Efficacy of Modified Magnolia champaca Bark Powder in Sequestration of Divalent Ions from Aqueous Matrices

Noxious effluents let out from large cum small-scale industries has led to acute adverse environmental impact over a time period. In spite of various types of pollutants present in the discharges, heavy metals have been proven to be lethal to all living organisms, whilst exceeding the tolerance levels. In this regard, their confiscation has become inevitable by adoption of varied suitable methodologies. The current inquest is engrossed on probing the efficiency of an eco-derived material, Magnolia champaca Barks (MCB) to trap Zn(II) / Cd(II) ions from laboratory aqueous medium. This ecofriendly material is acid treated (TMCB), so as to improve its surface nature, evidently favoured by microscopic image study. Fourier Transformation Infra-Red and Scanning Electron Microscopy / Energy Dispersive X-Ray Analysis spectra are recorded for sorbent characterization. The factors which influence the sorptive effectiveness of TMCB include particle sizes, initial concentrations of the sorbate molecules, agitation time frames, dosages, pH values and temperatures. The concentrations of divalent ions in the pre and post run samples are assessed using Atomic Absorption Spectrophotometer. Maximum chelation of 98% Zn(II) and 96% Cd(II) had occurred under aligned parametric conditions, with variations in dosage, concentration and contact time interval. The aforementioned observations support the promising nature of the identified bark to adsorb toxic metal species.


Introduction
Utilization of chemical substances, heavy metals in particular, for various day-to-day activities has gradually increased, posing a negative impact on the environment.Anthropogenic activities occurring in varied industrial sectors are the primary source of metal pollution in the environment. 1Industries require water on a large scale of consumption for ANDAL & INDHUMATHY, Curr.World Environ., Vol.19(1) 57-66 (2024) different operations, thereby release liquid wastes which in turn enter the aquatic ecosystem through a number of different channels. 2,3 a major environmental concern for sustainable existence of lives, various technologies in physical, chemical and biological modes have been adapted to diminish and mitigate the noxious effects of these wastewaters.Among the various traditional methods, adsorption is found to be a widely reported feasible method due to its many advantages, such as offering flexibility in design and operation along with regeneration of spent sorbents which add upto the operation's economy. 4,5A variety of commercial and natural materials have been utilized to treat industrial discharges contaminated with heavy metals and other toxicants. 6,7,8The current study explores into the potential of Magnolia champaca Barks (MCB), a natural low-cost sorbent, for the effective sequestration of heavy metals at small and large levels.
Zinc is one of the ubiquitous elements that enter the ecosystem through both natural and anthropogenic processes.Wood combustion and waste incineration are examples of natural sources.The majority of zinc produced worldwide is used for industrial processes which include hot-dip galvanising, electro-galvanizing, spraying, painting, and also to protect iron and steel from corrosion.Zinc poisoning symptoms include vomiting, tiredness and dizziness, lack of coordination in the muscles, dermatitis, compromised immune system, and other gastrointestinal diseases. 9,10,11other element of interest pertaining to this study is Cadmium, since it is well-known for its toxicity and extensively spent in industries such as batteries, mining, pigments, and alloys.Long-term exposure to cadmium can cause cadmium complexes to build up in the kidney, which can cause renal failure, reduced bone mineralization, lung function issues and is also referred to as a human carcinogen. 12,13,14us, the main objective of the present study involves in understanding the potentiality of the chosen bio-sorbent for the removal of divalent ions of zinc and cadmium.

Materials and Methods Collection and preparation of adsorbent
Magnolia champaca a tall tree (fig.1), of the family Magnoliaceae, is a native to India and found throughout Indo-China, Malaysia, Sumatra, Java, and south-western China.The tree barks were gathered from different locales of Coimbatore, Tamilnadu, India.The stacked materials were cleaned using deionized water in order to get rid of the impurities and then scorched completely.The parched materials were later macerated, minimized by grinding in mixer and separated using varied meshes like 85BSS, 72BSS, 52BSS, 36BSS and 22BSS via Scientific Test Molecular Sieves procured from Jayant Scientific Instruments Company, Mumbai.

Microscopic Analysis
Categorized TMCB was analysed using Optical Microscope (Magnus Microscope CH20ILED) so as to resolve the sizes of the particles.

Adsorbate (Preset Solution Preparation)
A preset solution of 1000 mg/L Zn (II) / Cd (II) were primed by disbanding appropriate dosage of analytical grade zinc sulphate / cadmium nitrate samples respectively in deionized water.From the preset solution, a standard concentration of 100 mg/L was diluted and subsequent substandard were prepared based on the experimental conditions.

