Agricultural Solid Wastes Based Adsorbent Materials in the Remediation of Heavy Metal Ions from Water and Wastewater by Adsorption: A Review

Abstract

Adsorption has become the most popular and effective separation technique that is used across the water and wastewater treatment industries. However, the present research direction is focused on the development of various solid waste-based adsorbents as an alternative to costly commercial activated carbon adsorbents, which make the adsorptive separation process more effective, and on popularising the sustainable options for the remediation of pollutants. Therefore, there are a large number of reported results available on the application of raw or treated agricultural biomass-based alternatives as effective adsorbents for aqueous-phase heavy metal ion removal in batch adsorption studies. The goal of this review article was to provide a comprehensive compilation of scattered literature information and an up-to-date overview of the development of the current state of knowledge, based on various batch adsorption research papers that utilised a wide range of raw, modified, and treated agricultural solid waste biomass-based adsorbents for the adsorptive removal of aqueous-phase heavy metal ions. Metal ion pollution and its source, toxicity effects, and treatment technologies, mainly via adsorption, have been reviewed here in detail. Emphasis has been placed on the removal of heavy metal ions using a wide range of agricultural by-product-based adsorbents under various physicochemical process conditions. Information available in the literature on various important influential physicochemical process parameters, such as the metal concentration, agricultural solid waste adsorbent dose, solution pH, and solution temperature, and importantly, the adsorbent characteristics of metal ion removal, have been reviewed and critically analysed here. Finally, from the literature reviewed, future perspectives and conclusions were presented, and a few future research directions have been proposed.

Comprehensive assessment of carbon-, biomaterial- and inorganic-based adsorbents for the removal of the most hazardous heavy metal ions from wastewater

“…Due to the high selectivity, porosity, and surface area of activated carbon, biochar, and charcoal produced from agricultural solid residuals, they have become emerging adsorbents for the removal of heavy metals. 95 …”

“…Due to the high selectivity, porosity, and surface area of activated carbon, biochar, and charcoal produced from agricultural solid residuals, they have become emerging adsorbents for the removal of heavy metals. 95 Jeyaseelan et al utilized green tea leaves (Camellia sinensis) as a natural adsorbent for the removal of Cr(VI) from water, achieving an impressive 99% removal efficiency under the optimized conditions including pH of 2, contact time of 180 min, and adsorbent dosage of 0.8 g L −1 . 96 Similarly, Eucalyptus bark (Eucalyptus globulus tree species) showed more than 99% removal efficiency at a concentration of 200 ppm.…”

Senteti̇k Atiksulardan Reakti̇f Sari 145 Boyasinin Uzaklaştirilmasi: Yer Fistiği Kabuklarinin Adsorban Olarak Değerlendi̇ri̇lmesi̇

“…Bu faktör de hidrojen (H + ) ve hidroksil (OH -) iyonlarının varlığı önem arz etmektedir. Çözelti pH'ındaki değişiklikler, hidroliz, yüzey kompleksleşmesi, redoks reaksiyonları ve çökelme gibi adsorbent bölgesinin ayrışmasını ve kirleticinin kimyasını kolaylaştırır (Sen, 2023). Asidik…”

“…Pozitif ΔH° değerlerinde süreç endotermik meydana gelmekte ve sıcaklık faktöründeki artışlar RS145'in bağlanmasını kolaylaştırmaktadır. Bununla birlikte, sıcaklık artışı ile qe'nin kısmi azalması, reaksiyonun ekzotermik hale geldiğini gösterebilir ve bu, kirletici ile adsorbent arasındaki etkileşim bağlarının sıcaklıkla değişiminden kaynaklanmaktadır (Sen, 2023). Ayrıca, qe üzerindeki sıcaklığın etkisi yüzey fonksiyonel gruplarına da atfedilebilir.…”

“…Oysa pH > pHZPC'de yüzey negatif yüklü hale gelir ve kirletici ile yüzey arasında zayıf bir bağ kurulur. Bu nedenle, katyonik boyar maddelerin giderimi, OH− ve COO− gruplarının varlığından dolayı pH > pHzpc'de tercih edilirken, anyonik azo grup boyar maddelerde adsorpsiyon süreci, H + iyonlarının varlığından dolayı pH < pHzpc'de tercih edilir(Sen, 2023). FK'nin pHzpc'sinin 6,25 olduğu Şekil 3'te görülmektedir.…”