Heavy Metals Adsorption on Cellulosic Materials from Agricultural Waste

Adsorption technique has been known to be a very effective method for treatment of heavy metals polluted wastewater, with the advantages of specific affinity, simple design and being user-friendly. However, the high cost of activated carbon commonly used as the adsorbent makes it necessary to explore the use of cheap cellulosic adsorbents. In this study, the adsorptive property of sugarcane bagasse (SB) and orange mesocarp (OM) was investigated. The cellulosic adsorbents were used for the sorption of lead and zinc ions from aqueous solutions. The effects of varying adsorbent dose, varying contact time and initial metal ion concentration on adsorption process of the metals were studied. The results show that both adsorbents (though waste materials) are viable for removal of metals from wastewater. Moreover, SB had higher sorption capacity for zinc (12.95 for SB and 12.68 for OM) while OM had higher sorption capacity for lead (9.90 for OM and 9.48 for SB) at optimum dosage. The isothermal studies shows that for lead adsorption, experimental data best fitted the Langmuir isotherm for both adsorbents (R2 of 0.9574 for OM and 0.98 for SB) while the data for zinc adsorption best fitted into Freundlich isotherm with SB (R2 of 0.9565)and Langmuir isotherm for OM(R2 of 0.814).

Heavy Metals Adsorption on Cellulosic Materials from Agricultural Waste

Adsorption technique has been known to be a very effective method for treatment of heavy metals polluted wastewater, with the advantages of specific affinity, simple design and being user-friendly. However, the high cost of activated carbon commonly used as the adsorbent makes it necessary to explore the use of cheap cellulosic adsorbents. In this study, the adsorptive property of sugarcane bagasse (SB) and orange mesocarp (OM) was investigated. The cellulosic adsorbents were used for the sorption of lead and zinc ions from aqueous solutions. The effects of varying adsorbent dose, varying contact time and initial metal ion concentration on adsorption process of the metals were studied. The results show that both adsorbents (though waste materials) are viable for removal of metals from wastewater. Moreover, SB had higher sorption capacity for zinc (12.95 for SB and 12.68 for OM) while OM had higher sorption capacity for lead (9.90 for OM and 9.48 for SB) at optimum dosage. The isothermal studies shows that for lead adsorption, experimental data best fitted the Langmuir isotherm for both adsorbents (R2 of 0.9574 for OM and 0.98 for SB) while the data for zinc adsorption best fitted into Freundlich isotherm with SB (R2 of 0.9565) and Langmuir isotherm for OM (R2 of 0.814).

3D Graphene Oxide Hydrogel Derived from Waste Toner as Adsorbent

Waste toner powders are considered as hazardous materials to human and living things, and should be properly recycled by many effective ways due to their fine particle sizes and complex components. In this paper, waste toner powders were used as raw materials to successfully synthesize three dimensions (3D) graphene oxide (GO) hydrogel by means of a one-pot chemical transformation based on the improved Hummers’ method. The obtained 3D GO hydrogel has porous structure and abundant oxygen-containing functional groups because of the inherent 3D solid structure of waste toner powder and the strong oxidation process of the improved Hummers’ method. Interestingly, the as-prepared 3D GO hydrogel with excellent adsorptive property could quickly remove Pb(II) ions (100 mg/L, removal efficiency of 96% and removal capacity of 144 mg/g) and methylene blue (50 mg/L, removal efficiency of 97% and removal capacity of 48 mg/g) from water, respectively. The preparation process of 3D GO hydrogel was simple and easy to operate, and the output can be moderately mass produced, thus it would provide a new and effective disposal way for the recycling and reusing of waste toner.

Remediation of pear iron chlorosis by nanocellulose-iron chelation and mechanisms

