinetics. Langmuir isotherm had a good fit with the experimental data with 0.97 of correlation coefficient (R2), and the maximum adsorption capacity obtained was 23.14 mg g-1 at 30 ºC. The results obtained from sorption thermodynamic studies suggested that the adsorption process is exothermic and spontaneous. SEM analysis showed tubular voids on the adsorbent. FTIR studies indicated the presence of functional groups like hydroxyl, –C-O, –C=O, and amide groups in the adsorbent, which can probably involve in metal ion adsorption. Therefore, dried bael flowers can be considered an effective low-cost adsorbent for treating Cu(II) ions.


2016 ◽  
Vol 36 (4) ◽  
pp. 329-362 ◽  
Author(s):  
Nurul F. Himma ◽  
Sofiatun Anisah ◽  
Nicholaus Prasetya ◽  
I Gede Wenten

Abstract Polypropylene (PP) is one of the most used polymers for microporous membrane fabrication due to its good thermal stability, chemical resistance, mechanical strength, and low cost. There have been numerous studies reporting the developments and applications of PP membranes. However, PP membrane with high performance is still a challenge. Thus, this article presents a comprehensive overview of the advances in the preparation, modification and application of PP membrane. The preparation methods of PP membrane are firstly reviewed, followed by the modification approaches of PP membrane. The modifications includes hydrophilic and superhydrophobic modification so that the PP membranes become more suitable to be applied either in aqueous applications or in non-aqueous ones. The fouling resistant of hydrophilized PP membrane and the wetting resistant of superhydrophobized PP membrane are then reviewed. Finally, special attention is given to the various potential applications and industrial outlook of the PP membranes.


2021 ◽  
Vol 9 (1) ◽  
pp. 260-269
Author(s):  
Huijuan Ran ◽  
Zhen Zhao ◽  
Xuewei Duan ◽  
Fuli Xie ◽  
Ruijun Han ◽  
...  

Three donor–acceptor (DA)-type pyrene-based blue emitters with good thermal stability and their applications in NUV OLEDs are demonstrated.


2020 ◽  
Vol 10 (5) ◽  
pp. 1738
Author(s):  
Kay Thwe Aung ◽  
Seung-Hee Hong ◽  
Seong-Jik Park ◽  
Chang-Gu Lee

Polyacrylonitrile (PAN) fibers were prepared via electrospinning and were modified with diethylenetriamine (DETA) to fabricate surface-modified PAN fibers. The surface-modified PAN fibers were used to evaluate their adsorption capacity for the removal of Cu(II) from aqueous solutions. Batch adsorption experiments were performed to examine the effects of the modification process, initial concentration, initial pH, and adsorbent dose on the adsorption of Cu(II). Kinetic analysis revealed that the experimental data fitted the pseudo-second-order kinetic model better than the pseudo-first-order model. Adsorption equilibrium studies were conducted using the Freundlich and Langmuir isotherm models, and the findings indicated that the PAN fibers modified with 85% DETA presented the highest adsorption capacity for Cu(II) of all analyzed samples. Moreover, the results revealed that the Freundlich model was more appropriate than the Langmuir one for describing the adsorption of Cu(II) onto the modified fibers at various initial Cu(II) concentrations. The maximum adsorption capacity was determined to be 87.77 mg/g at pH 4, and the percent removal of Cu(II) increased as the amount of adsorbent increased. Furthermore, the surface-modified PAN fibers could be easily regenerated using NaOH solution. Therefore, surface-modified PAN fibers could be used as adsorbents for the removal of Cu(II) from aqueous solutions.


Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 309
Author(s):  
Yurong Wu ◽  
Longshan Xu ◽  
Yanying Jiang

A uniform, monodispersed superfine cuprous oxide (Cu2O) sphere with a mean diameter of 850 nm has been synthesized by solution reduction. The study reported the synthesis and thermal properties of Cu2O/PP composites for the first time. The surface modification of the superfine Cu2O sphere was carried out by using a silane coupling agent KH-570. Fourier-transform infrared (FTIR) spectroscopy and the thermogravimetric analysis (TGA) curve revealed that the Cu2O had been successfully modified by silane coupling agent KH570. The scanning electron microscope (SEM) shows that the modified Cu2O can be uniformly dispersed in the polypropylene (PP) matrix, because through surface modification, there are some active functional groups on its surface, such as the ester group, which improves its compatibility with the PP matrix. The thermal stability of Cu2O/PP composites was improved by adding a small amount of Cu2O (1 wt % of PP). Therefore, based on the potential bacteriostasis of cuprous oxide, the low cost of PP and the results of this study, it is predicted that Cu2O/PP composites can be used in infant preparation (such as milk bottles) with low cost and good thermal stability in the near future.


2012 ◽  
Vol 599 ◽  
pp. 305-308 ◽  
Author(s):  
Ping Fang ◽  
Chao Ping Cen ◽  
Hong Tao Zhang ◽  
Zi Jun Tang ◽  
Ding Sheng Chen ◽  
...  

Efficient and cost-effective sludge-based adsorbents were developed and the adsorption of VOCs on the sludge-based adsorbents was studied in a fixed bed reactor. The results indicate that the adsorption of VOCs on sludge-based adsorbents is typical physical adsorption, the dynamic adsorption capacity of VOCs on adsorbents sharply increases as the VOCs concentration is increased at first, then increasing gradually, at last retains stable with the change of VOCs concentration. The dynamic adsorption capacity of sludge-based adsorbents for VOCs is O-Xylene > Butylcetate > Toluene > Ethylacetate > Benzene > Propanone > n-Hexane, the maximum dynamic adsorption capacity is 0.247, 0.225, 0.192, 0.186, 0.180, 0.176, 0.133g/g, respectively. Meanwhile the adsorption of VOCs on sludge-based adsorbents corresponds to the Langmuir adsorption isotherm equations. The sludge-based adsorbent is a low-cost alternative to activated carbon for VOCs treatment, and this technology is a promising method for the VOCs removal.


2013 ◽  
Vol 781-784 ◽  
pp. 2265-2268 ◽  
Author(s):  
Shi Yong Wei ◽  
Xu Hong Deng

HDTMA-modified vermiculite (HDTMA-Ver) was formed in a suspension by the interactions between vermiculite and hexadecyltrimethylammonium bromide (HDTMA). For vermiculite and HDTMA-Ver, the pH of the point of zero charge (pHpzc) is 3.16 and 5.09, the surface charge at pH 4.5 is-0.167 and 0.083 mmol/g, and the Langmuir adsorption capacity (qmax) is 4.98 and 8.67 mg/g, respectively. The adsorption data for fluoride by vermiculite and HDTMA-Ver could be fitted by Langmuir model. The as-prepared HDTMA-Ver exhibited excellent ability to remove fluoride ions from aqueous solutions.


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