Batch Optimization Studies
Batch experiments were conducted under varied influential parameters viz., particle size (0.18, 0.21, 0.30, 0.42, 0.71 mm); dosage (50 to 300 mg -50 mg intervals); initial concentration of the sorbate molecules (Zn (II) -5 to 20 mg/L -5 mg/L interval; Disappearing peaks corresponding to hydroxyl groups (3251 cm -1 ) and alkoxy group (1090 cm -1 ) in metal laden TMCB spectra suffice the involvement of groups during metal adsorption.A shift in the narrow peak (1629 cm -1 ) in the unloaded spectra corresponds to C=O stretching.Shift in lower wave numbers (1736 cm-1 and 1794 cm -1 ) of Zn(II) and Cd(II) loaded spectra evidence their contribution in sorption process.Occurrence of new peaks around 2949 cm -1 and 2937 cm -1 in the post run spectra implies the stretching of C-H bonds in precursors.Notable shifts in peaks less than 900 cmcm -1 indicates the active changes in C-H bending vibrations, reasoned out due to the binding action of the divalent metals.(as depicted by bar heights) at increasing sample size is evident.A maximum of 98.3% and 96.5% Zn(II) and Cd(II) ions had been sequestrated at the least studied particle size of 0.18mm, supporting the fact, that lower particle size, greater is the surface area and thence higher percentage removal of the sorbate species.Henceforth, 0.18 mm size of TMCB had been chosen for the upcoming experiments.

Influence of Initial Concentration and Agitation Time
Influence of initial metal ion concentration and agitation time, exhibit an inevitable role in predicting the sorption rate of a system.Fig. 8(a) and (b) elucidates the percentage removal of Zn(II) and Cd(II) ions as 98% and 96% under the optimized conditions of 20 and 10 mg/L, 9 and 12 minutes respectively, within the stipulated experimental particle size, dose and pH conditions.

Fig. 1 :
Fig. 1: Magnolia champac a tree Modification of the sorbent material The categorized material (Magnolia champaca) was processed with 0.1 N HCl to alter the surface features of the sorbent, thereafter called as Treated Magnolia champaca Barks (TMCB).The treated sorbents of various dimensions were cleansed several times with doubly deionized water to reach a neutral pH value.Only the chemically Treated Magnolia champaca Barks (TMCB) have been exploited for further experiments.Fig 2(a -c) represents the cleaned tree barks; raw sieved material and its treated counterpart (85 BSS).
The figured particle sizes fitting to the mesh sizes of 85BSS, 72BSS, 52BSS, 36BSS and 22BSS are 0.18 mm, 0.21 mm, 0.30 mm, 0.42 mm and 0.71 mm respectively.Microscopic examination disclosed the mesoporic nature of TMCB.The microscopic structure of MCB and TMCB (0.18 mm) is depicted in Fig 3 (a) and (b).

Fig. 2 (
Fig. 2(a): MCB Fig. 2(a): TMCB Fig. 2(b): Pulverized MCB Cd (II) -2 to 10 mg/L -2 mg/L interval); agitation time frames (3 to 30 mins-5 mins intervals); pH (3, 5, 7, 9 and 11) and temperatures, ( 293, 303, 313, 323, 333 K -10 K interval) so as to optimize the chelating efficiencies of Zn(II) -TMCB / Cd(II) -TMCB systems.50 mL of the specific divalent standards were added to 250 mL agitating flasks containing appropriate TMCB dosages.These flasks were agitated for preplanned time periods in a mechanical shaker rotating at 140 rpm.The concentrations of the pre and post experimental solutions were analyzed in AAS [Shimadzu AA 6200 Model].The percentage of sequestrated divalent ions was calculated as follows: % Removal = (C i -C e ) / C i x 100Characterization StudiesPeak variations relevant to functional groups, surface texture and elemental composition of TMCB and metal laden TMCB were analysed to evidence the metal chelating ability of TMCB.Fourier -Transform Infra-red Spectrophotometer (Shimadzu), Scanning Electron Microscope (SEM) and Energy Dispersive X-ray Analysis (EDAX) were the instruments employed to perform the aforementioned analyses.Results and DiscussionFourier Transform Infra-Red Analysis Fourier Transform Infra-Red spectra of TMCB, its metal loaded counterparts are shown inFig 4.

Fig. 9 :
Fig. 9: Influence of Dosage Influence of pH pH value of the adsorbate solutions play a vital controlling factor role in any sorbate -sorbent process.In the present study, the initial solution pH values was made acidic as low as 3 and basic as high as 11, by adding 0.1 N HCl and NaOH solutions to the metal solutions of fixed concentrations [20 mg/L: Zn(II) and 10 mg/L: Cd(II)] respectively.The sorbent species registered maximum removal of the studied divalent ions at pH 7 (Fig.10).The reason for this could be the high protonation of the binding sites by hydronium ions at acidic pH, resulting in repulsion between the sorbent and the sorbate molecules.Further in the basic medium, the metal ion preferentially binds with the hydroxides to form insoluble compounds, thus minimizing the availability of metal cations to get sorbed on TMCB surface.