Background: Nanocrystal cellulose has a strong ability to chelate iron and the nanocomposite possesses strong adsorptive property. Iron deficiency chlorosis (IDC) is a mineral disorder that weakens pear photosynthesis and cause a significant decline in plant yield and quality. Conventional methods to control IDC are generally due to low efficiency and overuse of chemicals. The purpose of this study was to explore the capability of nanocellulose (NC)-Fe chelate to remediate pear IDC. Acidic hydrolyzed NCs were chelated with Fe (NCFe) based on the net charge density of the components. Foliar application of NCFe was employed to pre-etiolated seedlings of Pyrus betulifolia as a plant material. The ability of NCFe to promote active iron content (CFe), photosynthesis rate, and relative gene expression was studied. Results: Nanocrystal cellulose prepared by acidic hydrolysis exhibit rod-like whiskers carrying on negative charges. When NCs were mixed with FeSO4, the NCFe particles maintained a small, whisker-like morphology with small dots (Fe) on the surface of the NC particles. The Z-average hydrodynamic diameter and zeta potential of the NC whiskers measured by DLS were 84.3 ± 0.2 nm and -47.3 ± 1.7 mV, respectively. The particle size and zeta potential of NCFe were 107.4±3.0 nm and -9.7±0.4 mV, respectively. The results showed that NCFe could significantly mitigate IDC in seedlings by increasing CFe, photosynthesis parameters, major physiological indicators, and regulating the expression of key enzymes. When NCFe was prepared at a NC-to-Fe charge density ratio of 1:3,000, CFe and chlorophyll contents were enhanced by approximately 9 times and 72.7%, respectively; the major physiological indicators were all significantly increased. Interestingly, NCFe treatment significantly downregulated the expression of the pectin methylesterase gene (PbPME) and upregulated the expression of the ferritin gene (PbFER) to increase CFe.Conclusion: NCs have strong potential to promote plant photosynthesis when chelated with Fe. The remediation capability of NCFe to IDC is attributed to the enhancement of photosynthesis parameters and indicators. NCFe treatment significantly downregulated the expression of the PME gene (PbPME) and upregulated the expression of the ferritin gene (PbFER) to increase the active iron content. This finding will provide a good alternative and a complementary strategy for Fe-chelate applications in plant iron chlorosis management.

Parametric Study of the Adsorption of Pb (II) and Cr (VI) Ions on Modified PAN-Kapok Fibers

This paper presents a parametric study on the adsorptive property of NaOH-treated polyacrylonitrile (PAN)-kapok fibers for the removal of Pb (II) and Cr (VI) ions in aqueous solutions. Generally, the NaOH-hydrolyzed PAN-kapok favors the adsorption of Pb (II) compared to Cr (VI). The adsorption capacity was in the range of 41.67-83.33 mg/g as the initial Pb (II) concentration was increased from 50 to 100 ppm. Similarly, the adsorption capacity for Cr (VI) was from 8.24 to 15.81 mg/g as the initial concentration was raised from 50 to 150 ppm. The adsorption capacity was also enhanced by increasing the adsorbent dosage. Finally, uptake of Pb (II) at the early stages of the adsorption was fast, with adsorption capacity reaching ~120 mg/g.

Facile preparation of porous biomass charcoal from peanut shell as adsorbent

Activated carbons derived from biomass have been proved to be one of the most promising adsorbents due to their abundance, low cost, reproducibility and environmental friendliness. In this study, a simple, facile and effective pyrolysis method was demonstrated to prepare hierarchical porous biomass charcoal by using peanut shells as precursor without chemical activation in an electric muffle furnace. The obtained products hold porous structure and abundant oxygen-containing functional groups, which were mainly due to in-built template of the structure of peanut shell and the preparation process without nitrogen protection, respectively. Interestingly, the obtained biomass charcoal sample with excellent adsorptive property quickly removed Pb2+ (100 mg/L) and methylene blue (50 mg/L) from water with removal efficiency of 96.5% and 97.1%, and removal capacity of 48 mg/g and 24 mg/g, respectively. The synthetic process was simple and economical, and it could be used as a beneficial reference in the recycling of biomass waste.

Feasibility of Ceria Nanocrystal Adsorbent for Amoxicillin Removal from Water

This study explored adsorptive property of ceria nanocrystal as an adsorbent for amoxicillin removal from water. Ceria nanocrystal was synthesized by employing precipitation method and characterized by using XRD and N2 adsorption-desorption analysis. The adsorption experiment was performed by managing amoxicillin in natural condition. Then, parameters in the adsorption experiment, such as adsorbent dosage, contact time, temperature and initial concentration of amoxicillin are varied. The XRD pattern illustrated that the average crystallite size of ceria nanocrystal formation was 13.08 nm. N2 adsorption-desorption analysis showed that ceria nanocrystal was mesoporous with specific surface area of ​​65.26 m2/g. The amoxicillin adsorption of ceria nanocrystal adsorbent was described by Langmuir isotherm model with maximum adsorption capacity of 37.17 mg/g. The adsorption kinetic of ceria nanocrystal corresponded to the pseudo-second order model. Removal efficiency of amoxicillin by ceria nanocrystal was approximately 80% within 60 minutes over temperature range 303-323K. Those parameter results are described that ceria nanocrystal adsorbent is feasible as a rapid amoxicillin removal from water.