A Review: Effect of Physicochemical and Hydro geochemical Factors on Arsenic Sedimentation and Mobilization

Author: Akbare Azam, Hemant Kumar Nirala, Manisha, Sankatha Prasad Sonkar, Awanish Kumar Pandey, Najm Ul Rafi, Suresh Kumar, Awanish Kumar Singh, Vipin Kumar and Richa Trivedi

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Abstract

The adsorption behavior of arsenic was studied experimentally for a wide pH range from 2 to 13.7. It was found that adsorption of As3+ occurs at pH 8, while adsorption of As5+ occurs at pH 4. At low pH like 2, the adsorption of As5+and As3+ is very low, while at high pH like 13.5 the adsorption rate increases. The order of adsorption of different constituents of As and aqueous media is AsO3->AsO33- H2AsO3-> H2O > H3AsO3 for As(III) and AsO43-> HAsO4- > H2AsO4-> H3AsO4> H2O for As(V). Arsenic acid (H3AsO3) adsorbed at pH 8, while arsenic acid (H3AsO4) adsorbed at pH 4. Arsenic forms in H3AsO3 and H3AsO4 are As3+ and As5+, respectively. Conjugate bases of H3AsO3 and H3AsO4 are AsO3- and AsO43-, respectively, which show increasing rates of adsorption at high pH like 13.5. Arsenic adsorption in aqueous media is aided by ions such as Cl-, HCO3-, H2PO4-, SiO32-, and PO43-. Cations such as Na+, Mg2+, and Ca2+ increase the rate of adsorption of As3+ and As5+ contents in groundwater, and this rate would be further increased with an increase in the concentration of these ions. The reason for the great adsorption of As contents is due to the electrostatic forces created on adsorbents by the origin of charge on the adsorbent surface after the adsorption of cations.

Keywords

Arsenic adsorption, Arsenate (As5+) and Arsenite (As3+), Co-existingions, Electro positivity, Electrostaticforce

Conclusion

We have obtained many results for understanding the effects of physicochemical and hydrogeochemical factors on arsenic sedimentation and mobilization properties, and researchers have conducted numerous studies related to morphology. adsorption laws of arsenic in water. Promising conclusions: 1. The morphology and adsorption of arsenic are affected by the pH of aqueous media, and with increasing pH, arsenic adsorption decreases. but the optimum pH for arsenic adsorption gives conflicting results regarding it. Under optimal environmental conditions, the adsorption of As(III) and As(V) as a function of pH gives even more different and conflicting conclusions regarding it. 2. It was observed that cations facilitate the process while anions coexisting in water interfere with the arsenic adsorption process. The presence of coexisting ions in water either suppresses or promotes the adsorption behavior of arsenic. Arsenic content in groundwater As a result, As(III) adsorption is inhibited by competitive effects between anions in water such as SO42-, SiO32-, PO43-, HCO3-, Cl-, F-, and HPO42-, and they could increase the adsorption of As(III) anions to varying degrees. 3. Minerals are positively correlated with arsenic content, and the Mn, Fe, and Al contents of the sediments facilitate the adsorption of arsenic. However, the adsorption of arsenic by organic matter remains a controversial issue. 4. Functional groups include carboxyl, phenolic hydroxyls, alcohol extract hydroxyls, ethers, and amides. Organic particles cooperate with arsenic, giving the sediment a greater adsorption capacity so it can adsorb large amounts of arsenic. 5. Presence of Arsenic enhances the electropositivity behavior of an adsorbent surface and directly enhances the electrostatic force of a cation. This enhancement of electrostatic force has the effect of attracting and binding more arsenic anions on the surface of the adsorbent. 6. Another potentially important process to increase As in water is the dissolution of iron oxide itself under reducing conditions. Research also reveals that excessive water use for irrigation and fertilizer use caused the mobilization of phosphate from fertilizers below shallow aquifers and the desorption of As through anion exchange at reactive mineral surfaces.

References

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How to cite this article

Akbare Azam, Hemant Kumar Nirala, Manisha, Sankatha Prasad Sonkar, Awanish Kumar Pandey, Najm Ul Rafi, Suresh Kumar, Awanish Kumar Singh, Vipin Kumar and Richa Trivedi (2023). A Review : Effect of Physicochemical and Hydro geochemical Factors on Arsenic Sedimentation and Mobilization. Biological Forum – An International Journal, 15(2): 1046-1052.