Aluminophosphates Derived from Tea Leaves and Pumpkin Seeds Ashes Adsorb Lead Ions from Contaminated Water

Abstract

One major global challenge is the existing disparity in water distribution resulting to millions of people lacking access to safe clean water. This will certainly be exacerbated by the impending climate change and increased pollution threats posed by industrialization and population growth. Therefore pursuing sustainable materials and technologies for water remediation is crucial. Adsorbents use for water treatment is preferable owing to its simplicity and cheap materials involved. Aluminophosphates molecular sieves have open-framework structures that possess a wide range of pore openings and large surface area for use as adsorbents that can be synthesized hydrothermally using alumina and phosphates. Literature reports indicate that accumulation of aluminum in tea leaves correlates positively with leaf age. The EDXRF analysis showed that tea leaves ash used contained 30.09% of Al2O3. Similarly, literature findings indicate that pumpkin seeds contain relatively large amounts of phosphorous with the pumpkin seed ash used containing 37.01% of P2O5. Consequently, aluminophosphate APA and APB were synthesized using tea leaves to pumpkin seeds ash ratios of 1:1 and 1:2 respectively. XRD characterization and lead ions batch sorption experiments were done. Turbidity column experiment was done. Data for adsorption of Pb (II) ions data on the adsorbents best fitted into the Langmuir isotherm model. Adsorption capacities obtained from the linearized graphs were 90.91 and 50.0 mg/g for APA and APB respectively. This shows that tea leaves and pumpkin waste can synthesize aluminophosphate adsorbents. Aluminophosphates have shown good potential of removing Pb (II) ions from wastewaters.