Electric Properties of Carboxymethyl Cellulose

Zhivkov, Alexandar M.

doi:10.5772/56935

Cited by 14 publications

(13 citation statements)

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“…As the pH decreased from 3 to 2, there was a large increase in the extent of iron leaching (Figure ). This is attributed to the reduction of ferric to ferrous iron, which is very soluble in water. , In addition, the p K a of the carboxylic acid groups is ∼3.3, leading to complete protonation of the acid groups at pH 2 . The combination of enhanced iron solubility and loss of negative surface charges leads to the leaching observed at low pH values.…”

Section: Discussionmentioning

confidence: 99%

Iron–Carboxymethyl Sawdust for the Removal of Inorganic Phosphate from Water

Ure

Mutus

2021

ACS Agric. Sci. Technol.

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Inorganic phosphate (P i ) is critical to modern agriculture; however, agricultural drainage leaches P i into aquatic ecosystems leading to eutrophication. The valorization of agricultural byproducts is an effective method for enhancing the environmental performance of the agricultural sector. The aim of this study was to produce iron-coated sawdust capable of tightly binding P i and thus removing it from water. Sawdust was converted to carboxymethyl sawdust (CMSD) by reaction with NaOH and monochloroacetic acid. The carboxymethyl (CM) functional groups on CMSD tightly chelate iron to form iron−carboxymethyl sawdust (Fe-CMSD). The P i binding capacity (PBC) of Fe-CMSD was 16.1 ± 0.940 mg/g. The saturation curve fit well to the Hill− Langmuir isotherm with an apparent dissociation constant (K D App ) of 65.66 μM. Fe-CMSD is stable across the pH range found in agricultural drainage. Desorption of bound P i regenerates the PBC of Fe-CMSD, which retains 75.5% of its initial PBC after four binding−desorption cycles. Lab scale studies on variable flow rate systems using field water show cumulative removals of 88.8− 99.8% depending on flow rate. Therefore, Fe-CMSD shows promise as a P i adsorbent.

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Section: Discussionmentioning

confidence: 99%

Iron–Carboxymethyl Sawdust for the Removal of Inorganic Phosphate from Water

Ure

Mutus

2021

ACS Agric. Sci. Technol.

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“…The pKa of the CM groups in CMC is ∼3.3. 30 As pH decreases, CM groups become protonated leading to a loss of the negative charge. In addition, ferric iron is more soluble in acidic media.…”

Section: Discussionmentioning

confidence: 99%

“…These phenomena are caused by the solubility of Fe and the protonation of the CM groups in acidic and basic media. The pKa of the CM groups in CMC is ∼3.3 30 . As pH decreases, CM groups become protonated leading to a loss of the negative charge.…”

Section: Discussionmentioning

confidence: 99%

“…The carboxymethyl (CM) groups on CMC have pKa values of ∼3.3 leading to complete deprotonation at neutral pH. 30 These negative charges can tightly chelate multivalent metals and confer the ability to absorb P i . 31 However, the sawdust scaffold is part of the dry weight of the material and does not confer P i sorption, which lowers the PBC.…”

Section: Introductionmentioning

confidence: 99%

“…The cellulosic sawdust forms the scaffold of the binding resin but the hydroxyl groups along the backbone have limited ability to chelate iron and thus confer the ability to bind P i . The carboxymethyl (CM) groups on CMC have pKa values of ∼3.3 leading to complete deprotonation at neutral pH 30 . These negative charges can tightly chelate multivalent metals and confer the ability to absorb P i 31 .…”

Section: Introductionmentioning

confidence: 99%

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The removal of inorganic phosphate from water using carboxymethyl cellulose‐iron hydrogel beads

Ure

Mutus

2020

J of Chemical Tech & Biotech

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BACKGROUND: Inorganic phosphate (P i) is key to improved crop yields; however, agricultural drainage leads to the accumulation of this nutrient in aquatic ecosystems and promotes the formation of harmful algal blooms. The aim of this study was to produce a hydrogel with high binding capacity and affinity towards P i produced from carboxymethyl cellulose (CMC) and iron (III) chloride (FeCl 3). RESULTS: CMC was converted to CMC-Fe composites by incubation with FeCl 3. The half-lives (t 1/2) of CMC functionalization with 25 mmol L −1 FeCl 3 were 11.56 min (1.5% CMC) and 13.91 min (3.0% CMC). The apparent dissociation constants (K D App) of CMC-Fe were estimated to be 33.99 ∼mol L −1 (1.5% CMC Fe) and 24.81 ∼mol L −1 (3.0% CMC-Fe). The phosphate binding capacity (PBC) of the hydrated hydrogels were 74.0 ± 3.06 mg g −1 (1.5% CMC Fe) and 91.4 ± 4.51 mg g −1 (3.0% CMC-Fe). Laboratory-scale continuous flow filtration studies showed an average removal of 91.3% (mixed filter) and 52.5% (unmixed filter). Batch type treatment of agricultural drainage showed a reduction in P i content from 0.40 to 0.11 mg L −1 (1.5% CMC-Fe) and 0.17 mg L −1 (3.0% CMC-Fe). The amount of bound-P i was 26.7 ± 0.63 ∼g g −1 (1.5% CMC-Fe) and 32.8 ± 1.31 ∼g g −1 (3.0% CMC-Fe). The iron leached from 1.5% and 3.0% CMC-Fe beads was 11.98 ± 1.80 and 3.57 ± 1.63 mg g −1 , respectively. CONCLUSION: The CMC-Fe hydrogel shows great promise as a P i-adsorbing material with applications in the treatment of agricultural drainage.

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